Weight Loss And Exercise Effects On Torque Development And Physical Function In Overweight Older Women

Abstract

PURPOSE: Obesity negatively impacts lower extremity physical function [LEPF] and is associated with loss of independent living in part due to reduced muscle quality and capacity, especially in older women. Concurrent exercise/physical activity and weight loss interventions have been shown to improve LEPF. However, the inclusion of power modulations, specifically rate of torque development [RTD] parameters in response to these interventions has not been investigated. The aim of this study was to determine the effects of weight loss, with or without exercise training, on RTD parameters and their potential impact on LEPF in overweight physically inactive older women. METHODS: This project involved a secondary data analysis from a 6-month parent project that involved weight loss involving different dietary regimens with or without exercise. Overweight inactive postmenopausal women (n = 44, 69.1 ± 3.6 yrs; 30.6 ± 4.3 kg/m2) completed the trial within two groups: 1) exercise and weight loss [EX+WL; (N = 30)] and weight loss alone [WL; (N = 14)]. Knee flexor and extensor strength and power were assessed via a maximum voluntary contraction [MVIC] using an isokinetic dynamometry with RTD parameters [RTD200 = RTD at 200 ms, RTDPeak = Peak RTD and T2P = Time to 1st Peak]. LEPF was assessed via 6-min walk, 8-ft up and go, and 30-s chair stand. RESULTS: Weight loss was similar in the groups (-7.1 ± 4.1 kg; -9.8 ± 4.2%, p > 0.95) whereas EX+WL had greater improvements in most LEPF tasks (p < 0.001). EX+WL had a greater increase in RTD200 Flexion compared with WL (36% vs. -16%, p = 0.031), with no other differences in RTD parameters observed. No significant regression models were observed predicting change in LEPF performance from changes in RTD parameters (all p > 0.05). CONCLUSIONS: These findings suggest weight loss, which incorporates exercise training, can improve LEPF and rate of torque development in overweight/obese physically inactive older women, yet these improvements do not appear to transfer to improvements in physical function task performance