Rehydration with drinks differing in sodium concentration and recovery from moderate exercise-induced hypohydration in man

Abstract

To investigate how differing moderate sodium chloride concentrations affect rehydration after exercise and subsequent exercise capacity, eight males lost 1.98 +/- 0.1% body mass exercising in the heat, then consumed one of four drinks in a volume equivalent to 150% of mass loss. Drinks were identical except for sodium chloride content (1 +/- 1, 31 +/- 1, 40 +/- 1, 50 +/- 1 mmol/l). After 4 h recovery subjects cycled for 5 min at 70% VO(2peak) then at 95% VO(2peak) until volitional fatigue. Urine output was inversely related to sodium intake: more was produced with the 1 than the 40 and 50 mmol/l drinks (P < 0.01). Time to exhaustion in the exercise capacity test was not different between treatments (P = 0.883). The addition of 40 or 50 mmol/l of sodium chloride to a rehydration beverage reduced subsequent urine output, thereby providing more effective rehydration than a sodium-free drink. This did not, however, result in improved performance 4 h after the end of the rehydration period.

2017 ACC/AHA/HRS Guideline for the Evaluation and Management of Patients With Syncope: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society

“…398,438,[440][441][442][443][444]502 Beverages with increased sodium concentration (closer to normal body osmolality) rehydrate faster than beverages with lower sodium concentration or increased osmolality (eg, because of glucose content). [498][499][500][501]503,506 IIa B-NR Reducing or withdrawing medications that may cause hypotension can be beneficial in selected patients with syncope.…”

Effect of whey protein isolate on rehydration after exercise

“…It seems that when rehydration drinks are ingested in a volume equivalent to 150% of sweat losses over 1 h, the addition of carbohydrate (Evans et al 2009), protein (James et al 2012) or potassium (Shirreffs et al 2007a) might not sufficiently reduce urine production to prevent fluid balance from becoming negative in the hours after drinking. In contrast, the addition of sodium to a rehydration drink has been shown to consistently influence urine production in a dosedependent manner (Maughan and Leiper 1995;Shirreffs et al 1996;Merson et al 2008). …”

“…In contrast to this, the addition of sodium (the major cation in the extracellular space) to a rehydration drink prevents the decline in serum sodium concentration and osmolality that occurs with the ingestion of a low sodium drink (Nose et al 1988) and consequently reduces urine production (Nose et al 1988;Maughan and Leiper 1995;Shirreffs and Maughan 1998;Merson et al 2008). …”

Part 13: First Aid

“…One LOE 2 284 and 1 LOE 5 285 study showed that oral rehydration is as effective as intravenous rehydration. In a model of exercise-and heat-induced mild hypohydration, 1 LOE 1 study 286 and 8 LOE 2 studies 284,[287][288][289][290][291][292][293] demonstrated that oral carbohydrate/electrolyte solutions were more effective than water in restoring intravascular volume. One LOE 2 study 293 showed that the volume consumed must exceed the volume lost in sweat.…”