Association of Testosterone With Lean Soft Tissue and Handgrip Strength Across Middle-Aged Men

Background: Testosterone declines by 0.4%-2% annually after the age of 30 and is potentially linked with muscle mass and strength. This study examined how testosterone levels are associated with handgrip strength (HGS) and appendicular lean soft tissue index (ALSTI) in men aged 40-49 and 50-59 years. Methods: Data were sourced from the National Health and Nutrition Examination Survey (NHANES) cycles (2011-2014). The median values of each cohort (378.2 and 378.6 ng/dL for those aged 40-49 and 50-59 years of age, respectively) and the European Association of Urology guidelines were used to define higher serum testosterone, HGS and ALSTI. Linear and logistic regressions assessed associations between higher/lower serum testosterone with higher/lower HGS and ALSTI for each age group. Results: In 1001 men aged 40-59 years, higher total testosterone levels were positively associated with higher HGS, with stronger links in the 50- to 59-year-olds (b = 1.35, 95% confidence interval [CI] 0.08-2.62, p < 0.01). In this group, higher testosterone was linked to increased odds ratio (OR) of having higher HGS (OR: 1.73, 95% CI 1.17-2.55, p < 0.01). Per European Association of Urology guidelines, men with testosterone levels above deficiency (≥ 230 ng/dL) had higher odds of increased ALSTI versus those with deficiency (OR: 3.31, 95% CI 1.42-7.74, p < 0.01), while normal testosterone (> 346 ng/dL) versus deficiency showed a significant albeit weaker association (OR: 2.48, 95% CI 1.35-4.57, p < 0.01). Linear regression confirmed an ALSTI increase above deficiency (b = 0.20, 95% CI 0.05-0.34, p < 0.01); however, normal versus suspected deficiency for total testosterone was linked to a small but potentially minor clinically significant difference with ALSTI in the whole cohort (b = 0.10, 95% CI 0.00-0.19, p = 0.049). Normal testosterone was linked to higher HGS overall (OR: 1.37, 95% CI 1.05-1.80, p = 0.02) and in men aged 50-59 years (OR: 1.53, 95% CI 1.03-2.28, p = 0.03). Conclusions: Normal and higher than deficiency testosterone levels in men aged 40-59, particularly 50- to 59-year-olds, are associated with higher HGS and ALSTI compared with those with deficient testosterone concentrations.