This study examined the effects of pre-exercise carbohydrate (CHO) supplementation on anaerobic exercise performance in adolescent males (n =11; 15.0 ± 0.9 yrs). On separate days, subjects consumed either a CHO or a placebo (PL) beverage followed by 2 Wingate anaerobic tests (WAnT) separated with ten by 10-second sprints. Peak (PP), mean power (MP) and fatigue index (FI) were assessed. Venous blood samples were obtained and analyzed for glucose, lactate, insulin, and catecholamines. A trial by time ANOVA (P < 0.05) was used in the analysis. PP and MP tended to be higher (P < 0.09) in CHO versus PL, and MP tended to decline more in CHO (P < 0.06); Fl for the two WAnT were similar. Glucose concentration significantly increased after CHO consumption and then returned to baseline post-exercise, whereas glucose level remained unchanged over time during PL; similarly observed for insulin. Lactate and catecholamine levels significantly increased over time, but a trial difference was only observed in epinephrine. The tendency for PP and MP to be higher in CHO might suggest a potential ergogenic benefit of pre-exercise CHO although the change in MP over time in CHO and the similarity in Fl might suggest otherwise. / School of Physical Education, Sport, and Exercise Science

Individuals with NIDDM and low insulin sensitivity (Si) have altered fuel use, which may appear in NIDDM relatives. Adolescent males, six with NIDDM relatives (POS) and six controls (CON), matched for fitness and fatness, participated. Peak oxygen uptake (V02pea), ventilatory threshold (VT) and body composition were measured. Insulin and glucose values were used for Si estimates. Oxygen consumption (V02) and respiratory exchange ratio (RER) measurements were made at rest and during exercise at 80,100 and 120% of VT for substrate use. No group differences were found in anthropometric data, V02pea, VT or blood measurements, although fat free mass (FFM) tended to be greater in CON. CON tended to use a higher percentage carbohydrate and a lower percentage of fat than POS, but differences were no longer present after normalization to FFM. Trends towards fuel use differences may suggest metabolic abnormalities are present in POS, but further investigation is necessary. / School of Physical Education, Sport, and Exercise Science

This study examined the influence of maturation on the oxygen uptake efficiency slope (OUES) in healthy male subjects. The variables comprising the OUES are known to be affected by metabolism which in turn is influenced by maturation. The subjects performed a graded exercise test on a cycle ergometer to determine the OUES and VO2max. Subjects were divided into groups based on maturation status: early-pubertal (EP, n = 15), mid-pubertal (MP, n = 20), late-pubertal (LP, n = 17), and young-adult (YA, n = 19) males. Cardiorespiratory fitness (measured as VO2max mL·min-1·kg-1) was not significantly different between groups. OUES values in absolute terms were higher in groups LP and YA versus MP and EP. Scaling OUES relative to body mass failed to eliminate between group differences whereby LP and YA had lower mass relative OUES values compared to LP and YA. Scaling OUES relative to fat free mass also failed to eliminate between group differences with EP group values being higher versus LP and YA, but only MP values being higher than YA. Differences in OUES values between male across maturation status remained after accounting for differences in body size, suggesting an affect of maturation on this measurement. / School of Physical Education, Sport, and Exercise Science

The purpose of this study is to determine physiological adaptations in trained male high-school runners before and after high-intensity training associated with a crosscountry season. Testing occurred on five separate occasions at the Human Performance Laboratory. After the first familiarization session, the subjects performed a treadmill graded exercise test in which maximal oxygen consumption and ventilatory threshold was measured. Submaximal oxygen consumption and blood lactate concentration at three running speeds (10, 12, and 14 km'hf 1 at 0% grade) was determined in a second testing session. After the cross-country season (13 weeks) the subjects returned to the laboratory and performed the same graded exercise and submaximal exercise tests. VO2max significantly increased, VT tended to increased, however, not significant. There were no changes in submaximal economy or lactate except for significant decline in blood lactate at 14 km hf' . Although these variables are associated with endurance performance in adults, there is very little information available regarding the effects of endurance training on these variables in the adolescent age group. Knowing the extent of the adaptations will help to optimize the training programs for age group. / School of Physical Education