Recent Advancements in Our Understanding of the Ergogenic Effect of Respiratory Muscle Training in Healthy Humans: A Systematic Review

Abstract

Shei, R-J. Recent advancements in our understanding of the ergogenic effect of respiratory muscle training in healthy humans: a systematic review. J Strength Cond Res 32(9): 2674-2685, 2018-Respiratory muscle training (RMT) has been shown to be an effective ergogenic aid for sport performance. Respiratory muscle training has been documented to improve performance in a wide range of exercise modalities including running, cycling, swimming, and rowing. The physiological effects of RMT that may explain the improvements in performance have been proposed to include diaphragm hypertrophy, muscle fiber-type switching, improved neural control of the respiratory muscles, increased respiratory muscle economy, attenuation of the respiratory muscle metaboreflex, and decreases in perceived breathlessness and exertion. This review summarizes recent studies on the ergogenicity and mechanisms of RMT since 2013 when the topic was last systematically reviewed. Recent evidence confirms the ergogenic effects of RMT and explores different loading protocols, such as concurrent exercise and RMT (i.e., "functional" RMT). These studies suggest that adapting new training protocols may have an additive improvement effect, but evidence of the efficacy of such an approach is conflicting thus far. Other recent investigations have furthered our understanding of the mechanisms underpinning RMT-associated improvements in performance. Importantly, changes in ventilatory efficiency, oxygen delivery, cytokine release, motor recruitment patterns, and respiratory muscle fatigue resistance are highlighted as potential mechanistic factors linking RMT with performance improvements. It is suggested that future investigations focus on development of sport-specific RMT loading protocols, and that further work be undertaken to better understand the mechanistic basis of RMT-induced performance improvements.

Eight Weeks of Inspiratory Muscle Training Improves Pulmonary Function in Disabled Swimmers—A Randomized Trial

“…One such innovation is strength training of the inspiratory muscles. According to the literature, exercise capacity and the strength of respiratory muscles is important to many athletes, especially competitive athletes [1,2,3,4]. The function of respiratory muscles, like all other skeletal muscles, improves in response to training.…”

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“…In accord with skeletal muscle adaptations to training, it is vital to identify the optimal training protocol prior to conclusions being drawn regarding the efficacy of any training stimulus. At least in healthy humans, the efficacy of IMT as an ergogenic aid appears to be optimal when the IMT loading protocol is closely matched to the ventilatory demands of the criterion task (i.e., exercise modality) [24, 25], which has not been identified in CF. Indeed, the optimization of IMT is likely to be a highly individualized process requiring the IMT protocol to be matched with specifically identified respiratory muscle impairments.…”

“…The specific mechanisms by which IMT can transfer to meaningful outcomes in individuals with CF are unclear and likely multifactorial. However, several putative mechanisms have emerged, including (i) hypertrophy of the diaphragm and external intercostal muscles, (ii) an increase in the proportion of type I fibers in the external intercostal muscles, (iii) improvement in respiratory muscle economy and efficiency, (iv) reduction in the work of breathing, (v) enhanced respiratory muscle strength and endurance, (vi) attenuation of the respiratory muscle metaboreflex, (vii) reduction in cytokine release, (viii) reorganization of respiratory muscle motor recruitment pattern, (ix) decreased inspiratory muscle motor drive with preserved inspiratory pressure generation, and (x) decreased rating of perceived breathlessness and/or rating of perceived exertion [24, 42]. These mechanisms are likely interrelated and not mutually exclusive.…”

“…IMT performed at 100% of P Imax has been shown to decrease exercising heart rate and perceived exertion, whereas IMT performed at 80% of P Imax did not produce any such adaptations [51]. Presently, the test of incremental respiratory endurance (TIRE) regimen, which consists of a series of training breaths with a decreasing work-rest ratio, may be the best example of such an IMT protocol [22, 24, 27, 52–54]. Specifically, this type of training prescription may be better suited to inducing respiratory muscle adaptations in those with CF compared with protocols simply requiring a fixed number of breaths in each training session.…”

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“…Performance-defeating acquired breathing behaviors, poor respiratory muscle condition and compromised diaphragm function have a negative impact on physiology, psychology, health, and performance [2,3] . However, these behaviors can be deconditioned and reversed by specific countermeasures to improve performance, physiological health, and psychological status [4,5] .…”