[Study on the limitation for detecting anaerobic threshold by respiratory frequency]

Area of Science:

• Exercise Physiology
• Cardiorespiratory Fitness

Context:

• The anaerobic threshold (AT) is a critical physiological marker in sports science.
• Respiratory frequency (F) has been proposed as a method for AT detection.
• The influence of factors like sport experience on F-based AT detection is not well understood.

Purpose:

• To investigate if respiratory frequency (F) is a reliable method for determining the anaerobic threshold (AT).
• To assess the influence of sport experience on AT determination using F.
• To compare F-based AT detection with established methods.

Summary:

• Four methods were used to determine VO2 at AT: AT-v (ventilatory equivalents), AT-VF (visual F estimation), AT-CF (F regression), and AT-CF2 (modified F regression).
• AT-VF and AT-CF yielded significantly higher VO2 values, potentially indicating respiratory compensation (RC) rather than AT.
• AT-CF2 showed strong correlation with AT-v, but individual variations in error suggest F is inadequate for AT determination due to entrainment effects.

Impact:

• Respiratory frequency (F) is deemed inadequate for accurately determining the anaerobic threshold (AT).
• Entrainment between breathing and pedaling frequency can confound F measurements.
• Established methods like ventilatory equivalents remain more reliable for AT assessment.