“This study investigated the relationship between the intensity of an inspiratory muscle training programme and its effect on respiratory muscle strength, exercising heart rate, and ratings of perceived exertion.”
Conclusion:
Six weeks of both MAX (subjects that trained at 100% of maximum inspiratory pressure i.e. MIP) and SUB (subjects that trained at 80% MIP) training were sufficient to improve inspiratory muscle strength. However, exercising heart rate and perceived exertion decreased with MAX training only.