Effects of a High-Sodium, Carbohydrate-Free Multi-Electrolyte Supplement on 15 km Treadmill Time-Trial Performance in Warm and Humid Conditions: A Randomized, Single-Blind, Placebo-Controlled Crossover Trial.
- 1Department of Exercise Science, Grove City College, Grove City, PA 16127, USA.
- 2Emeritus Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa.
Abstract
Sodium ingestion may support fluid balance and endurance performance in the heat, but most previous studies have used sodium-loading, hyperhydration, or carbohydrate-electrolyte protocols. This study examined the effects of a high-sodium, carbohydrate-free multi-electrolyte supplement (HSES) on 15 km treadmill time-trial performance and physiological responses in trained male runners under warm-humid conditions. In a randomized, single-blind, counterbalanced crossover design, ten trained male runners (V̇O₂max: 57.3 ± 8.1 mL·kg⁻¹·min⁻¹) completed two 15 km treadmill time trials at 26.7 °C and 60% relative humidity. Participants received HSES or a flavor-matched placebo (PLA) 30 min before exercise and every 15 min of running time. Repeated-measures analysis of cumulative completion time showed a significant main effect of condition (p = 0.034) and a significant condition × distance interaction (p = 0.023). Segment pace also showed a significant condition × segment interaction (p = 0.001); participants ran faster during HSES over the opening 0-5 km (p < 0.001), pace did not differ during 5-10 km (p = 0.091), and participants ran faster during PLA over the final 10-15 km (p = 0.032). Mean final 15 km completion time was 68.76 ± 12.28 min during HSES and 70.18 ± 13.33 min during PLA, a mean difference of 1.42 min (~2.0%). However, the direct paired comparison of final completion time did not reach statistical significance (HSES - PLA: -1.42 min; 95% CI, -3.60 to 0.77 min; p = 0.176; Cohen's dz = -0.46). No significant between-condition differences were observed in measured hydration-related, cardiovascular, metabolic, or perceptual outcomes. Estimated core temperature was higher during HSES at 15 km and 10 min post-exercise. Pacing differed between conditions during the 15 km time trial, with a faster opening 5 km during HSES and a faster final 5 km during PLA. Final 15 km completion time was approximately 2.0% faster during HSES, although the difference was not statistically significant.
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BibTeX
@article{prins2026effects,
title = {{Effects of a High-Sodium, Carbohydrate-Free Multi-Electrolyte Supplement on 15 km Treadmill Time-Trial Performance in Warm and Humid Conditions: A Randomized, Single-Blind, Placebo-Controlled Crossover Trial.}},
author = {Philip Prins and Jeffrey D Buxton and Abigail Helsel and Sarah Bonnett and Luke DeMember and Jackson Timko and Timothy Noakes},
journal = {Sports (Basel, Switzerland)},
year = {2026},
month = oct,
doi = {10.3390/sports14100435},
url = {https://europepmc.org/article/MED/42931572},
note = {CC BY},
}
RIS
TY - JOUR
TI - Effects of a High-Sodium, Carbohydrate-Free Multi-Electrolyte Supplement on 15 km Treadmill Time-Trial Performance in Warm and Humid Conditions: A Randomized, Single-Blind, Placebo-Controlled Crossover Trial.
AU - Philip Prins
AU - Jeffrey D Buxton
AU - Abigail Helsel
AU - Sarah Bonnett
AU - Luke DeMember
AU - Jackson Timko
AU - Timothy Noakes
PY - 2026
DA - 2026/10/07
JO - Sports (Basel, Switzerland)
DO - 10.3390/sports14100435
UR - https://europepmc.org/article/MED/42931572
AB - Sodium ingestion may support fluid balance and endurance performance in the heat, but most previous studies have used sodium-loading, hyperhydration, or carbohydrate-electrolyte protocols. This study examined the effects of a high-sodium, carbohydrate-free multi-electrolyte supplement (HSES) on 15 km treadmill time-trial performance and physiological responses in trained male runners under warm-humid conditions. In a randomized, single-blind, counterbalanced crossover design, ten trained male runners (V̇O₂max: 57.3 ± 8.1 mL·kg⁻¹·min⁻¹) completed two 15 km treadmill time trials at 26.7 °C and 60% relative humidity. Participants received HSES or a flavor-matched placebo (PLA) 30 min before exercise and every 15 min of running time. Repeated-measures analysis of cumulative completion time showed a significant main effect of condition (p = 0.034) and a significant condition × distance interaction (p = 0.023). Segment pace also showed a significant condition × segment interaction (p = 0.001); participants ran faster during HSES over the opening 0-5 km (p < 0.001), pace did not differ during 5-10 km (p = 0.091), and participants ran faster during PLA over the final 10-15 km (p = 0.032). Mean final 15 km completion time was 68.76 ± 12.28 min during HSES and 70.18 ± 13.33 min during PLA, a mean difference of 1.42 min (~2.0%). However, the direct paired comparison of final completion time did not reach statistical significance (HSES - PLA: -1.42 min; 95% CI, -3.60 to 0.77 min; p = 0.176; Cohen's dz = -0.46). No significant between-condition differences were observed in measured hydration-related, cardiovascular, metabolic, or perceptual outcomes. Estimated core temperature was higher during HSES at 15 km and 10 min post-exercise. Pacing differed between conditions during the 15 km time trial, with a faster opening 5 km during HSES and a faster final 5 km during PLA. Final 15 km completion time was approximately 2.0% faster during HSES, although the difference was not statistically significant.
SN - 2075-4663
ER -