The association between testosterone and muscle mass, muscle strength, and physical function in Korean men aged 60 and older

Abstract

BACKGROUND: Ageing in men is associated with decline in serum testosterone level. Previous studies have shown that low testosterone level is an important cause of sarcopenia which contributes to development of frailty in elderly men. Sarcopenia was defined by low muscle mass in prior studies. However this study is to see the association between serum testosterone level and sarcopenia according to the new sarcopenia definition which considers not only muscle mass, but also muscle strength and gait speed in Korean men aged 60 years and older. METHOD: Cross-sectional observational study of 161 participants who underwent routine check-up at Ajou University Hospital Health Promotion Center from March 1st, 2011 to September 30th, 2012. Participants were community-dwelling healthy men aged 60 years and older. Outcome measures include muscle mass using dual energy X-ray absorptiometry (DXA), muscle strength by grip strength and physical performance by gait speed. Hypogonadism was defined by serum testosterone level of less than 350ng/dL. Muscle mass was calculated with appendicular skeletal muscle (ASM) by height square or weight. RESULTS: Serum testosterone had significant relationship with muscle mass (ASM adjusted for body weight: p=0.023). However, serum testosterone had no significant relationship with muscle mass (ASM adjusted for height square: p=0.132), muscle strength (p=0.773), and gait speed (p=0.201). Subjects were divided into quartiles according to serum testosterone level, which had no significant relationship with muscle mass (ASM/ht²: p=0.224, ASM/wt: p=0.169), muscle strength (p=0.100), and gait speed (p=0.064). Hypogonadism did not show significant relationship with sarcopenia defined by ASM/ht² (p=0.463) nor by ASM/wt (p=0.115). CONCLUSION: Decreased serum testosterone has little predictive value of functional impairment represented by muscle mass adjusted by height (ASM/ht2), muscle strength, and gait speed. However, muscle mass adjusted by body weight (ASM/wt) had significant relationship with serum testosterone.

배경: 연령의 증가와 혈중 테스토스테론의 농도의 감소는 연관이 있다. 이전 연구에 따르면, 고령의 남성에서 노쇠를 일으키는 가장 큰 요소인 근감소증의 원인으로 낮은 혈중 테스토스테론이 밝혀진 바 있다. 본 논문의 요지는 60세 이상 한국 남성에서의 테스토스테론 수치에 따른 근육량, 근력, 보행속도와의 관계를 보는 것이다. 방법: 2011년 3월부터 2012년 9월까지 아주대학교 병원 건강검진센터에서 건강검진을 받은 161명의 건강검진 결과를 바탕으로 하였다. 근육량은 DXA, 근력은 악력, 보생속도는 2m 거리를 주행하는데 걸리는 시간으로 측정하였다. 결과: 혈중 테스토스테론의 농도와 근육량 (ASM/ht2: p=0.132, ASM/wt: p=0.023), 근력 (p=0.773), 보행속도 (p=0.201)의 연관성을 본 결과 몸무게로 보정한 근육량 값 이외에는 유의한 관련성을 보이지 않았다. 혈중 테스토스테론을 4분위로 나누어 다시 연관성을 살펴보았지만, 유의한 관련성을 보이지 않았다. 성선저하증 (혈중 테스토스테론 <3.50ng/dL)도 유의한 연관성을 보이지 않았다. 결론: 혈중 테스토스테론 농도의 감소는 근육량 (몸무게로 보정한 값) 이외에 근육량(키로 보정한 값, 근력, 보행속도)의 예측 인자로 보기 어렵다.