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  • 1.
    Peter, Annamaria
    et al.
    University of Jyväskylä, Finland.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet.
    Andersson, Eva
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet.
    Finni, Taija
    University of Jyväskylä, Finland.
    Hegyi, Andras
    University of Jyväskylä, Finland.
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Cronin, Neil
    University of Jyväskylä, Finland.
    Effect of footwear on plantar flexor fine-wire electromyography activity in walking.2019Inngår i: Footwear Science. 2019 Supplement, Vol. 11, p S120-S121: Proceedings of the Fourteenth Footwear Biomechanics Symposium (Kananaskis, Canada, 2019), Taylor & Francis, 2019, Vol. 11, s. S120-S121Konferansepaper (Annet vitenskapelig)
  • 2.
    Gago, Paulo
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska Institutet.
    Marques, Mário C.
    University of Beira Interior (UBI), Covilhã, Portugal.
    Marinho, Daniel A.
    University of Beira Interior (UBI), Covilhã, Portugal.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Effects of post activation potentiation on electromechanical delay2019Inngår i: Clinical Biomechanics, ISSN 0268-0033, E-ISSN 1879-1271, Vol. 70, s. 115-122Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electromechanical delay (EMD) presumably depends upon both contractile and tensile factors. It has recently been used as an indirect measure of muscle tendon stiffness to study adaptations to stretching and training. The aim of the present study was to investigate whether contractile properties induced by a 6 s maximum voluntary isometric contraction (MVIC) could affect EMD without altering passive muscle tendon stiffness or stiffness index. Plantar flexor twitches were evoked via electrical stimulation of the tibial nerve in eight highly trained male sprinters before and after a 6 s MVIC in passive isometric or passively shortening or lengthening muscles. For each twitch, EMD, twitch contractile properties and SOLM-Wave were measured. Passive muscle tendon stiffness was measured from the slope of the relation between torque and ankle angle during controlled passive dorsal flexion and stiffness index by curve-fitting the torque angle data using a second-order polynomial function. EMD did not differ between isometric, lengthening or shortening movements. EMD was reduced by up to 11.56 ± 5.64% immediately after the MVIC and stayed depressed for up to 60 s after conditioning. Peak twitch torque and rate of torque development were potentiated by up to 119.41 ± 37.15% and 116.06 ± 37.39%, respectively. Rising time was reduced by up to 14.46 ± 7.22%. No significant changes occurred in passive muscle tendon stiffness or stiffness index. Using a conditioning MVIC, it was shown that there was an acute enhancement of contractile muscle properties as well as a significant reduction in EMD with no corresponding changes in stiffness. Therefore, caution should be taken when using and interpreting EMD as a proxy for muscle tendon stiffness.

  • 3.
    Paanalahti, Markku
    et al.
    University of Gothenburg.
    Berzina, Guna
    Riga Stradiņš University, Latvia.
    Lundgren-Nilsson, Åsa
    University of Gothenburg .
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Sunnerhagen, Katharina S
    University of Gothenburg .
    Examination of the relevance of the ICF cores set for stroke by comparing with the Stroke Impact Scale.2019Inngår i: Disability and Rehabilitation, ISSN 0963-8288, E-ISSN 1464-5165, Vol. 41, nr 5, s. 508-513Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PURPOSE: To examine if the International Classification of Functioning (ICF) core set for stoke contains problems that are relevant for the persons living with stroke as expressed in the Stroke Impact Scale (SIS).

    METHODS: Cross-sectional study of 242 persons with previous stroke. The agreement between the perceived problems in the SIS items and problems in the categories of Comprehensive ICF Core Set for stroke were analyzed using percent of agreement and Kappa statistic.

    RESULTS: The analyses between 57 items of the SIS and 31 second-level categories of the ICF were conducted. The problems in domains of "Mobility", "Activities of daily living", "Hand function", "Strength" in the SIS had moderate agreement when compared to ICF categories. The SIS domains of "Emotion" and "Communication", as well as some aspects of the "Memory" had slight or fair agreement with corresponding ICF categories. The results of the study suggest that there is acceptable agreement between persons after stroke and health professionals in the physical aspects, but rather poor agreement in the cognitive and emotional aspects of functioning.

    CONCLUSIONS: Health professionals do not fully capture the magnitude of emotional or social problems experienced by persons after stroke when using the ICF Core Set as a framework for evaluation. Implications for Rehabilitation The ICF Core Set for Stroke provides comprehensive list of possible health and health related outcomes for persons after stroke. Problems reported in condition-specific patient-reported outcome scales can be important in decision making in rehabilitation. Patients and health professionals tend to agree more on physical than cognitive problems. Examination of the relevance of the ICF cores set for stroke by comparing with the Stroke Impact Scale.

  • 4.
    Dias, Caroline Pieta
    et al.
    Federal University of Rio Grande do Sul , Porto Alegre , Brazil.
    Freire, Bruno
    University of State of Santa Catarina , Florianópolis , Brazil..
    Goulart, Natália Batista Albuquerque
    Federal University of Rio Grande do Sul , Porto Alegre , Brazil..
    Dias De Castro, Camila
    Federal University of Rio Grande do Sul , Porto Alegre , Brazil..
    Lemos, Fernando De Aguiar
    Federal University of Rio Grande do Sul , Porto Alegre , Brazil..
    Becker, Jefferson
    Pontifical Catholic University of Rio Grande do Sul , Porto Alegre , Brazil..
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet, Stockholm, Sweden.
    Vaz, Marco Aurélio
    Federal University of Rio Grande do Sul , Porto Alegre , Brazil..
    Impaired mechanical properties of Achilles tendon in spastic stroke survivors: an observational study.2019Inngår i: Topics in Stroke Rehabilitation, ISSN 1074-9357, E-ISSN 1945-5119, Vol. 26, nr 4, s. 261-266Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: The spasticity could lead to decreased functional capacity and changes in musculoskeletal tissue.

    OBJECTIVE: To compare the Achilles tendon properties between the affected and contralateral limbs of participants with spasticity due to stroke and the healthy subjects.

    METHODS: Fifteen individuals with ankle spasticity due to stroke and 15 healthy subjects were recruited. Maximal isometric ankle joint torque was obtained with an isokinetic dynamometer, and an ultrasound was used to determine tendon length, tendon cross-sectional area, and the medial gastrocnemius myotendinous junction displacement. The Achilles tendon strength, displacement, stress, strain, stiffness, and Young's modulus were obtained during a maximum voluntary isometric plantarflexion contraction.

    RESULTS: There were no differences between Achilles tendon length among participants. Both limbs of participants with stroke showed reduced tendon cross-sectional area (~18%) compared to healthy limb. The affected limb showed decreased tendon strength (686 ± 293.3 N), displacement (10.6 ± 1.7 mm), Young's modulus values (849 ± 235.6 MPa), and lower stiffness (196.6 ± 67.6 N/mm) compared to the contralateral limb (strength, 1357.1 ± 294.8 N; displacement, 15.2 ± 5.5 mm; Young's modulus, 1431.8 ± 301.9 MPa; stiffness, 337.5 ± 98.1 N/mm) and to the healthy limb. The contralateral limb also showed decreased tendon strength (~26.2%) and stiffness (~21.5%) compared to the healthy group.

    CONCLUSION: There is a decrement in Achilles tendon morphological and mechanical properties of the affected limb in individuals with spasticity due to stroke. The contralateral limb had a thinner tendon more compliant likely to physical activity reduction.

  • 5.
    Körting, Clara
    et al.
    Royal Institute of Technology, Stockholm, Sweden.
    Schlippe, Marius
    Royal Institute of Technology, Stockholm, Sweden.
    Petersson, Sven
    Karolinska Institutet, Stockholm, Sweden..
    Pennati, Gaia Valentina
    Karolinska Institutet, Stockholm, Sweden..
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska Institutet, Stockholm, Sweden..
    Finni, Taija
    University of Jyväskylä, Jyväskylä, Finland.
    Zhao, Kangqiao
    Royal Institute of Technology, Stockholm, Sweden.
    Wang, Ruoli
    Royal Institute of Technology, Stockholm, Sweden.
    In vivo muscle morphology comparison in post-stroke survivors using ultrasonography and diffusion tensor imaging.2019Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, nr 1, artikkel-id 11836Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Skeletal muscle architecture significantly influences the performance capacity of a muscle. A DTI-based method has been recently considered as a new reference standard to validate measurement of muscle structure in vivo. This study sought to quantify muscle architecture parameters such as fascicle length (FL), pennation angle (PA) and muscle thickness (tm) in post-stroke patients using diffusion tensor imaging (DTI) and to quantitatively compare the differences with 2D ultrasonography (US) and DTI. Muscle fascicles were reconstructed to examine the anatomy of the medial gastrocnemius, posterior soleus and tibialis anterior in seven stroke survivors using US- and DTI-based techniques, respectively. By aligning the US and DTI coordinate system, DTI reconstructed muscle fascicles at the same scanning plane of the US data can be identified. The architecture parameters estimated based on two imaging modalities were further compared. Significant differences were observed for PA and tm between two methods. Although mean FL was not significantly different, there were considerable intra-individual differences in FL and PA. On the individual level, parameters measured by US agreed poorly with those from DTI in both deep and superficial muscles. The significant differences in muscle parameters we observed suggested that the DTI-based method seems to be a better method to quantify muscle architecture parameters which can provide important information for treatment planning and to personalize a computational muscle model.

