Tese
Determinantes da hipertermia durante o exercício físico extenuante: uma abordagem translacional
Fecha
2022-08-17Autor
Marcelo Teixeira de Andrade
Institución
Resumen
Although the increase in core body temperature (TCORE) favors physiological responses during
physical exercise, severe hyperthermia is associated with reduced performance and increased
occurrence of heat illnesses. The first objective of the thesis was to systematically review the
studies that investigated the TCORE of rats submitted to treadmill exercise to understand the
factors that influence the TCORE achieved in fatigue/exhaustion. In this review, multiple linear
regression analyses were performed on data extracted from studies that used both exercises
with incremental speed increase and exercises with fixed speed. The systematic review
indicated that the TCORE values obtained in fatigue/exhaustion were mainly explained by
ambient temperature, initial TCORE (pre-exercise), and parameters related to physical
performance (i.e., distance covered in incremental exercises and duration in constant
exercises). The second objective of the thesis was to understand the factors that influence the
increase of different indices (cerebral, abdominal, and colonic) of TCORE in rats submitted to
progressive exercise until fatigue. Three hundred and seventy individual records were
analyzed using hierarchical multiple linear regressions, which revealed that the magnitude of
hyperthermia in rats submitted to incremental running depends mainly on ambient
temperature, physical performance, and initial TCORE, regardless of the temperature
measurement site. These results corroborate the findings of the systematic review. The third
objective of the thesis was to identify the determinants of the increase in TCORE in individuals
submitted to a 10 km time trial under conditions of environmental heat stress. Seventy-five
individual records were analyzed using hierarchical multiple linear regression, which showed
that exercise-induced hyperthermia in runners depends primarily on initial TCORE,
environmental conditions, and running speed. We concluded that the main determinants of
hyperthermia induced by strenuous exercise are environmental conditions, initial TCORE, and
parameters related to physical performance. Interestingly, these findings were similar in rats
and humans, indicating the possibility of translating specific results between the two species.