Inspiratory critical pressure - new methodology for evaluating and training the inspiratory musculature for recreational cyclists: study protocol for a randomized control trial
Abstract Background: Inspiratory muscle training (IMT) has brought great benefits in terms of improving physical performance in healthy individuals. However, there is no consensus regarding the best training load being in most cases the maximal inspiratory pressure (MIP) is used, mainly the intensity of 60% of MIP. So, the prescription of an IMT protocol that considers respiratory muscle strength and endurance may bring additional benefits to commonly used protocols, since the respiratory muscles that differ from other muscles because of their greater muscular resistance. Thus, IMT using inspiratory critical pressure (PThC) can be an alternative as the calculation of PThC considers these characteristics. Therefore, the aim of this study is to propose a new IMT protocol to determine the best training load for recreational cyclists. Methods: Thirty recreational cyclists (between 20-40 years) will be randomized into the SHAM Group (SG), the PThC Group (PCG) and the 60% of MIP Group (60G), according to age and aerobic functional capacity. All participants will undergo the following evaluations: pulmonary function test (PFT), respiratory muscle strength test (RMS), cardiopulmonary test (CPET), incremental respiratory muscle endurance test (iRME) [maximal sustained respiratory pressure for 1 minute (PThMAX)] and constant load test (CLT) (95%, 100% and 105% of PThMÁX) using a linear load inspiratory resistor (PowerBreathe K5). The PThC will be calculated from the inspiratory muscle endurance time (TLIM) and inspiratory loads of each CLT. The IMT will last 11 weeks (3 times/week and 1 hour/session). The session will consist of 5-minute warm-ups (50% of the training load) and 3 sets of 15-minute breaths (100% of the training load), with a 1-minute interval between them. RMS, iRME, CLT and CPET will be performed beforehand, at week 3 and 7 (to adjust the training load) and after training. PFT will be performed before and after training. The data will be analyzed using specific statistical tests (parametric or non-parametric) according to the data distribution and their respective variances. The p <0.05 will be established. Discussions: It is expected that the results of this study will enable the training performed with PThC to be used by health professionals as a new tool to evaluate and prescribe IMT. Clinical Trial: ClinicalTrial.gov, ID Number NCT02984189. Registered on December 6, 2016, https://clinicaltrials.gov/ct2/show/NCT02984189. Keywords: Physical Exercise, Physiotherapy, Physical Performance, Critical Power, Respiratory Muscle