Physiological, biochemical, anthropometric, and biomechanical influences on exercise economy in humans

Interindividual variation in running and cycling exercise economy (EE) remains unexplained although studied for more than a century. This study is the first to comprehensively evaluate the importance of biochemical, structural, physiological, anthropometric, and biomechanical influences on running and cycling EE within a single study. In 22 healthy males (VO2max range 45.5‐72.1 mL·min−1·kg−1), no factor related to skeletal muscle structure (% slow‐twitch fiber content, number of capillaries per fiber), mitochondrial properties (volume density, oxidative capacity, or mitochondrial efficiency), or protein content (UCP3 and MFN2 expression) explained variation in cycling and running EE among subjects. In contrast, biomechanical variables related to vertical displacement correlated well with running EE, but were not significant when taking body weight into account. Thus, running EE and body weight were correlated (R2=.94; P