Doering Thomas M, Jenkins David G, Reaburn Peter R, Borges Nattai R, Hohmann Erik, Phillips Stuart M
1School of Medical and Applied Sciences, Central Queensland University, Rockhampton, QLD, AUSTRALIA; 2School of Human Movement and Nutrition Sciences, The University of Queensland, St. Lucia, QLD, AUSTRALIA; 3Musculoskeletal Research Unit, Central Queensland University, Rockhampton, QLD, AUSTRALIA; 4Medical School, University of Queensland, St. Lucia, QLD, AUSTRALIA; and 5Department of Kinesiology, Exercise Metabolism Research Group, McMaster University, Hamilton, ON, CANADA.
Med Sci Sports Exerc. 2016 Aug;48(8):1613-8. doi: 10.1249/MSS.0000000000000935.
The objective of this study is to compare the integrated muscle protein synthesis (MPS) rates of masters and younger triathletes over three consecutive days of intense endurance training. Recovery of cycling performance, after muscle-damaging running, was also compared between groups.
Five masters (age, 53 ± 2 yr; V˙O2max, 55.7 ± 6.9 mL·kg·min) and six younger (age, 27 ± 2 yr; V˙O2max, 62.3 ± 1.5 mL·kg·min) trained triathletes volunteered for the study. Baseline skeletal muscle and saliva were initially sampled, after which a 150-mL bolus of deuterium oxide (70%) was consumed. Participants then completed a 30-min downhill run; three 20-km cycling time trials (TT) were completed 10, 24, and 48 h after the run. Saliva was collected each morning, and skeletal muscle was again sampled 72 h after the run; both were used for MPS analysis. Diet was controlled throughout the study.
Over 3 d, masters triathletes showed a significantly lower myofibrillar fractional synthetic rate (1.49% ± 0.12%·d) compared with the younger (1.70% ± 0.09%·d) triathletes (P = 0.009, d = 1.98). There was also a trend for masters triathletes to produce a slower cycle TT (-3.0%, d = 0.46) than younger triathletes (-1.4%, d = 0.29) at 10 h postrun in comparison with the baseline performance. The between-group comparison of change was moderate (d = 0.51), suggesting slower acute recovery among masters triathletes.
The present data show lower MPS rates in well-trained masters triathletes over 3 d of training, and this likely contributes to poorer muscle protein repair and remodeling. Furthermore, acute recovery of cycle TT performance tended to be poorer in the masters triathletes.
本研究的目的是比较成年和年轻铁人三项运动员在连续三天的高强度耐力训练中的肌肉蛋白合成（MPS）综合速率。同时，还比较了两组运动员在肌肉损伤性跑步后骑行成绩的恢复情况。
五名成年（年龄53±2岁；最大摄氧量55.7±6.9 mL·kg·min）和六名年轻（年龄27±2岁；最大摄氧量62.3±1.5 mL·kg·min）的训练有素的铁人三项运动员自愿参与本研究。首先采集基线骨骼肌和唾液样本，之后摄入150 mL大剂量氧化氘（70%）。参与者随后完成一次30分钟的下坡跑；在跑步后10、24和48小时完成三次20公里的骑行计时赛（TT）。每天早晨收集唾液，在跑步后72小时再次采集骨骼肌样本；两者均用于MPS分析。在整个研究过程中控制饮食。
在三天的时间里，成年铁人三项运动员的肌原纤维分数合成速率（1.49%±0.12%·天）显著低于年轻铁人三项运动员（1.70%±0.09%·天）（P = 0.009，d = 1.98）。与基线表现相比，成年铁人三项运动员在跑步后10小时的骑行TT成绩下降幅度（-3.0%，d = 0.46）也有比年轻铁人三项运动员（-1.4%，d = 0.29）更大的趋势。组间变化的比较为中等（d = 0.51），表明成年铁人三项运动员的急性恢复较慢。
目前的数据表明，训练有素的成年铁人三项运动员在三天训练中的MPS速率较低，这可能导致肌肉蛋白修复和重塑较差。此外，成年铁人三项运动员骑行TT成绩的急性恢复往往较差。
