Abstract

INTRODUCTION:

The aim of this study was to examine the effect of body fat percentage on the plasma catecholamine response to a cycling sprint test (CST) in sedentary adolescent boys.

METHODS:

In this study, 31 adolescent boys (9 obese (% body fat = 31.0% ± 3.0%), 11 overweight (% body fat = 24.0% ± 1.6%), and 11 lean (% body fat = 16.0% ± 1.9%)), matched for peak oxygen consumption, completed a CST consisting of six 6-s maximal sprints with 2 min of passive rest between each repetition. Performance of each subject was determined as the mean power output (PO(mean)) developed during the CST. Plasma lactate, epinephrine, and norepinephrine concentrations were determined successively at rest, after a 10-min warm-up, immediately after the CST, and after 20 min of passive recovery.

RESULTS:

Although groups were not different in age, height, or peak oxygen consumption (mL·kg(-1) fat-free mass·min(-1)), maximal epinephrine concentration was significantly (P < 0.05) higher in lean vs obese and was negatively correlated to body fat percentage (r = -0.60, P < 0.05). Maximal norepinephrine values were higher in lean versus overweight and obese, and a negative relationship was found between maximal norepinephrine concentration and body fat percentage (r = -0.60, P < 0.05). Maximal lactate concentration was higher in lean versus overweight and obese (14.7 ± 3.3, 10.4 ± 2.7, and 10.2 ± 2.5 mM in lean, overweight, and obese, respectively). A significant relationship was also obtained between maximal norepinephrine and maximal epinephrine values with both maximal lactate concentration (r = 0.60 and r = 0.60, P < 0.05, respectively) and PO(mean) (r = 0.65 and r = 0.6, P < 0.05).

CONCLUSIONS:

Our results show that the catecholamine response to a CST was affected by body fat percentage, with reduced epinephrine and norepinephrine values in overweight and obese adolescents.