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

  • Johannes A de W Strauss Department of Physiological Sciences, Stellenbosch University, Stellenbosch, Republic of South Africa
  • Kathryn H Myburgh Department of Physiological Sciences, Stellenbosch University, Stellenbosch, Republic of South Africa

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
Published
2006-10-06
Section
Articles

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print ISSN: 0379-9069