Current limits for flowmeter resistance in metabolic carts can negatively affect exercise performance

Area of Science:

• Exercise Physiology
• Respiratory Physiology
• Sports Medicine

Background:

• Metabolic carts are essential tools for assessing exercise physiology.
• Flowmeter resistance in metabolic carts can influence cardiorespiratory responses.
• Current American Thoracic Society guidelines define acceptable airflow resistance limits.

Purpose of the Study:

• To determine if metabolic carts with high airflow resistance impede exercise performance in healthy individuals.
• To investigate the impact of varying flowmeter resistance on physiological and perceptual responses during incremental exercise.

Main Methods:

• 16 recreationally active males underwent incremental cycling tests using two metabolic carts with differing airflow resistance (low vs. high).
• Measurements included mouth pressures, gas exchange, blood lactate, and perceived exertion.
• Tests were conducted over two separate visits to ensure reliability.

Main Results:

• Higher airflow resistance (Innocor) led to significantly shorter test durations and increased maximal flow resistance.
• Peak oxygen consumption, minute ventilation, breathing frequency, heart rate, and blood lactate were lower with high resistance.
• Perception of breathlessness significantly increased with higher airflow resistance.

Conclusions:

• Airflow resistance within the upper range of current guidelines significantly alters exercise performance and respiratory patterns.
• These findings suggest a need to re-evaluate existing guidelines for metabolic cart flowmeters used in ergospirometry.
• High resistance devices may underestimate exercise capacity and alter the physiological experience of exertion.