Gymnastik- och idrottshögskolan, GIH

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  • 1.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Achilles tendon biomechanics and functional anatomy2012Conference paper (Other academic)
  • 2.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Biomechanical concepts of Achilles Tendon pathogenesis2012Conference paper (Other academic)
  • 3.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    In vivo, intrinsic kinematics of the foot and ankle2012Conference paper (Other academic)
  • 4.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    The effects of running in minimalistic shoes on non-uniform displacement in the Achilles tendon2019Conference paper (Refereed)
  • 5.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    The evolution of running shoes2012Conference paper (Other academic)
  • 6.
    Arndt, Anton
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Bengtsson, Ann-Sophie
    Peolsson, Michael
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Movin, Tomas
    Non-uniform displacement within the Achilles tendon durig passive ankle joint motion.2012In: Knee Surgery, Sports Traumatology, Arthroscopy, ISSN 0942-2056, E-ISSN 1433-7347, Vol. 20, no 9, p. 1868-74Article in journal (Refereed)
    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.

  • 7.
    Arndt, Anton
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Grau, Stefan
    University of Gothenburg, Sweden.
    Editorial2021In: Footwear Science, ISSN 1942-4280, E-ISSN 1942-4299, Vol. 13, no SUP1, p. S1-S3Article in journal (Other academic)
  • 8.
    Arndt, Anton
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Gutierrez-Farewik, LanieKTH Royal Institute of Technology, Stockholm, Sweden.Felländer-Tsai, LiKarolinska Institutet, Stockholm, Sweden.
    XXVIII Congress of the International Society of Biomechanics (ISB): Program & Abstracts2021Conference proceedings (editor) (Other academic)
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  • 9.
    Arndt, Anton
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    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.2013In: Footwear Science, ISSN 1942-4280, Vol. 5, no 1, p. 63-69Article in journal (Refereed)
    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.

  • 10.
    Arndt, Toni
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Barfota eller rejäl stötdämpning – vilka löparskor är bäst?2016In: Idrottsforskning, ISSN 2002-3944, article id 18 majArticle in journal (Other (popular science, discussion, etc.))
    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?

  • 11.
    Arndt, Toni
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Forskning inom rörelselära2014In: 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, p. 245-252Chapter in book (Other (popular science, discussion, etc.))
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  • 12.
    Arndt, Toni
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Swedish Sch Sport & Hlth Sci GIH, Stockholm, Sweden..
    Potthast, Wolfgang
    German Sport Univ Cologne, Cologne, Germany..
    The past, present and future of footwear biomechanics: celebrating 50 years of the International Society of Biomechanics2023In: Footwear Science, ISSN 1942-4280, E-ISSN 1942-4299, Vol. 15, no 2, p. 121-122Article in journal (Other academic)
  • 13.
    Azcarate, Laura
    et al.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Sandamas, Paul
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Gutierrez-Farewik, Elena M.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Wang, Ruoli
    KTH, Royal Institute of Technology, Stockholm, Sweden.
    Muscle contributions to body mass centre acceleration during the first stance of sprint running2019Conference paper (Refereed)
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  • 14. Begon, Mickaël
    et al.
    Dal Maso, Fabien
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Monnet, Tony
    Can optimal marker weightings improve thoracohumeral kinematics accuracy?2015In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 48, no 10, p. 2019-2025Article in journal (Refereed)
    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.

  • 15.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Lindberg, Thomas
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    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
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Effects of seated double-poling ergometer training on aerobic and mechanical power in paraplegics2012Conference paper (Refereed)
    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.

  • 16.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Lindberg, Thomas
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    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
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Effects of seated double-poling ergometer training on oxygen uptake, upper-body muscle strength and motor performance in paraplegics2012Conference paper (Refereed)
    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.

