Aim: 

To determine if strength training reduces circulating leptin levels in the same way in men and women, and if this effect is exclusively dependent on the changes in fat mass.

Methods: 

Forty-three male physical education students and twenty-three female physical education students were randomly assigned to two groups: one group performed strength training combined with plyometric jumps (TG), and the other group served as a control group (CG). Maximum dynamic strength (1RM) was assessed immediately before and at the end of the strength-training period, body composition was determined by DXA and leptin serum concentration was measured with an ELISA kit.

Results: 

Both genders experienced a similar relative strength improvements in all exercises (p<0.01). Body fat mass was unchanged in all groups after the study intervention, whereas whole body lean body mass increased significantly by 1.6 and 1.4% in the male and female TG, respectively (ANOVA time effect: p<0.001). Lower extremities lean mass was similarly increased by 4.5 and 5.3% in TG men and women (P<0.05). Plasma leptin concentration was reduced with training (group by time interaction: p<0.05), but only in women (gender by time interaction in the training group: p=0.009). This difference remained significant after accounting for the percentage of body fat as a co-variable (p<0.05).

Conclusion: 

In young women, serum leptin concentration is reduced after 9 weeks of strength training combined with plyometric exercises. This effect was not explainable by changes in fat mass, since fat mass was not modified by strength training. This finding is compatible with enhanced leptin sensitivity in women after strength training.