Mary McKillop Institute for Health Research, Australian Catholic University, Melbourne, AUSTRALIA.
Female Athlete Program, Boston Children's Hospital and Harvard Medical School, Boston, MA.
Med Sci Sports Exerc. 2023 Jan 1;55(1):55-65. doi: 10.1249/MSS.0000000000003022. Epub 2022 Aug 12.
Although an acute exercise session typically increases bone turnover markers (BTM), the impact of subsequent sessions and the interaction with preexercise calcium intake remain unclear despite the application to the "real-life" training of many competitive athletes.
Using a randomized crossover design, elite male rowers ( n = 16) completed two trials, a week apart, consisting of two 90-min rowing ergometer sessions (EX1, EX2) separated by 150 min. Before each trial, participants consumed a high (CAL; ~1000 mg) or isocaloric low (CON; <10 mg) calcium meal. Biochemical markers including parathyroid hormone (PTH), serum ionized calcium (iCa) and BTMs (C-terminal telopeptide of type I collagen, osteocalcin) were monitored from baseline to 3 h after EX2.
Although each session caused perturbances of serum iCa, CAL maintained calcium concentrations above those of CON for most time points, 4.5% and 2.4% higher after EX1 and EX2, respectively. The decrease in iCa in CON was associated with an elevation of blood PTH ( P < 0.05) and C-terminal telopeptide of type I collagen ( P < 0.0001) over this period of repeated training sessions and their recovery, particularly during and after EX2. Preexercise intake of calcium-rich foods lowered BTM over the course of a day with several training sessions.
Preexercise intake of a calcium-rich meal before training sessions undertaken within the same day had a cumulative and prolonged effect on the stabilization of blood iCa during exercise. In turn, this reduced the postexercise PTH response, potentially attenuating the increase in markers of bone resorption. Such practical strategies may be integrated into the athlete's overall sports nutrition plan, with the potential to safeguard long-term bone health and reduce the risk of bone stress injuries.
尽管一次急性运动训练通常会增加骨转换标志物（BTM），但随后的训练课程的影响以及与运动前钙摄入量的相互作用仍不清楚，尽管这适用于许多竞技运动员的“现实生活”训练。
使用随机交叉设计，16 名精英男性赛艇运动员在相隔一周的两次试验中完成了两次 90 分钟的划船测功仪训练（EX1、EX2），每次训练之间间隔 150 分钟。在每次试验之前，参与者都摄入了高钙（CAL；约 1000 毫克）或等热量低钙（CON；<10 毫克）餐。从基线到 EX2 后 3 小时，监测甲状旁腺激素（PTH）、血清离子钙（iCa）和 BTM（I 型胶原 C 端肽、骨钙素）等生化标志物。
尽管每次训练都会引起血清 iCa 波动，但在大多数时间点，CAL 使钙浓度保持在 CON 之上，分别高出 4.5%和 2.4%。CON 中 iCa 的下降与血液 PTH 的升高（P<0.05）和 I 型胶原 C 端肽（P<0.0001）相关，这一时期内重复的训练课程及其恢复过程中，特别是在 EX2 期间和之后。运动前摄入富含钙的食物可以降低 BTM，特别是在一天内进行多次训练课程的情况下。
在同一天内进行的训练课程之前摄入富含钙的膳食，对运动期间血液 iCa 的稳定具有累积和持久的影响。反过来，这减少了运动后的 PTH 反应，可能会减轻骨吸收标志物的增加。这种实用策略可以整合到运动员的整体运动营养计划中，有潜力保护长期的骨骼健康并降低骨应激损伤的风险。
