Biomechanical, metabolic and cardiopulmonary responses of masters recreational runners during running at different speeds.

This study tested interactions between age and running speed on biomechanics, metabolic responses and cardiopulmonary responses. Three-hundred participants ran at preferred and standardized speeds. Age group (younger, masters [≥40 years]) by speed (self-selected 8.8 km/h, 11.2 km/h and 13.6 km/h) interactions were tested on main outcomes of sagittal kinematic, temporal spatial, metabolic and cardiopulmonary parameters. At all speeds, angular displacements of the ankle, pelvis and knee were less in masters than younger runners (Hedges g effect size range = 0.30-1.04; all p < 0.05). A significant age group by speed interaction existed for hip angular displacement (Wald χ = 10.753; p = 0.013). Masters runners ran at higher relative heart rates (p < 0.05) but at similar rates of oxygen use and energy expenditure. Masters runners used hip-dominant motion and step lengthening as running speed increased, but did not change centre of mass vertical displacement. This may increase mechanical stresses on tissues of the lower extremity in masters runners, especially hamstrings, hip joint and Achilles.