Optimal loading involves the prescription of an exercise stimulus that promotes positive tissue adaptation, restoring function in patients undergoing rehabilitation and improving performance in healthy athletes. Implicit in optimal loading is the need to monitor the response to load, but what constitutes a normal response to loading? And does it differ among tissues (e.g., muscle, tendon, bone, cartilage) and systems? In this paper, we discuss the “normal” tissue response to loading schema and demonstrate the complex interaction among training intensity, volume, and frequency, as well as the impact of these training variables on the recovery of specific tissues and systems. Although the response to training stress follows a predictable time course, the recovery of individual tissues to training load (defined herein as the readiness to receive a similar training stimulus without deleterious local and/or systemic effects) varies markedly, with as little as 30 min (e.g., cartilage reformation after walking and running) or 72 h or longer (e.g., eccentric exercise-induced muscle damage) required between loading sessions of similar magnitude. Hyperhydrated and reactive tendons that have undergone high stretch–shorten cycle activity benefit from a 48-h refractory period before receiving a similar training dose. In contrast, bone cells desensitize quickly to repetitive loading, with almost all mechanosensitivity lost after as few as 20 loading cycles. To optimize loading, an additional dose (≤ 60 loading cycles) of bone-centric exercise (e.g., plyometrics) can be performed following a 4–8 h refractory period. Low-stress (i.e., predominantly aerobic) activity can be repeated following a short (≤ 24 h) refractory period, while greater recovery is needed (≥ 72 h) between repeated doses of high stress (i.e., predominantly anaerobic) activity. The response of specific tissues and systems to training load is complex; at any time, it is possible that practitioners may be optimally loading one tissue or system while suboptimally loading another. The consideration of recovery timeframes of different tissues and systems allows practitioners to determine the “normal” response to load. Importantly, we encourage practitioners to interpret training within an athlete monitoring framework that considers external and internal load, athlete-reported responses, and objective markers, to contextualize load–response data.

最佳负荷包括开具运动刺激剂的处方，以促进积极的组织适应，恢复接受康复的患者的功能并提高健康运动员的表现。最佳加载中隐含着需要监控对负载的响应，但什么构成了对负载的正常响应呢？它在不同的组织（例如肌肉、肌腱、骨骼、软骨）和系统之间是否不同？在本文中，我们讨论了“正常”组织对负荷模式的反应，并展示了训练强度、体积和频率之间的复杂相互作用，以及这些训练变量对特定组织和系统恢复的影响。尽管对训练压力的反应遵循可预测的时间过程，但单个组织对训练负荷的恢复（本文定义为准备接受类似的训练刺激而没有有害的局部和/或全身影响）差异很大，短至 30 分钟（例如，步行和跑步后软骨整形）或 72 小时或更长时间（例如， 离心运动引起的肌肉损伤）在类似幅度的负荷训练之间需要。在接受类似的训练剂量之前，经过高拉伸缩短周期活动的缺水和反应性肌腱受益于 48 小时的不应期。相比之下，骨细胞对重复负荷迅速脱敏，几乎所有的机械敏感性在短短 20 个负荷循环后就消失了。为了优化负荷，可以在 4-8 小时不应期后进行额外剂量（≤ 60 次负荷循环）的以骨为中心的运动（例如增强式训练）。低应力（即，主要是好氧）活动可以在短暂 （≤ 24 小时） 不应期后重复，而在重复剂量的高应激 （即，主要厌氧） 活动之间需要更大的恢复 （≥ 72 小时）。特定组织和系统对训练负荷的响应是复杂的;在任何时候，从业者都有可能以最佳方式加载一种组织或系统，而以次优方式加载另一种组织或系统。考虑不同组织和系统的恢复时间框架使从业者能够确定对负荷的“正常”反应。重要的是，我们鼓励从业者在运动员监测框架内解释训练，该框架考虑了外部和内部负荷、运动员报告的反应和客观标记，以将负荷-反应数据置于上下文中。