     

  • 17.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Rosén, Johanna S
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Three-Dimensional Kinematics and Power Output in Elite Para-Kayakers and Elite Able-Bodied Flat-Water Kayakers.2019In: Journal of Applied Biomechanics, ISSN 1065-8483, E-ISSN 1543-2688, p. 93-100Article in journal (Refereed)
    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.

  • 18.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Rosén, Johanna S
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Zakaria, Pascal
    Swedish School of Sport and Health Sciences, GIH.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    Three-dimensional kinematic analysis and power output of elite flat-water kayakers.2018In: Sports Biomechanics, ISSN 1476-3141, E-ISSN 1752-6116, Vol. 17, no 3, p. 414-427Article in journal (Refereed)
    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.

  • 19.
    Bjerkefors, Anna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tinmark, Fredrik
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Nilsson, Johnny
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, The Laboratory of Applied Sports Science (LTIV).
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Seated Double-Poling Ergometer Performance of Individuals with Spinal Cord Injury - A New Ergometer Concept for Standardized Upper Body Exercise2013In: International Journal of Sports Medicine, ISSN 0172-4622, E-ISSN 1439-3964, Vol. 34, no 2, p. 176-182Article in journal (Refereed)
    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

  • 20.
    da Silva, Julio Cézar Lima
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Andersson, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    Rönquist, Gustaf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Grundström, Helene
    Danderyds Hospital.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    Effect of increasing workload on knee extensor and flexor muscular activity during cycling as measured with intramuscular electromyography.2018In: PLOS ONE, E-ISSN 1932-6203, Vol. 13, no 8, article id e0201014Article in journal (Refereed)
    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.

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  • 21.
    da Silva, Julio Cézar Lima
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Andersson, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Rönquist, Gustaf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Quadriceps and hamstring muscle activity during cycling as measured with intramuscular electromyography.2016In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 116, no 9, p. 1807-1817Article in journal (Refereed)
    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.

  • 22. Dal Maso, Fabien
    et al.
    Blache, Yoann
    Raison, Maxime
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Begon, Mickaël
    Distance between rotator cuff footprints and the acromion, coracoacromial ligament, and coracoid process during dynamic arm elevations: Preliminary observations : Technical and measurement report2016In: Manual Therapy, ISSN 1356-689X, E-ISSN 1532-2769, Vol. 25, p. 94-99Article in journal (Refereed)
    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.

  • 23. Dal Maso, Fabien
    et al.
    Raison, Maxime
    Lundberg, Arne
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Allard, Paul
    Begon, Mickaël
    Glenohumeral translations during range-of-motion movements, activities of daily living, and sports activities in healthy participants.2015In: Clinical Biomechanics, ISSN 0268-0033, E-ISSN 1879-1271, Vol. 30, no 9, p. 1002-1007Article in journal (Refereed)
    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.

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  • 24. Dal Maso, Fabien
    et al.
    Raison, Maxime
    Lundberg, Arne
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Begon, Mickaël
    Coupling between 3D displacements and rotations at the glenohumeral joint during dynamic tasks in healthy participants.2014In: Clinical Biomechanics, ISSN 0268-0033, E-ISSN 1879-1271, Vol. 29, no 9, p. 1048-1055Article in journal (Refereed)
    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.

  • 25.
    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
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. 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.2019In: Topics in Stroke Rehabilitation, ISSN 1074-9357, E-ISSN 1945-5119, Vol. 26, no 4, p. 261-266Article in journal (Refereed)
    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.

  • 26.
    Dickinson, Andrew
    et al.
    Queen’s University, Kingston, ON, Canada.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Rainbow, Michael J.
    Queen’s University, Kingston, ON, Canada.
    Image Resolution Affects Tracking in vivo Biplanar X-ray Images of the Human Foot During Dynamic Motion2019Conference paper (Refereed)
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  • 27.
    Fischer, Katina Mira
    et al.
    German Sport University Cologne.
    Willwacher, Steffen
    German Sport University Cologne.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Wolf, Peter
    ETH Zurich.
    Brueggemann, Gert-Peter
    German Sport University Cologne.
    Calcaneal adduction in slow running: three case studies using intracortical pins.2017In: Footwear Science, ISSN 1942-4280, E-ISSN 1942-4299, Vol. 9, no 2, p. 87-93Article in journal (Refereed)
    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.

