Effects of inspiratory muscles pre-activation and intermittent hypoxia pre-efforts on mechanical, thermographic and physiological parameters in tethered and free swimming: investigation by complex networks model

• Grant number: 24/03587-7
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: January 01, 2025
• End date: December 31, 2026
• Field of knowledge: Biological Sciences - Physiology - Physiology of Effort
• Principal Investigator: Fúlvia de Barros Manchado Gobatto
• Grantee: Lara Soares de Araujo
• Host Institution: Faculdade de Ciências Aplicadas (FCA). Universidade Estadual de Campinas (UNICAMP). Limeira , SP, Brazil
• Associated research grant(s): 25/03966-0 - ECSS Rimini 2025 - 30th Annual Congress of the European College of Sport Science, AR.EXT

Abstract

The warm-up prior to main efforts, or pre-activation, is often used in the physical sports field. Among the strategies that can be included in this context, the inspiratory muscles pre-activation (IMPA) has received wide attention in the literature. In swimming, the use of IMPA has been proposed, as these muscle groups are heavily relied upon to sustain physical effort in the aquatic environment. In addition to IMPA, intermittent hypoxia (IH) may be another strategy potentially capable to reduce the inspiratory metaboreflex in subsequent efforts. However, there is a significant gap regarding the effects of IMPA and IH on different mechanical, thermographic, and physiological parameters in swimmers. Thus, the general aim of this current project will be to investigate the effects of IMPA and IH strategies on swimming mechanical parameters, skin temperature in different body regions, and physiological responses, as well as their possible correlations with performance in tethered (all-out 30 seconds - study 1) and free (400-meter race - study 2) swim efforts. Computational analysis using complex network modeling will aim to enhance understanding of the potential effects of IMPA and IH on the parameters analyzed in these two different swimming scenarios. Fifteen healthy swimmers aged between 16 and 24 years will participate in the study. The project will be divided into two phases, according to the specific objectives of two studies, in which swimmers will undergo five evaluation sessions in each study. In the first, anthropometric and body composition assessments will be conducted, as well as measurement of maximal inspiratory pressure (MIP) and global strength index (S-Index). In subsequent sessions, participants will undergo a maximal 30-second tethered swim test (study 1) or a 400m freestyle swim (study 2), with two sessions preceded or not by IMPA with a load equivalent to 40% of MIP at a volume of 2x30, and two sessions preceded using a mask for hypoxia exposure (H; FiO2=8%) or normoxia (N; FiO2=20.9%), consisting of 6 cycles of 4 minutes with 2 minutes interval between cycles. Muscle oxygenation by NIRS will be observed during the respiratory strategies. Mechanical parameters (force, impulse, velocity, total swim time, splits every 25m, stroke frequency and length) and physiological parameters (heart rate, blood lactate levels, and muscle oxygenation), as well as perceived effort and dyspnea will be monitored before and after protocol application. Thermographic recordings will be conducted in both experimental sessions. For both studies, results analysis will be carried out using conventional methods, following parametric or non-parametric statistics after testing for normality and homogeneity. Finally, computational analysis using complex network modeling will investigate centrality metrics (Degree, Betweenness, Eigenvector, and Pagerank), aiming to enhance understanding of the potential effects of IMPA and IH on the mechanical, thermographic, and physiological parameters of swimmers undergoing all-out 30-second tethered efforts and 400m free swim. Through this project, we aim to advance knowledge on the real effects of IMPA and IH on their relationships with swimmers' performance.