  • 6.
    Sandamas, Paul
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Gutierrez-Farewik, Elena M
    KTH, Karolinska institutet.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet.
    The effect of a reduced first step width on starting block and first stance power and impulses during an athletic sprint start.2019Inngår i: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 37, nr 9, s. 1046-1054Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study investigated how manipulating first step width affects 3D external force production, centre of mass (CoM) motion and performance in athletic sprinting. Eight male and 2 female competitive sprinters (100m PB: 11.03 ± 0.36 s male and 11.6 ± 0.45 s female) performed 10 maximal effort block starts. External force and three-dimensional kinematics were recorded in both the block and first stance phases. Five trials were performed with the athletes performing their preferred technique (Skating) and five trials with the athletes running inside a 0.3 m lane (Narrow). By reducing step width from a mean of 0.31 ± 0.06 m (Skating) to 0.19 ± 0.03 m (Narrow), reductions were found between the two styles in medial block and medial 1st stance impulses, 1st stance anterior toe-off velocity and mediolateral motion of the CoM. No differences were found in block time, step length, stance time, average net resultant force vector, net anteroposterior impulse nor normalised external power. Step width correlated positively with medial impulse but not with braking nor net anteroposterior impulse. Despite less medially directed forces and less mediolateral motion of the CoM in the Narrow trials, no immediate improvement to performance was found by restricting step width.

  • 7.
    Spiegl, Ondrej
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    The effects of new Edea and Graf figure skating boots and used Graf boots on the kinetics and kinematics of landing after simulated on-ice jumps2019Inngår i: Footwear Science, ISSN 1942-4280, E-ISSN 1942-4299, Vol. 11, nr 2, s. 121-129Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An increase in training intensity and the number of active participants and competitors in figure skating has been accompanied by an increasing frequency of injuries. The aim of this study was to investigate whether different brands of skates as well as the usage of the skates modify the kinetics and kinematics of the landing impact from a jump. New Graf Edmonton (NG), old used Graf Edmonton (OG) and new Edea Concerto (NE) skates were compared. Twelve participants completed six jump trials from 30 cm and 50 cm high boxes, respectively in all three skates and landed on a section of artificial ice placed on a laboratory floor. Landing kinematics (Oqus4 system, Qualisys, Sweden) and kinetics (force plate: Kistler, Switzerland; insoles: Pedar, Novel, Germany) were examined. Each participant acted as their own control for statistical comparison between the skates. The results confirmed that the kinetics and kinematics of the landing are affected by wearing different skates. During landing impacts in NG, participants had significantly greater dorsiflexion at initial contact (IC) and peak dorsiflexion of the ankle, peak flexion of the knee and also greater in-skate plantar forces (PF) than in NE, which may increase the risk of injury. In OG, participants had significantly greater peak flexion of knee and longer time from IC to first peak dorsiflexion (TP) of the ankle than in NG. The differences observed may be due to the different construction designs, such as height of the heel, used materials, and stiffness of the skates, which may affect injury occurrence.

  • 8.
    Rosén, Johanna S
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet.
    Goosey-Tolfrey, Victoria L
    Loughborough University, UK.
    Mason, Barry S
    Loughborough University, UK.
    Hutchinson, Michael J
    Loughborough University, UK.
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Bjerkefors, Anna
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    The impact of impairment on kinematic and kinetic variables in Va'a paddling: Towards a sport-specific evidence-based classification system for Para Va'a.2019Inngår i: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 37, nr 17, s. 1942-1950Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Para Va'a is a new Paralympic sport in which athletes with trunk and/or leg impairment compete over 200 m. The purpose of this study was to examine the impact of impairment on kinematic and kinetic variables during Va'a ergometer paddling. Ten able-bodied and 44 Para Va'a athletes with impairments affecting: trunk and legs (TL), legs bilaterally (BL) or leg unilaterally (UL) participated. Differences in stroke frequency, mean paddling force, and joint angles and correlation of the joint angles with paddling force were examined. Able-bodied demonstrated significantly greater paddling force as well as knee and ankle flexion ranges of movement (ROM) on the top hand paddling side compared to TL, BL and UL. Able-bodied, BL and UL demonstrated greater paddling force and trunk flexion compared to TL, and UL demonstrated larger bottom hand paddling side knee and ankle flexion ROM compared to BL. Significant positive correlations were observed for both male and female athletes between paddling force and all trunk flexion angles and ROM in the trunk and pelvis rotation and bottom hand paddling side hip, knee and ankle flexion. The results of this study are important for creating an evidence-based classification system for Para Va'a.

  • 9.
    Bjerkefors, Anna
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Rosén, Johanna S
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Three-Dimensional Kinematics and Power Output in Elite Para-Kayakers and Elite Able-Bodied Flat-Water Kayakers.2019Inngår i: Journal of Applied Biomechanics, ISSN 1065-8483, E-ISSN 1543-2688, s. 93-100Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Trunk, pelvis and leg movement are important for performance in sprint kayaking. Para-kayaking is a new Paralympic sport in which athletes with trunk and/or leg impairment compete in three classification groups. The purpose of this study was to identify how physical impairments impact on performance by examining: differences in three-dimensional joint range of motion (RoM) between 10 (4 females, 6 males) elite able-bodied kayakers and 41 (13 females, 28 males) elite para-kayakersfrom the three classification groups, and which joint angles were correlated with power output during high intensity kayak ergometer paddling. There were significant differences in RoM between the able-bodied kayakers and the three para-kayak groups for the shoulders (flexion, rotation: able-bodied kayakers<para-kayakers), trunk and pelvis (rotation: able-bodied kayakers>para-kayakers) and legs (hip, knee, ankle flexion: able-bodied kayakers>para-kayakers) during paddling. Furthermore, athletes with greater impairment exhibited lower trunk and leg RoM compared to those with less impairment. Significant positive correlations were observed for both males and females between power output and peak shoulder and trunk flexion, trunk and pelvis rotation RoM and hip, knee and ankle flexion RoM. This information is important for understanding how key kinematic and kinetic variables for para-kayaking performance vary between athletes from different classification groups.

  • 10.
    Zhou, Guang-Quan
    et al.
    Southeast University, Nanjing, China.
    Zhang, Yi
    Southeast University, Nanjing, China.
    Wang, Ruo-Li
    Karolinska Institute & Royal Institute of Technology, Stockholm.
    Zhou, Ping
    Southeast University, Nanjing, China.
    Zheng, Yong-Ping
    The Hong Kong Polytechnic University, Hung Hom, Hong Kong.
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska Institute.
    Chen, Qiang
    Southeast University, Nanjing, China.
    Automatic Myotendinous Junction Tracking in Ultrasound Images with Phase-Based Segmentation.2018Inngår i: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141, artikkel-id 3697835Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Displacement of the myotendinous junction (MTJ) obtained by ultrasound imaging is crucial to quantify the interactive length changes of muscles and tendons for understanding the mechanics and pathological conditions of the muscle-tendon unit during motion. However, the lack of a reliable automatic measurement method restricts its application in human motion analysis. This paper presents an automated measurement of MTJ displacement using prior knowledge on tendinous tissues and MTJ, precluding the influence of nontendinous components on the estimation of MTJ displacement. It is based on the perception of tendinous features from musculoskeletal ultrasound images using Radon transform and thresholding methods, with information about the symmetric measures obtained from phase congruency. The displacement of MTJ is achieved by tracking manually marked points on tendinous tissues with the Lucas-Kanade optical flow algorithm applied over the segmented MTJ region. The performance of this method was evaluated on ultrasound images of the gastrocnemius obtained from 10 healthy subjects (26.0±2.9 years of age). Waveform similarity between the manual and automatic measurements was assessed by calculating the overall similarity with the coefficient of multiple correlation (CMC).<italic> In vivo</italic> experiments demonstrated that MTJ tracking with the proposed method (CMC = 0.97±0.02) was more consistent with the manual measurements than existing optical flow tracking methods (CMC = 0.79±0.11). This study demonstrated that the proposed method was robust to the interference of nontendinous components, resulting in a more reliable measurement of MTJ displacement, which may facilitate further research and applications related to the architectural change of muscles and tendons. [ABSTRACT FROM AUTHOR]

  • 11.
    Fischer, Katina Mira
    et al.
    German Sport University, Cologne.
    Willwacher, Steffen
    German Sport University, Cologne.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Brüggemann, Gert-Peter
    German Sport University, Cologne.
    Calcaneal adduction and eversion are coupled to talus and tibial rotation.2018Inngår i: Journal of Anatomy, ISSN 0021-8782, E-ISSN 1469-7580, Vol. 233, nr 1, s. 64-72Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this study was to quantify isolated coupling mechanisms of calcaneal adduction/abduction and calcaneal eversion/inversion to proximal bones in vitro. The in vitro approach is necessary because in vivo both movements appear together, making it impossible to determine the extent of their individual contribution to overall ankle joint coupling. Eight fresh frozen foot-leg specimens were tested. Data describing bone orientation and coupling mechanisms between segments were obtained using bone pin marker triads. The bone movement was described in a global coordinate system to examine the coupling between the calcaneus, talus and tibia. The strength of coupling was determined by means of the slope of a linear least squares fit to an angle-angle plot. The coupling coefficients in the present study indicate that not only calcaneal eversion/inversion (coupling coefficient: 0.68 ± 0.15) but to an even greater extent calcaneal adduction/abduction (coupling coefficient: 0.99 ± 0.10) was transferred into talus and tibial rotation, highlighting the relevance of calcaneal adduction for the overall ankle joint coupling. The results of this study present the possibility that controlling calcaneal adduction/abduction can affect talus and tibial rotation and therefore the possible genesis of overuse knee injuries.

