Analysis of heart rate and oxygen uptake kinetics studied by two different pseudo-random binary sequence work rate...

Area of Science:

• Exercise Physiology
• Cardiovascular Physiology
• Human Performance

Background:

• Understanding oxygen uptake kinetics is crucial for assessing exercise tolerance.
• Pseudo-random binary sequence (PRBS) protocols offer a dynamic method to study physiological responses.
• Previous research has explored the relationship between work rate and oxygen uptake, but the specific impact of varying work rate amplitudes on kinetics requires further investigation.

Purpose of the Study:

• To compare the kinetics of heart rate (HR), pulmonary oxygen uptake (V˙O₂pulm), and predicted muscular oxygen uptake (V˙O₂musc) under two different PRBS work rate (WR) amplitudes.
• To determine if varying WR amplitudes below the anaerobic threshold influences these physiological kinetics.

Main Methods:

• Eight healthy individuals completed two PRBS WR protocols with different amplitude ranges (30-80W and 30-110W).
• HR and V˙O₂pulm were measured continuously.
• V˙O₂musc was estimated using a circulatory model and cross-correlation functions (CCF).

Main Results:

• Heart rate (HR) and predicted muscular oxygen uptake (V˙O₂musc) kinetics were not significantly different between the two WR amplitudes (p>0.05).
• Pulmonary oxygen uptake (V˙O₂pulm) kinetics exhibited significant differences in the CCF maximum lag time (39±9s vs. 31±4s; p<0.05).

Conclusions:

• A 14W difference in PRBS WR amplitude significantly impacts venous return.
• Despite changes in venous return, heart rate (HR) and muscle oxygen uptake (V˙O₂musc) kinetics remain consistent across tested WR intensities below the anaerobic threshold.