Critical inspiratory 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 to improving physical performance in healthy individuals. However, there is no consensus regarding the best training load as in most cases the maximum inspiratory pressure(MIP) has been used, whereby 60% of MIP is the most used. Therefore, the prescription of an IMT protocol that takes into account respiratory muscle strength and endurance may bring additional benefits to the commonly used protocols as respiratory muscles differ from other muscles because of their greater muscular resistance. Thus, IMT using inspiratory critical pressure(PThC) appears as an alternative since 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 to the SHAM Group(SG), the PThC Group(PCG) and the 60% of MIP Group(60G), taking into account 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) [maximum 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 before, 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 by specific statistical tests (parametric or non-parametric) according to the data distribution and their respective variances. The p <0.05 will be established. Conclusions: 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 in December 6, 2016, https://clinicaltrials.gov/ct2/show/NCT02984189.