  • 12.
    da Silva, Julio Cézar Lima
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet.
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Andersson, Eva
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet.
    Rönquist, Gustaf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Grundström, Helene
    Danderyds Hospital.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet.
    Effect of increasing workload on knee extensor and flexor muscular activity during cycling as measured with intramuscular electromyography.2018Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, nr 8, artikkel-id e0201014Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this study was to describe the effect of increasing workload on individual thigh muscle activation during a 20 minute incremental cycling test. Intramuscular electromyographic signals were recorded from the knee extensors rectus femoris, vastus lateralis, vastus medialis and vastus intermedius and the knee flexors semimembranosus, semitendinosus, and the short and long heads of the biceps femoris during increasing workloads. Mean activation levels were compared over the whole pedaling cycle and the crank angles at which onset and offset of activation and peak activity occurred were identified for each muscle. These data were compared between three workloads. EMG activation level significantly increased (p<0.05) with increasing workload in the rectus femoris, vastus medialis, vastus lateralis, vastus intermedius, biceps femoris long head, semitendinosus and semimembranosus but not in the biceps femoris short head. A significant change in activation timing was found for the rectus femoris, vastus lateralis, vastus medialis and semitendinosus. Of the knee flexors only the short head of the biceps femoris had its peak activity during the upstroke phase at the two highest workloads indicating a unique contribution to knee flexion.

  • 13.
    Peter, Annamaria
    et al.
    Neuromuscular Research Center, University of Jyväskylä, Finland.
    Andersson, Eva
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Finni, T
    Neuromuscular Research Center, University of Jyväskylä, Finland.
    Cronin, NJ
    Neuromuscular Research Center, University of Jyväskylä, Finland.
    Impact of footwear type and walking speed on ankle plantar flexor fine-wire electromyographic activity2018Inngår i: Sport science at the cutting edge, 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    INTRODUCTION:

    Ankle plantar flexors substantially contribute to propulsion in human walking, and their relative contributions may be affected by the type of footwear used. In this study, we aimed to examine plantar flexor fine-wire electromyography (wEMG) activity in different footwear types and barefoot walking. We further examined the effect of walking speed on the relative activity of ankle plantar flexors.

    METHODS:

    Nine healthy people volunteered to this study (five males) with two sessions. In session 1, participants were familiarized to the study protocol. In session 2, electrical activity of flexor hallucis longus (FHL), soleus (SOL), medial and lateral gastrocnemius (MG and LG) muscles were measured with wEMG during eight overground walking tasks: preferred speed walking with shoes, barefoot and with flip-flops; with shoes: 30% slower and faster than preferred speed walking with shoes, and maximum walking speed; walking barefoot and with flip-flops at the same speed as preferred speed walking with shoes (matched speed). Then they performed maximal isometric plantar flexion contractions and maximal big toe flexions superimposed on ankle plantar flexion (MVICs) in an isokinetic dynamometer for wEMG normalization. Root mean square activity was calculated in the push-off phase of individual step cycles based on ground reaction force data. The relative contribution of each muscle to propulsion was calculated as: (mean RMS value %MVIC of the given muscle / mean RMS value %MVIC of all muscles) * 100. Cohen’s d±90% confidence intervals were calculated to define the magnitude of differences.

    RESULTS:

    In all muscles, wEMG activity increased with speed. With increasing speed the relative contribution to propulsion increased in FHL (from 19 to 22%), did not change in SOL (32%), decreased in MG (from 32 to 25%) and increased in LG (from 18 to 21%). There were no differences between preferred and matched barefoot walking speed or wEMG activity level (d range = 0.06-0.17). wEMG activity for all muscles was lower during matched barefoot walking than preferred speed walking with shoes (7-10% MVIC, d range=0.31-0.47). Flip-flop data are under analysis.

    CONCLUSION:

    We found that relative wEMG activity of the examined muscles was affected by speed and absence or presence of shoes. During barefoot walking, wEMG activity of plantar flexor muscles was lower than during shod walking at the same speed, which presumably means that shod walking limits the contribution of intrinsic foot muscles to propulsion, which should be further examined.

    REFERENCES:

    1 Murley GS, Menz HB, Landorf KB. (2014). Gait & Posture, 39(4), 1080-5.

    2 Goldmann JP, Potthast W, Brüggemann GP. (2013). Footwear Sci, 5 (1): 19-25.

    3 Franklin et al., Gait & Posture. 60: 1-5, 2018.

    CONTACT:

    annamaria.a.peter@jyu.fi

  • 14.
    Yan, S
    et al.
    Royal Institute of Technology, Stockholm, Sweden.
    Schlippe, M
    Royal Institute of Technology, Stockholm, Sweden.
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Pennati, G V
    Karolinska institutet, Stockholm, Sweden.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Yang, L
    Sichuan University, Chengdu, China.
    Shi, B
    Sichuan University, Chengdu, China.
    Wang, R
    Royal Institute of Technology, Stockholm, Sweden.
    P 158 - A method to estimate passive mechanical properties of the soleus and gastrocnemius aspects of Achilles tendon.2018Inngår i: ESMAC 2018 abstracts: special issue of Gait & Posture, 2018, Vol. 65 Suppl 1, s. 501-502, artikkel-id S0966-6362(18)31146-9Konferansepaper (Fagfellevurdert)
  • 15.
    Bjerkefors, Anna
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet.
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Rosén, Johanna S
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Zakaria, Pascal
    Gymnastik- och idrottshögskolan, GIH.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska institutet.
    Three-dimensional kinematic analysis and power output of elite flat-water kayakers.2018Inngår i: Sports Biomechanics, ISSN 1476-3141, E-ISSN 1752-6116, Vol. 17, nr 3, s. 414-427Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose was to examine power output and three-dimensional (3D) kinematic variables in the upper limbs, lower limbs and trunk in elite flat-water kayakers during kayak ergometer paddling. An additional purpose was to analyse possible changes in kinematics with increased intensity and differences between body sides. Six male and four female international level flat-water kayakers participated. Kinematic and kinetic data were collected during three tasks; low (IntL), high (IntH) and maximal (IntM) intensities. No differences were observed in any joint angles between body sides, except for shoulder abduction. Significantly greater range of motion (RoM) values were observed for IntH compared to IntL and for IntM compared to IntL in trunk and pelvis rotation, and in hip, knee and ankle flexion. The mean maximal power output was 610 ± 65 and 359 ± 33 W for the male and female athletes, respectively. The stroke frequencies were significantly different between all intensities (IntL 59.3 ± 6.3; IntH 108.0 ± 6.8; IntM 141.7 ± 18.4 strokes/min). The results showed that after a certain intensity level, the power output must be increased by other factors than increasing the joint angular RoM. This information may assist coaches and athletes to understand the relationship between the movement of the kayaker and the paddling power output.

