Related Experiment Video
Updated: Aug 9, 2026

Getting to Compliance in Forced Exercise in Rodents: A Critical Standard to Evaluate Exercise Impact in Aging-related Disorders and Disease
Published on: August 22, 2014
Effect of daily exercise and food intake on leucine oxidation
Abstract:
Oxidation of the branched-chain amino acid leucine was studied in 22 male Sprague-Dawley rats (70-90 g) over 3 days following the ingestion on Day 1 of a mixed diet containing a tracer dose (10 muCi) of L-[1-14C]Leu. One group (E) completed 1 hr exercise at 80% VO2 max immediately after a 2-hr feeding period on all 3 days, while a second group served as a control. Rats from group E were sacrificed immediately after the 2 hr feeding on Day 1, following exercise on Days 1 and 3, and at the end of Day 3. The following were determined: (1) continuous 14CO2 production, (2) radioactivity remaining in the gastrointestinal tract, and (3) distribution of free vs protein bound 14C in muscle and liver. The results indicated that (1) 14CO2 production increased during exercise on all 3 days (P less than 0.01), (2) 14CO2 production also increased (P less than 0.05) following food intake (unlabeled diet), (3) 14CO2 production due to exercise was greater than that due to food intake (P less than 0.05), (4) absolute 14CO2 production decreased dramatically by 15 hr of Day 1 (P less than 0.01) with little change thereafter (except with exercise and food intake on Days 2 and 3), (5) greater than 98% of the labeled diet was absorbed from the GIT 51 hr postingestion, and (6) 14C in the free pool of muscle and liver could account for less than 15% of the total 14CO2 production. These results suggest that protein bound 14C in addition to free 14C may be responsible for a significant proportion of the observed increased 14CO2 production during exercise.
Related Concept Videos
Overview of Metabolism
Plant Metabolism
Sunlight, the primary source of energy in plants, is first absorbed by the chlorophyll pigments present in their leaves. Plants then use this energy to carry out photosynthesis, where water is oxidized into oxygen and carbon dioxide...
Muscle Recovery and Fatigue
Exercise and Cardiac Output
Sustained exercise increases the muscles' oxygen demand, which can be met...
Exercise and Cardiovascular Response
Light to moderate physical activity initiates a series of interconnected responses in the body. The heart rate modestly increases in anticipation of the workout, followed by widespread vasodilation as oxygen consumption by skeletal muscles increases. This results in decreased peripheral resistance, increased capillary blood flow, and accelerated...

