The age-associated reduction in muscle mass is well characterized; however, less is known regarding the mechanisms responsible for the decline in oxidative capacity also observed with advancing age. The purpose of the current study was therefore to compare mitochondrial gene expression and protein content between young and old recreationally active, and older highly active individuals. Muscle biopsies were obtained from the vastus lateralis of young males (YG: 22 ± 3 years) and older (OG: 67 ± 2 years) males not previously engaged in formal exercise and older male master cyclists (OT: 65 ± 5 years) who had undertaken cycling exercise for 32 ± 17 years. Comparison of gene expression between YG, OG, and OT groups revealed greater expression of mitochondrial-related genes, namely, electron transport chain (ETC) complexes II, III, and IV (p < .05) in OT compared with YG and OG. Gene expression of mitofusion (MFN)-1/2, mitochondrial fusion genes, was greater in OT compared with OG (p < .05). Similarly, protein content of ETC complexes I, II, and IV was significantly greater in OT compared with both YG and OG (p < .001). Protein content of peroxisome proliferator-activated receptor gamma, coactivator 1 α (PGC-1α), was greater in OT compared with YG and OG (p < .001). Our results suggest that the aging process per se is not associated with a decline in gene expression and protein content of ETC complexes. Mitochondrial-related gene expression and protein content are substantially greater in OT, suggesting that exercise-mediated increases in mitochondrial content can be maintained into later life.

中文翻译：

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晚年高水平的身体活动与线粒体代谢标志物的增强有关。

与年龄相关的肌肉量减少已得到充分表征；然而，对于随着年龄的增长也观察到的氧化能力下降的机制，人们知之甚少。因此，当前研究的目的是比较年轻和年老的娱乐活跃者以及年长的高度活跃个体之间的线粒体基因表达和蛋白质含量。肌肉活检取自股外侧肌年轻男性（YG：22 ± 3 岁）及以上（OG：67 ± 2 岁）以前未参加过正式锻炼的男性以及进行过 32 ± 17年。比较 YG、OG 和 OT 组之间的基因表达表明，与 YG 和 OG 相比，OT 中线粒体相关基因，即电子传递链 (ETC) 复合物 II、III 和 IV (p < .05) 的表达更高。与 OG 相比，线粒体融合基因 mitofusion (MFN)-1/2 的基因表达在 OT 中更高 ( p < .05)。同样，与 YG 和 OG 相比，OT 中 ETC 复合物 I、II 和 IV 的蛋白质含量显着更高（p<.001）。与 YG 和 OG 相比，OT 中过氧化物酶体增殖物激活受体 γ、共激活因子 1 α (PGC-1α) 的蛋白质含量更高 ( p < .001)。我们的结果表明，衰老过程本身与 ETC 复合物的基因表达和蛋白质含量下降无关。OT 中线粒体相关基因表达和蛋白质含量显着增加，表明运动介导的线粒体含量增加可以维持到以后的生活。