EFFECTS OF BODY MASS AND CHAIR HEIGHT ON MUSCLE ACTIVATION AND BALANCE DURING SIT TO STAND
P. Mack, A. Gutierrez, G. Weiler, N. Denny, R.S. McCulloch
Gonzaga University, Spokane, WA
Performance of the sit to stand movement (STSm), a critical aspect of daily life, has been primarily studied in elderly populations. In addition, obesity has been shown to affect stability, but its relation to STSm has not been studied. PURPOSE: This study examined the impact of simulated weight gain on muscle activation and balance at varying chair heights in a young, healthy population. METHODS: Subjects (n=30, aged 20.9±1.25 yr), were asked to perform six STSm, at three different chair heights, under a bodyweight (BW) and added-weight (AW) condition. The chair heights were set at 80%, 100% and 120% of their knee height (lateral condyle of tibia to the floor) while the added weight (via a weight vest) was equal to 15% of their body weight. Muscle activation was evaluated for the rectus femoris (RF) and biceps femoris (BF) and normalized to their respective maximum voluntary contractions (MVCs). All trials were randomized and counter-balanced. CoP distance and velocity were compared between trials. RESULTS: RF Activation was the highest at the 80% seat height in both the AW (78.37 + 30.37%) and BW conditions (63.42 + 26.73%). Additionally, RF recruitment was significantly higher in AW vs. BW at all seat heights (p<.05). BF activation was significantly higher at the 80% AW seat height (19.80 + 11.56%) when compared to the 120% AW height (18.05 + 9.90%, p=.004). There were no changes in CoP distance or velocity for either seat height or weight condition. CONCLUSION: Increasing chair height under added and body weight conditions leads to decreased activation of the RF and BF suggesting a reduced difficulty in performing this movement. The RF, under the AW condition, was most effected by seat height changes. The findings indicate that increasing seat height does not alter balance. Our study suggests that weight gain impedes the ability to perform the STSm and that increasing chair height is a successful method in easing the difficulty of performing this movement.
Mack, P; Gutierrez, A; Weiler, G; Denny, N; and McCulloch, RS
"EFFECTS OF BODY MASS AND CHAIR HEIGHT ON MUSCLE ACTIVATION AND BALANCE DURING SIT TO STAND,"
International Journal of Exercise Science: Conference Proceedings: Vol. 8:
8, Article 64.
Available at: https://digitalcommons.wku.edu/ijesab/vol8/iss8/64