Effects of prolonged running in the heat and cool environments on selected physiological parameters and salivary lysozyme responses

Introduction: Lysozyme is one of the salivary antimicrobial proteins which act as the "first line of defence" at the mucosal surface. The effects of prolonged exercise in the hot and cool environments among recreational athletes on salivary lysozyme responses are very limited in the literature, especially in the Asian countries.

Objective: To determine the effects of prolonged running in the hot and cool environments on selected physiological parameters and salivary lysozyme responses among recreational athletes.

Methods: Randomised and cross-over study design. Thirteen male recreational athletes (age: 20.9 ± 1.3 years old) from Universiti Sains Malaysia participated in this study. They performed two separate running trials; 90 min running at 60% of their respective maximum oxygen uptake [Formula: see text] One running trial was performed in the hot (31ºC) while the other was in the cool (18ºC) environment and this sequence was randomised. Each running trial was started with a 5 min warm-up at 50% of participant's respective [Formula: see text] Recovery period between these two trials was one week. In the both trials, saliva samples, blood samples, heart rate, ratings of perceived exertion, skin and tympanic temperatures, oxygen consumption, nude body weight, room temperature, and relative humidity were collected.

Results: Participants' skin temperature, tympanic temperature, body weight changes, heart rate, ratings of perceived exertion, and plasma volume changes were significantly higher (p