Inferred Influence of Human Lateral Profile on Limb Load Asymmetry during a Quiet Standing Balance Test

Although the identification and characterisation of a participant's lateral profile during quiet standing have not received much research attention, they have the potential to greatly extend our understanding of upright stance stability control. This study further examines limb load asymmetries during quiet bipedal stance. During voluntary frontal-plane weight shifting for 2 min, 300 centre-of-pressure displacements on 14 blindfolded right-handed young adults were recorded. Four biomechanical indices were used to assess postural behaviour. These were the bias of time and the magnitude of the partial ground reaction forces from both legs, and the bias in the number and magnitude of microshifts influencing stability. Our study identifies a significant level of asymmetry in the quiet bipedal stance of right-handed people. This asymmetry is associated with the right-sided bias of the ground reaction force and the angle of inclination to the upright (vertical) centroidal line. We found that the initial lateralisation of the partial ground reaction forces from both feet, as well as the period of ground reaction force bias, are important elements in any clinical tests involving quiet bipedal stance.</p

Comparison of electromyographic activity of quadriceps muscle in persons with unilateral traumatic transtibial amputation using patellar tendon bearing supracondylar endoskeletal prosthesis with the unaffected limb in weight bearing positions.

Abstract Purpose: comparison of electromyographic activity of quadriceps muscle in persons with unilateral traumatic transtibial amputation using patellar tendon bearing supracondylar endoskeletal prosthesis with the unaffected limb in weight bearing positions. Method: 30 individuals&nbsp; aged 18-60 years were assessed using surface electromyography with functional level K3 according to K-level functional assessment scale to compare the activity of quadriceps of affected side using patellar tendon bearing supracondylar endoskeletal prosthesis with the unaffected side. The data was analysed using paired t-test. Result:&nbsp; There was a significant difference in the activity of VMO and VLO muscles of the quadriceps in high sitting positions. There was also a significant difference in the activity of VMO muscle in single limb stance and bipedal stance. However, there was no significant difference between the activity of VLO muscle in bipedal stance but there was reduced activity of VLO muscle in the prosthetic limb in single limb stance. Conclusion: The quadriceps activity was reduced in the affected limb in high sitting position, single&nbsp; limb stance and bipedal stance. However, no difference in the muscle activity was noted in VLO muscle in bipedal stance. Keywords: trans tibial amputation, patellar tendon bearing supracondylar prosthetis, surface electromyography.&nbsp

Comparison of electromyographic activity of quadriceps muscle in persons with unilateral traumatic transtibial amputation using patellar tendon bearing supracondylar endoskeletal prosthesis with the unaffected limb in weight bearing positions.

Abstract Purpose: comparison of electromyographic activity of quadriceps muscle in persons with unilateral traumatic transtibial amputation using patellar tendon bearing supracondylar endoskeletal prosthesis with the unaffected limb in weight bearing positions. Method: 30 individuals&nbsp; aged 18-60 years were assessed using surface electromyography with functional level K3 according to K-level functional assessment scale to compare the activity of quadriceps of affected side using patellar tendon bearing supracondylar endoskeletal prosthesis with the unaffected side. The data was analysed using paired t-test. Result:&nbsp; There was a significant difference in the activity of VMO and VLO muscles of the quadriceps in high sitting positions. There was also a significant difference in the activity of VMO muscle in single limb stance and bipedal stance. However, there was no significant difference between the activity of VLO muscle in bipedal stance but there was reduced activity of VLO muscle in the prosthetic limb in single limb stance. Conclusion: The quadriceps activity was reduced in the affected limb in high sitting position, single&nbsp; limb stance and bipedal stance. However, no difference in the muscle activity was noted in VLO muscle in bipedal stance. Keywords: trans tibial amputation, patellar tendon bearing supracondylar prosthetis, surface electromyography.&nbsp

Intrinsic foot muscles act to stabilise the foot when greater fluctuations in centre of pressure movement result from increased postural balance challenge

