Intensity of acute exercise does not affect serum leptin concentrations in young men

Purpose: We examined the effects of exercise intensity on serum leptin levels. Methods: Seven men (age = 27.0 yr; height = 178.3 cm; weight = 82.2 kg) were tested on a control (C) day and on 5 exercise days (EX). Subjects exercised (30 min) at the following intensities: 25% and 75% of the difference between the lactate threshold (LT) and rest (0.25 LT, 0.75 LT), at LT, and at 25% and 75% of the difference between LT and V̇O₂peak (1.25 LT, 1.75 LT). Results: Kcal expended during the exercise bouts ranged from 150 ± 11 kcal (0.25 LT) to 529 ± 45 kcal (1.75 LT), whereas exercise + 3.5 h recovery kcal ranged from 310 ± 14 kcal (0.25 LT) to 722 ± 51 kcal (1.75 LT). Leptin area under the curve (AUC) (Q 10-min samples) for all six conditions (C + 5 Ex) was calculated for baseline (0700-0900 h) and for exercise + recovery (0900-1300 h). Leptin AUC for baseline ranged from 243 ± 33 to 291 ± 56 ng·mL^-1 x min; for exercise + recovery results ranged from 424 ± 56 to 542 ± 99 ng·mL^-1 x min. No differences were observed among conditions within either the baseline or exercise + recovery time frames. Regression analysis confirmed positive relationships between serum leptin concentrations and percentage body fat (r = 0.94) and fat mass (r = 0.93, P < 0.01). Conclusion: We conclude that 30 min of acute exercise, at varying intensity of exercise and caloric expenditure, does not affect serum leptin concentrations during exercise or for the first 3.5 hours of recovery in healthy young men.