Adam J. Santanasto, Department, of Epidemiology, University of Pittsburgh, Pittsburgh, PA, USA,
J Frailty Aging. 2022;11(1):40-44. doi: 10.14283/jfa.2021.47.
Body composition and muscle strength change vary by age and ethnicity, and have a major impact on health and physical function. Little is known about the patterns of these changes in African-ancestry populations. Herein, we examined age-specific (5-year age groups) rates-of-change in lean and fat mass in 1918 African-ancestry men on the Caribbean island of Tobago (baseline age: 62.0±11.8 years, range: 40-99 years). Body composition (DXA) and grip strength were measured at three time points (baseline, 4- and 9-year follow-up). Annualized rates of change were calculated with all 3 time-points using Generalized Estimating Equations. We found that whole body lean mass declined at constant rate until age 65 (-0.72%/year; 95% CI: -0.76, -0.67), which accelerated to -0.92 %/year (-1.02, -0.82) among those 65-69, and again to -1.16 %/year (-1.30, -1.03 ) among those aged 70+. Whole body fat mass increased by a near constant rate of 2.93 %/year (2.72, 3.15%) across the lifespan. Finally, grip strength decline accelerated at age 50, and about 2x faster than lean mass through the lifespan after the age of 50. To conclude, in African-Caribbean men, the acceleration in muscle strength decline precedes the acceleration in lean mass decline by 10-15 years, suggesting decrements in factors other than lean mass drive this initial acceleration in muscle strength decline. We also found that African-Caribbean men undergo a constant shift to a more adipogenic phenotype throughout the adult lifespan (aged 40-99), which likely contributes to age-related loss of muscle and physical function.
人体成分和肌肉力量的变化因年龄和种族而异，对健康和身体功能有重大影响。关于非裔人群这些变化的模式知之甚少。在此，我们研究了特立尼达岛上的 1918 名非裔男性（基线年龄：62.0±11.8 岁，范围：40-99 岁）在特定年龄段（每 5 年一个年龄段）的瘦体重和脂肪量的变化率。使用双能 X 线吸收法（DXA）和握力在三个时间点（基线、4 年和 9 年随访）进行测量。使用广义估计方程，通过所有 3 个时间点计算年变化率。我们发现，全身瘦体重以恒定速度下降，直到 65 岁（-0.72%/年；95%CI：-0.76，-0.67），在 65-69 岁之间加速到-0.92%/年（-1.02，-0.82），在 70 岁以上再次加速到-1.16%/年（-1.30，-1.03）。全身脂肪量以近乎恒定的速度增加，终生增加 2.93%/年（2.72，3.15%）。最后，握力下降在 50 岁时加速，并且在 50 岁以后的整个生命周期中，比瘦体重快约 2 倍。总之，在非裔加勒比男性中，肌肉力量下降的加速比瘦体重下降的加速早 10-15 年，这表明除瘦体重以外的因素的减少导致了肌肉力量下降的最初加速。我们还发现，非裔加勒比男性在整个成年期（40-99 岁）经历了向更脂肪生成表型的持续转变，这可能导致与年龄相关的肌肉和身体功能丧失。