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  • 28.
    Fischer, Katina Mira
    et al.
    German Sport University, Cologne.
    Willwacher, Steffen
    German Sport University, Cologne.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Brüggemann, Gert-Peter
    German Sport University, Cologne.
    Calcaneal adduction and eversion are coupled to talus and tibial rotation.2018In: Journal of Anatomy, ISSN 0021-8782, E-ISSN 1469-7580, Vol. 233, no 1, p. 64-72Article in journal (Refereed)
    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.

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  • 29.
    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
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska Institutet.
    Altered patterns of displacement within the Achilles tendon following surgical repair2017In: Knee Surgery, Sports Traumatology, Arthroscopy, ISSN 0942-2056, E-ISSN 1433-7347, Vol. 25, no 6, p. 1857-1865Article in journal (Refereed)
    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.

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  • 30.
    Fröberg, Åsa
    et al.
    Karolinska Institute, Stockholm, Sweden.
    Mårtensson, Mattias
    KTH, Stockholm, Sweden.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska Institute, Stockholm, Sweden.
    The Effect of Ankle Foot Orthosis' Design and Degree of Dorsiflexion on Achilles Tendon Biomechanics: Tendon Displacement, Lower Leg Muscle Activation, and Plantar Pressure During Walking2020In: Frontiers in Sports and Active Living, E-ISSN 2624-9367, Vol. 2, article id 16Article in journal (Refereed)
    Abstract [en]

    Background: Following an Achilles tendon rupture, ankle foot orthoses (AFO) of different designs are used to protect the healing tendon. They are generally designed to protect against re-rupture by preventing undesired dorsiflexion and to prevent elongation by achieving plantarflexion in the ankle. There is limited knowledge of the biomechanical effects of different AFO designs and ankle angles on the tendon and lower leg muscles.Hypothesis: The hypothesis was that non-uniform displacement in the Achilles tendon, lower leg muscle activity, and plantar pressure distribution would be affected differently in different designs of AFO and by varying the degree of dorsiflexion limitation.Study Design: Controlled laboratory study.Methods: Ultrasound of the Achilles tendon, EMG of the lower leg muscles and plantar pressure distribution were recorded in 16 healthy subjects during walking on a treadmill unbraced and wearing three designs of AFO. Ultrasound speckle tracking was used to estimate motion within the tendon. The tested AFO designs were a rigid AFO and a dorsal brace used together with wedges and an AFO with an adjustable ankle angle restricting dorsiflexion to various degrees.Results: There were no significant differences in non-uniform tendon displacement or muscle activity between the different designs of AFO. For the rigid AFO and the adjustable AFO there was a significant reduction in non-uniform displacement within the tendon and soleus muscle activity as restriction in dorsiflexion increased.Conclusion: The degree of dorsiflexion allowed within an AFO had greater effects on Achilles tendon displacement patterns and muscle activity in the calf than differences in AFO design. AFO settings that allowed ankle dorsiflexion to neutral resulted in displacement patterns in the Achilles tendon and muscle activity in the lower leg which were close to those observed during unbraced walking.

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  • 31. Fröberg, Åsa
    et al.
    Mårtensson, Mattias
    Larsson, Matilda
    Janerot-Sjöberg, Birgitta
    D'Hooge, Jan
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    High variability in strain estimation errors when using a commercial ultrasound speckle tracking algorithm on tendon tissue.2016In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 57, no 10, p. 1223-1229Article in journal (Refereed)
    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.

