The influence of local and whole-body cooling on pulmonary and muscle oxygen uptake kinetics during moderate exercise

Abstract

This study investigated oxygen kinetics and blood flow in response to core and muscle cooling at the onset of moderate exercise. Eight males performed two 3-min cycling bouts at moderate intensity (80% of the first ventilatory threshold) with (leg cooling; LC), and without (thermoneutral; TN) cooling of the vastus laterals (VL) muscle by 6 °C, and when core temperature was also decreased (whole-body cooling; WBC) by 1 °C. Muscle blood flow, and muscle (VO2m) oxygen uptake, and kinetics, as well as cardiovascular hemodynamics kinetics, were assessed. VO2 was higher in WBC (+1.96 mL kg -min', p = 0.023). Despite central (reduced cardiac output, heart rate pH, PO, SO2, and increased VO20 whole-body A-VO,Diff, PCO,) and local changes (decreased muscle blood flow and increased local-leg A-VO,Diff) induced by core and muscle cooling, oxygen and cardiovascular hemodynamics kinetics remained unaltered. This study demonstrated that local muscle cooling by 6 °C and core cooling by 1 °C do not influence local muscle or pulmonary oxygen kinetics during moderate exercise. Whether muscle priming, antagonist muscle activity, exercise intensity, cooling intensity or modality influenced the lower oxidative capacity of cooled muscles on kinetics remains unclear.