Interleukin-6 and insulin resistance response to exercise training and detraining in middle-aged and obese men: a randomized clinical trial

The aim of present study was to compare the effects of 12 weeks of nonlinear resistance training (NRT) and aerobic interval training (AIT), and also effects of 4 weeks of detraining after these training on interleukin-6 (IL-6) and insulin resistance in young obese men.
In this randomized clinical trial, at first 38 obese men were matched by aerobic fitness, age and percentage of body fat. Then, they were randomly assigned to NRT (n=14), AIT (n=12) and control (Con, n=12) groups. The training groups performed 3 weekly sessions for 12 weeks followed by a 4 weeks detraining period. NRT consisted of 40-65 minutes of weight training at different intensities with flexible periodization. AIT consisted of running on a treadmill (4 sets of 4 minutes at 80-90% of maximal heart rate, with 3-minute recovery intervals). Serum levels of IL-6 and insulin resistance were measured by enzyme-linked immunosorbent assay (ELISA) and the glucose oxidase method for serum glucose concentration.
Compared to Con, it was not observed in serum IL-6 levels any change significantly after the NRT (P=0.593) and AIT (P=0.623), but this cytokine worsened significantly after detraining with the NRT (P=0.011) and AIT (P=0.017). Both NRT (P=0.006) and AIT (P=0.046) groups was equally effective at reducing insulin resistance, but these values returned to the pre-training levels after detraining.
The young obese men can use the two exercise programs to reduce insulin resistance. Also, IL-6 increased significantly in both training groups after detraining. Thus, it is recommended that the training programs should not be discontinued to prevent worsening of inflammatory conditions.