Metabolic and perceptual responses to short-term cycle training in children

Author

Glen E. Duncan

Date of Award

5-1997

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Education

Major Professor

Edward T. Howley

Committee Members

Naima Moustaid, Dixie Thompson, David Bassett Jr.

Abstract

This investigation examined metabolic and perceptual responses to short-term cycle training in children. Twenty-three boys and girls were assigned to training (TG, N=10) and control (CG, N=13) groups. An orientation and practice session was conducted to familiarize parents and their children with the laboratory procedures to be used. At this time, informed consent forms and a physical activity-health questionnaire were completed, descriptive information such as height, weight and skinfold thicknesses were obtained, instructions for the Borg rating of perceived exertion (RPE) scale were read, and children practiced riding a cycle ergometer with a breathing valve and noseclip in place. Children completed 3 minute work bouts at 30, 60 and 90 Watts on the cycle while heart rate and RPE were obtained at each level. On the next testing date, maximal aerobic power (VO_2max) was assessed. On a separate occasion, subjects performed a submaximal test ride at 35, 45, 55, 65, and 75% VO_2max in the morning following an overnight fast. Each intensity was performed for 6 minutes with a 2-3 minute rest period between bouts. Gas collection was performed utilizing 30-second averages after rigorous calibration of the gas analyzers. The percent of energy derived from fat and carbohydrate was estimated under steady-state conditions using the respiratory exchange ratio (RER) averaged over the last 3 minutes of each bout of exercise. Steady-state was assessed by calculating end-tidal CO₂ values in addition to assuring that there was no more than a 0.10 change in F_ECO₂ between successive 30-second collection periods. Heart rate and RPE were assessed at the end of each work bout. Following this initial evaluation, TG performed 12 cycle training sessions consisting of three 10-minute work bouts conducted 3 times per week at 50% VO_2max. After 4 weeks, RER and RPE were re-evaluated at the same absolute exercise intensities in both groups. Descriptive characteristics and maximal exercise responses were compared between groups using Student's t-test for independent samples. There were no differences (P > 0.05) between TG and CG with respect to age (9.8 ± 1.0 vs. 9.7 ± 1.2 yr.), body mass index (21.7 ± 4.6 vs. 22.2 ±9.5 kg/m²), percent fat (27.8 ± 8.4 vs. 27.1 ± 11.6%) and VO_2max (37.9 ± 6.6 vs. 38.8 ± 7.8 ml•kg^-1•min^-1). ANOVA on difference scores (post- pre test) for RER and RPE revealed a highly significant (P<0.01) group effect for each dependent variable. Overall difference scores indicated a decrease in RER and RPE in the TG, and an increase in RER with no change in RPE in the CG. These data demonstrate that a short-term cycle training program results in enhanced fat use and increased exercise tolerance in young children as compared to a matched control group. These data may have relevance in our understanding of how to achieve a balance between fat intake and fat oxidation, a factor believed to be related to weight control.

Recommended Citation

Duncan, Glen E., "Metabolic and perceptual responses to short-term cycle training in children. " PhD diss., University of Tennessee, 1997.
https://trace.tennessee.edu/utk_graddiss/9476