Increased Ventilatory Efficiency in Supramaximal Compared to Graded Exercise in Athletes.

Area of Science:

• Exercise Physiology
• Cardiopulmonary Function
• Sports Medicine

Background:

• Supramaximal constant work rate tests (CWR) can induce hyperventilation in athletes, potentially leading to misinterpretation of ventilatory efficiency.
• The classic interpretation of increased ventilation (VE)-to-carbon dioxide (CO2) responses may incorrectly suggest ventilatory inefficiency.
• Distinguishing physiological hyperventilation from cardiac conditions in athletes requires accurate assessment of ventilatory efficiency.

Purpose of the Study:

• To develop and validate a new method for quantifying ventilatory efficiency during supramaximal constant work rate tests (CWR) in athletes.
• To challenge the traditional interpretation of ventilatory responses during CWR and differentiate them from signs of ventilatory inefficiency.
• To improve the ability to distinguish between physiological hyperventilation and potential cardiac issues in athletes undergoing exercise testing.

Main Methods:

• Twenty-seven athletes performed both a graded exercise test (GXT) and a CWR test at 110% of their maximal velocity.
• Ventilatory efficiency was assessed using standard linear regression and novel log-transformed variables.
• Paired t-student statistics were employed to compare results between the GXT and CWR conditions.

Main Results:

• All measured ventilatory efficiency parameters, including VE-to-CO2 slope, intercept, nadir, and log-transformed variables, were significantly higher during CWR compared to GXT.
• A novel bi-modal nadir response for VE/CO2 was observed in 22 out of 27 athletes during CWR.
• A weak association was found between the VE/CO2 nadir and time to exhaustion.

Conclusions:

• The new method provides improved quantification and interpretation of ventilatory efficiency in athletes during CWR.
• This approach avoids misinterpreting exercise-induced hyperventilation as ventilatory inefficiency, which can occur with traditional methods.
• Ventilatory adaptations during CWR contribute to enhanced ventilatory efficiency, supporting the validity of the new assessment method.