The effect of short-duration resistance training on insulin sensitivity and muscle adaptations in overweight men

What is the central question of this study? What is the time course of muscular adaptations to short-duration resistance exercise training? What is the main finding and its importance? Short-duration resistance training results in early and progressive increases in muscle mass and function and an increase in insulin sensitivity.

The aim of the study was to investigate the effects of 6 weeks of resistance exercise training, composed of one set of each exercise to voluntary failure, on insulin sensitivity and the time course of adaptations in muscle strength/mass. Ten overweight men (age 36 ± 8 years; height 175 ± 9 cm; weight 89 ± 14 kg; body mass index 29 ± 3 kg m^-2 ) were recruited to the study. Resistance exercise training involved three sessions per week for 6 weeks. Each session involved one set of nine exercises, performed at 80% of one-repetition maximum to volitional failure. Sessions lasted 15-20 min. Oral glucose tolerance tests were performed at baseline and post-intervention. Vastus lateralis muscle thickness, knee-extensor maximal isometric torque and rate of torque development (measured between 0 and 50, 0 and 100, 0 and 200, and 0 and 300 ms) were measured at baseline, each week of the intervention, and after the intervention. Resistance training resulted in a 16.3 ± 18.7% (P < 0.05) increase in insulin sensitivity (Cederholm index). Muscle thickness, maximal isometric torque and one-repetition maximum increased with training, and at the end of the intervention were 10.3 ± 2.5, 26.9 ± 8.3, 18.3 ± 4.5% higher (P < 0.05 for both) than baseline, respectively. The rate of torque development at 50 and 100 ms, but not at 200 and 300 ms, increased (P < 0.05) over the intervention period. Six weeks of single-set resistance exercise to failure results in improvements in insulin sensitivity and increases in muscle size and strength in young overweight men.