Age-related Decline in Handgrip Strength and Loss of Forearm Muscle Size and/or Muscle Quality in Men

Abstract

Age-related decline in handgrip strength (HGS) is associated with several unfavorable health conditions and an increased risk of all-cause mortality. In general, muscle strength declines at a higher rate than muscle mass. Thus, an age-related decline in muscle strength/mass ratio (i.e., muscle quality) would be expected, however, it is unknown whether muscle quality in the forearm associates with HGS in the aging process. PURPOSE: To investigate the relationships between age-related declines in HGS and loss of forearm muscle size and/or muscle quality in men. METHODS: Two hundred fifty men aged 20-89 had muscle thickness (MT) measured by ultrasound at the anterior forearm of the dominant hand. MT was measured as the perpendicular distance between the subcutaneous adipose tissue-muscle interface and muscle-bone interface of the ulna (MT-ulna). HGS was also measured for the dominant hand with a hand dynamometer. Muscle quality (MQ) was defined as a ratio of HGS to MT-ulna. A one-way ANOVA determined differences between age groups for each variable and Pearson correlation coefficients were performed for all variables. Statistical significance was set at p<0.05. RESULTS: HGS was similar among younger groups (47.6 [7.5] kg in aged 20-29 (n=34), 48.8 [7.7] kg in aged 30-39 (n=23) and 47.5 [7.2] kg in aged 40-49 (n=25)) and it decreased (p<0.001) gradually with age (43.8 [6.7] kg in aged 50-59 (n=47), 40.6 [6.7] kg in aged 60-69 (n=46), 36.7 [5.1] kg in aged 70-79 (n=47) and 33.4 [4.6] kg in aged 80-89 (n=28). MT-ulna was similar among young and middle-aged groups (3.92 [0.30] cm in aged 20-29, 3.85 [0.38] cm in aged 30-39, 3.83 [0.35] cm in aged 40-49, 3.82 [0.33] cm in aged 50-59 and 3.81 [0.29] cm in age 60-69) and was lower (p<0.01) in aged 70-79 (3.66 [0.26] cm) and aged 80-89 (3.58 [0.32] cm) compared to the aged 20-29. MQ was similar among younger groups (aged 20-29 to aged 40-49) and it decreased (p<0.01) gradually with age. MQ was strongly correlated to HGS in each age group (r=0.767-0.873), while MT-ulna was low to moderately correlated to HGS in each age group (r=0.344-0.759). CONCLUSIONS: Age-related decline in HGS is associated with MQ, but it appears to be accelerated after age 70 due to forearm muscle loss. Future research could investigate this further by looking at the association between loss of forearm muscle mass/MQ and mortality.