Obesity and catecholamine responses to maximal exercise in adolescent girls

The aim of this study was to investigate plasma catecholamine [adrenaline (A) and noradrenaline (NA)] concentrations at rest and in response to maximal exercise in three different groups of adolescent girls. According to their body mass index, 34 adolescent girls aged 15–16 years were divided into three groups: a normal weight group (NO) (n = 11), an overweight group (OW) (n = 11) and an obese group (OB) (n = 12). Plasma A and NA concentrations were measured at rest during fasting conditions (A ₀ and NA₀), after a standardized breakfast (A _rest and NA_rest) and immediately after an incremental exhaustive exercise (A _EX and NA_EX). A ₀ and NA₀ were not significantly different among the three groups. However, the A ₀/NA₀ was statistically lower in OB compared to OW and NO. A _EX and NA_EX were significantly higher than resting values in the three groups. However, in response to exercise, no significant differences were reported between OB (A _EX = 2.20 ± 0.13 nmol/l, NA_EX = 12.28 ± 0.64 nmol/l), OW (A _EX = 2.39 ± 0.23 nmol/l, NA_EX = 12.94 ± 0.93 nmol/l) and NO (A _EX = 2.52 ± 0.24 nmol/l, NA_EX = 12.60 ± 0.63 nmol/l). In conclusion, our results showed that at rest, in adolescent girls, the responsiveness of the adrenal medulla to the sympathetic nervous activity is lower in OB subjects compared to OW and NO ones. However, in response to maximal exercise, plasma catecholamines are not affected by obesity.