This article asks, “Is there a physiologic rationale for respiratory muscle training effects on exercise performance?”

Conclusion:

“Recent studies provide evidence that respiratory muscle training improves exercise performance in well-controlled and rigorously designed studies utilizing exercise tests with the lowest coefficient of variation for repeated testing, appropriate outcome measures, and fitness of the participants. Further studies, however, are needed to define the mechanisms by which RMT improves exercise performance.”

Read Does training of respiratory muscles affect exercise performance in healthy subjects? >