Skip Navigation LinksHome > December 2009 - Volume 41 - Issue 12 > Fuel Selection during Prolonged Arm and Leg Exercise with 13...
Medicine & Science in Sports & Exercise:
doi: 10.1249/MSS.0b013e3181ab2579
Basic Sciences

Fuel Selection during Prolonged Arm and Leg Exercise with 13C-Glucose Ingestion

TREMBLAY, JONATHAN H.1; PÉRONNET, FRANÇOIS1; LAVOIE, CAROLE2; MASSICOTTE, DENIS3

Collapse Box

Abstract

Purpose: To compare fuel selection during prolonged arm (AE) and leg exercise (LE) with water or glucose ingestion.

Methods: Ten subjects (V˙O2max: 4.77 ± 0.20 and 3.36 ± 0.15 L·min−1 for LE and AE, respectively) completed 120 min of LE and AE at 50% of the mode-specific maximal power output (353 ± 18 and 160 ± 9 W, respectively) with ingestion of water (20 mL·kg−1) or 13C-glucose (2 g·kg−1). Substrate oxidation was measured using indirect respiratory calorimetry corrected for urea excretion and 13CO2 production at the mouth.

Results: The contribution of protein oxidation to the energy yield (%En) was higher during AE than LE (∼8% vs ∼4%) because of the lower energy expenditure and was not significantly modified with glucose ingestion. With water ingestion, the %En from CHO oxidation was not significantly different during LE and AE (64 ± 2% and 66 ± 2%, respectively). Glucose ingestion significantly increased the %En from total CHO oxidation during AE (78 ± 3%) but not during LE (71 ± 2%). Exogenous glucose oxidation was not significantly different in AE and LE (56 ± 4 and 65 ± 3 g, respectively), but the %En from exogenous glucose was higher during AE than LE (30 ± 1% and 24 ± 1%) because of the lower energy expenditure. When glucose was ingested, the %En from endogenous CHO oxidation was significantly reduced during both AE (66 ± 2% to 48 ± 3%) and LE (64 ± 2% to 47 ± 3%) and was not significantly different in the two modes of exercise.

Conclusions: The difference in fuel selection between AE and LE when water was ingested was modest with a slightly higher reliance on CHO oxidation during AE. The amount of exogenous glucose oxidized was lower but its %En was higher during AE because of the lower energy expenditure.

©2009The American College of Sports Medicine

Login

Article Tools

Share

Search for Similar Articles
You may search for similar articles that contain these same keywords or you may modify the keyword list to augment your search.

Connect With Us