The Interaction of Cognitive Interference, Standing Surface, and Fatigue on Lower Extremity Muscle Activity

BACKGROUND: Performing cognitive tasks and muscular fatigue have been shown to increase muscle activity of the lower extremity during quiet standing. A common intervention to reduce muscular fatigue is to provide a softer shoe-surface interface. However, little is known regarding how muscle activity is affected by softer shoe-surface interfaces during static standing. The purpose of this study was to assess lower extremity muscular activity during erect standing on three different standing surfaces, before and after an acute workload and during cognitive tasks. METHODS: Surface electromyography was collected on ankle dorsiflexors and plantarflexors, and knee flexors and extensors of fifteen male participants. Dependent electromyography variables of mean, peak, root mean square, and cocontraction index were calculated and analyzed with a 2 × 2 × 3 within-subject repeated measures analysis of variance. RESULTS: Pre-workload muscle activity did not differ between surfaces and cognitive task conditions. However, greater muscle activity during post-workload balance assessment was found, specifically during the cognitive task. Cognitive task errors did not differ between surface and workload. CONCLUSIONS: The cognitive task after workload increased lower extremity muscular activity compared to quite standing, irrespective of the surface condition, suggesting an increased demand was placed on the postural control system as the result of both fatigue and cognitive task.

Predictors of bone mineral density among asian indians in northern mississippi: a pilot study

Background: Osteoporosis is a systemic skeletal disorder characterized by low bone mineral density [BMD] that leads to an increase in bone fragility, causing an individual to be at an increased risk for fractures. Asian-Indians are at an increased risk for developing Osteoporosis. Considering the number of Asian-Indians in the US is rapidly growing, they likely could be an underappreciated population at risk for bone fractures. The aim of this study was to investigate bone health and determine the factors affecting BMD in Asian-Indians living in the US

Methods: Asian-Indians residing in Northern Mississippi [n = 87] were enrolled in this cross-sectional study from June 2013 to August 2014. Eligible participants completed a self-administered Osteoporosis Risk Factor Assessment questionnaire. BMD and body composition were measured using a dual energy x-ray absorptiometry scan [DXA]

Results: Eight-seven Asian-Indians [male: 62.1%] participated, with the average age being 28.49 yr old [SD = +/-6.62]. Overall, 31.0% and 48.3% had low femoral neck BMD and spinal BMD, respectively. Multiple regression analysis revealed that age, percent body fat, and body mass index [BMI] significantly predicted BMD at femur neck [P<0.05]. Additionally, percent body fat, BMI, childhood milk consumption, and gender were statistically significant predictors of spinal BMD [P<0.05]

Conclusions: The findings from this study should be beneficial to healthcare providers that work with Asian-Indian population groups. Health promotion programs focusing on Osteoporosis prevention are needed among Asian-Indians to prevent the risk of fractures