Health Benefits of Aerobic and Resistance Training in Individuals With Type 2 Diabetes (HART-D)

Although it is generally accepted that regular exercise provides substantial health benefits to individuals with T2D, the exact exercise prescription in terms of type (AT versus RT versus AT+RT) still remains an important research issue, particularly in regard to week-to-week glucose control as assessed by HbA1C.

There is a need for more adequately powered and well-controlled studies to examine the effects of RT, AT and AT+RT on HbA1C in individuals with T2D. With the incidence of T2D expected to increase dramatically in the coming years, it is essential to have a better understanding of the relative benefits of various exercise interventions. This information can help better formulate exercise recommendations for patients with T2D as well as potentially provide more exercise options, which is important given the small percentage of individuals with TD2 who regularly exercise. The study group was sedentary women and men with T2D, aged 30 to 75 years. We randomly assigned 262 individuals to an aerobic exercise training only group (AT; n=72), a resistance training only group (RT; n=73), a combination of aerobic plus resistance training (AT+RT; n=76), or a standard care group (SC; n=41). The AT individuals participated in 3 or 4 training sessions each week for 9 months progressing to a total energy expenditure of 12 kcal/kg/week (KKW), which is an exercise dose consistent with the current public health recommendations for physical activity for individuals with T2D. The target exercise intensity was 50%-80% of baseline VO2 max. The RT group participated in 3 sessions per week (9 exercises, 2-3 sets each), which focuses on large muscle groups. This RT regimen is based on the studies that most successfully improved HbA1C in individuals with T2D. Individuals in the AT+RT group completed 10 KKW of aerobic training and a reduced resistance-training regimen of 2 sessions per week (9 exercises, 1 set of each). The AT+RT regimen represents the exercise recommendations of the American College of Sports Medicine (ACSM) and the American Diabetes Association (ADA).

Simply stated, we compared the effect of resistance training alone, resistance in combination with aerobic training, and aerobic training alone to standard care on HbA1C, in initially sedentary women and men with T2D. The primary outcome measure was HbA1C, an integrated measure of blood glucose control over the past 8-12 weeks. Other outcomes of interest included resting blood pressure, C-reactive protein (CRP), total body fat, and lean muscle mass as measured by DEXA, cardiorespiratory fitness, muscular strength, and metabolic measures including serum cholesterol and triglycerides.