Leukocyte counts and lymphocyte responsiveness associated with repeated bouts of strenuous endurance exercise

Abstract

This study compared leukocyte counts and lymphocyte responsiveness during and after a second bout of high-intensity endurance exercise on the same day with the response to a similar but single bout of exercise. Nine athletes participated in three 24-h trials: 1) rest in bed (Rest); 2) one bout of exercise (One); and 3) two bouts of exercise (Two). All bouts consisted of 75 min at ∼75% of maximal O2 uptake on a cycle ergometer. Lymphocytes in whole blood were stimulated with monoclonal antibodies against CD2 and assessed by flow cytometry for expression of the early activation molecule CD69. The second bout of exercise in the Two trial was associated with significantly increased concentrations of total leukocytes, neutrophils, lymphocytes, CD4+, CD8+, and CD56+ cells and a significantly decreased percentage of CD56+ cells expressing CD69 compared with a single bout. Additionally, there was a significantly decreased CD69 fluorescence in CD56+ cells postexercise. These differences suggest a “carry-over” effect in the immune system from a first to a second bout of exercise on the same day.

The effect of a professional cricket match schedule on selected immune parameters

“…Although both CD4+ and CD8+ cell counts decreased proportionally (CD4:CD8 ratio stayed similar), the %CD4+CD69+ on stimulation in vitro increased significantly. This is in contrast to the results of Ronsen et al 27 who showed no change in %CD4+CD69+ cells when determined directly after a second bout of exercise performed on the same day. Therefore, while a few acute bouts of exercise seem to have no effect on CD69 expression in CD4+ cells, many long-duration exercise bouts with additional cumulative stressors over 5 weeks resulted in significantly increased relative CD69 expression.…”

“…25 The decreases in total lymphocyte, T-cell subpopulation, B and NK cell counts reported here, are similar to results obtained in earlier studies of endurance athletes. 1,27,32 It is known that exercise-induced increases in concentrations of stress hormones, such as catecholamines, 8 may be responsible for the exercise-induced depression of the lymphocyte counts. 3,9 Due to the nature of the game of cricket, all players are active for several hours each day when their side is bowling and fielding, and successful batsmen may also play for many hours on end, whilst those batsmen still to follow are under psychological stress.…”

“…Studies have indicated that an acute bout of aerobic exercise decreased CD4:CD8 ratio during exercise, with a subsequent transient increase above baseline, post-exercise. 17,27,30,33 However, strenuous training and competition over time may lead to chronically decreased CD4:CD8 ratios in athletes. 1 Specifically, Baj et al 1 reported a significantly decreased CD4+ cell count accounting for the decrease in CD4:CD8 ratio in competitive cyclists after a 6-month season.…”

“…Few studies 10,12,27 have investigated exercise-induced modulation of CD69 expression. Ronsen et al 27 reported that 1 bout of cycling (65 minutes at 75% maximal oxygen uptake (VO 2max )) did not significantly affect mitogen-induced CD69 expression in CD4+, CD8+ or NK cells.…”

“…Ronsen et al 27 reported that 1 bout of cycling (65 minutes at 75% maximal oxygen uptake (VO 2max )) did not significantly affect mitogen-induced CD69 expression in CD4+, CD8+ or NK cells. However, after 2 bouts of cycling separated by 3 hours, no effect was evident in the CD69 expression of CD4+ or CD8+ cells, but percentage of CD69+ NK cells was transiently decreased for 4 hours after the second bout.…”