Dual Stress Warm-Up Protocol Does Not Significantly Alter Blood Glucose Concentration

Abstract

Dual stress challenges (e.g. paired physical and psychological challenges) have been shown to increase catecholamine and cortisol responses above that of exercise alone; however, the underlying mechanisms to explain this effect are not well defined. The increased hormonal response is thought to be the result of a greater glucose demand due to the challenges imposed on both the brain and skeletal muscle. PURPOSE: To determine whether a dual stress warm-up protocol significantly alters circulating glucose concentrations before and after a Wingate Anaerobic Test (WAnT). METHODS: Thirteen college-aged subjects (Mean ± SD; age = 21 ± 3 yr; Height = 177 ± 9 cm; Weight = 81.8 ± 11.8 kg) volunteered to participate and completed a familiarization WAnT on a Monark cycle ergometer using a resistance of 7.5% bodyweight prior to testing. On two separate visits, separated by at least 3 d but no more than 1 wk, subjects randomly completed a WAnT preceded by either a 5 min warm-up at a resistance of 1.5% BW at a pedal rate of 70-80 rpm (CTRL) or the same warm-up while also completing the Paced Auditory Serial Test, which is a mental arithmetic challenge (EXPT). Blood glucose was measured at 5 time points (pre, post warm up, post WAnT, and at 5 min and 10 min post WAnT) using a Contour NEXT Blood Glucose Monitor. Subjects abstained from caffeine, alcohol, and exercise for the 24 hr prior to testing. Diet was standardized across subjects for the 12 hr prior to each visit. Data were analyzed using a 2x5 repeated measures ANOVA (α < 0.05). RESULTS: There were no significant interactions between the two conditions. However, there was a main effect for time (p = .001) with glucose concentrations significantly increased at 5 min post WAnT. CONCLUSION: These findings suggest that incorporating a psychological challenge during a warm-up session had no effect on glucose concentrations following a WAnT when compared to warm-up session alone. The lack of a significant finding may be due to the relatively small sample size or by the lack of difficulty of the mental challenge. Future studies are warranted using higher-stress cognitive tests to gain a better understanding of the effect of dual stress challenges on glucose concentrations prior to and following exercise.