Changes In Biomechanical Factors Research Articles

Perception of task duration affects metabolic cost during split-belt adaptation.

Individuals can markedly reduce the metabolic cost of a walking adaptation task if they believe they must sustain the task for a prolonged time. The variables typically used to track adaptation do not track the reductions in metabolic cost observed in our study. Metabolic cost reduction can occur without clear changes in biomechanical factors.

Changes in Thoroughbred speed and stride characteristics over successive race starts and their association with musculoskeletal injury.

Certain stride characteristics have been shown to affect changes in biomechanical factors that are associated with injuries in human athletes. Determining the relationship between stride characteristics and musculoskeletal injury (MSI) may be key in limiting injury occurrence in the racehorse. This study aimed to determine whether changes in race day speed and stride characteristics over career race starts are associated with an increased risk of MSI in racehorses. Case-control study. Speed, stride length, and stride frequency data were obtained from the final 200 m sectional of n=5660 race starts by n=584 horses (case n=146, control n=438). Multivariable joint models, combining longitudinal and survival (time to injury) analysis, were generated. Hazard ratios and their 95% confidence intervals (CI) are presented. The risk of MSI increased by 1.18 (95% CI 1.09, 1.28; P< 0.001) for each 0.1m/s decrease in speed and by 1.11 (95% CI 1.02, 1.21; P= 0.01) for each 10cm decrease in stride length over time (career race starts). A more marked rate of decline in speed and stride length was observed approximately 6 races prior to injury. Risk of MSI was highest early in the horse's racing career. Only final sectional stride characteristics were assessed in the model. The model did not account for time between race starts. Decreasing speed and stride length over multiple races is associated with MSI in racehorses. Monitoring stride characteristics over time may be beneficial for the early detection of MSI.

Cervical Total Disc Replacement and Heterotopic Ossification: A Review of Literature Outcomes and Biomechanics.

Anterior cervical discectomy and fusion (ACDF) immobilizes surgical segments and can lead to the development of adjacent segment degeneration and adjacent segment disease. Thus, cervical total disc replacement (CTDR) has been developed with the aim to preserve the biomechanics of spine. However, heterotopic ossification (HO), a complication following CTDR, can reduce the segmental range of motion (ROM) and defects the motion-preservation benefit of CTDR. The pathological process of HO in CTDR remains unknown. HO has been suggested to be a self-defense mechanism in response to the non-physiological biomechanics of the cervical spine following CTDR. The current literature review is concerned with the association between the biomechanical factors and HO formation and the clinical significance of HO in CTDR. Endplate coverage, disc height, segmental angle, and center of rotation may be associated with the development of HO. The longer the follow-up, the higher the rate of ROM-limiting HO. Regardless of the loss of motion-preservation benefit of CTDR in patients with HO, CTDR confers patients with a motion-preservation period before the development of ROM-limiting HO. This may delay the development of adjacent segment degeneration compared with ACDF. Future clinical studies should explore the association between HO and changes in biomechanical factors of the cervical spine.

The impact of ankle\u2013foot orthoses on toe clearance strategy in hemiparetic gait: a cross-sectional study

