Effects of short-term training and detraining on VO2 kinetics: Faster VO2 kinetics response after one training session

摘要

This study examined the time course of short-term training and detraining-induced changes in oxygen uptake ((V) over dotO(2)) kinetics. Twelve men (24 +/- 3 years) were assigned to either a 50% or a 70% of (V) over dotO(2max) training intensity (n = 6 per group). (V) over dotO(2) was measured breath-by-breath. Changes in deoxygenated-hemoglobin concentration (Delta[HHb]) were measured by near-infrared spectroscopy. Moderate-intensity exercise on-transient (V) over dotO(2) and Delta[HHb] were modeled with a mono-exponential and normalized (0-100% of response) and the [HHb]/(V) over dotO(2) ratio was calculated. Similar changes in time constant of (V) over dotO(2) (tau(V) over dotO(2)) were observed in both groups. The combined group mean for tau(V) over dotO(2) decreased similar to 14% (32.3 to 27.9 s, P < 0.05) after one training session with a further similar to 11% decrease (27.9 to 24.8 s, P < 0.05) following two training sessions. The tau(V) over dotO(2) remained unchanged throughout the remaining of training and detraining. Asignificant "overshoot" in the [HHb](V) over dotO(2) ratio was decreased (albeit not significant) after one training session, and abolished (P < 0.05) after the second one, with no overshoot observed thereafter. Speeding of (V) over dotO(2) kinetics was remarkably quick with no further changes being observed with continuous training or during detraining. Improve matching of local O-2 delivery to O-2 utilization is a mechanism proposed to influence this response.