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  • 1.
    Crommert, M Eriksson
    et al.
    Örebro Universitet.
    Nordlund Ekblom, Maria M
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Activation of transversus abdominis varies with postural demand in standing.2011In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 33, no 3, p. 473-7Article in journal (Refereed)
    Abstract [en]

    Transversus abdominis (TrA) is a multifunctional muscle, being involved in pressure regulation within the abdominal cavity and thereby in direction independent stabilization of the spine and resistance to imposed trunk flexion moments. Indirect evidence suggests a role of TrA also in postural control of the erect human trunk. The main purpose here was to investigate if the magnitude of TrA activation is related to postural demand. Eleven healthy males performed seven different symmetrical static bilateral arm positions holding 3 kg in each hand. The arm positions were selected to systematically vary the height of the centre of mass (COM) keeping imposed moments constant and vice versa. EMG was recorded bilaterally with fine-wire intramuscular electrodes from TrA and obliquus internus (OI) and with surface electrodes from rectus abdominis (RA) and erector spinae (ES). Intra-abdominal pressure (IAP) was measured via a pressure transducer in the gastric ventricle. TrA was the only muscle that displayed activation co-varying with the vertical position of the COM. Further, TrA activation increased, together with IAP and ES activation, with imposed flexion moment, i.e. with arms extended horizontally forward. In contrast to OI, RA and ES, TrA activation was independent of the direction of the imposed moment (arms held inclined forward or backward). In conclusion, TrA activation level is uniquely associated with increased postural demand caused by elevated COM. Also, TrA appears to assist in counteracting trunk flexion via increased IAP, and contribute to general spine stabilization when the trunk is exposed to moderate flexion and extension moments.

  • 2.
    Halvorsen, Kjartan
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Eriksson, Martin
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Gullstrand, Lennart
    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, Laboratory for Biomechanics and Motor Control.
    Minimal marker set for center of mass estimation in running.2009In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 30, no 4, p. 552-555Article in journal (Refereed)
    Abstract [en]

    The purpose was to study the validity of a recently proposed method [Forsell C, Halvorsen K. A method for determining minimal sets of markers for the estimation of center of mass, linear and angular momentum. Journal of Biomechanics 2009;42(3):361-5] for estimating the trajectory of the whole-body center of mass (CoM) in the case of running at velocities ranging from 10 to 22 kmh(-1). The method gives an approximation to the CoM using the position of fewer markers on the body than the standard method of tracking each segment of the body. Fourteen male athletes participated. A standard method for determining the CoM from a model of 13 segments and using the position of 36 markers was used as reference method. Leave-one-out cross-validation revealed errors that decreased with increasing number of markers used in the approximative method. Starting from four markers, the error in absolute position of the CoM decreased from 15mm to 3mm in each direction. For the velocity of the CoM the estimation bias was neglectable, and the random error decreased from 0.15 to 0.05 ms(-1). The inter-subject and intra-subject variability in the estimated model parameters increased with increasing number of markers. The method worked well also when applied to running at velocities outside the range of velocities in the data used to determine the model parameters. The results indicate that a model using 10 markers represents a good trade-off between simplicity and accuracy, but users must take into account requirements of their specific applications.

  • 3. Harringe, M L
    et al.
    Halvorsen, Kjartan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Renström, Per
    Karolinska institutet.
    Werner, S
    Postural control measured as the center of pressure excursion in young female gymnasts with low back pain or lower extremity injury.2008In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 28, no 1, p. 38-45Article in journal (Refereed)
    Abstract [en]

