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Title: Electrolyte supplementation during severe energy restriction increases exercise capacity in the heat
Authors: James, Lewis J.
Mears, Stephen A.
Shirreffs, Susan M.
Keywords: Hydration
Fluid balance
Dehydration
Hypohydration
Fasting
Issue Date: 2015
Publisher: © Springer
Citation: JAMES, L., MEARS, S. and SHIRREFFS, S., 2015. Electrolyte supplementation during severe energy restriction increases exercise capacity in the heat. European Journal of Applied Physiology, 115 (12), pp.2621-2629.
Abstract: PURPOSE. This study examined the effects of sodium chloride and potassium chloride supplementation during 48-h severe energy restriction on exercise capacity in the heat. METHODS. Nine males completed three 48-h trials: adequate energy intake (100 % requirement), adequate electrolyte intake (CON); restricted energy intake (33 % requirement), adequate electrolyte intake (ER-E); and restricted energy intake (33 % requirement), restricted electrolyte intake (ER-P). At 48 h, cycling exercise capacity at 60 % V˙V˙O2 peak was determined in the heat (35.2 °C; 61.5 % relative humidity). RESULTS. Body mass loss during the 48 h was greater during ER-P [2.16 (0.36) kg] than ER-E [1.43 (0.47) kg; P < 0.01] and CON [0.39 (0.68) kg; P < 0.001], as well as greater during ER-E than CON (P < 0.01). Plasma volume decreased during ER-P (P < 0.001), but not ER-E or CON. Exercise capacity was greater during CON [73.6 (13.5) min] and ER-E [67.0 (17.2) min] than ER-P [56.5 (13.1) min; P < 0.01], but was not different between CON and ER-E (P = 0.237). Heart rate during exercise was lower during CON and ER-E than ER-P (P < 0.05). CONCLUSIONS. These results demonstrate that supplementation of sodium chloride and potassium chloride during energy restriction attenuated the reduction in exercise capacity that occurred with energy restriction alone. Supplementation maintained plasma volume at pre-trial levels and consequently prevented the increased heart rate observed with energy restriction alone. These results suggest that water and electrolyte imbalances associated with dietary energy and electrolyte restriction might contribute to reduced exercise capacity in the heat.
Description: The final publication is available at Springer via http://dx.doi.org/10.1007/s00421-015-3254-1.
Version: Accepted for publication
DOI: 10.1007/s00421-015-3254-1
URI: https://dspace.lboro.ac.uk/2134/20828
Publisher Link: http://dx.doi.org/10.1007/s00421-015-3254-1
ISSN: 1439-6319
Appears in Collections:Published Articles (Sport, Exercise and Health Sciences)

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