Health Benefits of Aerobic and Resistance Training in Individuals With Type 2 Diabetes

The goal of the proposed study, Health Benefits of Aerobic and Resistance Training in individuals with type 2 diabetes (HART-D), is to compare the effect of resistance training alone (RT), resistance in combination with aerobic training (AT+RT), and aerobic training alone (AT) to standard care (SC) on hemoglobin A1C (HbA1C), in initially sedentary women and men with type 2 diabetes (T2D).

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.

Eligibility Criteria:
Inclusion Criteria:

* Age 30-75 years
* type 2 diabetes determined by self-report with verification
* 6.5% \< HbA1C \< 11%
* sedentary lifestyle - not being physically active greater than or equal to 3 days per week for 20 minutes each time for the previous 6 months, and not performing regular resistance exercise

Exclusion Criteria:

* inadequate control of co-morbid conditions
* resting blood pressure greater than or equal to 160/100 mm Hg
* Triglycerides greater than or equal to 500 mg/dL
* BMI is greater than or equal to 48
* current use of an insulin pump or insulin injections other than Lantus
* metal object in the body that may interfere with MRI/MRS scans
* factors that may limit adherence to intervention or affect conduct of the trial

  1. unable or unwilling to communicate with staff, to provide written informed consent, or accept the randomized assignment
  2. failure to complete behavioral run-in and baseline testing
  3. hospitalization for depression in the last 6 months
  4. not physically capable of performing the exercise required for the study protocols
  5. consuming \> 14 alcoholic beverages per week
  6. plans to be away \> 4 weeks in the next 9 months
  7. lack of support from primary health care provider or family members
  8. significant weight loss in the past year (\>20 lbs) or current use of weight loss medications
  9. current diagnosis of schizophrenia, other psychotic disorders, or bipolar disorder
  10. another member of household is a participant or staff member of HART-D
  11. bariatric surgery
  12. other temporary intervening event, such as sick spouse, bereavement, or recent move
  13. other medical, psychiatric, or behavioral limitations that, in the view of the principal investigator, may interfere with study participation or the ability to follow the intervention protocol
* underlying diseases or conditions likely to limit lifespan and/or affect the safety of the intervention

  1. pregnant or plan on becoming pregnant in the next 9 months
  2. cancers requiring treatment in the past 5 years, unless prognosis is excellent
  3. self-reported HIV or tuberculosis
  4. history or evidence of serious arrythmias, cardiomyopathy, congestive heart failure, aortic aneurysm, or heart transplantation
  5. renal disease: urine dipstick 4+ protein, serum creatinine is greater than or equal to 1.4 mg/dL (women) or is greater than or equal to 1.5 mg/dL (men) or currently receiving dialysis
  6. any other medical condition or disease that is life threatening or that can interfere with or be aggravated by exercise
  7. advanced neuropathy or retinopathy