A conceptual integration of physiological and biomechanical load in distance running

The distinction between physiological and biomechanical load has become increasingly salient in both scientific and coaching discourse on endurance running. While physiological load has long been operationalised through metrics such as heart rate, lactate, and training impulse (TRIMP), biomechanical load remains conceptually and empirically less defined. This paper examines the current debate surrounding the measurement of biomechanical stress and proposes an integrative framework that situates both forms of load within a neuromuscular systems perspective. Drawing on recent work in biomechanics (Edwards, 2018; Matijevich et al., 2019) and exercise physiology (Seiler, 2010; Jones & Burnley, 2009), it is argued that the two domains cannot be adequately understood in isolation. Rather, they must be conceptualised as interacting dimensions of the same adaptive process. Physiological load governs metabolic strain and recovery kinetics, whereas biomechanical load shapes the structural tolerance and efficiency of movement. The paper outlines the limitations of current modelling approaches, such as device-derived impact scores, and advances a conceptual synthesis, an integrated model, which views neuromuscular recruitment as the mediating process through which metabolic and mechanical stress co-evolve.

This paper proposes an integrative framework for understanding physiological and biomechanical loads in distance running.