A modified D-max method to estimate heart rate at a ventilatory threshold during an incremental exercise test.

Area of Science:

• Exercise Physiology
• Cardiorespiratory Fitness Assessment
• Biomechanical Analysis

Background:

• Determining the heart rate at ventilatory threshold (HRVT) is crucial for assessing exercise intensity and training.
• Existing methods for HRVT estimation, such as the conventional D-max, three-piece linear regression, and parallel straight line slope methods, have limitations in accuracy.

Purpose of the Study:

• To design and validate a modified D-max method for estimating HRVT during incremental exercise tests.
• To compare the efficacy of the modified D-max method against conventional HRVT determination techniques.

Main Methods:

• A modified D-max method was developed, estimating HRVT from the maximal difference between linear and quadratic HR trends.
• Simultaneous collection of heart rate and ventilatory gas data from 105 participants during incremental treadmill tests.
• Manual identification of reference HRVTs by an experienced sports physiologist for comparison.

Main Results:

• The modified D-max method demonstrated a strong positive correlation (r=0.71) with reference HRVTs, outperforming other methods.
• Combining the modified D-max method with subject's age further improved prediction accuracy (r=0.74).
• The modified D-max method showed a lower HR difference (9.94 ± 7.10 bpm) compared to reference values.

Conclusions:

• The modified D-max method is a valid and highly applicable tool for predicting HRVT during incremental exercise.
• Integrating subject's age with the modified D-max method enhances the accuracy of HRVT detection.
• This novel approach offers improved precision in assessing cardiorespiratory responses to exercise.