Cardiorespiratory kinetics: comparisons between athletes with different training habits

Abstract

Purpose

Fast muscular oxygen uptake (${\dot{V}}{\text{O}_\text{2musc}}$) kinetics are limiting factors for high exercise capacities. It is hypothesized that ${\dot{V}}{\text{O}_\text{2musc}}$ and heart rate (HR) kinetics would be faster in individuals, performing long-distance endurance training (CONT) compared with athletes performing predominantly interval-based sports (INT).

Methods

17 subjects (INT: n = 7, 24 ± 5 years, 183 ± 7 cm, 85 ± 10 kg, 6 ± 3 h of training per week, CONT: n = 10, 37 ± 7 years, 175 ± 9 cm, 69 ± 10 kg, 6 ± 3 h of training per week) completed a treadmill work rate (WR) protocol with pseudo-randomized WR changes with velocities of 6.5 and 9.5 km h⁻¹. ${\dot{V}}$O_2musc and the respective kinetics were estimated from the measured pulmonary oxygen uptake and HR combined with a circulatory model. Kinetics information were calculated using time series analysis. Higher maxima of the cross-correlation function (CCF) of WR and the respective parameter (${\dot{V}}{\text{O}_\text{2musc}}$, HR) indicate faster kinetics responses.

Results

The kinetics of HR (INT: 0.23 ± 0.04 vs. CONT: 0.42 ± 0.18; P = 0.001), ${\dot{V}}$O_2pulm (0.30 ± 0.05 vs. 0.53 ± 0.20; P = 0.005) and ${\dot{V}}$O_2musc (0.31 ± 0.06 vs. 0.53 ± 0.16; P = 0.005) were significantly slower in INT compared with the CONT athletes.

Conclusions

It seems that at least in the long-term CONT exercise, training without the need of changing intensities is favorable for fast ${\dot{V}}$O₂ and HR kinetics compared with INT exercise including frequently changing intensities.