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  • 32.
    Gago, Paulo
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska Institutet.
    Marques, Mário C.
    University of Beira Interior (UBI), Covilhã, Portugal.
    Marinho, Daniel A.
    University of Beira Interior (UBI), Covilhã, Portugal.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Effects of post activation potentiation on electromechanical delay2019In: Clinical Biomechanics, ISSN 0268-0033, E-ISSN 1879-1271, Vol. 70, p. 115-122Article in journal (Refereed)
    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.

  • 33.
    Gago, Paulo
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Maria M
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Post activation potentiation can be induced without impairing tendon stiffness.2014In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 114, no 11, p. 2299-2308Article in journal (Refereed)
    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.

  • 34.
    Gago, Paulo
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences. Research Center for Sport, Health and Human Development, (CIDESD), Portugal.
    Arndt, Toni
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Department of CLINTEC, Karolinska Institutet, Stockholm.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences. Department of Neuroscience, Karolinska Institutet, Stockholm.
    Post Activation Potentiation of the Plantarflexors: Implications of Knee Angle Variations2017In: Journal of Human Kinetics, ISSN 1640-5544, E-ISSN 1899-7562, Vol. 57, p. 29-38Article in journal (Refereed)
    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.

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  • 35.
    Gago, Paulo
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Toni
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Post activation potentiation electromechanical delay and achilles tendon stiffness in athletes2014Conference paper (Refereed)
  • 36.
    Gago, Paulo
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Toni
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Tarrassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Post activation potentiation and Achilles tendon stiffness in power athletes2013Conference paper (Refereed)
  • 37. Halvorsen, Kjartan
    et al.
    Tinmark, Fredrik
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    The concept of mobility in single- and double handed manipulation.2014In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 47, no 14, p. 3569-3573Article in journal (Refereed)
    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.

  • 38.
    Hegyi, Andras
    et al.
    University of Jyväskylä, Finland.
    Peter, Annamaria
    University of Jyväskylä, Finland.
    Andersson, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Finni, Taija
    University of Jyväskylä, Finland.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Cronin, Neil J.
    University of Jyväskylä, Finland.
    Ankle joint angle influences hamstring fine-wire and high-density electromyography activity in ramp isometric knee flexions2019Conference paper (Refereed)
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  • 39. Itayem, Raed
    et al.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Daniel, Joseph
    McMinn, Derek J W
    Lundberg, Arne
    A two-year radiostereometric follow-up of the first generation Birmingham mid head resection arthroplasty.2014In: HIP International, ISSN 1120-7000, E-ISSN 1724-6067, Vol. 24, no 4, p. 355-62Article in journal (Refereed)
    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.

  • 40.
    Jacques, Tiago Canal
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Bini, Rodrigo
    La Trobe Rural Health School, Bendigo, Australia.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Karolinska Institutet, Sweden..
    Bilateral In Vivo Neuromechanical Properties Of Thetriceps Surae And Achilles Tendon In Runners And Tri-Athletes2021In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 123, article id 110493Article in journal (Refereed)
    Abstract [en]

    Inter-limb differences in Achilles tendon mechanical, material and morphological properties have previously been described in non-athletes and attributed to the preferential use of a given limb. Achilles tendon overuse tendon injury generally initiate unilaterally and alters triceps surae activation and Achilles tendon properties. The investigation of inter-limb differences in muscle activation and tendon properties may provide directions for injury prevention in habitual runners. In this study triceps surae and Achilles tendon properties were investigated bilaterally in habitual runners during unilateral maximal isometric contractions. Morphological, mechanical and material Achilles tendon properties were assessed using isokinetic dynamometry, motion capture and ultrasonography while triceps surae activation strategies were assessed using electromyography. Lower limb preference was assessed for inter-limb comparisons using the Waterloo questionnaire. Zero and one-dimensional statistical analysis and Cohen’s d were employed to investigate possible inter-limb differences. Inter-limb associations in Achilles tendon properties and intra-limb associations between triceps surae activations were assessed using Pearson’s correlation coefficients. No differences were observed between the preferred and non-preferred limb in terms of triceps surae muscle activation amplitude and Achilles tendon properties. However, intra-limb association among triceps surae activation ratios were not identical between limbs. Runners and triathletes present similar Achilles tendons properties between limbs, and thus initial observations of unilateral changes in the Achilles tendon properties might be used as a strategy to prevent the onset of overuse tendon injury. The non-similar associations within activation ratios between limbs should be further explored since triceps surae activation strategies may alter loading of the Achilles tendon.