    Gymnasts are known to practice and compete although suffering from injuries and pain. Pain may change strategies for postural control. The primary aim of the present study was to investigate how center of pressure (COP) measurements are influenced by low back pain and lower extremity injury in top-level female gymnasts. A secondary aim was to study the reliability of these measurements using a test-retest design, and how this depends on the duration of the test. Fifty-seven top-level gymnasts were included in four groups: non-injured (NI, n=18), low back pain (LBP, n=11), lower extremity injury (LEI, n=17) and a multiple injury group (MI, n=11). COP excursion during quiet stance was measured on a force platform, during 120s: (1) hard surface/eyes open, (2) hard surface/eyes closed, (3) foam surface/eyes open and (4) foam surface/eyes closed. The COP excursion increased, for all groups, during the foam surface/eyes closed measurement compared to the other three tests. Furthermore, the LBP group showed a 49% (p=0.01) larger COP area compared to the LEI group in the foam surface/eyes closed condition. Measurements on foam surface were in general more reliable than tests on hard surface and tests with eyes closed were more reliable than tests with eyes open. Tests during 120s were in most cases more reliable than tests during 60s. In conclusion the COP excursion is influenced by injury location. Quiet stance measurements on foam surface with eyes closed seems to be reliable and sensitive in young female gymnasts.

  • 4. Hodges, P W
    et al.
    Cresswell, A G
    Daggfeldt, Karl
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Three dimensional preparatory trunk motion precedes asymmetrical upper limb movement.2000In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 11, no 2, p. 92-101Article in journal (Refereed)
    Abstract [en]

    Three-dimensional trunk motion, trunk muscle electromyography and intra-abdominal pressure were evaluated to investigate the preparatory control of the trunk associated with voluntary unilateral upper limb movement. The directions of angular motion produced by moments reactive to limb movement in each direction were predicted using a three-dimensional model of the body. Preparatory motion of the trunk occurred in three dimensions in the directions opposite to the reactive moments. Electromyographic recordings from the superficial trunk muscles were consistent with preparatory trunk motion. However, activation of transversus abdominis was inconsistent with control of direction-specific moments acting on the trunk. The results provide evidence that anticipatory postural adjustments result in movements and not simple rigidification of the trunk.

  • 5. Hodges, Paul W
    et al.
    Cresswell, Andrew G
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Thorstensson, Alf
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Intra-abdominal pressure response to multidirectional support-surface translation.2004In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 20, no 2, p. 163-70Article in journal (Refereed)
    Abstract [en]

    A complex response of the trunk muscles occurs to restore equilibrium in response to movement of the support surface. Intra-abdominal pressure (IAP) is considered to contribute to control of the trunk. This study investigated the contribution of IAP to the postural response to multidirection support-surface translation. IAP was recorded with a thin-film pressure transducer inserted via the nose into the stomach and trunk motion was recorded with an optoelectronic system with markers over the spinous process of L1. A pattern of trunk movement was recorded in response to the support-surface translations that was consistent with a 'hip' strategy of postural control. The trunk moved in a manner appropriate to move the centre of gravity over the new base of support. IAP was increased with movement in each direction, but varied in timing and amplitude between translation directions. In general, the IAP was greater with translations in the sagittal plane compared to the frontal plane and was initiated earlier for translations in the backward direction. These data indicate that IAP contributes to the postural response associated with support-surface translation and suggest that this is consistent with stiffening the spine.

  • 6. Houdijk, H.
    et al.
    ter Hoeve, N.
    Nooijen, Carla
    Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, The Netherlands.
    Rijntjes, D.
    Tolsma, M.
    Lamoth, C.
    Energy expenditure of stroke patients during postural control tasks2010In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 32, no 3, p. 321-6Article in journal (Refereed)
    Abstract [en]

    Two common impairments in patients after stroke are loss of balance control and fatigue. We propose that both could be inter-related. The purpose of this study was to investigate the metabolic energy demand for balance control in patients after stroke during upright standing. Ten stroke patients and 12 able-bodied controls performed four 5-min upright standing tasks on a force plate; unperturbed (SU), blindfolded (SUB), on foam surface (SUF) and with feet parallel against each other (SUP). Metabolic energy expenditure, posturography measures and muscle activity (EMG) of lower leg muscles were measured. Patients required on average 125% (33Jkg(-1)s(-1)) more metabolic energy for upright standing under the various conditions than controls. In addition, balance manipulation significantly (p<0.05) affected energy expenditure (21% higher in SUB, 52% in SUF, 40% in SUP compared to SU). Although the increase in energy expenditure was on average twice as high in patients than controls no significant group by condition interaction effect was found. Overall correlations between posturography measures, EMG and energy expenditure (r=0.33-0.60) were significant (p<0.001). We conclude that impaired balance control puts an extra demand on the energy expenditure during motor activities in stroke patients. This should be considered when prescribing interventions aimed at reducing physiological strain.

