05/09/2026
From a physiologic standpoint, higher-intensity work increases both mechanical load and metabolic stress per session. Ground reaction forces rise with speed, the rate of force development increases, and tissue loading becomes more rapid and less forgiving. At the same time, metabolic demand shifts toward greater glycolytic contribution, increasing lactate production, sympathetic activation, and overall recovery burden.
The cardiovascular system adapts quickly to these stresses, which often gives my patients a false sense of readiness. Connective tissues, however, adapt more slowly. Tendons require a long duration of progressive loading to increase stiffness and tolerance. Bone responds over time to impact through remodeling. Cartilage health is influenced by load, but also by the surrounding muscular system that distributes that load.
When intensity is introduced before these adaptations occur, the system becomes unbalanced. Patients often present with achilles tendinopathy, patellofemoral pain, proximal hamstring irritation, or bone stress injuries after a relatively short period of increased training intensity. The onset is described as sudden, but the underlying issue is a mismatch between applied load and tissue capacity that developed over time.
From a programming perspective, most recreational athletes benefit from a distribution in which the majority of training occurs at lower intensities, with limited, intentional exposure to higher-intensity work. This allows for continued development of aerobic capacity while preserving the ability to recover and maintain consistency.
The clinical goal is not to reduce intensity, but to ensure it is introduced into a system that is prepared to tolerate it.
