Int J Sports Med 2014; 35(14): 1216-1222
DOI: 10.1055/s-0034-1375635
Nutrition
© Georg Thieme Verlag KG Stuttgart · New York

Self-selecting Fluid Intake while Maintaining High Carbohydrate Availability Does not Impair Half-marathon Performance

M. J. C. Lee
1   Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
,
K. M. Hammond
1   Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
,
A. Vasdev
1   Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
,
K. L. Poole
1   Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
,
S. G. Impey
1   Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
,
G. L. Close
1   Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
,
J. P. Morton
1   Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
› Author Affiliations
Further Information

Publication History



accepted after revision 13 April 2014

Publication Date:
21 August 2014 (online)

Abstract

We aimed to test the hypothesis that self-selecting fluid intake but maintaining high exogenous CHO availability (60 g/h) does not compromise half-marathon performance. 15 participants completed 3 half-marathons while drinking a 6% CHO solution to guidelines (DRINK) or a non-caloric solution in self-selected volumes when consuming 3×glucose (20 g) gels (G-GEL) or glucose-fructose (13 g glucose+7 g fructose) gels (GF-GEL) per hour. Fluid intake (DRINK: 1 557±182, G-GEL: 473±234, GF-GEL: 404±144 ml) and percent body mass loss (DRINK: − 0.8±0.9, G-GEL: − 2.0±0.6, GF-GEL: −2.3±1.1) were different (P<0.05) between conditions, though race time did not differ (DRINK: 110.6±14.4, G-GEL: 110.3±14.6, GF-GEL: 113.7±12.8 min). In G-GEL, there was a positive correlation (P<0.05) between body mass loss and race time. Plasma glucose was lower (P<0.05) in GF-GEL compared with other conditions, and total CHO oxidation (DRINK: 3.2±0.5, G-GEL: 3.0±0.4, GF-GEL: 2.6±0.4 g/min) was lower (P=0.06) in this trial. Self-selecting fluid intake but maintaining high CHO availability does not impair half-marathon performance. Additionally, consuming glucose-fructose mixtures in sub-optimal amounts reduces plasma glucose and total rates of CHO oxidation.