Optimizing respiratory muscle strength has emerged as a critical strategy in enhancing aerobic performance, especially during high-intensity physical activity. Respiratory muscle fatigue, often overlooked in training regimens, can restrict oxygen delivery to muscles and limit endurance due to the respiratory metaboreflex. To address this, several studies have examined the effects of RMT on various performance markers.

One large-scale review found that RMT improves time trial outcomes, exercise duration, and inspiratory muscle strength in able-bodied athletes (HajGhanbari et al., 2013). More recently, a trial involving college runners demonstrated that a four-week inspiratory muscle training protocol reduced blood flow fluctuation in limbs and improved running times in an 800-meter track test (Chang et al., 2021).

In athletes with disabilities, RMT also shows promise. A systematic review of para-athletes revealed significant gains in respiratory strength and some improvements in endurance, though its role as a primary performance enhancer was questioned (Akinci et al., 2024).

The most in-depth findings, however, come from a comprehensive 2024 study involving 41 national-level athletes from judo, biathlon, and cross-country skiing (Deliceoğlu et al., 2024). The study confirmed that maximum expiratory pressure (MEP) and inspiratory diaphragmatic circumference were consistently associated with VO₂max, ventilation (VE), oxygen uptake (VO₂), and carbon dioxide output (VCO₂).

In statistical terms, these factors explained over 89% of the variation in VO₂max when combined in a model with interaction terms, underscoring their physiological relevance.

The study also highlights the importance of expiratory muscle strength in eliminating carbon dioxide during exercise, which can prevent metabolic acidosis and muscular failure. While training inspiratory muscles receives more attention, these findings suggest that expiratory strength is equally vital in sustaining high-level performance.

However, inconsistencies in previous studies suggest that outcomes may depend on individual athlete profiles and training intensity.