  • 7. Laughton, Carrie A
    et al.
    Slavin, Mary
    Katdare, Kunal
    Nolan, Lee
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Bean, Jonathan F
    Kerrigan, D Casey
    Phillips, Edward
    Lipsitz, Lewis A
    Collins, James J
    Aging, muscle activity, and balance control: physiologic changes associated with balance impairment.2003In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 18, no 2, p. 101-8Article in journal (Refereed)
    Abstract [en]

    Older adults demonstrate increased amounts of postural sway, which may ultimately lead to falls. The mechanisms contributing to age-related increases in postural sway and falls in the elderly remain unclear. In an effort to understand age-related changes in posture control, we assessed foot center-of-pressure (COP) displacements and electromyographic data from the tibialis anterior, soleus, vastus lateralis, and biceps femoris collected simultaneously during quiet-standing trials from elderly fallers, elderly non-fallers, and healthy young subjects. Both traditional measures of COP displacements and stabilogram-diffusion analysis were used to characterize the postural sway of each group. Regression analyses were used to assess the relationship between the COP measures and muscle activity. Elderly fallers demonstrated significantly greater amounts of sway in the anteroposterior (AP) direction and greater muscle activity during quiet standing compared with the young subjects, while elderly non-fallers demonstrated significantly greater muscle activation and co-activation compared with the young subjects. No significant differences were found between elderly fallers and elderly non-fallers in measures of postural sway or muscle activity. However, greater postural sway in both the AP and mediolateral (ML) directions and trends of greater muscle activity were found in those older adults who demonstrated lower scores on clinical measures of balance. In addition, short-term postural sway was found to be significantly correlated with muscle activity in each of these groups. This work suggests that high levels of muscle activity are a characteristic of age-related declines in postural stability and that such activity is correlated with short-term postural sway. It is unclear whether increases in muscle activity preclude greater postural instability or if increased muscle activity is a compensatory response to increases in postural sway.

  • 8. Maiwald, Christian
    et al.
    Arndt, Anton
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Nester, Chris
    Jones, Richard
    Lundberg, Arne
    Wolf, Peter
    The effect of intracortical bone pin application on kinetics and tibiocalcaneal kinematics of walking gait2017In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 52, p. 129-134Article in journal (Refereed)
    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.

  • 9.
    Nolan, Lee
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Kerrigan, D Casey
    Postural control: toe-standing versus heel-toe standing.2004In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 19, no 1, p. 11-5Article in journal (Refereed)
    Abstract [en]

    Toe-standing is observed in a number of populations who are able to stand without loss of balance and also those who have balance problems. Intuitively, individuals who stand on their toes are able to successfully regulate their whole body movement in order to keep themselves stable. Force platform data were collected for ten able-bodied subjects during three quiet standing postures, (a) heel-toe standing; (b) half-toe standing and (c) standing en demi pointe (full toe-standing). Differences in control mechanisms with each posture were compared using stabilogram diffusion analysis. During open-loop control (short-term), toe-standing is less stable than heel-toe standing (P<0.05). There is greater stochastic activity when toe-standing (P<0.05), suggesting that any short-term instability is being compensated for by an increase in muscle activity across the lower joints. During closed-loop control (long-term), there is no difference in mediolateral (ML) stochastic activity (increased activity has been linked to falls) between toe-standing and heel-toe standing. In addition, toe-standing is more stable than heel-toe standing (P< s0.05). Toe-standing, in and of itself, may not be responsible for balance problems in populations who compulsorily toe-stand.

