Search

Sugar administration prior acute psychosocial stress exposure was shown to enhance subsequent salivary cortisol responses. However, this finding is based on studies that have administered high doses of glucose to male subjects after long fasting periods. Therefore, in the present study, we investigated the effect of different sugar-containing drinks on acute cortisol stress responses under experimental conditions that are commonplace in stress research and our sample included females and males. Our primary aim was to derive feasible recommendations for a standardized sugar administration in future studies. Of the 103 healthy young participants (49 females, 54 males), 72 were confronted with the Trier Social Stress Test after being randomly assigned to one of three sugar conditions (200 ml of grape juice, a 75 g glucose or a 75 g maltodextrin drink); 31 subjects served as control sample and were exposed to the TSST without sugar administration. Cortisol stress responses were significantly enhanced in the grape juice as well as the glucose group as compared to the control group. Post hoc analysis revealed that this effect seemed to be more pronounced in males than in females. We did not find a significant effect of maltodextrin. Cortisol responder rates in all three experimental groups were higher than in the control group. Our results suggest that, at least in males, the administration of 200 ml of grape juice is sufficient to facilitate HPA axis reactivity and to minimize confounding effects due to interindividual differences in energy availability while being exposed to a laboratory stress paradigm. The unexpected gender-specific effect is of potential relevance and should be scrutinized in future studies., Competing Interests: Declaration of Competing Interest All authors report no conflict of interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Research has shown that carbohydrate consumption can increase body temperature at rest and, in some cases, during exercise. Most exercise studies, however, haven't matched exercise intensity between carbohydrate and placebo conditions. The purpose of this randomized, double-blind, placebo-controlled trial was to examine whether pre-exercise carbohydrate consumption independently accelerates the usual temperature rise with intense exercise. Twenty-eight runners self-reported 5-km performance (16-23 min) and were randomized, using a matched-pairs design, to 750 ml water containing 100 g sucrose or 0.8 g aspartame. Beverages were consumed 60 min before running at 93% of maximum 5-km speed in temperate conditions. Gastrointestinal temperature, Thermal Sensation Scale (TSS) and Feeling Scale (FS) were recorded before ingestion, every 10 min during 60 min of rest, and every 1-km during the 5-km run. Rating of Perceived Exertion was recorded every 1-km. Independent samples t-tests and two-way mixed ANOVAs with repeated measures assessed whether there were baseline differences or treatment effects. Gastrointestinal temperature didn't differ between carbohydrate (38.7 ± 0.4 °C) and placebo (38.6 ± 0.4 °C) by the end of the 5-km (p = 0.49). No group x time interactions or main group effects were found, except for a modest interaction for TSS (F = 2.1, p = 0.02, partial η 2 = 0.075). Time effects were found for all outcomes, with temperature, TSS, and RPE increasing, and FS decreasing, during the run. Ingesting 100 g of sucrose prior to intense running lasting < 25 min didn't influence gastrointestinal temperature and therefore doesn't likely impact on the risk of heat illness., (Copyright © 2018 Elsevier Ltd. All rights reserved.)