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  • 41.
    Jacques, Tiago Canal
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Bini, Rodrigo
    La Trobe Rural Health School, Bendigo, Australia.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Inter-limb differences in vivo tendon behavior, kinematics, kinetics and muscle activation during running2022In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 141, article id 111209Article in journal (Refereed)
    Abstract [en]

    Overloading of tendon tissue may result in overuse tendon injuries in runners. One possible cause of overloading could be the occurrence of biomechanical inter-limb differences during running. However, scarce information exists concerning the simultaneous analysis of inter-limb differences in external and internal loading-related variables in habitual runners. In this study ground reaction force, joint kinematics, triceps surae and tibialis anterior activations, and medial gastrocnemius muscle-tendon junction displacement were assessed bilaterally during treadmill running at 2.7 m.s-1 and 4.2 m.s-1. Statistical parametric t-tests and effect sizes were calculated to identify eventual inter-limb differences across the stance phase and stride cycle. Hip flexion angle was 9° greater (p = 0.03, ES = 0.30) in the non-preferred limb during the flight phase at 4.2 m.s-1. Hip extension velocity was 45 deg.s-1 greater (p = 0.04, ES = 0.41) during ground contact and 25 deg.s-1 greater (p = 0.02, ES = 0.41) immediately after toe-off in the non-preferred limb at 4.2 m.s-1. Hip extension velocity was also 40 deg.s-1 greater (p = 0.01, ES = 0.46) in the non-preferred limb prior to touch-down at 4.2 m.s-1. Brief inter-limb differences in joint kinematics were not accompanied by inter-limb differences in variables associated to internal loading, suggesting they are unlikely to be underlying factors leading to tendon overloading in healthy non-injured runners.

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  • 42.
    Jacques, Tiago Canal
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Bini, Rodrigo
    La Trobe Rural Health School , Bendigo, Australia.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska Institute, Sweden.
    Running after cycling induces inter-limb differences in muscle activation but not in kinetics or kinematics.2021In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 39, no 2, p. 154-160Article in journal (Refereed)
    Abstract [en]

    Overuse injuries are a common problem to triathletes' population. Overuse injuries may arise from inter-limb biomechanical differences during running, but the literature lacks information regarding inter-limb differences in triathletes. In this study inter-limb differences were investigated in injury-free triathletes during the running portion of a simulated cycle-run transition. Thirteen triathletes performed a 5 km run preceded by a 20 min cycling trial at 70% of maximal power output. During the Start, Mid and End stages of running, kinetic, kinematic and muscle activation variables were compared between the preferred and non-preferred limbs across the stance phase. A statistical parametric mapping analysis showed no differences between limbs when considering kinetic and kinematic variables (p > 0.05, ES<0.60). A lower soleus activation was observed in the preferred limb (p < 0.05, ES>0.60) from 53.40-75.9% of the stance phase at the End stage of running. In conclusion, inter-limb differences in kinetic or kinematic variables may not represent a risk for overloading in triathletes. However, inter-limb differences in triceps surae activation during running after cycling may represent one potential factor leading to overuse injuries in triathletes and should be further investigated.

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  • 43.
    Jacques, Tiago Canal
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Bini, Rodrigo R.
    La Trobe University, Bendigo, Australien.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    BILATERAL TENDON STRAIN DURING A 5-KM RUNNING TIME-TRIAL2019Conference paper (Refereed)
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  • 44.
    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
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. 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.2019In: Scientific Reports, E-ISSN 2045-2322, Vol. 9, no 1, article id 11836Article in journal (Refereed)
    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.

