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Date of Award

Spring 2013

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Department of Kinesiology

Abstract

The purpose of this investigation was to examine the effects of glucose and fructose coingestion on cycling time trial performance and physiological responses to exercise. Eight trained male cyclists (age: 25 ± 6.2 yrs, height: 180.2 ± 4.3 cm, weight: 76.9 ± 9.2 kg, and VO2max: 61.9 ± 6.2 mL∙kg-1∙min-1) completed the study. Subjects ingested either an artificially-sweetened placebo (PL), a moderate-glucose beverage (MG: 1.0 g•min-1), a high-glucose beverage (HG: 1.5 g•min-1), or a glucose and fructose beverage (GF: 1.5 g•min-1; 2:1 ratio) during ~3 hrs of exercise; consisting of 2 hours of constant load cycling (55% Wmax, 195 ± 17.3 W), immediately followed by a computer-simulated 30-km time trial. Physiological responses (VE, VO2, RER, heart rate, blood glucose, blood lactate, and RPE) and incidences of GI distress were assessed during early- (15-20 min), middle- (55-60 min), and late-exercise (115-20 min), and during the time-trial. Treatment differences were analyzed using qualitative inferences. Time trial performances were ‘likely’ improved with GF (50.4 ± 2.2 min) and MG (51.1 ± 2.4) versus PL (52.9 ± 3.7 min), while differences between HG (52.0 ± 3.7 min) and PL were ‘unclear.’ GF resulted in ‘likely’ (3.0%) improvement versus HG and an ‘unclear’ (1.2%) benefit relative to MG. MG was ‘possibly’ beneficial (1.8%) versus HG. Few incidences of GI distress were reported in any trials. GF ingestion appears to enhance performance relative to PL, and HG. However, further study is necessary to determine if GF improves performance versus moderate (currently recommended) doses of glucose.

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