Exercise-induced dehydration with and without environmental heat stress results in increased oxidative stress

Abstract

While in vitro work has revealed that dehydration and hyperthermia can elicit increased cellular and oxidative stress, in vivo research linking dehydration, hyperthermia, and oxidative stress is limited. The purpose of this study was to investigate the effects of exercise-induced dehydration with and without hyperthermia on oxidative stress. Seven healthy male, trained cyclists (power output (W) at lactate threshold (LT): 199 ± 19 W) completed 90 min of cycling exercise at 95% LT followed by a 5-km time trial (TT) in 4 trials: (i) euhydration in a warm environment (EU-W, control), (ii) dehydration in a warm environment (DE-W), (iii) euhydration in a thermoneutral environment (EU-T), and (iv) dehydration in a thermoneutral environment (DE-T) (W: 33.9 ± 0.9 °C; T: 23.0 ± 1.0 °C). Oxidized glutathione (GSSG) increased significantly postexercise in dehydration trials only (DE-W: p < 0.01, DE-T: p = 0.03), and while not significant, total glutathione (TGSH) and thiobarbituric acid reactive substances (TBARS) tended to increase postexercise in dehydration trials (p = 0.08 for both). Monocyte heat shock protein 72 (HSP72) concentration was increased (p = 0.01) while lymphocyte HSP32 concentration was decreased for all trials (p = 0.02). Exercise-induced dehydration led to an increase in GSSG concentration while maintenance of euhydration attenuated these increases regardless of environmental condition. Additionally, we found evidence of increased cellular stress (measured via HSP) during all trials independent of hydration status and environment. Finally, both 90-min and 5-km TT performances were reduced during only the DE-W trial, likely a result of combined cellular stress, hyperthermia, and dehydration. These findings highlight the importance of fluid consumption during exercise to attenuate thermal and oxidative stress during prolonged exercise in the heat.

Oxidative stress in aspic vipers facing pregnancy and water constraints

“…no significant interaction; Table 1). These results might look surprising given the known impact of dehydration on oxidative homeostasis in humans (Hillman et al, 2011). However, it is likely that resistance mechanisms exist in species naturally facing extended periods of water deprivation, as recently suggested by the increased innate immunity found in response to dehydration in a desert reptile (Moeller et al, 2013).…”

Heat shock response and autophagy—cooperation and control

“…In subjects who completed a half marathon (21.1 km) with an increased plasma creatine kinase activity indicating exercise-induced skeletal muscle damage and rectal temperature reaching 44 C, there is a post-exercise increase in HSP70 protein expression in monocytes and granulocytes that remains elevated for up to 1 d post-exercise. 149,150 Similarly, exhaustive treadmill exercise, 148,151 strenuous cycling, 152,153 or repeated sprint cycle exercise 154 augments HSP70 protein expression in leukocytes that lasts up to 48 h post exercise.…”

Extracellular Hsp72 concentration relates to a minimum endogenous criteria during acute exercise-heat exposure

“…The confounding variables of smoking (Anbarasi et al 2006), caffeine (Lu et al 2008), glutamine (Singleton et al 2004), generic supplementation (Hillman et al 2011), thermal exposures (Selkirk et al 2009), hypoxic exposures (Taylor et al 2010a), hyperbaric exposures (Taylor et al 2012) and alcohol (Taylor et al 2010b) were all controlled in line with previous work in the field . Each volunteer was given instructions for dietary requirements in accordance with published guidelines and requested to maintain identical diets in the immediate 48 h prior to each experimental session (Canada 2009).…”