This study examined the effect of electrolyte addition to drinks ingested after severe fluid and energy restriction (FER). Twelve subjects (six male, six female) completed three trials consisting of 24 h FER (energy intake: 21 kJ[middle dot]kg-1 body mass; water intake: 5 ml[middle dot]kg-1 body mass), followed by a 2 h rehydration period and a 4 h monitoring period. During rehydration, subjects ingested a volume of drink equal to 125% of the body mass lost during FER in 6 aliquots, once every 20 min. Drinks were a sugar free lemon squash (P) or the P drink with the addition of 50 mmol[middle dot]l-1 sodium chloride (Na) or 30 mmol[middle dot]l-1 potassium chloride (K). Total void urine samples were given before and after FER and every hour during rehydration and monitoring. Over all trials, FER produced a 2.1% reduction in body mass and negative sodium (-67 mmol), potassium (-48 mmol) and chloride (-84 mmol) balances. Urine output after drinking was 1627 (540) ml (P), 1391 (388) ml (K) and 1150 (438) ml (Na), with a greater post-drinking urine output during P than Na (P<0.05). Ingestion of drink Na resulted in a more positive sodium balance compared to P or K (P<0.001), whilst ingestion of drink K resulted in a more positive potassium balance compared to P or Na (P<0.001). These results demonstrate that after 24 h FER, ingestion of a high sodium drink results in an increased sodium balance that augments greater drink retention compared to a low electrolyte placebo drink.
Copyright (C) 2014 by the National Strength & Conditioning Association.