  • 16.
    Fröberg, Åsa
    et al.
    Karolinska Institutet.
    Cisse, Ann-Sophie
    Karolinska Institutet.
    Larsson, Matilda
    KTH Royal Inst Technol.
    Mårtensson, Mattias
    KTH Royal Inst Technol.
    Peolsson, Michael
    Swedish ICT Res Inst, SICS.
    Movin, Tomas
    Karolinska Institutet.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Karolinska Institutet.
    Altered patterns of displacement within the Achilles tendon following surgical repair2017Inngår i: Knee Surgery, Sports Traumatology, Arthroscopy, ISSN 0942-2056, E-ISSN 1433-7347, Vol. 25, nr 6, s. 1857-1865Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ultrasound speckle tracking was used to compare tendon deformation patterns between uninjured and surgically repaired Achilles tendons at 14-27-month follow-up. The hypothesis was that the non-homogenous displacement pattern previously described in uninjured tendons, where displacement within deep layers of the tendons exceeds that of superficial layers, is altered following tendon rupture and subsequent surgical repair. In the first part of this study, an in-house-developed block-matching speckle tracking algorithm was evaluated for assessment of displacement on porcine flexor digitorum tendons. Displacement data from speckle tracking were compared to displacement data from manual tracking. In the second part of the study, eleven patients with previous unilateral surgically treated Achilles tendon rupture were investigated using ultrasound speckle tracking. The difference in superficial and deep tendon displacement was assessed. Displacement patterns in the surgically repaired and uninjured tendons were compared during passive motion (Thompson's squeeze test) and during active ankle dorsiflexion. The difference in peak displacement between superficial and deep layers was significantly (p < 0.01) larger in the uninjured tendons as compared to the surgically repaired tendons both during Thompson's test (-0.7 +/- 0.2 mm compared to -0.1 +/- 0.1 mm) and active dorsiflexion (3.3 +/- 1.1 mm compared to 0.3 +/- 0.2 mm). The evaluation of the speckle tracking algorithm showed correlations of r ae<yen> 0.89 between displacement data acquired from speckle tracking and the reference displacement acquired from manual tracking. Speckle tracking systematically underestimated the magnitude of displacement with coefficients of variation of less than 11.7%. Uninjured Achilles tendons display a non-uniform displacement pattern thought to reflect gliding between fascicles. This pattern was altered after a mean duration of 19 +/- 4 months following surgical repair of the tendon indicating that fascicle sliding is impaired. This may affect modulation of the action between different components of the triceps surae, which in turn may affect force transmission and tendon elasticity resulting in impaired function and risk of re-rupture.

  • 17.
    Fischer, Katina Mira
    et al.
    German Sport University Cologne.
    Willwacher, Steffen
    German Sport University Cologne.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Wolf, Peter
    ETH Zurich.
    Brueggemann, Gert-Peter
    German Sport University Cologne.
    Calcaneal adduction in slow running: three case studies using intracortical pins.2017Inngår i: Footwear Science, ISSN 1942-4280, E-ISSN 1942-4299, Vol. 9, nr 2, s. 87-93Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to use bone-anchored markers to determine the bone movement of calcaneal adduction, eversion and tibial rotation in a global coordinate system and to describe the relationship of calcaneal adduction to tibial rotation. Furthermore, the amount of overall intra-foot motion in the transverse plane (metatarsal I relative to calcaneus) and its relationship to calcaneal adduction were quantified. Three male participants were assessed during slow running. A 10-camera motion analysis system was used for kinematic data capture of global bone orientations in 3D space for all bones of the foot and ankle complex. For the description of intrinsic articulations within the foot, the skeletal motion relative to the adjacent proximal segment in the transverse plane was calculated. Furthermore, the time of occurrence of maximum values was determined. The findings showed that calcaneal adduction of all participants amounted to 7.8 ± 4.8°, which exceeded the magnitude of calcaneal eversion (4.7 ± 3.1°). Although the inter-participant variability was high, considerable overall intra-foot motion in the transverse plane of the metatarsal I relative to the calcaneus was found to be 4.7 ± 4.6° and could be qualitatively related to calcaneal adduction. The present data provide evidence that next to calcaneal eversion, calcaneal adduction seems related to tibial rotation. Furthermore, overall intra-foot motion in the transverse plane seems related to calcaneal adduction. Controlling calcaneal adduction and overall intra-foot motion in the transverse plane may be a mechanism to control excessive tibial rotation in runners who suffer from overuse knee injuries. These findings could be used to provide an additional approach for future motion-control footwear design to control rearfoot adduction or overall within-foot motion.

  • 18.
    Gago, Paulo
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap. Research Center for Sport, Health and Human Development, (CIDESD), Portugal.
    Arndt, Toni
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC). Department of CLINTEC, Karolinska Institutet, Stockholm.
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap. Department of Neuroscience, Karolinska Institutet, Stockholm.
    Post Activation Potentiation of the Plantarflexors: Implications of Knee Angle Variations2017Inngår i: Journal of Human Kinetics, ISSN 1640-5544, E-ISSN 1899-7562, Vol. 57, s. 29-38Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Flexing the knee to isolate the single joint soleus from the biarticular gastrocnemius is a strategy forinvestigating individual plantarflexor's post activation potentiation (PAP). We investigated the implications of testingplantarflexor PAP at different knee angles and provided indirect quantification of the contribution of gastrocnemiuspotentiation to the overall plantarflexor enhancements post conditioning. Plantarflexor supramaximal twitches weremeasured in ten male power athletes before and after a maximal isometric plantarflexion (MVIC) at both flexed andextended knee angles. Mean torque and soleus (SOLRMS) and medial gastrocnemius (MGRMS) activity were measuredduring the MVIC. The mean torque and MGRMS of the MVIC were lower (by 33.9 and 42.4%, respectively) in the flexedcompared to the extended position, with no significant difference in SOLRMS. After the MVIC, twitch peak torque (PT)and the rate of torque development (RTR) potentiated significantly more (by 17.4 and 14.7% respectively) in theextended as compared to the flexed knee position, but only immediately (5 s) after the MVIC. No significant differenceswere found in the twitch rate of torque development (RTD) potentiation between positions. It was concluded that kneejoint configuration should be taken into consideration when comparing studies of plantarflexor PAP. Furthermore,results reflect a rather brief contribution of the gastrocnemius potentiation to the overall plantarflexor twitchenhancements.

  • 19. Maiwald, Christian
    et al.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Nester, Chris
    Jones, Richard
    Lundberg, Arne
    Wolf, Peter
    The effect of intracortical bone pin application on kinetics and tibiocalcaneal kinematics of walking gait2017Inngår i: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 52, s. 129-134Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]
    • Gait analysis using bone anchored markers requires local anaesthesia, which may affect subjects gait patterns.
    • Kinetic and kinematic variables were collected using two protocols (skin vs. bone anchored markers).
    • No systematic differences were found between the two protocols.
    • We conclude that the validity of the recorded variables is not affected by local anaesthesia.

    Bone anchored markers using intracortical bone pins are one of the few available methods for analyzing skeletal motion during human gait in-vivo without errors induced by soft tissue artifacts. However, bone anchored markers require local anesthesia and may alter the motor control and motor output during gait. The purpose of this study was to examine the effect of local anesthesia and the use of bone anchored markers on typical gait analysis variables. Five subjects were analyzed in two different gait analysis sessions. In the first session, a protocol with skin markers was used. In the second session, bone anchored markers were added after local anesthesia was applied. For both sessions, three dimensional infrared kinematics of the calcaneus and tibia segments, ground reaction forces, and plantar pressure data were collected. 95% confidence intervals and boxplots were used to compare protocols and assess the data distribution and data variability for each subject. Although considerable variation was found between subjects, within-subject comparison of the two protocols revealed non-systematic effects on the target variables. Two of the five subjects walked at reduced gait speed during the bone pin session, which explained the between-session differences found in kinetic and kinematic variables. The remaining three subjects did not systematically alter their gait pattern between the two sessions. Results support the hypothesis that local anesthesia and the presence of bone pins still allow a valid gait pattern to be analyzed.

  • 20.
    Arndt, Toni
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Barfota eller rejäl stötdämpning – vilka löparskor är bäst?2016Inngår i: Idrottsforskning, ISSN 2002-3944, artikkel-id 18 majArtikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    Kraftig dämpning i våra löparskor skulle minska skadorna. Men att stötarna i nedslaget är ett problem har svagt stöd i forskningen. Är det då bättre att springa i minimalistiska skor eller helt barfota? Vad ska motionären välja?

  • 21. Michaud, B.
    et al.
    Jackson, M.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Lundberg, A.
    Begon, M.
    Determining in vivo sternoclavicular, acromioclavicular and glenohumeral joint centre locations from skin markers, CT-scans and intracortical pins: A comparison study2016Inngår i: Medical Engineering and Physics, ISSN 1350-4533, E-ISSN 1873-4030, Vol. 38, nr 3, s. 290-296Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]
    • CoR were located using anatomical, predictive, functional and imaging-based methods.
    • Gold-standard locations were obtained using intracortical pins.
    • Sternoclavicular joint: our findings are in agreement with ISB (Wu, 2005).
    • Acromioclavicular joint: anatomical method of by van der Helm (1996) is suggested.
    • Glenohumeral joint: the regression equation of Rab (2002) is suggested. 

    To describe shoulder motion the sternoclavicular, acromioclavicular and glenohumeral joint centres must be accurately located. Within the literature various methods to estimate joint centres of rotation location are proposed, with no agreement of the method best suited to the shoulder. The objective of this study was to determine the most reliable non-invasive method for locating joint centre locations of the shoulder complex. Functional methods using pin mounted markers were compared to anatomical methods, functional methods using skin mounted markers, imaging-based methods using CT-scan data, and regression equations. Three participants took part in the study, that involved insertion of intracortical pins into the clavicle, scapula and humerus, a CT-scan of the shoulder, and finally data collection using a motion analysis system. The various methods to estimate joint centre location did not all agree, however suggestions about the most reliable non-invasive methods could be made. For the sternoclavicular joint, the authors suggest the anatomical method using the most ventral landmark on the sternoclavicular joint, as recommended by the International Society of Biomechanics. For the acromioclavicular joint, the authors suggest the anatomical method using the landmark defined as the most dorsal point on the acromioclavicular joint, as proposed by van der Helm. For the glenohumeral joint, the simple regression equation of Rab is recommended.