BackgroundAnkle–foot orthoses (AFOs) are frequently used to improve gait stability, toe clearance, and gait efficiency in individuals with hemiparesis. During the swing phase, AFOs enhance lower limb advancement by facilitating the improvement of toe clearance and the reduction of compensatory movements. Clinical monitoring via kinematic analysis would further clarify the changes in biomechanical factors that lead to the beneficial effects of AFOs. The purpose of this study was to investigate the actual impact of AFOs on toe clearance, and determine the best strategy to achieve toe clearance (including compensatory movements) during the swing phase.MethodsThis study included 24 patients with hemiparesis due to stroke. The gait performance of these patients with and without AFOs was compared using three-dimensional treadmill gait analysis. A kinematic analysis of the paretic limb was performed to quantify the contribution of the extent of lower limb shortening and compensatory movements (such as hip elevation and circumduction) to toe clearance. The impact of each movement related to toe clearance was assessed by analyzing the change in the vertical direction.ResultsUsing AFOs significantly increased toe clearance (p = 0.038). The quantified limb shortening and pelvic obliquity significantly differed between gaits performed with versus without AFOs. Among the movement indices related to toe clearance, limb shortening was increased by the use of AFOs (p < 0.0001), while hip elevation due to pelvic obliquity (representing compensatory strategies) was diminished by the use of AFOs (p = 0.003). The toe clearance strategy was not significantly affected by the stage of the hemiparetic condition (acute versus chronic) or the type of AFO (thermoplastic AFOs versus adjustable posterior strut AFOs).ConclusionsSimplified three-dimensional gait analysis was successfully used to quantify and visualize the impact of AFOs on the toe clearance strategy of hemiparetic patients. AFO use increased the extent of toe clearance and limb shortening during the swing phase, while reducing compensatory movements. This approach to visualization of the gait strategy possibly contributes to clinical decision-making in the real clinical settings.Trial registrationUMIN000028946. Registered 31 August 2017 (retrospectively registered).

Running Economy Changes After Altitude Training: Role Of Running Mechanics

The oxygen cost of running at submaximal workloads is influenced in large part by individual differences in running mechanics. Several recent studies suggest that chronic altitude training may cause changes in submaximal oxygen uptake in elite endurance runners. Whether any change in running economy after altitude training is due to altered running mechanics is undetermined. PURPOSE: To determine if potential running economy changes after altitude training can be explained by changes in biomechanical factors. METHODS: Six elite male distance runners (VO2max 70.6 ± 4.5 mL/kg/min) completed a 28 day altitude training intervention in Flagstaff, Arizona, elevation 2150m, following a "live high - train low" training model. Running economy and gait parameters were measured 2-9 days prior to departure to altitude and 1-2 days after returning to sea level. Running economy was determined from VO2 measured in the final minute of 3 minute stages at 3 constant submaximal treadmill speeds of 291, 301, and 311 m/min. To measure variables related to running mechanics, subjects completed separate 30 second stages at constant treadmill speeds of 300, 315, 330, 345, and 360 m/min. Each running stage was separated by a period of standing rest. Wireless tri-axial 10g accelerometer devices, sampling at 1024 Hz, were securely attached to the laces of each shoe. Values of ground contact time, stride time, swing time, stride length, and stride frequency were determined from accelerometric output corresponding to foot strike and toe-off events obtained from a minimum of 25 consecutive steps. RESULTS: Post-altitude VO2 was higher at each submaximal workload (DVO2 pre- to post-altitude range 2.3 - 3.2 mL/kg/min; p range 0.037 - 0.115; n = 6). No significant differences were found in ground contact time, stride time, swing time, stride length or stride frequency at any speed after altitude training. CONCLUSIONS: Changes in running economy in elite endurance runners after chronic altitude training are not due to altitude mediated changes in running mechanics. Supported by the AAU/Bell-Updyke-Willett Kinesiology Research Fund, Indiana University School of HPER, and a grant from the High Performance Division, USA Track and Field.

L-DOPA-induced air-stepping in the preweanling rat: electromyographic and kinematic analyses.

Ontogenetic changes in intralimb coordination may result from maturation of the central pattern for locomotion, maturation of peripheral efferents, changes in afferent modulation of the centrally generated pattern, interactions with the substrate, biomechanical changes within the limb itself, or a combination of these. Electromyograms obtained from three hindlimb extensors of rats on Postnatal Days (PND) 5, 10, 15, or 20, during episodes of coordinated L-DOPA-induced air-stepping, showed that muscle activation preceded extension of the corresponding joints at all ages. The delay between the onset of extensor activity and the onset of joint extension increased during ontogeny and was greatest at PND 20. Ontogenetic changes in the relative timing of muscle activity and corresponding joint movements probably resulted from changes in biomechanical factors, changes in afferent modulation of central motor output, or both.