The effect of baseline metabolic rate on pulmonary O2 uptake kinetics during very heavy intensity exercise in boys and men

► We modelled VO2 kinetic responses during work-to-work transitions in boys and men. ► We monitored changes in the surface electromyogram (EMG) of quadriceps muscle. ► Increased baseline EMG activity slowed phase II VO2 kinetics independent of age. ► Reduced VO2 slow component coincided with a lower change in EMG activity in boys. ► Age differences in VO2 kinetics are linked to altered muscle recruitment patterns.