  • 22. Lanferdini, Fábio J
    et al.
    Bini, Rodrigo R
    Figueiredo, Pedro
    Diefenthaeler, Fernando
    Mota, Carlos B
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Vaz, Marco A
    Differences in Pedaling Technique in Cycling: A Cluster Analysis.2016Inngår i: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 11, nr 7, s. 959-964Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PURPOSE: To employ cluster analysis to assess if cyclists would opt for different strategies in terms of neuromuscular patterns when pedaling at the power output of their second ventilatory threshold (POVT2) compared with cycling at their maximal power output (POMAX).

    METHODS: Twenty athletes performed an incremental cycling test to determine their power output (POMAX and POVT2; first session), and pedal forces, muscle activation, muscle-tendon unit length, and vastus lateralis architecture (fascicle length, pennation angle, and muscle thickness) were recorded (second session) in POMAX and POVT2. Athletes were assigned to 2 clusters based on the behavior of outcome variables at POVT2 and POMAX using cluster analysis.

    RESULTS: Clusters 1 (n = 14) and 2 (n = 6) showed similar power output and oxygen uptake. Cluster 1 presented larger increases in pedal force and knee power than cluster 2, without differences for the index of effectiveness. Cluster 1 presented less variation in knee angle, muscle-tendon unit length, pennation angle, and tendon length than cluster 2. However, clusters 1 and 2 showed similar muscle thickness, fascicle length, and muscle activation. When cycling at POVT2 vs POMAX, cyclists could opt for keeping a constant knee power and pedal-force production, associated with an increase in tendon excursion and a constant fascicle length.

    CONCLUSIONS: Increases in power output lead to greater variations in knee angle, muscle-tendon unit length, tendon length, and pennation angle of vastus lateralis for a similar knee-extensor activation and smaller pedal-force changes in cyclists from cluster 2 than in cluster 1.

  • 23. Dal Maso, Fabien
    et al.
    Blache, Yoann
    Raison, Maxime
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Begon, Mickaël
    Distance between rotator cuff footprints and the acromion, coracoacromial ligament, and coracoid process during dynamic arm elevations: Preliminary observations : Technical and measurement report2016Inngår i: Manual Therapy, ISSN 1356-689X, E-ISSN 1532-2769, Vol. 25, s. 94-99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background The objective of this study was to provide preliminary measures of the distance between the supraspinatus, infraspinatus, and subscapularis footprints and the acromion, coracoacromial ligament, and coracoid process, during dynamic arm elevations through the entire range-of-motion.

  • 24. Fröberg, Åsa
    et al.
    Mårtensson, Mattias
    Larsson, Matilda
    Janerot-Sjöberg, Birgitta
    D'Hooge, Jan
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    High variability in strain estimation errors when using a commercial ultrasound speckle tracking algorithm on tendon tissue.2016Inngår i: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 57, nr 10, s. 1223-1229Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: Ultrasound speckle tracking offers a non-invasive way of studying strain in the free Achilles tendon where no anatomical landmarks are available for tracking. This provides new possibilities for studying injury mechanisms during sport activity and the effects of shoes, orthotic devices, and rehabilitation protocols on tendon biomechanics.

    PURPOSE: To investigate the feasibility of using a commercial ultrasound speckle tracking algorithm for assessing strain in tendon tissue.

    MATERIAL AND METHODS: A polyvinyl alcohol (PVA) phantom, three porcine tendons, and a human Achilles tendon were mounted in a materials testing machine and loaded to 4% peak strain. Ultrasound long-axis cine-loops of the samples were recorded. Speckle tracking analysis of axial strain was performed using a commercial speckle tracking software. Estimated strain was then compared to reference strain known from the materials testing machine. Two frame rates and two region of interest (ROI) sizes were evaluated.

    RESULTS: Best agreement between estimated strain and reference strain was found in the PVA phantom (absolute error in peak strain: 0.21 ± 0.08%). The absolute error in peak strain varied between 0.72 ± 0.65% and 10.64 ± 3.40% in the different tendon samples. Strain determined with a frame rate of 39.4 Hz had lower errors than 78.6 Hz as was the case with a 22 mm compared to an 11 mm ROI.

    CONCLUSION: Errors in peak strain estimation showed high variability between tendon samples and were large in relation to strain levels previously described in the Achilles tendon.

  • 25.
    da Silva, Julio Cézar Lima
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Andersson, Eva
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Rönquist, Gustaf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Quadriceps and hamstring muscle activity during cycling as measured with intramuscular electromyography.2016Inngår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 116, nr 9, s. 1807-1817Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PURPOSE: The aim of this study was to describe thigh muscle activation during cycling using intramuscular electromyographic recordings of eight thigh muscles, including the biceps femoris short head (BFS) and the vastus intermedius (Vint).

    METHODS: Nine experienced cyclists performed an incremental test (start at 170 W and increased by 20 W every 2 min) on a bicycle ergometer either for a maximum of 20 min or to fatigue. Intramuscular electromyography (EMG) of eight muscles and kinematic data of the right lower limb were recorded during the last 20 s in the second workload (190 W). EMG data were normalized to the peak activity occurring during this workload. Statistical significance was assumed at p ≤ 0.05.

    RESULTS: The vastii showed a greater activation during the 1st quadrant compared to other quadrants. The rectus femoris (RF) showed a similar activation, but with two bursts in the 1st and 4th quadrants in three subjects. This behavior may be explained by the bi-articular function during the cycling movement. Both the BFS and Vint were activated longer than, but in synergy with their respective agonistic superficial muscles.

    CONCLUSION: Intramuscular EMG was used to verify muscle activation during cycling. The activation pattern of deep muscles (Vint and BFS) could, therefore, be described and compared to that of the more superficial muscles. The complex coordination of quadriceps and hamstring muscles during cycling was described in detail.

  • 26. Begon, Mickaël
    et al.
    Dal Maso, Fabien
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Monnet, Tony
    Can optimal marker weightings improve thoracohumeral kinematics accuracy?2015Inngår i: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 48, nr 10, s. 2019-2025Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Local and global optimization algorithms have been developed to estimate joint kinematics to reducing soft movement artifact (STA). Such algorithms can include weightings to account for different STA occur at each marker. The objective was to quantify the benefit of optimal weighting and determine if optimal marker weightings can improve humerus kinematics accuracy. A pin with five reflective markers was inserted into the humerus of four subjects. Seven markers were put on the skin of the arm. Subjects performed 38 different tasks including arm elevation, rotation, daily-living tasks, and sport activities. In each movement, mean and peak errors in skin- vs. pins-orientation were reported. Then, optimal marker weightings were found to best match skin- and pin-based orientation. Without weighting, the error of the arm orientation ranged from 1.9° to 17.9°. With weighting, 100% of the trials were improved and the average error was halved. The mid-arm markers weights were close to 0 for three subjects. Weights of a subject applied to the others for a given movement, and weights of a movement applied to others for a given subject did not systematically increased accuracy of arm orientation. Without weighting, a redundant set of marker and least square algorithm improved accuracy to estimate arm orientation compared to data of the literature using electromagnetic sensor. Weightings were subject- and movement-specific, which reinforces that STA are subject- and movement-specific. However, markers on the deltoid insertion and on lateral and medial epicondyles may be preferred if a limited number of markers is used.

  • 27.
    Tinmark, Fredrik
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Hellström, John
    Halvorsen, Kjartan
    Endpoint mobility in bimanual manipulation: insights from golf ball striking2015Inngår i: XXV Congress of the International Society of Biomechanics: Abstract book, 2015, s. 1283-1284Konferansepaper (Fagfellevurdert)
  • 28. Dal Maso, Fabien
    et al.
    Raison, Maxime
    Lundberg, Arne
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Allard, Paul
    Begon, Mickaël
    Glenohumeral translations during range-of-motion movements, activities of daily living, and sports activities in healthy participants.2015Inngår i: Clinical Biomechanics, ISSN 0268-0033, E-ISSN 1879-1271, Vol. 30, nr 9, s. 1002-1007Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: Glenohumeral translations have been mainly investigated during static poses while shoulder rehabilitation exercises, activities of daily living, and sports activities are dynamic. Our objective was to assess glenohumeral translations during shoulder rehabilitation exercises, activities of daily living, and sports activities to provide a preliminary analysis of glenohumeral arthrokinematics in a broad range of dynamic tasks.

