Journal Title (Medline/Pubmed accepted abbreviation): J. Strength Cond. Res
Page number: 2544-2551
Background: During exercise, carbohydrates and fat are the most utilized energy sources. As exercise intensity increases, it has been shown that carbohydrates are preferentially burned compared to fat. There has been some evidence that females tend to burn a higher ratio of fat:carbohydrates during exercise than males. Also, it is thought that the self-selected pace of an individual is the approximate pace that burns the highest proportion of fat.
Hypothesis: Men and women will self-select a pace that burns the highest fat:carbohydrate ratio and, because women tend to exhibit higher fat:carbohydrate oxidation ratios, they will have the highest fat:carbohydrate oxidation rates.
Subjects: There were 34 participants in total, 17 men and 17 women, age about 21-27 yrs old. The subjects were classified as sedentary to moderately trained with mean body mass index (BMI) of 22-23 kg/m2.
Experimental design: ex post facto research design (research questions were posed based on data that were already gathered)
Protocol : Participants first were assessed for height, weight, body fat percentage (skinfold), and were familiarized with the treadmill. At their second visit to the laboratory, they underwent a maximal exercise test and their VO2max was established. Two days later, they performed the experimental trial. They walked on the treadmill for 20 min at a self-selected pace. They were able to adjust their pace at 5, 10, and 15 min, if desired. Respiratory gases were measured throughout the trial, from which the respiratory exchange ratio (RER) was calculated. (The RER is used to estimate the ratio of fat:carbohydrate oxidation). Total energy expenditure was estimated from VO2 during the experimental trail and RER.