Self-pacing increases critical power and improves performance during severe-intensity exercise.

Area of Science:

• Exercise Physiology
• Sports Science
• Human Performance

Background:

• The power-duration relationship, defined by critical power (CP) and curvature constant (W'), is crucial for understanding severe-intensity exercise.
• Pulmonary O2 uptake kinetics are linked to these parameters and may be influenced by pacing strategies during exercise testing.

Purpose of the Study:

• To investigate whether critical power (CP) is higher when determined using self-paced time-trials (TT) versus conventional constant work-rate (CWR) exercise tests.
• To examine the influence of pacing strategy on the parameters of the power-duration relationship and pulmonary O2 uptake kinetics.

Main Methods:

• Ten male participants completed 3-4 constant work-rate (CWR) and 3-4 self-paced time-trial (TT) protocols on a cycle ergometer.
• Critical power (CP) and curvature constant (W') were determined for both protocols.
• Pulmonary O2 uptake kinetics, including mean response time, were measured.

Main Results:

• The CP derived from the TT protocol (265 ± 44 W) was significantly higher than that from the CWR protocol (250 ± 47 W).
• The curvature constant (W') did not differ significantly between the TT (18.1 ± 5.7 kJ) and CWR (20.6 ± 7.4 kJ) protocols.
• Mean response time of pulmonary O2 uptake was faster during TTs (34 ± 16 s) compared to CWR trials (39 ± 19 s).

Conclusions:

• A self-selected pacing strategy, as employed in time-trials, enhances critical power (CP) compared to constant work-rate testing.
• The findings suggest that CP and W' derived from CWR protocols may underestimate severe-intensity exercise capacity and overestimate performance.
• These results have significant implications for exercise performance prediction models.