    METHODS: Glenohumeral translations were computed from trajectories of markers fitted to intracortical pins inserted into the scapula and the humerus. Two participants (P1 and P2) performed full range-of-motion movements including maximum arm elevations and internal-external rotations rehabilitation exercises, six activities of daily living, and five sports activities.

    FINDINGS: During range-of-motion movements, maximum upward translation was 7.5mm (P1) and 4.7mm (P2). Upward translation during elevations was smaller with the arm internally (3.6mm (P1) and 2.9mm (P2)) than neutrally (4.2mm (P1) and 3.7mm (P2)) and externally rotated (4.3mm (P1) and 4.3mm (P2)). For activities of daily living and sports activities, only anterior translation during reach axilla for P1 and upward translation during ball throwing for P2 were larger than the translation measured during range-of-motion movements (108% and 114%, respectively).

    INTERPRETATION: While previous electromyography-based studies recommended external rotation during arm elevation to minimize upward translation, measures of glenohumeral translations suggest that internal rotation may be better. Similar amplitude of translation during ROM movement and sports activities suggests that large excursions of the humeral head may be caused not only by fast movements, but also by large amplitude movements.

  • 29. Seynnes, Olivier R
    et al.
    Bojsen-Møller, Jens
    Albracht, Kirsten
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Cronin, Neil J
    Finni, Taija
    Magnusson, S Peter
    Ultrasound-Based Testing Of Tendon Mechanical Properties: A Critical Evaluation.2015Inngår i: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 118, nr 2, s. 133-141Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the past twenty years, the use of ultrasound-based methods has become a standard approach to measure tendon mechanical properties in vivo. Yet, the multitude of methodological approaches adopted by various research groups probably contributes to the large variability of reported values. The technique of obtaining and relating tendon deformation to tensile force in vivo has been applied differently, depending on practical constraints or scientific points of view. Divergence can be seen in i) methodological considerations such as the choice of anatomical features to scan and to track, force measurements or signal synchronisation and ii), in physiological considerations related to the viscoelastic behaviour or length measurements of tendons. Hence, the purpose of the present review is to assess and discuss the physiological and technical aspects connected to in vivo testing of tendon mechanical properties. In doing so, our aim is to provide the reader with a systematic, qualitative analysis of ultrasound-based techniques. Finally, a list of recommendations is proposed for a number of selected issues.

  • 30. Itayem, Raed
    et al.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Daniel, Joseph
    McMinn, Derek J W
    Lundberg, Arne
    A two-year radiostereometric follow-up of the first generation Birmingham mid head resection arthroplasty.2014Inngår i: HIP International, ISSN 1120-7000, E-ISSN 1724-6067, Vol. 24, nr 4, s. 355-62Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During the first decade of the 21st century, metal-on-metal hip resurfacing became one of the main treatment options for younger, more active patients with osteoarthritis. However, as a result of the reported failure rate of both total hip replacement (THR) and resurfacing in patients with considerable loss of bone stock in the femoral head (e.g., in extensive avascular necrosis), other solutions have been sought for these patients. The short-stemmed Birmingham Mid Head Resection prosthesis (BMHR) combines a metal-on-metal articulation and a femoral neck preserving feature. In this study, radiostereometric analysis (RSA) was used to study migration of the BMHR femoral component in 13 hips. Translations and rotations were measured up to two years. Relative values showed no statistically significant migration. Absolute values demonstrated settling in occurring between zero and two months postoperatively in all directions studied. From two months to two years no significant migration occurred except for rotation around the x-axis of the femoral segment (p = 0.049). After initial settling-in, absolute values were low, indicating that there was no evidence of early migration or loosening of the components.

  • 31. Dal Maso, Fabien
    et al.
    Raison, Maxime
    Lundberg, Arne
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Begon, Mickaël
    Coupling between 3D displacements and rotations at the glenohumeral joint during dynamic tasks in healthy participants.2014Inngår i: Clinical Biomechanics, ISSN 0268-0033, E-ISSN 1879-1271, Vol. 29, nr 9, s. 1048-1055Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    BACKGROUND: Glenohumeral displacements assessment would help to design shoulder prostheses with physiological arthrokinematics and to establish more biofidelic musculoskeletal models. Though displacements were documented during static tasks, there is little information on their 3D coupling with glenohumeral angle during dynamic tasks. Our objective was to characterize the 3D glenohumeral displacement-rotation couplings during dynamic arm elevations and rotations.

    METHODS: Glenohumeral displacements were measured from trajectories of reflective markers fitted on intracortical pins inserted into the scapula and humerus. Bone geometry was recorded using CT-scan. Only four participants were recruited to the experiment due to its invasiveness. Participants performed dynamic arm abduction, flexion and axial rotations. Linear regressions were performed between glenohumeral displacements and rotations. The pin of the scapula of one participant moved, his data were removed from analysis, and results are based on three participants.

    FINDINGS: The measurement error of glenohumeral kinematics was less than 0.15mm and 0.2°. Maximum glenohumeral displacements were measured along the longitudinal direction and reached up to +12.4mm for one participant. Significant couplings were reported especially between longitudinal displacement and rotation in abduction (adjusted R(2) up to 0.94).

    INTERPRETATION: The proposed method provides the potential to investigate glenohumeral kinematics during all kinds of movements. A linear increase of upward displacement during dynamic arm elevation was measured, which contrasts with results based on a series of static poses. The systematic investigation of glenohumeral displacements under dynamic condition may help to provide relevant recommendation for the design of shoulder prosthetic components and musculoskeletal models.

  • 32.
    Lundberg, Arne
    et al.
    Department of Orthopaedics, CLINTEC, Karolinska Institute, Stockholm, Sweden.
    Aguilera, Ana
    Centre of Analysis, Treatment and Data Modelling, Faculty of Science and Technology,.
    Cappozzo, Aurelio
    Department of Human Movement and.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Begon, Mickael
    Department of Kinesiology, University of Montreal, Canada.
    Entropy in the List of Authors of Scientific Papers2014Inngår i: Annals of improbable research, Vol. 20, nr 1, s. 15-17Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    Conclusion

    It is the firm belief of the present authors that there should not be more than three names on an author list, and rather than appear on a longer list of authors, one should withdraw willingly. Furthermore, the remaining authors should determine an order such that the respective work of each contributor is known, whatever it is. If not, then the lack of input from the mysterious authors should be officially recognized by all journals real, imaginary, or improbable. We hope that this paper will serve as a guideline to future authors and mysterious contributors as well.

  • 33.
    Arndt, Toni
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Forskning inom rörelselära2014Inngår i: Från Kungl. Gymnastiska Centralinstitutet till Gymnastik- och idrottshögskolan: en betraktelse av de senaste 25 åren som del av en 200-årig historia / [ed] Suzanne Lundvall, Stockholm: Gymnastik- och idrottshögskolan, GIH , 2014, s. 245-252Kapittel i bok, del av antologi (Annet (populærvitenskap, debatt, mm))
  • 34.
    Gago, Paulo
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Maria M
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Post activation potentiation can be induced without impairing tendon stiffness.2014Inngår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 114, nr 11, s. 2299-2308Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PURPOSE: This study aimed to investigate conditioning effects from a single 6-s plantar flexion maximal voluntary isometric contraction (MVIC) on Achilles tendon stiffness (ATS) and twitch properties of the triceps surae in athletes.

    METHODS: Peak twitch (PT), rate of torque development (RTD), rising time (RT10-90%) and half relaxation time (HRT) were measured from supramaximal twitches evoked in the plantar flexors of 10 highly trained athletes. Twitches were evoked before and at seven occasions during 10 min of recovery after a 6-s MVIC. In a second session, but at identical post-conditioning time points, ATS was measured at 30 and 50 % of MVIC (ATS30% and ATS50%) using an ultrasonography-based method.

    RESULTS: The magnitude and duration of the conditioning MVIC on muscle contractile properties were in accordance with previous literature on post activation potentiation (PAP), i.e., high potentiation immediately after MVIC, with significant PAP for up to 3 min after the MVIC. While PT and RTD were significantly enhanced (by 60.6 ± 19.3 and 90.1 ± 22.5 %, respectively) and RT10-90% and HRT were reduced (by 10.1 ± 7.7 and 18.7 ± 5.6 %, respectively) after conditioning, ATS remained unaffected.

    CONCLUSIONS: Previous studies have suggested that changes in stiffness after conditioning may interfere with the enhancements in twitch contractile properties. The present study, however, provided some evidence that twitch enhancements after a standard PAP can be induced without changes in ATS. This result may suggest that athletes can use this protocol to enhance muscle contractile properties without performance deficits due to changes in ATS.

