Influence of Banana Versus Sports Beverage Ingestion On Phagocytic Cell Responses To 75-Km Cycling Time Trials

Abstract

PURPOSE: The purpose of this project was to compare the acute effect of ingesting bananas (BAN) versus a 6% carbohydrate sports drink (CHO) on phagocytic cell responses to 75-km cycling in cyclists. DESIGN: Trained cyclists (N=14, age 37±1.9 y, Wattsmax 379±12.5) completed two 75-km cycling time trials (3 weeks apart, randomized, crossover) while ingesting BAN or CHO. Subjects ingested 0.4 gm/kg carbohydrate from BAN or CHO, and then cycled on CompuTrainers (RacerMate Inc., Seattle, WA) for 75-km at the fastest pace possible while ingesting 0.2 gm/kg carbohydrate from BAN or CHO every 15 min. Blood samples were taken pre-exercise, immediately following and 1-h post-exercise, and analyzed for granulocyte and monocyte phagocytosis (PHAG) and oxidative burst activity (OBA) using a flow cytometric procedure with FITC-labeled bacteria (Staphylococcus aureus; Molecular Probes, Eugene, OR) and hydroethidine (HE; Molecular Probes). All blood samples were prepared at the same ratio of eight bacteria per phagocytic cell. RESULTS: The time to complete the 75-km cycling trials did not differ between BAN and CHO (2.41±0.06 and 2.36±0.05 h, respectively, P=0.258). Exercise caused significant increases (P<0.001) above baseline levels in granulocyte PHAG (25% immediately- and 41% 1-h-post-exercise) and monocyte PHAG (50% and 72%, respectively), with no differences between BAN and CHO trials (interaction effects, P=0.215 and 0.191, respectively). Granulocyte and monocyte OBA did not differ between BAN and CHO trials and did not change with exercise (interaction effects, P=0.697 and 0.810, respectively). CONCLUSIONS: Bacterial phagocytosis but not OBA by blood granulocytes and monocytes was strongly increased following 75-km cycling time trials, with no differences between BAN and CHO conditions. The increase in phagocytosis with unchanged OBA reflects an inflammatory response to the physiologic stress of heavy exertion. Supported by a grant from Dole Foods, Inc.