Oxidation of Solid versus Liquid CHO Sources during Exercise

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Abstract

Purpose:

To investigate exogenous CHO oxidation from CHO provided in either solid (BAR) or solution (DRINK) form during cycling.

Methods:

Eight well-trained subjects (age = 31 ± 7 yr, mass = 73 ± 5 kg, height = 1.79 ± 0.05 m, V˙O2max = 69 ± 6 mL·kg−1·min−1) cycled at 58% ± 4% V˙O2max for 180 min while receiving one of the following three treatments in randomized order: BAR plus water, DRINK, or water. The BAR and DRINK was delivered glucose + fructose (GLU + FRC) in a ratio of 2:1 at a rate of 1.55 g·min−1, and fluid intake was matched between treatments.

Results:

During the final 2 h of exercise, overall mean exogenous CHO oxidation rate was −0.11 g·min−1 lower in BAR (95% confidence interval = −0.27 to 0.05 g·min−1, P = 0.19) relative to DRINK, whereas exogenous CHO oxidation rates were 15% lower in BAR (P < 0.05) at 120, 135, and 150 min of exercise. Peak exogenous CHO oxidation rates were high in both conditions (BAR 1.25 ± 0.15 g·min−1 and DRINK 1.34 ± 0.27 g·min−1) but were not significantly different (P = 0.36) between treatments (mean difference = −0.9 g·min−1, 95% confidence interval = −0.32 to 0.13 g·min−1).

Conclusions:

The present study demonstrates that a GLU + FRC mix administered as a solid BAR during cycling can lead to high mean and peak exogenous CHO oxidation rates (>1 g·min−1). The GLU + FRC mix ingested in the form of a solid BAR resulted in similar mean and peak exogenous CHO oxidation rates and showed similar oxidation efficiencies as a DRINK. These findings suggest that CHO from a solid BAR is effectively oxidized during exercise and can be a practical form of supplementation alongside other forms of CHO.

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