Hand cooling induces changes in the kinetics of oxygen uptake

The objective of this investigation was to assess the impact of elevated catecholamine concentrations, induced through cold-water hand immersion, on the oxygen consumption (V̇O₂) kinetics during intense exercise, and to contrast this effect with that of the priming effect. Ten active participants underwent three 8-minute constant work rate exercises (CWR) at ∆25%, with one CWR preceded by hand cooling (2 min at 0 °C, HC) and two consecutive CWR to induced priming effect on the second bout (SB). Pulmonary gas exchange and blood samples were analyzed to measure levels of epinephrine (E) and norepinephrine (NE). Results demonstrated a significant increase in the primary phase amplitude of V̇O₂ kinetics in response to both hand HC (33.9 mL.min^-1.kg^-1; CI [32.2;35.7], p < 0.001) and SB (34.6 mL.min^-1.kg^-1; CI [33.0;36.3], p < 0.001) relative to the control (32.7 mL.min^-1.kg^-1; CI [31.5;35.1]). Additionally, the amplitude of the V̇O₂ slow component was reduced for both HC (3.2 mL.min^-1.kg^-1; CI [2.2;4.1], p = 0.018) and SB (2.9 mL.min^-1.kg^-1; CI [1.8;4.2], p = 0.009) in comparison to control (3.9 mL.min^-1.kg^-1; CI [2.9;4.2]). These findings suggest that the increase in E and NE induced by hand cooling prior to exercise modifies V̇O₂ kinetics in a manner akin to the priming effect. This research underscores the potential role of catecholamines in facilitating the priming effect and its subsequent impact on V̇O₂ kinetics. However, further studies are necessary to clearly establish this link.