Exercise Effects On Muscle Capacity And Physical Function In Older Overweight Women And Chronic Stroke Survivors.

Purpose: Mobility is critical to maintain physical independence especially for overweight older adults and individuals afflicted by stroke. Leg rate of torque development [RTD] as a measure of peak muscle power and asymmetry of muscle power [%ASYM] have emerged as potential predictors of lower extremity physical function [LEPF] but the plasticity of these outcomes in response to exercise training is unknown. Methods: Utilizing secondary data analysis from two separate intervention studies: 1) a 6-month exercise and diet-induced weight loss intervention for overweight inactive older women, and 2) an 8-week POWER training intervention for chronic stroke survivors, the three primary aims of this dissertation were: a) to determine the relative effect of weight loss with or without exercise training [EX+WL vs. WL] on changes in RTD (Aim 1) and %ASYM (Aim 2) and subsequent associations with changes in LEPF in overweight and obese older women, b) to determine the effect of power training on RTD parameters and subsequent changes in gait and walking performance in chronic stroke survivors (Aim 3). Results: For primary aims 1 and 2, weight loss was similar in both groups (p > 0.95) averaging -7.14.1kg; -9.8%  4.2%. RTD Flexion improved in EX+WL compared with WL (36% vs. -16%; p = 0.031), with no other changes in RTD parameters being apparent; change in RTD was not associated with changes in LEPF. No group changes in %ASYM were observed. Reductions in Leg Flexors %ASYM, alone, were associated with improvements in UPGO independently explaining 15.8% of the variance (p <0.05). For primary aim 3, our results suggest POWER training to be an effective intervention for improving RTD in both the paretic and nonparetic limbs, however, only improvements in the nonparetic limb RTD were associated (p < 0.05) with changes in walking speed (r = 0.66) and walking task performance (r = 0.88). Conclusion: Our results suggest exercise training can improve RTD, but not %ASYM indices of power in older women undergoing weight loss but the impact on LEPF appears negligible. Furthermore, POWER training can be an effect intervention post-stroke to improve gait characteristics and walking ability.