  • 35.
    Gago, Paulo
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Toni
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tarassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Post activation potentiation electromechanical delay and achilles tendon stiffness in athletes2014Konferansepaper (Fagfellevurdert)
  • 36. Halvorsen, Kjartan
    et al.
    Tinmark, Fredrik
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    The concept of mobility in single- and double handed manipulation.2014Inngår i: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 47, nr 14, s. 3569-3573Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The concept of mobility describes an important property of the human body when performing manipulation tasks. It describes, in a sense, how easy it is to accelerate a link or a point on the manipulator. Most often it is calculated for the end-link or end-point of the manipulator, since these are important for the control objective of the manipulator. Mobility is the inverse of the inertia experienced by a force acting on the end-point, or a combined force and torque acting on the end-link. The concept has been used in studies of reaching tasks with one arm, but thus far not for bi-manual manipulation. We present here the concept for both single-handed and double-handed manipulation, in a general manner which includes any type of grip of the hands on the object. The use of the concept is illustrated with data on the left and right arm in a golf swing.

  • 37. Paanalahti, Markku
    et al.
    Lundgren-Nilsson, Asa
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Sunnerhagen, Katharina S
    Applying the Comprehensive International Classification of Functioning, Disability and Health Core Sets for stroke framework to stroke survivors living in the community.2013Inngår i: Journal of Rehabilitation Medicine, ISSN 1650-1977, E-ISSN 1651-2081, Vol. 45, nr 4, s. 331-40Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    OBJECTIVE: The aims of this study were to explore the perspective of functioning in community-dwelling people with prior stroke and to confirm, if possible, the comprehensive international classification of functioning, disability and health (ICF) Comprehensive Core Set for stroke.

    METHODS: Qualitative interviews were analysed (using the content analysis method and established ICF linking rules) from 22 persons following stroke (age range 59-87 years), as well as their spouses/partners, where relevant.

    RESULTS: Ninety-nine (76%) of 130 second-level ICF categories in the existing Comprehensive ICF Core Set for stroke were confirmed: 31 categories (of 41) in the component of body functions, 38 categories (of 51) in the component of activities and participation, 26 (of 33) in the component of environmental factors and 4 (of 5) in the component of body structures. Eleven additional ICF categories and one personal factor, a coping style of "I take it as it comes" were also identified in the transcribed text.

    CONCLUSION: The Comprehensive ICF Core Set for stroke was largely confirmed.

  • 38.
    Nilsson, Johnny
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tinmark, Fredrik
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Halvorsen, Kjartan
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Kinematic, kinetic and electromyographic adaptation to speed and resistance in double poling cross country skiing2013Inngår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 113, nr 6, s. 1385-1394Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study incorporated variations in speed and the horizontal resistance acting upon elite female skiers during double poling (DP) on a treadmill and specifically analyzed biomechanical adaptations to these variations. Whole body kinematics and pole force data were recorded and used to calculate the moment of force acting on the shoulder and elbow joints. Data were obtained with a 3D optoelectronic system using reflective markers at given anatomical landmarks. Forces along the long axis of the right pole were measured with a piezoelectric force transducer. Surface electrodes were used to record EMG activity in the rectus femoris, rectus abdominis, latissimus dorsi and triceps brachii muscles. In a first set of recordings, the participants double poled with zero elevation at five different speeds from 8 to 17 km h−1. In a second set of recordings, horizontal resistance was added by weights (0.4–1.9 kg) attached to a pulley system pulling the skier posteriorly during DP at 14 km h−1. Results showed increasing relative duration of the thrust phase with increasing resistance, but not with speed. Significant kinematic differences occurred with increase in both speed and resistance. The mean (±SD) horizontal force components ranged between 1.7 (±1.3) and 2.8 (±1.1) percent (%) bodyweight (BW) in the speed adaptation and 3.1 (±0.6) and 4.0 (±1.3) % BW in the adaptation to horizontal resistance. Peak muscle activity showed a central to peripheral (proximo-distal) activation sequence. The temporal cycle phase pattern in the adaptation to speed and horizontal resistance differed.

  • 39.
    Gago, Paulo
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Toni
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tarrassova, Olga
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Ekblom, Maria
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Post activation potentiation and Achilles tendon stiffness in power athletes2013Konferansepaper (Fagfellevurdert)
  • 40.
    Bjerkefors, Anna
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Tinmark, Fredrik
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Nilsson, Johnny
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för tillämpad idrottsvetenskap (LTIV).
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Seated Double-Poling Ergometer Performance of Individuals with Spinal Cord Injury - A New Ergometer Concept for Standardized Upper Body Exercise2013Inngår i: International Journal of Sports Medicine, ISSN 0172-4622, E-ISSN 1439-3964, Vol. 34, nr 2, s. 176-182Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study aimed to evaluate biomechanics during seated double-poling exercises in individuals with spinal cord injury (SCI) and to compare these with those of able-bodied persons (AB). 26 participants volunteered for the study; 13 with SCI (injury levels C7-T12), and 13 AB. A seated double-poling ergometer (SDPE) was developed. 3-dimensional kinematics was measured and piezoelectric force sensors were used to register force in both poles for calculation of power during incremental intensities. Significantly lower power outputs, (143.2 ± 51.1 vs. 198.3 ± 74.9 W) and pole forces (137.1 ± 43.1 vs. 238.2 ± 81.2 N) were observed during maximal effort in SCI compared to AB. Sagittal upper trunk range of motion increased with intensity and ranged from 6.1–34.8 ° for SCI, and 6.9–31.3 ° for AB, with larger peak amplitudes in flexion for AB (31.4 ± 12.9 °) compared to SCI (10.0 ± 8.0 °). All subjects with SCI were able to exercise on the SDPE. Upper body kinematics, power and force outputs increased with intensity in both groups, but were in general, lower in SCI. In conclusion, the SDPE could be successfully used at low to high work intensities enabling both endurance and strength training for individuals with SCI

  • 41.
    Arndt, Anton
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Lundgren, Paul
    Liu, Anmin
    Nester, Christopher
    Maiwald, Christian
    Jones, Richard
    Lundberg, Arne
    The effect of a midfoot cut in the outer sole of a shoe on intrinsic foot kinematics during walking.2013Inngår i: Footwear Science, ISSN 1942-4280, Vol. 5, nr 1, s. 63-69Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Modifications in shoe outer soles are frequently made with the intention of altering biomechanics of the foot inside the shoe. These modifications are however, generally based upon intuition with little or no scientific data for support. The purpose of this study was to quantify changes in intrinsic foot segmental kinematics between walking in a neutral shoe and a shoe modified with a clear cut forming a break underneath the midfoot, approximating the Lisfrancs joint.

    Five healthy male subjects participated in the study. Intracortical pins were inserted under sterile conditions and local anaesthetic in nine different bones of the foot and shank. The subjects performed 10 walking trials in both a neutral, standard, flatsoled, flexible walking shoe and in the same shoe with an approximately 1 cm deep cut aligned with the subjects’ Lisfrancs joint. Material tests showed that the cut reduced midfoot shoe bending stiffness by 23% to 38% and torsional stiffness by 23% to 28%. A helical axis approach was applied for calculating the 3D rotations about relevant joints.

    Kinematic trajectories in the sagittal, frontal, and transverse planes were normalised to the stance phase for seven selected joints to compare rotation patterns when wearing the two shoe conditions. Although one out of 21 ranges of motion (ROM) showed a significant difference, there is strong reason to regard this as the result of a type 1 error. Apart from this no differences in ROM occurred between the shoe conditions.

    The low subject number reduced the statistical power of the results. However, the study indicated that outer sole modifications that may be assumed to have clear effects upon foot kinematics, do not necessarily do so.

  • 42.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Achilles tendon biomechanics and functional anatomy2012Konferansepaper (Annet vitenskapelig)
  • 43.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Biomechanical concepts of Achilles Tendon pathogenesis2012Konferansepaper (Annet vitenskapelig)
  • 44.
    Tinmark, Fredrik
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Hellström, John
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Halvorsen, Kjartan
    Contributions to club velocity in golf swings to submaximal and maximal shot distances2012Inngår i: eProceedings of the 30th Conference of the International Society of Biomechanics in Sports, 2012: Volume 3 / [ed] Bradshaw, E.J., Burnett, A., Hume, P.A., 2012, s. 81-83Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The contribution of joint rotations to endpoint velocity was investigated in golf shots to submaximal and maximal shot distances using a 41degrees of freedom (DOF) kinematic model. A subset of 16 DOFs was found to explain 97%-99% of endpoint velocity regulation at club–ball contact. The largest contributors, for both groups at every shot condition, were pelvis and torso twist rotation among the most proximal DOFs, elbow pronation/supination and wrist flexion/extension among DOFs in the left arm, and shoulder internal/external rotation and wrist flexion/extension among DOFs in the right arm. The contributions from pelvis obliquity, left wrist flexion/extension, left wrist ulnar/radial deviation and right shoulder flexion/extension differed significantly between the advanced and intermediate group.

