Cardiac-Autonomic and Hemodynamic Responses to a Hypertonic, Sugar-Sweetened Sports Beverage in Physically Active Men.

Hydration practices may confound heart rate variability (HRV) measurements when collected in the pre-training period. We aimed to determine the effects of ingesting a hypertonic, sugar-sweetened sports beverage on HRV and hemodynamic parameters in physically active young men. Fifteen subjects consumed 591 ml of Gatorade (6% carbohydrate, ~330 mOsmol/kg), 591 ml water, or 10 ml water (control) in random order on separate days following overnight fasting. HRV and hemodynamics were evaluated in 5-min windows immediately before (T1) and 5-10 min (T2), 25-30 min (T3), 40-45 min (T4), and 55-60 min (T5) post-drinking. Root-mean square of successive differences and the standard deviation of normal RR intervals increased post-water intake at all time-points relative to T1 (P 0.05, ES = 0.27 - 0.32). Systemic vascular resistance increased at T2 post-Gatorade intake and at T2 and T3 post-water intake (P 60 min post-water intake. Key Findings: ● Equal volumes of cold water and Gatorade produce inequivalent cardiac-autonomic and hemodynamic responses. ● HRV responses of greater amplitude and duration were observed following intake of water versus Gatorade. ● Failure to account for recent fluid intake may result in misinterpretation of autonomic status.