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  • 45. Lanferdini, Fábio J
    et al.
    Bini, Rodrigo R
    Figueiredo, Pedro
    Diefenthaeler, Fernando
    Mota, Carlos B
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Vaz, Marco A
    Differences in Pedaling Technique in Cycling: A Cluster Analysis.2016In: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 11, no 7, p. 959-964Article in journal (Refereed)
    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.

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  • 46.
    Leardini, Alberto
    et al.
    Movement Analysis Laboratory, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy.
    Stebbins, Julie
    Oxford Gait Laboratory, Oxford University Hospitals NHS Foundation Trust, UK.
    Hillstrom, Howard
    MD Motion Analysis Laboratory, Hospital for Special Surgery, NY, USA..
    Caravaggi, Paolo
    Movement Analysis Laboratory, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy..
    Deschamps, Kevin
    Faculty of Movement & Rehabilitation Sciences, KULeuven, Bruges, Belgium..
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Karolinska Institute, Stockholm, Sweden.
    ISB recommendations for skin-marker-based multi-segment foot kinematics.2021In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 125, article id 110581Article in journal (Refereed)
    Abstract [en]

    The foot is anatomically and functionally complex, and thus an accurate description of intrinsic kinematics for clinical or sports applications requires multiple segments. This has led to the development of many multi-segment foot models for both kinematic and kinetic analyses. These models differ in the number of segments analyzed, bony landmarks identified, required marker set, defined anatomical axes and frames, the convention used to calculate joint rotations and the determination of neutral positions or other offsets from neutral. Many of these models lack validation. The terminology used is inconsistent and frequently confusing. Biomechanical and clinical studies using these models should use established references and describe how results are obtained and reported. The International Society of Biomechanics has previously published proposals for standards regarding kinematic and kinetic measurements in biomechanical research, and in this paper also addresses multi-segment foot kinematics modeling. The scope of this work is not to prescribe a particular set of standard definitions to be used in all applications, but rather to recommend a set of standards for collecting, calculating and reporting relevant data. The present paper includes recommendations for the overall modeling and grouping of the foot bones, for defining landmarks and other anatomical references, for addressing the many experimental issues in motion data collection, for analysing and reporting relevant results and finally for designing clinical and biomechanical studies in large populations by selecting the most suitable protocol for the specific application. These recommendations should also be applied when writing manuscripts and abstracts.

  • 47.
    Liljedahl, Johanna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Nooijen, Carla F J
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Bjerkefors, Anna
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Isometric, dynamic, and manual muscle strength measures and their association with cycling performance in elite para-cyclists.2023In: American Journal of Physical Medicine & Rehabilitation, ISSN 0894-9115, E-ISSN 1537-7385, Vol. 102, no 5, p. 461-467Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: Para-cycling classification aims to generate fair competition by discriminating between levels of activity limitation. This study investigated the relationship between lower limb Manual Muscle Tests (MMT) with ratio-scaled measures of isometric and dynamic strength, and of the ratio-scaled measures with cycling performance.

    DESIGN: Fifty-six para-cyclists (44 males, 12 females) with leg impairments performed isometric and dynamic strength tests: leg push and pull, and an all-out 20 s sprint. MMT results were obtained from the classification database (n = 21) and race speeds from time trials (n = 54).

    RESULTS: Regression analyses showed significant associations of MMT with isometric push (R2 = .49), dynamic push (R2 = .35), and dynamic pull (R2 = .28). Isometric strength was significantly correlated with dynamic push (ρ = .63) and pull (ρ = .54). The isometric and dynamic tests were significantly associated with sprint power and race speed (R2 = .16-.50).

    CONCLUSION: The modified MMT and ratio-scaled measures were significantly associated. The significant relation of isometric and dynamic strength with sprint power and race speed maps the impact of lower limb impairments on para-cycling performance. MMT and the isometric and dynamic measures show potential for use in para-cycling classification.

