The acute effect of slow deep breathing variation techniques on ventilatory capacity and inspiratory muscle endurance

The study aimed to examine the post-effect of deep breathing warm-up techniques on ventilatory capacity and inspiratory muscle endurance.

In a randomized crossover design, fourteen active women performed four different inspiratory muscle warm-up (IMW) protocols followed by maximum voluntary ventilation (MVV) and repeated inspiratory resistance breathing (RIRB) tests. Heart rate variability was also monitored before and after IMW. IMW techniques included deep inspiration with normal expiration (DI), deep inspiration with short breath-holding (DI-H), deep inspiration with short breath-holding followed by shallow breathing alternate (DI-H/SB), and deep inspiration and expiration (DI-DE). Each protocol was performed six breathing cycles per set for five sets, one-minute rest between sets.

MVV and RIRB score were significantly increased by both protocols with breath-holding (MVV: p = 0.002, p = 0.021; RIRB p = 0.002, p = 0.002, in DI-H and DI-H/SB, respectively). Deep inspiration alone did not affect both parameters. On the other hand, slow deep inspiration and deep expiration increased RIRB attempts (p = 0.020) without any effect on MVV value. Electrocardiogram indicated a significant decrease in RMSSD heart rate variability in deep inspiration with short breath-holding continuously (p = 0.043) and slow deep inspiration and deep expiration techniques (p = 0.032). However, a decrease was not observed in the technique of deep/shallow breathing alternate.

The data suggested that the addition of short breath-holding during IMW exerted significant stress on inspiratory muscles, which consequently activated a higher tolerance to fatigue. Deep/shallow alternate breathing helped lessen the stress due to breath-holding.