Cardiorespiratory kinetics: comparisons between athletes with different training habits

Area of Science:

• Exercise Physiology
• Sports Science
• Cardiovascular Physiology

Background:

• Fast oxygen uptake kinetics are crucial for high exercise capacity.
• The impact of different training modalities on oxygen uptake and heart rate kinetics is of significant interest in sports science.

Purpose of the Study:

• To investigate whether continuous endurance training (CONT) leads to faster muscular oxygen uptake ([Formula: see text]O2musc) and heart rate (HR) kinetics compared to interval-based training (INT).

Main Methods:

• Seventeen athletes (7 INT, 10 CONT) underwent a treadmill protocol with pseudo-randomized work rate changes.
• Muscular oxygen uptake ([Formula: see text]O2musc) and heart rate (HR) kinetics were estimated using a circulatory model and time series analysis.
• Cross-correlation function (CCF) was used to quantify the speed of the kinetics responses.

Main Results:

• Heart rate (HR) kinetics were significantly slower in INT athletes (0.23 ± 0.04) compared to CONT athletes (0.42 ± 0.18).
• Pulmonary oxygen uptake ([Formula: see text]O2pulm) kinetics were slower in INT (0.30 ± 0.05) versus CONT (0.53 ± 0.20).
• Muscular oxygen uptake ([Formula: see text]O2musc) kinetics were also significantly slower in INT (0.31 ± 0.06) compared to CONT (0.53 ± 0.16).

Conclusions:

• Continuous endurance training appears more beneficial for developing rapid oxygen uptake and heart rate kinetics than interval training.
• Training without frequent intensity changes, as in long-term CONT, may be favorable for optimizing physiological responses for exercise capacity.