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  • 48.
    Liljedahl, Johanna B
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Bjerkefors, Anna
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control. Karolinska institutet.
    Nooijen, Carla F J
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences. Karolinska institutet.
    Para-cycling race performance in different sport classes.2021In: Disability and Rehabilitation, ISSN 0963-8288, E-ISSN 1464-5165, Vol. 43, no 24, p. 3440-3444Article in journal (Refereed)
    Abstract [en]

    Purpose: The para-cycling classification system, consisting of five classes (C1-C5) for bicycling (C5 athletes having least impairments), is mostly based on expert-opinion rather than scientific evidence. The aim of this study was to determine the differences in race performance between para-cycling classes. Methods: From official results of the men's 1 km time trials for classes C1-C5 of seven Union Cycliste Internationale World Championships and Paralympics, median race speed of the five fastest athletes in each class was calculated (n = 175). Para-cycling results were expressed as a percentage of able-bodied performance using race results from the same years (n = 35). To assess differences between consecutive classes, Kruskal-Wallis tests with Mann-Whitney U post hoc tests were performed, correcting for multiple testing (p < 0.013). Results: Para-cyclists in C1 reached 75% (median ± interquartile range = 44.8 ± 4.2 km/h) and in C5 90% (53.5 ± 2.9 km/h) of able-bodied race speed (59.4 ± 0.9 km/h). Median race speed between consecutive classes was significantly different (χ2 = 142.6, p < 0.01), except for C4 (52.1 ± 2.8 km/h) and C5 (U = 447.0, p = 0.05). Conclusion: Current para-cycling classification does not clearly differentiate between classes with least impairments.IMPLICATIONS FOR REHABILITATIONThe current classification system is not evidence-based and does not clearly differentiate between relevant groups of para-cyclists.An evidence-based para-cycling classification system is essential for a fair and equitable competition.Fair competition will make it more interesting and increase participation.Para-cycling can inspire everyone with and even those without disabilities to be physically active.

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  • 49.
    Lindberg, Thomas
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    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
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Effects of seated double-poling ergometer training on aerobic and mechanical power in individuals with spinal cord injury2012In: Journal of Rehabilitation Medicine, ISSN 1650-1977, E-ISSN 1651-2081, Vol. 44, no 10, p. 893-898Article in journal (Refereed)
    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.

  • 50. Liu, Anmin
    et al.
    Nester, Christopher
    Jones, Richard
    Lundgren, Paul
    Lundberg, Arne
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Wolf, Peter
    The Effect of an Antipronation Foot Orthosis on Ankle and Subtalar Kinematics2012In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 44, no 12, p. 2384-91Article in journal (Refereed)
    Abstract [en]

    INTRODUCTION/PURPOSE:

    The aim of this study was to describe the effect of an anti pronation foot orthosis on motion of the heel relative to the leg and explore the individual contributions of the ankle and subtalar joints to this effect.

    METHODS:

    Five subjects were investigated using invasive intracortical pins to track the movement of the tibia, talus and calcaneus during walking with and without a foot orthosis.

    RESULTS:

    The anti pronation foot orthosis produced small and unsystematic reductions in eversion and abduction of the heel relative to the leg at various times during stance. Changes in calcaneus-tibia motion were comparable to those described in the literature (1-3°). Changes at both the ankle and subtalar joints contributed to this orthotic effect. However, the nature and scale of changes was highly variable between subjects. Peak angular position, range of motion and angular velocity in frontal and transverse planes were affected to different degrees in different subjects. In some cases changes occurred mainly at the ankle, in other cases changes occurred mainly at the subtalar joint.

    CONCLUSION:

    The changes in ankle and subtalar kinematics in response to the foot orthosis contradict existing orthotic paradigms that assume that changes occur only at the subtalar joint. The kinematic changes due to the orthosis are indicative of a strong interaction between the often common function of the ankle and subtalar joints.

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