Abstract
Assessing vertical ground reaction forces (VGRF) during a chair rise may yield insight regarding age-related differences in physical function, but a comprehensive assessment of rate of force development (RFD) during this task is lacking. PURPOSE: To compare RFD parameters during a chair rise in young (YM) and older (OM) males, and examine correlates of chair rise time. METHODS: Healthy, YM (n=15, age=20.7±2.2 yrs) and OM (n=15, age=71.6±3.9 yrs) performed a single chair rise as quickly as possible on a force plate without upper-body assistance. Peak VGRF (PF), as well as peak (highest 100 ms rolling average), early (minimum VGRF to 50% PF), late (50% PF to PF), and overall (minimum VGRF to PF) RFD were recorded. RFD was calculated as the linear slope of the force-time curve (Δforce/Δtime) during the corresponding time spans. All force measures were derived from the normalized (body mass) force signal. Chair rise time was also obtained and the trial with the shortest time was used for subsequent analysis. Independent samples t-tests were used for group comparisons, and Pearson correlation coefficients were calculated for each group to examine select relationships. RESULTS: Chair rise time was similar between groups (p=0.256). Early RFD was similar (p=0.051), while PF (YM=1.57±0.13 vs. OM=1.33±0.10 N·kg; p<0.001), peak (YM=12.60±1.56 vs. OM=9.05±1.46 N/s·kg-1; p<0.001), late (YM=8.12±1.63 vs. OM=4.97±1.10 N/s·kg-1; p<0.001), and overall RFD (YM=7.57±1.24 vs. OM= 5.49±1.16 N/s·kg-1; p<0.001) were lower in the OM. For OM, only PF (r=-0.875; p<0.001) and peak RFD (r=-0.783; p=0.001) were correlated with chair rise time, while no correlations were present in YM. CONCLUSION: PF and RFD, especially peak and late RFD, were dramatically diminished during a chair rise in OM. PF and peak RFD demonstrated a strong inverse relationship with chair rise time in OM.
Published Version
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