  • 10.
    Nolan, Lee
    et al.
    Liverpool John Moores University.
    Wit, Andrzej
    Dudziñski, Krzysztof
    Lees, Adrian
    Lake, Mark
    Wychowañski, Michał
    Adjustments in gait symmetry with walking speed in trans-femoral and trans-tibial amputees.2003In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 17, no 2, p. 142-51Article in journal (Refereed)
    Abstract [en]

    The effect of increased walking speed on temporal and loading asymmetry was investigated in highly active trans-femoral and trans-tibial amputees. With increasing walking speed, temporal gait variables reduced in duration, particularly on the prosthetic limb, while vertical ground reaction force (vGRF) increased in magnitude, particularly on the intact limb. Thus, temporal asymmetry reduced and loading asymmetry increased with walking speed. The greater force on the intact limb may reflect the method by which the amputees achieve greater temporal symmetry in order to walk fast, and could possibly account for greater instances of joint degeneration in the intact limb reported in the literature.

  • 11.
    Åberg, Anna Cristina
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Frykberg, Gunilla Elmgren
    Halvorsen, Kjartan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Medio-lateral stability of sit-to-walk performance in older individuals with and without fear of falling.2010In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 31, no 4, p. 438-43Article in journal (Refereed)
    Abstract [en]

    Most falls in older people are due to loss of balance during everyday locomotion, e.g., when initiating walking from sitting; sit-to-walk (STW). It has been considered that the broader stride width in walking that is seen in many people with fear of falling (FoF) does not increase stability, but could be predictive of future falls because of increased medio-lateral (ML) velocity of the body centre of mass (CoM). This study was aimed to examine step-, velocity- and stability-related parameters, focusing on ML stability, in STW performance of people with and without FoF. Ten subjects with FoF and 10 matched controls, aged > or = 70 years, were included. Kinematic and kinetic data were collected in a laboratory. Stability parameters were calculated from a formula implying that the vertical projection of the CoM extrapolated by adding its velocity times a factor radicall/g (height of inverted pendulum divided by gravity) should fall within the base of support (BoS). A related spatial margin of stability (SMoS), defined as the minimum distance from the extrapolated CoM (XCoM) to the boundaries of the BoS, was also calculated. In the phase 'seat-off-second-toe-off', the FoF group had significantly (p<0.05) shorter and broader steps, lower forward but similar ML CoM velocity, and broader CoM and XCoM widths. The FoF group therefore exhibited a disproportionately large sideways velocity compared to the controls. This indicates that STW may be a hazardous transfer for older people with FoF, which should be relevant in assessment and training aimed at preventing falls.

  • 12.
    Åberg, Anna Cristina
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Thorstensson, Alf
    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.
    Halvorsen, Kjartan
    School of Technology and Health, KTH-Royal Institute of Technology, Stockholm, Sweden.
    Calculations of mechanisms for balance control during narrow and single-leg standing in fit older adults: A reliability study.2011In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 34, no 3, p. 352-7Article in journal (Refereed)
    Abstract [en]

    For older people balance control in standing is critical for performance of activities of daily living without falling. The aims were to investigate reliability of quantification of the usage of the two balance mechanisms M1 ‘moving the centre of pressure’ and M2 ‘segment acceleration’ and also to compare calculation methods based on a combination of kinetic (K) and kinematic (Km) data, (K–Km), or Km data only concerning M2. For this purpose nine physically fit persons aged 70–78 years were tested in narrow and single-leg standing. Data were collected by a 7-camera motion capture system and two force plates. Repeated measure ANOVA and Tukey's post hoc tests were used to detect differences between the standing tasks. Reliability was estimated by ICCs, standard error of measurement including its 95% CI, and minimal detectable change, whereas Pearson's correlation coefficient was used to investigate agreement between the two calculation methods. The results indicated that for the tasks investigated, M1 and M2 can be measured with acceptable inter- and intrasession reliability, and that both Km and K–Km based calculations may be useful for M2, although Km data may give slightly lower values. The proportional M1:M2 usage was approximately 9:1, in both anterio-posterior (AP) and medio-lateral (ML) directions for narrow standing, and about 2:1 in the AP and of 1:2 in the ML direction in single-leg standing, respectively. In conclusion, the tested measurements and calculations appear to constitute a reliable way of quantifying one important aspect of balance capacity in fit older people.

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