Effects of Exercise Intensity, Duration and Recovery on in vitro Neutrophill Function in Male Athletes

The aim of the present study was to compaire the effects of exercise at 80 %VO2max (resulting in fatigue wiithin 1 h) with more prolonged exercise at a lower work rate (55 % V0₂max for up to 3 h) on blood neutrophil function and plasnria concentrations of Cortisol, glutamine and glucose. Eighteen: healthy male subjects (mean ± SD age 22.5±3.7yrs, V0₂max 60.1 ±6.6 ml · kg-1 · min-1) cycled on an electrically braked ergoimeter at 80 % V02max to fatigue (37 ± 19 min). On another occaision, separated by at least one week, subjects performed excercise on the same ergometer at 55 % V0₂max for 3 h or to fatigiue, whichever was the sooner. Mean exercise time was 164 ± 23 rmin. The order of the trials was randomised. Both exercise bouts caused significant (p < 0.05) elevations of the blood leucocyte craunt and plasma Cortisol concentration and reductions in the in vitro neutrophil degranulation response to bacterial lipopolys.accharide and oxidative burst activity. After exercise at the lower work rate for a longer duration, plasma Cortisol concentratiotn was higher, blood leucocyte and neutrophil counts were highier, blood lymphocytes, plasma glucose and indices of neutrophil function were lower than those observed at 80 % V0₂max. Plasma glutamine only fell significantly during recovery after (the more prolonged exercise. We conclude that when exercis.e is very prolonged, the diminution of innate immune functiom is greater, or at least as great as that observed after fatiguing exercise at higher work rates. Furthermore, reductions in neutrophil function after exercise at 80 % V0₂max were not relatied to changes in the plasma glutamine concentration, although both plasma glutamine and neutrophil function were decreaised at 1 and 2.5 h post-exercise in the long duration exercise trrial.

Key words

Exercise - neutrophils - glutamine - Cortisol - immune