Effects of Lower Extremity Training on Unstable Surfaces on Muscular Strength and Balance in Middle-aged Women

Abstract

Purpose: This study examines the influence of lower extremity muscular training on stable supporting surfaces and unstable supporting surfaces on muscle strength and balance in middle-aged women. It aims to contribute to the design of a lower extremity exercise program for middle-aged females. Methods: In this study, 20 middle-aged women were randomly assigned into two groups―experimental group (ET, n = 10) and control group (CT, n = 10)―and tested at baseline and at the 8-week follow-up. Subjects in both groups were put on a lower extremity training program 2 times per week for 8 weeks. The intensity was set at 40%-50% intensity of 1RM for weeks 1-2, 50%-60% intensity of 1RM for weeks 3-6, and 60%-70% intensity of 1RM for weeks 7-8, with 10-15 repetitions. Subjects in the ET exercised on unstable surfaces, while those in the control group exercised on stable surfaces. Conclusion: In this study, the static balance was significantly improved in both the experimental group exercising on the unstable support surface and the control group exercising on the stable support surface. The dynamic balance, which was only improved in the experimental group exercising on the unstable support surface, improved in all directions except the backward. In this study, the strength and endurance of the knee extensors were improved in both the experimental group and the control group, and the strength and endurance of the knee flexors were improved only in the experimental group that exercised on an unstable support surface. Exercises on unstable surfaces further improve knee flexion. Thus, this study suggests that training on unstable support surfaces has a greater favorable effect on muscle strength and balance in middle-aged women than exercise on stable support surfaces.