Respostas fisiológicas e perceptuais com ênfase na termorregulação durante e após uma corrida de longa duração (6 horas)

Abstract

INTRODUCTION: Thermoregulation is an essential physiological mechanism responsible for maintaining core body temperature within safe limits, even under varying environmental conditions. During physical exercise, particularly in long-distance running, heat production increases significantly due to muscular work. Understanding how these thermoregulatory processes function during prolonged exertion is crucial to ensuring athlete safety, optimizing sports performance, and preventing complications related to thermal stress. OBJECTIVE: To analyze the physiological, metabolic and perceptual responses during and after a 6-hour running, with an emphasis on thermoregulation and specific focus on the dynamics of skin temperature throughout prolonged exertion. METHODS: This thesis was structured in two scientific articles. Article 1: Correlation between distance covered, body temperature and perceived exertion during a long-term endurance running. Objectives: (1) to longitudinally assess body and thigh temperature dynamics and (2) to evaluate their temporal correlations with the distance covered and perceived exertion before and after 2, 4, and 6 hours of running. Article 2: Analysis of cardiovascular, metabolic, and perceptual responses before, during, and after a long-term endurance running. Objective: To analyze cardiovascular, metabolic, and perceptual responses in trained male runners before, during, and after sixhour long-term endurance running, with emphasis on performance-based differences and recovery dynamics up to 48 hours post-running. Thirty-nine male elite soldiers (age: 31.4 ± 5.7 years) participated in a six-hour long-term endurance running on a 400-m track. Participants were retrospectively categorized into three groups according to the total distance covered: submarathoners (<40 km), marathoners (40–44 km), and ultramarathoners (>44 km). The variables evaluated included physiological indicators (skin temperature, heart rate, blood pressure, and body mass), metabolic markers (urinary analysis), and perceptual responses (pain, thirst, thermal sensation, skin moisture, thermal comfort, and perceived exertion). Data collection was performed at eight distinct time points: 24 h and 1 h before the race (PRE24h and PRE1h), during the effort (2h, 4h and 6h), and after the end of the race (POST1h, POST24h, and POST48h). RESULTS: Article 1: All groups showed an increased temperature at POST6h vs. PRE [1.9 (0.1; 3.7) °C; p=0.037] and POST2h [2.3 (0.7; 4.0) °C; p=0.002]. For anterior thigh there was a significant difference between PRE and POST2h vs. POST4h and POST6h (p≤0.001 for all comparison). Total distance showed positive correlation between with the temperature of the right and left thigh POST6h (p≤0.036 for all comparison) and RPE at POST4h and POST6h (p≤0.008 for all comparison). Body surface temperature (BST) at POST4h showed inverse correlation with total distance (p≤0.001). Article 2: Ultrarunners showed greater reductions in body mass, higher heart rate responses, and increased discomfort across multiple perceptual domains. Several variables remained significantly altered even 48 hours post-exercise, particularly in the ultramarathon group. Repeated-measures analysis revealed significant time effects (p < 0.001) for most variables, and interaction effects indicating performance-level differences in recovery profiles. CONCLUSIONS: Perceived exertion (RPE) at POST4h and post-race, as well as thigh temperature at POST4h, emerged as significant predictors of the total distance covered. Monitoring these variables can assist athletes and coaches in developing more effective pacing strategies and hydration protocols aimed at preventing excessive increases in core temperature. Greater distances were associated with more intense and prolonged physiological and perceptual strain, highlighting the importance of individualized recovery strategies following ultra-endurance efforts. The integration of cardiovascular, metabolic, and perceptual markers provides a comprehensive understanding of fatigue and recovery mechanisms, with practical implications for endurance training and performance management.