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Effect of Personalized Sodium Replacement on Fluid and Sodium Balance and Thermophysiological Strain During and After Ultraendurance Running in the Heat.
- Source :
- International Journal of Sports Physiology & Performance; Feb2024, Vol. 19 Issue 2, p105-115, 11p
- Publication Year :
- 2024
-
Abstract
- Purpose: To investigate the effect of personalized sweat sodium replacement on drinking behavior, sodium and water balance, and thermophysiological responses during and after ultraendurance running in hot conditions. Methods: Nine participants (7 male, 2 female) completed two 5-hour treadmill runs (60% maximum oxygen uptake, 30°C ambient temperature), in a double-blind randomized crossover design, consuming sodium chloride (SODIUM) capsules to replace 100% of previously assessed losses or placebo (PLACEBO). Fluid was consumed ad libitum. Results: No effect of SODIUM was observed for ad libitum fluid intake or net fluid balance (P >.05). Plasma sodium concentration increased in both trials, but to a greater extent in SODIUM at 2.5 hours (mean [SD]: 4 [4] mmol·L<superscript>−1</superscript> vs 1 [5] mmol·L<superscript>−1</superscript>; P <.05) and postexercise (4 [3] mmol·L<superscript>−1</superscript> vs 1 [5] mmol·L<superscript>−1</superscript>; P <.05). Plasma volume change was not different between trials (P >.05) but was strongly correlated with sodium balance in SODIUM (r =.880, P <.01). No effect of sodium replacement was observed for heart rate, rectal temperature, thermal comfort, perceived exertion, or physiological strain index. During the 24 hours postexercise, ad libitum fluid intake was greater following SODIUM (2541 [711] mL vs 1998 [727] mL; P =.04), as was urinary sodium excretion (NaCl: 66 [35] mmol, Pl: 21 [12] mmol; P <.01). Conclusions: Personalized sweat sodium replacement during ultraendurance running in hot conditions, with ad libitum fluid intake, exacerbated the rise in plasma sodium concentration compared to no sodium replacement but did not substantially influence overall body-water balance or thermophysiological strain. A large sodium deficit incurred during exercise leads to substantial renal sodium conservation postexercise. [ABSTRACT FROM AUTHOR]
- Subjects :
- SODIUM metabolism
HEAT
SALT
HYDRATION
LONG-distance running
WATER-electrolyte balance (Physiology)
OXYGEN consumption
SODIUM
PERSPIRATION
EXERCISE physiology
ATHLETES
TREADMILLS
PHYSICAL fitness
RANDOMIZED controlled trials
PLACEBOS
COMPARATIVE studies
COOLDOWN
ENDURANCE sports
BLIND experiment
DESCRIPTIVE statistics
RESEARCH funding
DRINKING behavior
BODY temperature regulation
STATISTICAL sampling
CROSSOVER trials
EXTREME sports
METABOLISM
Subjects
Details
- Language :
- English
- ISSN :
- 15550265
- Volume :
- 19
- Issue :
- 2
- Database :
- Complementary Index
- Journal :
- International Journal of Sports Physiology & Performance
- Publication Type :
- Academic Journal
- Accession number :
- 175024688
- Full Text :
- https://doi.org/10.1123/ijspp.2023-0295