Effects of Inspiratory Muscle Warm-Up on Physical Exercise: A Systematic Review

SIMPLE SUMMARY: In physical training, it is common to perform preparatory activities to improve the performance of subsequent exercise. One of these activities is inspiratory exercise, which has been increasingly applied as a muscle-warm-up strategy due to the demands on the respiratory muscles in high-intensity effort. Generally, inspiratory exercise is performed by a device that works as an inspiratory exerciser, imposing resistance to the respiratory muscles in the inspiratory phase by restricting airflow. This resistance is based on the assessment of the individual’s global inspiratory-muscle strength (maximum inspiratory pressure). Our review aimed to systematically review the literature in order to examine the effects of inspiratory muscle warm-up on the inspiratory, metabolic, respiratory and performance parameters of a main exercise performed by athletes and healthy and active individuals, taking into account the protocols applied as well as the equipment used as the inspiratory exerciser. According to the results, the inspiratory-muscle warm-up was mostly performed in two series of thirty inspirations at 40% of the maximum inspiratory pressure, using POWERbreathe(®) (IMT Technologies Ltd., Birmingham, UK). Our review demonstrated that inspiratory-muscle warm-up can be a practical and simple additional resource to improve performance in high-intensity physical exercise, taking into account its individualized prescription. ABSTRACT: This study aimed to systematically review the literature to examine the effects of inspiratory-muscle warm-up (IMW) on the inspiratory, metabolic, respiratory and performance parameters of a main exercise performed by athletes and healthy and active individuals. Methods: This systematic review included randomized studies in English based on the criteria of the PICOS model. The exclusion criteria adopted were studies that applied inspiratory exercise to: i. promote long-term adaptations through inspiratory training (chronic responses); ii. obtain acute responses to inspiratory load (overload) during and in breaks from physical effort and in an inspiratory-exercise session (acute training effect); iii. evaluate the effects of IMW on participants with cardiorespiratory and/or metabolic disease. Data Sources: PubMed, Embase, MedLine, Scopus, SPORTDiscus and Google Scholar (until 17 January 2023). Results: Thirty-one studies were selected. The performance and respiratory parameters were the most investigated (77% and 74%, respectively). Positive effects of IMW were reported by 88% of the studies that investigated inspiratory parameters and 45% of those that evaluated performance parameters. Conclusions: The analyzed protocols mainly had positive effects on the inspiratory and performance parameters of the physical exercises. These positive effects of IMW are possibly associated with the contractile and biochemical properties of inspiratory muscles.