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Influence of glucose on the leukocyte response in women athletes during prolonged exercise


Johannes A de W Strauss
Kathryn H Myburgh

Abstract

Objective. This study investigated the influence of carbohydrate versus placebo beverage intake on leukocyte and cortisol responses to 90 minutes of running on a treadmill at 70% VO 2max in women.

Subjects. Ten moderately trained women athletes (age: 27.6±3.7 yr; VO 2max: 46.6±2.0ml.kg-1.min-1) from the local athletic club volunteered to participate in the study.

Design. In a randomised, single blind, placebo-controlled crossover study, subjects received three beverages during exercise: a placebo ad lib (Pla), 6% glucose (voluntary glucose: VG) and 1 000 ml 6% glucose (forced glucose: FG). Blood samples were analysed for serum glucose ([Gluc]) and cortisol ([Cort]), as well as for total white blood cell (WBC) counts and WBC subpopulations.

Results. No difference was observed in the volume of beverage intake during Pla and VG trials. [Gluc] was significantly higher in the VG and FG trials when compared with the Pla trial at 45 and 90 minutes (p<0.05). [Cort] was stable in the VG and FG trials, but was significantly increased in the Pla trial at 90 minutes (p<0.05). Total WBC counts were raised at all stages in all three trials when compared with pre-exercise values, but the significance differed between trials. In the Pla trial, the greatest increase in total WBC count (p<0.01) was seen at the 45- minute time point, with significant increases (p<0.05) in neutrophil, lymphocyte and monocyte counts. The total WBC count increased in the VG trial, but to a lesser extent than in the Pla trial (p<0.05). In the VG trial, only the lymphocyte subpopulation increased significantly (p<0.05). There were no significant differences in the total WBC count or WBC subpopulations in the FG trial. All measured parameters, except the total WBC and neutrophil counts (p<0.01), returned to preexercise levels during recovery (90-180 minutes).

Conclusion. We conclude that both voluntary and forced ingestion of 6% glucose solutions prevented a rise in cortisol at the end of a 90-minute period of exercise. Although the effect of the unforced ingestion of 6% glucose was less explicit, both forced and unforced ingestion of 6% glucose had an attenuated effect on WBC counts during exercise.

South African Journal for Research in Sport, Physical Education and Recreation Vol. 27(2) 2005: 101-111

Journal Identifiers


eISSN: 2960-2386
print ISSN: 0379-9069