Brightwell Camille R, Markofski Melissa M, Moro Tatiana, Fry Christopher S, Porter Craig, Volpi Elena, Rasmussen Blake B
Department of Nutrition and Metabolism University of Texas Medical Branch Galveston Texas.
Division of Neuroscience, Cell Biology and Anatomy University of Texas Medical Branch Galveston Texas.
Transl Sports Med. 2019 Apr;2(3):109-119. doi: 10.1002/tsm2.70. Epub 2019 Feb 20.
Sarcopenia, age-associated involuntary loss of muscle and strength, can progress to clinically relevant functional decline. Resistance exercise attenuates muscle and strength loss but may not be feasible for some older adults. Aerobic exercise training (AET) improves cardiopulmonary health; however, effects on protein turnover, muscle mass, and strength are less clear. We aimed to determine whether AET improves basal myofibrillar protein synthesis (MPS) and capillarization, promoting hypertrophy and strength. We hypothesized that AET improves strength with increased MPS and capillarization. Older adults were randomized to non-exercise (NON; n = 11, 71.4 ± 4.18 years) or exercise (EX; n = 12, 73.7 ± 4.05 years). EX completed 24 weeks of AET (walking 3×/week, 45 minutes, 70% heart rate reserve); NON remained sedentary. A stable isotope tracer was infused. MPS and capillarization were analyzed from muscle biopsies. Strength was measured via isokinetic dynamometry. Lean mass was determined with dual-energy X-ray absorptiometry. Basal MPS increased in EX (+50.7%, =0.01) along with capillary density (+66.4%, =0.03), peak oxygen consumption (+15.8%, =0.01), quadriceps strength (+15.1%, =0.01), and muscle quality (peak torque divided by leg lean mass, +15.5%, =0.01). Lean mass did not change (>0.05). AET increases muscle protein turnover and capillarization in older adults, improving muscle quality.
肌肉减少症是与年龄相关的肌肉和力量的非自愿性丧失，可能会发展为具有临床意义的功能衰退。抗阻运动可减轻肌肉和力量的丧失，但对一些老年人来说可能不可行。有氧运动训练（AET）可改善心肺健康；然而，其对蛋白质周转、肌肉质量和力量的影响尚不清楚。我们旨在确定AET是否能改善基础肌原纤维蛋白合成（MPS）和毛细血管化，促进肌肉肥大和力量增强。我们假设AET通过增加MPS和毛细血管化来提高力量。老年人被随机分为非运动组（NON；n = 11，71.4 ± 4.18岁）或运动组（EX；n = 12，73.7 ± 4.05岁）。EX组完成了24周的AET（每周步行3次，每次45分钟，心率储备的70%）；NON组保持久坐不动。注入稳定同位素示踪剂。通过肌肉活检分析MPS和毛细血管化。通过等速测力法测量力量。用双能X线吸收法测定瘦体重。EX组的基础MPS增加（+50.7%，P = 0.01），同时毛细血管密度增加（+66.4%，P = 0.03）、峰值耗氧量增加（+15.8%，P = 0.01）、股四头肌力量增加（+15.1%，P = 0.01）以及肌肉质量（峰值扭矩除以腿部瘦体重）增加（+15.5%，P = 0.01）。瘦体重没有变化（P>0.05）。AET可增加老年人的肌肉蛋白质周转和毛细血管化，改善肌肉质量。
