Effects of Carbohydrate Supplementation on Salivary Immunoglobulin- A During Long Duration Arduous Work

Abstract

2191 Prior short-term exercise studies have shown no effect of carbohydrate (CHO) supplementation on post-exercise suppression of salivary Immunoglobulin-A (sIgA). PURPOSE: This study evaluated the effects of CHO supplementation in wildland. re. ghters (WLFF) over an extended work shift on post-exercise and 12 hr recovery sIgA values. METHODS: Subjects were 29 WLFF evaluated during an extended shift of firefighting. In a single blind, random crossover design, WLFF on subsequent days received either a CHO [200ml/hr, 20% maltodextrin (160 kcal/hr)] or placebo (PLA) drink each hour. At the completion of the shift the CHO group received an additional bolus of 400 kcal CHO. Four minute forced salivary samples were collected pre- and post-shift and the morning after each treatment. Samples were analyzed using an Elisa assay. A two-way repeated measures ANOVA was used to evaluate the salivary data. RESULTS: Immediately post-shift both groups had a significant decrease in sIgA content over pre-shift values while the CHO group had significantly less sIgA suppression compared to the PLA group (pre-shift: CHO = 429 ± 139, PLA = 437 ± 159; post-shift: CHO = 290 ± 160, PLA = 230 ± 111, p<0.05). Following 12 hours of rest the CHO groups had returned to pre-shift values, while the PLA group remained significantly immune depressed (CHO = 442 ± 171, PLA = 337 ± 136, p<0.05). Additionally, during the final 6 hours of the CHO trial the subjects performed 23% more work (CHO = 486 ± 36, PLA = 395 ± 28 kcal/hr, p<0.01) and maintained higher blood glucose values compared to PLA, but there were no differences in RPE across trials. CONCLUSION: Exercise has been shown to cause a decrease in sIgA and is associated with increased incidence of upper respiratory tract infection. CHO supplementation during long shifts of arduous work in WLFF enhances maintenance of immune function and improved recovery after extended arduous work in spite of the greater self-selected work with CHO. The mechanism for the improved immune function is unknown but may be related to increased cortisol concentrations associated with longer duration exercise. Supported by the U.S. Forest Service, Missoula Technology Development Center.