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The adaptogen Rhodiola rosea (RR) may mitigate stress responses and have beneficial effects on endurance capacity (EC) and mental performance. Heat acclimation (HA) improves EC in the heat, but the potential impact of RR on the HA process is unknown. Therefore, our intent was to determine if RR has a positive impact on HA. Twenty male subjects (age, 22.5 ± 3.0 years) completed 2 EC tests involving walking (6 km·h−1) until volitional exhaustion in a climate chamber (air temperature, 42 °C; relative humidity, 18%) before (H1) and after (H2) an 8-day HA period. One group (SHR; n = 10) ingested standardised extract SHR-5 of RR (a single daily dose of 432 mg), while a second group (PLC; n = 10) administered a placebo prior to each HA session. Efficacy of HA was evaluated on the basis of changes that occurred from H1 to H2 in the time to exhaustion (TTE), exercise heart rate (HR), core and skin temperatures ( Tc, Tsk), stress hormones, ratings of perceived exertion (RPE) and fatigue (RPF), and thermal sensation (TS). HA significantly increased TTE (133.1 ± 44.1 min in H1; 233.4 ± 59.8 min in H2; p < 0.0001) and decreased ( p < 0.0001) HR, Tc, Tsk, stress hormones as well as RPE, RPF, and TS. However, the magnitude of all these changes was similar ( p > 0.05) in the SHR and PLC groups. These results suggest that the use of RR during HA has no beneficial performance, physiological, or perceptual effects in young healthy males. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine if the ingestion of sodium citrate (CIT) alters blood levels of fluid and electrolyte regulatory hormones at rest and during exercise. Using a randomized, double-blinded, crossover design, 13 young, male well-trained runners performed continuous incremental running tests to volitional exhaustion on a treadmill 2 h after ingestion of 0.5 g·kg-1 body mass of CIT or placebo (PLC) in 1000 mL of solution. These trials were separated by 2 weeks. Baseline (before ingestion) aldosterone concentration did not differ between the 2 trials; however, it was 36.5% (p = 0.003) lower in the CIT trial compared with the PLC trial before the running test (i.e., after ingestion). The extent of the running-induced increase in aldosterone was 33% (p = 0.009) smaller in the CIT trial. There were no between-trial differences in the levels of adrenocorticotropic hormone, N-terminal pro-B-type natriuretic peptide, or renin activity at any stage of the study. However, a greater relative increase in plasma volume (mean ± SD, 6.41% ± 3.78% vs. 4.08% ± 3.33%; p = 0.042) was observed after administering the CIT compared with the PLC drink. Serum Na+ concentration increased (by 3.1 ± 1.2 mmol·L-1; p < 0.0001) after ingestion of the CIT but not the PLC drink. A higher Na+ level was observed in the CIT trial than in the PLC trial (142.4 ± 1.6 vs. 139.3 ± 1.4 mmol·L-1, p = 0.00001) after completion of the run. In conclusion, pre-exercise ingestion of CIT induces a decrease in serum aldosterone concentration in the resting condition and a blunting of the aldosterone response during incremental running exercise to volitional exhaustion. The observed effect of CIT on the serum aldosterone level may be mediated by an acute increase in plasma volume and serum Na+ concentration alterations. Cette étude se propose de vérifier si la consommation de citrate de sodium (CIT) modifie les taux des hormones responsables de l’équilibre hydrique et des électrolytes, au repos et à l’effort. Treize jeunes hommes bien entraînés à la course participent à un test d’effort progressif continu sur tapis roulant, jusqu’à épuisement, et ce, 2 h après avoir consommé 0,5 g·kg-1 de masse corporelle de CIT ou d’un placebo (PLC) dissous dans 1000 mL d’une solution. La stratégie de recherche consiste en un plan expérimental contrebalancé à double insu. Les deux essais sont réalisés à deux semaines d’intervalle. D’un essai à l’autre, la concentration d’aldostérone de référence avant la consommation de la boisson ne diffère pas; par contre, elle diminue de 36,5 % (p = 0,003) après la consommation de la boisson dans la condition CIT comparativement à la condition PLC avant le début du test. Dans la condition CIT, l’augmentation de la concentration d’aldostérone suscitée par la course est 33 % plus faible (p = 0,009). D’une condition à l’autre et à toutes les étapes de l’étude, on n’observe aucune différence des concentrations de l’hormone adrénocorticotrope, du fragment N-terminal du peptide natriurétique pro-B et de l’activité de la rénine. Cependant, on observe une plus grande augmentation du volume plasmatique relatif après la consommation du CIT comparativement à la consommation du PLC : moyenne ± écart-type, 6,41 ± 3,78 % comparativement à 4,08 ± 3,33 %; p = 0,042. La concentration sérique de Na+ augmente de 3,1 ± 1,2 mmol·L-1 (p < 0,0001) après la consommation du CIT, mais n’augmente pas après la consommation du PLC. Après la fin de la course, on observe une plus grande concentration de Na+ dans la condition CIT que dans la condition PLC : 142,4 ± 1,6 mmol·L-1 comparativement à 139,3 ± 1,4 mmol·L-1 (p = 0,00001). En conclusion, la consommation de CIT avant le début de l’exercice physique suscite une diminution de la concentration sérique d’aldostérone au repos et une atténuation de la réponse de l’aldostérone au cours du test d’effort progressif jusqu’à épuisement. L’effet noté du CIT sur la concentration sérique d’aldostérone est probablement dû à l’augmentation rapide du volume plasmatique et à la modification du taux sérique de Na+. [ABSTRACT FROM AUTHOR]