Rehydration during Endurance Exercise: Challenges, Research, Options, Methods

Abstract

During endurance exercise, two problems arise from disturbed fluid–electrolyte balance: dehydration and overhydration. The former involves water and sodium losses in sweat and urine that are incompletely replaced, whereas the latter involves excessive consumption and retention of dilute fluids. When experienced at low levels, both dehydration and overhydration have minor or no performance effects and symptoms of illness, but when experienced at moderate-to-severe levels they degrade exercise performance and/or may lead to hydration-related illnesses including hyponatremia (low serum sodium concentration). Therefore, the present review article presents (a) relevant research observations and consensus statements of professional organizations, (b) 5 rehydration methods in which pre-race planning ranges from no advanced action to determination of sweat rate during a field simulation, and (c) 9 rehydration recommendations that are relevant to endurance activities. With this information, each athlete can select the rehydration method that best allows her/him to achieve a hydration middle ground between dehydration and overhydration, to optimize physical performance, and reduce the risk of illness.

Oral and intravenous hydration in the treatment of orthostatic hypotension and postural tachycardia syndrome

“…There have been multiple studies looking at the optimal oral fluid replacement beverages. Studies in the sports medicine literature have compared different methods of oral hydration, and more than just sodium is required to achieve sufficient hydration (McCubbin et al, 2020;Armstrong, 2021). Rehydration solutions need 75 mM of glucose per liter of water for efficient intestinal absorption of sodium (Binder et al, 2014).…”

Young Adults with Higher Salt Intake Have Inferior Hydration Status: A Cross-Sectional Study

“…Furthermore, high sodium or salt intake has also been linked with a high risk of cardiovascular diseases in the general population [4,5]. Studies have demonstrated that water and sodium deficits are predisposing factors for exertional heat stroke and exertional heat exhaustion [6]. Therefore, it is of vital importance to maintain the proper consumption of water and sodium for the human body.…”

Fitness level and the relationship between heart rate, body water, dehydration symptoms in adolescents during a pandemic

“…Fluid intake during exercise is essential and must be considered before, during, and after exercise (Armstrong, 2021;Je´quier & Constant, 2010;Kenefick & Cheuvront, 2012;McDermott et al, 2017). For sports that are carried out for less than 60 minutes, the reduced fluid can be replaced with mineral water intake only (Je´quier & Constant, 2010;Porcari et al, 2015).…”

“…For sports that are carried out for less than 60 minutes, the reduced fluid can be replaced with mineral water intake only (Je´quier & Constant, 2010;Porcari et al, 2015). If the exercise duration ranges from 60 -120 minutes, then mineral water alone is not enough, but an additional intake of electrolytes contained in sweat as metabolic waste is also required (Armstrong, 2021;Porcari et al, 2015), usually contained in milk (Amiri et al, 2019;Castro-Sepúlveda et al, 2016;Dow et al, 2019;Russo et al, 2019) and coconut water (Syafriani et al, 2014). After more than two hours of physical activity, in addition to water and electrolytes, it is also necessary to have an additional intake containing carbohydrates and protein, which are usually only found in milk.…”