Análise da força propulsiva no nado crawl em triatletas juvenis sob diferentes padrões respiratórios

Abstract

Triathlon requires technical adaptations in swimming because it is performed in open water, including breathing patterns such as front-lateral breathing for navigation, which can increase hydrodynamic drag and require greater force application. Although propulsive force in front crawl swimming is a determinant of performance, its relationship with the different breathing patterns used in triathlon is not yet well understood. The objective of this study was to analyze the propulsive force of the front crawl stroke in triathletes during the execution of different breathing patterns. Thirty youth triathletes (20 men, 10 women) participated in a maximum 30-second tethered swimming test to obtain peak force (FPNA), mean force (FMNA), impulse (INA), and stroke frequency (FBNA) , and a 100-meter front crawl test to obtain mean clean velocity (VM), stroke length (CB), stroke frequency (FBNL), and swimming index (IN). Statistical analysis included Generalized Estimating Equations (GEE), Student’s t-tests, Spearman correlations, and simple linear regressions. The results indicated that FMNA, FBNL, and INA were superior in apnea compared to front-lateral breathing (p<0.05), while CB was inferior in this same condition and VM remained stable between across the three breathing conditions. Positive and moderate to strong correlations were observed between the force variables in tethered swimming and VM, CB, and IN (r between 0.53 and 0.78), which were confirmed by linear regression analyses. Significant asymmetries between body sides were identified, mainly in impulse (24% difference in the general group), being more pronounced in females, but with no difference between athletes of higher and lower proficiency. It is concluded that, although front-lateral breathing reduces mean force and impulse compared to apnea, compensation mechanisms between CB and FB allow speed maintenance. The propulsive force measured in tethered swimming correlates positively with efficiency parameters in front crawl swimming, reinforcing its validity as a tool for evaluating and monitoring swimming. The asymmetries observed, although significant, do not appear to be a limiting factor in performance in short-term maximum efforts in this population of youth triathletes.