Few studies have compared changes in cardiorespiratory fitness between aerobic training only or in combination with resistance training. In addition, no study to date has compared strength gains between resistance training and combined exercise training in type II diabetes mellitus (T2DM).
Purpose: We evaluated the effects of aerobic exercise training (A group), resistance exercise training (R group), combined aerobic and resistance training (A + R group), and sedentary lifestyle (C group) on cardiorespiratory fitness and muscular strength in individuals with T2DM.
Methods: Two hundred and fifty-one participants in the Diabetes Aerobic and Resistance Exercise trial were randomly allocated to A, R, A + R, or C. Peak oxygen consumption (V O(2peak)), workload, and treadmill time were determined after maximal exercise testing at 0 and 6 months. Muscular strength was measured as the eight-repetition maximum on the leg press, bench press, and seated row. Responses were compared between younger (aged 39-54 yr) and older (aged 55-70 yr) adults and between sexes.
Results: VO(2peak) improved by 1.73 and 1.93 mL O(2)*kg(-1)*min(-1) with A and A + R, respectively, compared with C (P < 0.05). Strength improvements were significant after A + R and R on the leg press (A + R: 48%, R: 65%), bench press (A + R: 38%, R: 57%), and seated row (A + R: 33%, R: 41%; P < 0.05). There was no main effect of age or sex on training performance outcomes. There was, however, a tendency for older participants to increase VO(2peak) more with A + R (+1.5 mL O(2)*kg(-1)*min(-1)) than with A only (+0.7 mL O(2)*kg(-1)*min(-1)).
Conclusions: Combined training did not provide additional benefits nor did it mitigate improvements in fitness in younger subjects compared with aerobic and resistance training alone. In older subjects, there was a trend to greater aerobic fitness gains with A + R versus A alone.