Oxfeldt Mikkel, Phillips Stuart M, Andersen Ole Emil, Johansen Frank Ted, Bangshaab Maj, Risikesan Jeyanthini, McKendry James, Melin Anna Katarina, Hansen Mette
Department of Public Health, Aarhus University, Aarhus C, Denmark.
Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada.
J Physiol. 2023 Aug;601(16):3481-3497. doi: 10.1113/JP284967. Epub 2023 Jun 29.
Low energy availability (LEA) describes a state where the energy intake is insufficient to cover the energy costs of both exercise energy expenditure and basal physiological body functions. LEA has been associated with various physiological consequences, such as reproductive dysfunction. However, the effect of LEA on skeletal muscle protein synthesis in females performing exercise training is still poorly understood. We conducted a randomized controlled trial to investigate the impact of LEA on daily integrated myofibrillar and sarcoplasmic muscle protein synthesis in trained females. Thirty eumenorrheic females were matched based on training history and randomized to undergo 10 days of LEA (25 kcal · kg fat-free mass (FFM) · day ) or optimal energy availability (OEA, 50 kcal · kg FFM · day ). Before the intervention, both groups underwent a 5-day 'run-in' period with OEA. All foods were provided throughout the experimental period with a protein content of 2.2 g kg lean mass · day . A standardized, supervised combined resistance and cardiovascular exercise training programme was performed over the experimental period. Daily integrated muscle protein synthesis was measured by deuterium oxide (D O) consumption along with changes in body composition, resting metabolic rate, blood biomarkers and 24 h nitrogen balance. We found that LEA reduced daily integrated myofibrillar and sarcoplasmic muscle protein synthesis compared with OEA. Concomitant reductions were observed in lean mass, urinary nitrogen balance, free androgen index, thyroid hormone concentrations and resting metabolic rate following LEA. These results highlight that LEA may negatively affect skeletal muscle adaptations in females performing exercise training. KEY POINTS: Low energy availability (LEA) with potential health and performance impairments is widespread among female athletes. We investigated the impact of 10 days of LEA on daily integrated myofibrillar and sarcoplasmic muscle protein synthesis in young, trained females. We show that LEA impairs myofibrillar and sarcoplasmic muscle protein synthesis in trained females performing exercise training. These findings suggest that LEA may have negative consequences for skeletal muscle adaptations and highlight the importance of ensuring adequate energy availability in female athletes.
低能量可利用状态（LEA）是指能量摄入不足以满足运动能量消耗和基础生理身体功能的能量需求的一种状态。LEA与多种生理后果相关，如生殖功能障碍。然而，LEA对进行运动训练的女性骨骼肌蛋白质合成的影响仍知之甚少。我们进行了一项随机对照试验，以研究LEA对受过训练的女性每日肌原纤维和肌浆蛋白合成的综合影响。30名月经正常的女性根据训练史进行匹配，并随机分为两组，分别接受10天的低能量可利用状态饮食（25千卡·千克去脂体重·天）或最佳能量可利用状态饮食（OEA，50千卡·千克去脂体重·天）。在干预前，两组均经历了为期5天的最佳能量可利用状态饮食“适应期”。在整个实验期间提供所有食物，蛋白质含量为2.2克·千克瘦体重·天。在实验期间进行了标准化的、有监督的抗阻和心血管运动训练计划。通过氧化氘（D₂O）消耗以及身体成分、静息代谢率、血液生物标志物和24小时氮平衡的变化来测量每日肌肉蛋白质合成的综合情况。我们发现，与最佳能量可利用状态饮食相比，低能量可利用状态饮食降低了每日肌原纤维和肌浆蛋白合成的综合水平。低能量可利用状态饮食后，瘦体重、尿氮平衡、游离雄激素指数、甲状腺激素浓度和静息代谢率也随之降低。这些结果表明，低能量可利用状态可能对进行运动训练的女性骨骼肌适应性产生负面影响。要点：存在潜在健康和运动表现损害的低能量可利用状态在女性运动员中普遍存在。我们研究了10天低能量可利用状态饮食对年轻、受过训练的女性每日肌原纤维和肌浆蛋白合成综合情况的影响。我们发现，低能量可利用状态饮食会损害进行运动训练的女性的肌原纤维和肌浆蛋白合成。这些发现表明，低能量可利用状态可能对骨骼肌适应性产生负面影响，并突出了确保女性运动员有足够能量可利用的重要性。
