Int J Sports Physiol Perform. 2020 Feb 28;15(6):808-815. doi: 10.1123/ijspp.2019-0208. Print 2020 Jul 1.
The growing prevalence and popularity of interval training necessitate additional guidelines in regard to maximal levels of time and intensity.
To correlate salivary hormones and time in varying heart-rate (HR) zones. The hypothesis was that chronic exercise durations >9% of total exercise time in the >90% maximum HR zone would lead to decreased variation in salivary cortisol concentration after exercise in a 2-bout high-intensity protocol compared with less or more time in this zone.
A total of 35 healthy adults who regularly exercised for an average of 8 hours per week recorded their HR during every training session for 3 weeks. Later, they completed an experimental day composed of two 30-minute high-intensity interval sessions separated by 4 hours of nonactive recovery. The authors collected saliva samples before, immediately following, and 30 minutes after each exercise session to assess changes in cortisol concentrations.
There was a correlation between weekly time training at an intensity >90% maximum HR and the variables associated with overtraining. Salivary cortisol concentration fluctuated less in the participants who exercised in this extreme zone for >40 minutes per week (P < .001).
Based on the current study data, for individuals who regularly exercise, 4% to 9% total training time above 90% maximum HR is the ideal duration to maximize fitness and minimize symptoms related to overreaching.
间歇训练的流行程度不断增加，因此有必要针对时间和强度的最高水平制定额外的指南。
分析不同心率（HR）区间内唾液激素与时间的相关性。研究假设是，在高强度两回合方案中，与该区间内的时间较少或较多相比，慢性运动时间超过总运动时间的 9%，并且在最大 HR 的 90%以上，会导致运动后唾液皮质醇浓度的变化减少。
共有 35 名健康成年人平均每周锻炼 8 小时，他们在 3 周内记录了每次训练的 HR。之后，他们完成了一个由两个 30 分钟高强度间歇训练组成的实验日，中间间隔 4 小时非活动恢复期。作者在每次运动前后收集唾液样本，以评估皮质醇浓度的变化。
每周在最大 HR 的 90%以上强度训练的时间与与过度训练相关的变量之间存在相关性。每周在该极限区域运动超过 40 分钟的参与者，唾液皮质醇浓度波动较小（P <.001）。
根据本研究数据，对于经常锻炼的人来说，最大 HR 的 90%以上的总训练时间占 4%至 9%是最大限度地提高健身效果并最大程度减少过度训练相关症状的理想持续时间。
