Forearm muscle quality as a better indicator of physical performance than handgrip strength in older male ground golf players aged 70 to 89

OBJECTIVES To examine the associations between absolute and relative handgrip strength (HGS) and physical performance. METHODS A total of 135 old men aged 70-89 years had muscle thickness (MT) measured by ultrasound at anterior forearm (MT-ulna). Maximum voluntary HGS was measured for the dominant hand. Relative HGS was calculated as ratios of HGS to MT-ulna (HGS/MT-ulna, kg/cm), HGS to forearm girth (HGS/forearm-girth, kg/cm), and HGS to body mass (HGS/body mass, kg/kg). Physical performance was also assessed using the short physical performance battery (SPPB). RESULTS Age was significantly correlated with absolute and relative HGS (r=-0.479 and r=-0.315 to -0.427, respectively all p<0.001) and physical performance (walking speed, r=-0.218, p=0.011; chair stand, r=0.348, p<0.001), but not with SPPB score (r=-0.083). Absolute HGS was positively correlated with usual-walking speed (r=0.354, p<0.001) and was inversely correlated with chair-stand time (r=-0.386, p<0.001). The strongest correlations were seen between HGS/MT-ulna and usual-walking speed (r=0.426, p<0.001) or chair-stand (r=-0.461, p<0.001). Stepwise regression analysis revealed that HGS/MT-ulna was a significant predictor for U-walk speed (R2=0.205) and chair-stand time (R2=0.241) while absolute HGS was not a significant predictor of either one. CONCLUSION Thus, we suggest that forearm muscle quality (HGS/MT-ulna) may be a stronger predictor of physical performance than absolute HGS in active old men.