Substrate utilization during treadmill running in prepubertal girls and female adults by Martinez, Lucia R., Ph.D., The Florida State University, 1991, 271 pages; AAT 9126982

Abstract (Summary)

To determine if there are differences in substrate utilization of prepubertal girls and female adults during treadmill running, ten girls (mean age 9.1 $\pm$.6 years) and ten women (mean age 24.4 $\pm$ 5.2) underwent a 30 minute run at the same relative (70% VO$\sb2$ Max) (RI) and absolute (4mph/0% grade) (AI) intensity. Oxygen consumption (VO$\sb2$) and respiratory exchange ratio (RER) were monitored continuously during the exercise test by standard open circuit spirometry. Venous blood samples were obtained from an antecubital vein before and immediately after the termination of the exercise bout and were analyzed for lactate, glucose, FFA and glycerol concentrations. Differences between groups and over time were analyzed using ANOVA and ANCOVA design with repeated measures on the second factor. The Newman Keuls' post-hoc test was used to find significant differences between means (P $<$.05).

During exercise at the same RI, RER was significantly lower in the girls as compared to the women. In addition RER significantly decreased in the girls by the 20th and 25th minute of exercise at the same RI and AI respectively, while the change did not reach significance in the women. Lactate concentration increased significantly during the exercise tests. This change was significantly greater in the women (M = 1.36 mmol/L) than in the girls (M =.76 mmol/L) during exercise at the same RI, but greater in the girls (M =.603) than in the women (M =.356) during exercise at the same AI. FFA and glycerol concentrations were significantly higher after the exercise tests in both groups, while glucose concentration did not change significantly during tests. No inter-group differences were found in these energy substrates.

These results suggest that prepubertal girls rely more on fat utilization and less on carbohydrate metabolism than adults during treadmill running at the same relative intensity. In addition a significant shift in the relative contribution of CHO and fats to exercise occurs earlier in girls than adults during submaximal treadmill exercise at the same relative or absolute intensity.

Indexing (document details)

Advisor: Haymes, Emily

School: The Florida State University

School Location: United States -- Florida

Keyword(s): women

Source: DAI-A 52/04, p. 1254, Oct 1991

Source type: Dissertation

Subjects: Physical education, Anatomy & physiology, Animals