  • 45.
    Lindberg, Thomas
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Norrbrink, Cecilia
    Department of Clinical Sciences, Karolinska Institutet Danderyd Hospital, Stockholm, Sweden.
    Wahman, Kerstin
    Department of Neurobiology, Care Sciences and Society (NVS), Division of Neurorehabilitation, Karolinska Institutet.
    Bjerkefors, Anna
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Effects of seated double-poling ergometer training on aerobic and mechanical power in individuals with spinal cord injury2012Inngår i: Journal of Rehabilitation Medicine, ISSN 1650-1977, E-ISSN 1651-2081, Vol. 44, nr 10, s. 893-898Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    OBJECTIVE: To determine whether regular interval training on a seated double-poling ergometer can increase physical capacity and safely improve performance towards maximal level in individuals with spinal cord injury.

    METHODS: A total of 13 subjects with spinal cord injury (injury levels T5-L1) performed 30 sessions of seated double-poling ergometer training over a period of 10 weeks. Sub-maximal and maximal double-poling ergometer tests were performed before (test-retest) and after this training period. Oxygen uptake was measured using the Douglas Bag system. Three-dimensional kinematics were recorded using an optoelectronic system and piezoelectric force sensors were used to register force in both poles.

    RESULTS: The mean intra-class correlation coefficient for test-retest values was 0.83 (standard deviation 0.11). After training significant improvements were observed in people with spinal cord injury in oxygen uptake (22.7%), ventilation (20.7%) and blood lactate level (22.0%) during maximal exertion exercises. Mean power per stroke and peak pole force increased by 15.4% and 23.7%, respectively. At sub-maximal level, significantly lower values were observed in ventilation (-12.8%) and blood lactate level (-25.0%).

    CONCLUSION: Regular interval training on the seated double-poling ergometer was effective for individuals with spinal cord injury below T5 level in terms of improving aerobic capacity and upper-body power output. The training was safe and did not cause any overload symptoms.

  • 46.
    Bjerkefors, Anna
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Lindberg, Thomas
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Norrbrink, Cecilia
    Department of Clinical Sciences, Karolinska Institutet Danderyd Hospital .
    Wahman, Kerstin
    Department of Neurobiology, Care Sciences and Society (NVS), Division of Neurorehabilitation, Karolinska Institutet.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Effects of seated double-poling ergometer training on aerobic and mechanical power in paraplegics2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Introduction In wheelchair-dependent individuals with paraplegia, over 80 % would benefit from health-intervention programmes due to increased risks for cardiovascular diseases. One way to reduce the likelihood of secondary complications and/or to enhance physical capacity is to add structured exercise activities to the regular schedule throughout life. A seated double-poling ergometer (SDPE) has been developed and recently evaluated on a group of people with SCI. The results indicated that the SDPE appeared to be a suitable training tool; the shoulder movement was within a range of motion not conducive to musculoskeletal injury and it provided a large range of controllable intensities enabling both endurance and strength training.

    Purpose To study if regular interval training on a SDPE can increase physical capacity and hence improve performance towards maximal level with safety in individuals with spinal cord injury.

    Methods Thirteen healthy wheelchair users (8 M, 5 F; 47 ± 12 years, 1.75 ± 0.08 m, 67.9 ± 10.2 kg) with SCI levels ranging from T5 to L1, volunteered for the study. Years post injury varied from 3 to 35. All subjects performed 30 sessions of SDPE training during 10 weeks. Each session lasted approximately 55 min, and included a warm-up, interval training (15 s – 3 min work and 15 s – 2 min rest) and a cool-down. The intensity of the intervals was determined to lead up to 70 – 100 % of peak heart rate. Sub-maximal and maximal double-poling ergometer tests were performed before and after this training period. Oxygen uptake was measured using the Douglas Bag system. Three-dimensional kinematics were recorded using an optoelectronic system. 

    Results Significant improvements after training were observed in oxygen uptake (23 %), ventilation (21 %) and blood lactate (22 %) during maximal exertion exercises (Table 1). Mean power per stroke and peak pole force increased with 15 % and 24 %, respectively. At sub-maximal level, significantly lower values were observed in ventilation (-13 %) and blood lactate (-25 %).

    Conclusion Regular interval training on the seated double-poling ergometer (SDPE) increased oxygen uptake and power out-put and can be recommended for people with paraplegia below T5 level due to SCI. Despite the high intensity training in this study, no overload symptoms were reported. On the contrary, certain types of musculoskeletal and neuropathic pain seem to benefit from training on the SDPE.

  • 47.
    Bjerkefors, Anna
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Lindberg, Thomas
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Norrbrink, Cecilia
    Department of Clinical Sciences, Karolinska Institutet Danderyd Hospital .
    Wahman, Kerstin
    Department of Neurobiology, Care Sciences and Society (NVS), Division of Neurorehabilitation, Karolinska Institutet.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Effects of seated double-poling ergometer training on oxygen uptake, upper-body muscle strength and motor performance in paraplegics2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Background:  In wheelchair-dependent individuals with paraplegia, over 80 % would benefit from health-intervention programmes due to increased risks for cardiovascular diseases. One way to reduce the likelihood of secondary complications and/or to enhance physical capacity is to add structured exercise activities throughout life.

    Objective:  To study the effects of seated double-poling ergometer (SDPE) training on aerobic capacity, upper-body muscle strength, and cross-over effects on functional performance.   

    Methods: Thirteen individuals with paraplegia performed 30 sessions of SDPE training during 10 weeks. Before and after the training period a) oxygen uptake was measured using the Douglas Bag system during sub-maximal and maximal double-poling ergometer tests, b) trunk, shoulder and elbow muscle strength measurements were performed during maximal voluntary contractions using an isokinetic dynamometer and c) functional tests in wheelchair were performed included; sit-and-reach test, propelling 15 m on a level surface, propelling 50 m up a 3º incline, and propelling 6 min on a 200 m indoor track. Test-retests were performed for all tests before the training began.

    Results: The average intra-class correlation coefficient for test-retest values was 0.91 (SD 0.07). Significant improvements after training were observed in oxygen uptake (22.7 %), ventilation (20.7 %) and blood lactate (22.0 %) during maximal exertion exercises. At sub-maximal level, significantly lower values were observed in ventilation (-12.8 %) and blood lactate (-25.0 %). Maximal isometric trunk muscle strength (17.0 %) and maximal isokinetic shoulder muscle strength (4.4 %) in flexion and extension improved after training. There were significant improvements in sit-and-reach test in forward directions (7.8 %) and in 15 m sprint test (5.2 %).     

    Conclusion: Regular interval training on the SPDE was effective for individuals with paraplegia to improve aerobic capacity and upper-body muscle strength. Some cross-over effects on functional performance were also shown. Furthermore, the training did not cause any overload symptoms.

     

  • 48.
    Wolf, Peter
    et al.
    ETH Zürich, Switzerland.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Nester, Christopher
    Liu, Anmin
    Jones, Richard
    Lundgren, Paul
    Lundberg, Arne
    In vivo Bewegungen der Fussknochen im Gehen und langsamen Joggen2012Inngår i: Orthopädieschuhtechnik, ISSN 0344-6026, nr 2, s. 24-27Artikkel i tidsskrift (Annet vitenskapelig)
  • 49.
    Arndt, Anton
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    In vivo, intrinsic kinematics of the foot and ankle2012Konferansepaper (Annet vitenskapelig)
  • 50.
    Arndt, Anton
    et al.
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Bengtsson, Ann-Sophie
    Peolsson, Michael
    Thorstensson, Alf
    Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).
    Movin, Tomas
    Non-uniform displacement within the Achilles tendon durig passive ankle joint motion.2012Inngår i: Knee Surgery, Sports Traumatology, Arthroscopy, ISSN 0942-2056, E-ISSN 1433-7347, Vol. 20, nr 9, s. 1868-74Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PURPOSE:

    An initial step in the understanding of Achilles tendon dynamics is to investigate the effects of passive motion, thereby minimising muscle activation and reducing internal joint forces. Internal tendon dynamics during passive ankle joint motion have direct implications for clinical rehabilitation protocols after Achilles tendon surgery. The aim of this study was to test the hypothesis that tendon tissue displacement is different in different layers of the Achilles tendon during controlled passive ankle joint movements.

    METHODS:

    Ultrasound imaging was conducted on the right Achilles tendon of nine healthy recreationally active males. Standardised isokinetic passive dorsi-plantar-flexion movements were performed with a total range of motion of 35°. The tendon was divided into superficial, central and deep layers in the resulting B-mode ultrasound images viewed in the sagittal plane. A block-matching speckle tracking algorithm was applied post-process, with kernels for the measurement of displacement placed in each of the layers.

    RESULTS:

    The mean (SD) displacement of the Achilles tendon during passive dorsiflexion was 8.4 (1.9) mm in the superficial layer, 9.4 (1.9) mm in the central portion and 10.4 (2.1) mm in the deep layer, respectively. In all cases, the movement of the deep layer of the tendon was greater than that of the superficial one (P < 0.01).

    CONCLUSIONS:

    These results, achieved in vivo with ultrasonographic speckle tracking, indicated complex dynamic differences in different layers of the Achilles tendon, which could have implications for the understanding of healing processes of tendon pathologies and also of normal tendon function.

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