Glucose–Fructose Enhances Performance versus Isocaloric, but Not Moderate, Glucose

PURPOSEThe effects of glucose-and-fructose (GF) coingestion on cycling time trial (TT) performance and physiological responses to exercise were examined under postprandial conditions. METHODSEight trained male cyclists (age, 25 ± 6 yr; height, 180 ± 4 cm; weight, 77 ± 9 kg; V˙O2max, 62 ± 6 mL·kg·min...

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Published in:Medicine and science in sports and exercise 2014-09, Vol.46 (9), p.1778-1786
Main Authors: BAUR, DANIEL A, SCHROER, ADAM B, LUDEN, NICHOLAS D, WOMACK, CHRISTOPHER J, SMYTH, SARAH A, SAUNDERS, MICHAEL J
Format: Article
Language:English
Subjects:
Administration, Oral
Adult
Athletic Performance - physiology
Bicycling - physiology
Biological and medical sciences
Blood Glucose - metabolism
Colic - chemically induced
Dizziness - chemically induced
Double-Blind Method
Exercise Test
Fructose - administration & dosage
Fructose - adverse effects
Fundamental and applied biological sciences. Psychology
Glucose - administration & dosage
Glucose - adverse effects
Headache - chemically induced
Heart Rate
Human physiology applied to population studies and life conditions. Human ecophysiology
Human viral diseases
Humans
Immunodeficiencies
Immunodeficiencies. Immunoglobulinopathies
Immunopathology
Infectious diseases
Lactic Acid - blood
Male
Medical sciences
Nausea - chemically induced
Oxygen Consumption
Performance-Enhancing Substances - administration & dosage
Performance-Enhancing Substances - adverse effects
Physical Exertion
Postprandial Period
Pulmonary Gas Exchange
Pulmonary Ventilation
Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports
Viral diseases
Viral diseases of the lymphoid tissue and the blood. Aids
Vomiting - chemically induced
Young Adult
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Summary:PURPOSEThe effects of glucose-and-fructose (GF) coingestion on cycling time trial (TT) performance and physiological responses to exercise were examined under postprandial conditions. METHODSEight trained male cyclists (age, 25 ± 6 yr; height, 180 ± 4 cm; weight, 77 ± 9 kg; V˙O2max, 62 ± 6 mL·kg·min) completed the study. Subjects ingested either an artificially sweetened placebo (PL), a moderate-glucose beverage (MG, 1.03 g·min), a high-glucose beverage (HG, 1.55 g·min), or a GF beverage (1.55 g·min, 2:1 ratio) during approximately 3 h of exercise, including 2 h of constant-load cycling (55% Wmax, 195 ± 17 W), immediately followed by a computer-simulated 30-km TT. Physiological responses (V˙E, V˙O2, RER, HR, blood glucose level, blood lactate level, and RPE) and incidences of gastrointestinal distress were assessed during early (15–20 min), middle (55–60 min), and late exercise (115–120 min) and during the TT. Magnitude-based qualitative inferences were used to evaluate differences between treatments. RESULTSIn comparison with that in PL (52.9 ± 3.7 min), TT performances were faster with GF (50.4 ± 2.2 min, “very likely” benefit), MG (51.1 ± 2.4 min, “likely” benefit), and HG (52.0 ± 3.7 min, “possible” benefit). GF resulted in a “likely” improvement versus HG (3.0%) and an “unclear” effect relative to MG (1.2%). MG was “possibly” beneficial versus HG (1.8%). Few incidences of GI distress were reported in any trials. CONCLUSIONSGF ingestion seems to enhance performance, relative to PL and HG. However, it is unclear whether GF improves performance versus moderate doses of glucose.
ISSN:0195-9131
1530-0315
DOI:10.1249/MSS.0000000000000284