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Summary

Objective  Controversial data on ghrelin concentration during exercise in human subjects have been published. We tested the hypothesis that exercise could affect acylated ghrelin (AG) and unacylated ghrelin (UAG), which could partly explain the previously reported inconsistent findings on the association of exercise with changes in ghrelin.

Design   A prospective randomized study.

Patients and measurements  We randomized 17 overweight volunteers (11-year-old boys) to a 12-week combined exercise group (EG, n = 8) or control group (CG, n = 9). At baseline, 1, 4 and 12 weeks, we measured body weight and composition, insulin, leptin, total ghrelin and acylated ghrelin.

Results  Compared with the CG, body weight, percentage body fat and homeostatic model assessment (HOMA) indices were significantly lower throughout the 12 weeks in the EG. Total ghrelin and UAG levels gradually increased to 131·9 ± 5·2% and 130·4 ± 5·2% of baseline, respectively, at week 12 in the EG, whereas AG concentration remained unchanged throughout the 12 weeks both within each group and between the groups. At week 12, there were differences in the total ghrelin level and UAG level between the groups.

Conclusions  This study shows an increase in unacylated acylated ghrelin and unchanged acylated ghrelin after a 12-week combined exercise programme in overweight children. These findings provide evidence of favourable effects of exercise on improving energy metabolism.