© 2020 The Author(s) Background: Increased postural balance challenge is associated with more fluctuations in centre of pressure movement, indicating increased interference from the postural control system. The role of intrinsic foot muscles in balance control is relatively understudied and whether such control system interference occurs at the level of these muscles is unknown. Research Question: Do fewer fluctuations in intrinsic foot muscle excitation occur in response to increased postural balance challenge? Methods: Surface EMGs were recorded using a grid of 13 × 5 channels from the plantar surface of the foot of 17 participants, who completed three balance tasks: bipedal stance; single leg stance and bipedal tip-toe. Centre of pressure (CoP) movement was calculated from simultaneously recorded force plate signals. Fluctuations in CoP and EMGs for each task were quantified using a sample entropy based metric, Entropy Halflife (EnHL). Longer EnHL indicates fewer signal fluctuations. Results: The shortest EMG EnHL, 9.27 ± 3.34 ms (median ± interquartile range), occurred during bipedal stance and the longest during bipedal tip-toe 15.46 ± 11.16 ms, with 18.80 ± 8.00 ms recorded for single leg stance. Differences were statistically significant between bipedal stance and both bipedal tip-toe (p < 0.001) and single leg stance (p < 0.001). CoP EnHL for both anterior-posterior and medial-lateral movements also differed significantly between tasks (p < 0.001, both cases). However, anterior-posterior CoP EnHL was longest for bipedal stance 259.84±230.22 ms and shortest for bipedal tip-toe 146.25±73.35 ms. Medial-lateral CoP EnHL was also longest during bipedal stance 215.73±187.58 ms, but shortest for single leg stance 113.48±83.01 ms. Significance: Fewer fluctuations in intrinsic foot muscle excitation occur in response to increased postural balance challenge. Fluctuations in CoP movement during balance must be predominantly driven by excitation of muscles extrinsic to the foot. Intrinsic foot muscles therefore likely play a greater role in stabilisation of the foot than balance control during the postural tasks studied

THE INFLUENCE OF HEAD POSITION ON POSTURAL STABILITY

The influence of head position on the stance stability was studied in a set of 51 healthy university students (men, n = 21; women, n = 30) in a bipedal stance and the stance on left and right leg respectively. The head position was standardised by observation of a fixed point through dominant and nondominant eye. Two AMTI force plates and 3D kinematic analysis (APAS system) were used for the evaluation of posture stability. No significant differences were found in the bipedal stance in all test procedures. The differences in the head positions have statistically and significantly influenced only the posture stability by stance on the left leg in both groups (dominant eye right and left) in contrast to the stance on the right leg where the differences were not statistically significant

Nutrition and Feeding Behavior of Goats and Sheep Grazing Deciduous Shrub-Woodland in Northeastern Brazil

Production of sheep and goats in the Brazilian Northeast is important for the livelihood of both subsistence and market-oriented producers. Seasonal nutritional stress oh animals in the caatinga vegetational zone of this region causes periodic high mortality and chronically low productivity. Under such conditions, the survivability of goats has been higher than for other domestic livestock. Possible reasons for this include unique aspects of dietary selection and goat feeding behavior. The objectives of this research were to seasonally determine the botanical and nutritive content of goat and sheep diets, to determine forage intake by grazing goats and sheep, and to compare their feeding behavior. Dietary selections by sheep and goats were similar during the dry season, but diverged markedly during the wet season. Leaf litter from the deciduous trees was the major dietary component for both species during the dry season, and provided the bulk of dry season forage. Current hypotheses predict that goats select diets of higher nutritional quality and have a greater forage intake than do sheep. Goats selected diets significantly (P.05) in cell wall content, and lower (P This study confirmed the vertical stratification of foraging by goats and sheep. Sheep foraged more in lower vertical strata than did goats. Goats spent about 4% of their grazing time in a bipedal stance, while sheep virtually never used a bipedal stance to feed. In addition, no nutritional advantage was found for goats over sheep through use of a bipedal stance. This latter finding is constrained by the deciduous nature of the caatinga woodland during the dry season

Parameter Reduction in the Frequency Analysis of Center of Pressure in Stabilometry

During postural stability evaluation frequency analyses are applied on the motion of the foot center of pressure (CoP). In this study we compared the most widely used frequency type CoP parameters (median frequency, mean power frequency, bandwidth) including some newly defined parameters (frequency range power ratios, spectral power ratio between the anteroposterior and mediolateral directions, largest CoP amplitude with the corresponding frequency). The parameters were acquired from 25 young and healthy participants. Correlation analysis was used to exclude parameters that contain redundant information. Variance analysis was used to evaluate the behavior and usability of the parameters in different stance conditions (bipedal stance with eyes open and eyes closed, single leg stance with eyes open) where the balancing capability alters. Based on our results we recommend using the largest amplitude and frequency power ratios between specified frequency bands, spectral power ratio between anteroposterior and mediolateral direction and mean power frequency

The effect of contact sport expertise on postural control

It has been demonstrated that expertise in sport influences standing balance ability. However, little is known concerning how physical contact in sport affects balance ability. The aim of this study was to examine whether differences between contact and limited-contact sport experiences results in differences in postural control. Twenty male collegiate athletes (10 soccer/contact, 10 baseball/limited contact) and ten male untrained students stood quietly on a force plate under various bipedal and unipedal conditions, with and without vision. Significant differences for sway area and COP speed were found between the soccer players and the other two groups for unipedal stances without vision. Soccer players were found to have superior postural control compared with participants involved in limited contact sport or no sport at all. Contact sports may lead to increased postural control through enhanced use of proprioceptive and vestibular information