Ronald J. Sigal, MD, MPH; Glen P. Kenny, PhD; Normand G. Boulé, PhD; George A. Wells, PhD; Denis Prud'homme, MD, MSc; Michelle Fortier, PhD; Robert D. Reid, PhD, MBA; Heather Tulloch, MSc; Douglas Coyle, PhD; Penny Phillips, MA; Alison Jennings, MA; James Jaffey, MSc
Acknowledgments: The authors thank the DARE study participants; Diana Pepin, Kim Fetch, Rikst Attema, Katherine Dittmann, Kelley Phillips, Paul Healey, Karen Holland, Jane Murrin, Natalie McInnis, Jason Fetch, and Tina Leech, students in the School of Human Kinetics, University of Ottawa; and the Ottawa-Carleton Regional YMCA/YWCA and Nautilus Plus of Gatineau, Québec, Canada, for their contributions to study coordination, exercise training, and evaluation of study participants.
Grant Support: The DARE trial was supported by grants from the Canadian Institutes of Health Research (grant MCT-44155) and the Canadian Diabetes Association (The Lillian Hollefriend Grant). Dr. Sigal was supported by a New Investigator Award from the Canadian Institutes of Health Research and the Ottawa Health Research Institute Lifestyle Research Chair. Dr. Kenny was supported by a Career Scientist Award from the Ontario Ministry of Health and Long Term Care. Dr. Boulé was supported by a Postgraduate Scholarship from the National Sciences and Engineering Research Council of Canada. Dr. Reid was supported by a New Investigator Award from the Heart and Stroke Foundation of Canada. Ms. Tulloch was supported by a Doctoral Research Award from the Social Sciences and Humanities Research Council of Canada. Ms. Jennings was supported by an Ontario Graduate Scholarship.
Potential Financial Conflicts of Interest: None disclosed.
Requests for Single Reprints: Ronald J. Sigal, MD, MPH, University of Calgary, 7th Floor, North Tower, Foothills Medical Center, 1403 29 Street NW, Calgary, Alberta T2N 2T9, Canada; e-mail, firstname.lastname@example.org.
Current Author Addresses: Dr. Sigal: University of Calgary, 7th Floor, North Tower, Foothills Medical Center, 1403 29 Street NW, Calgary, Alberta T2N 2T9, Canada.
Dr. Kenny: University of Ottawa, Laboratory of Human Bioenergetics and Environmental Physiology, Montpetit Hall, 125 University Avenue, Ottawa, Ontario K1N 6N5, Canada.
Dr. Boulé: Faculty of Physical Education and Recreation, P420, Van Vliet Centre, Edmonton, Alberta T6G 2H9, Canada.
Dr. Wells: University of Ottawa Heart Institute, 40 Ruskin Street, Room H1-1, Ottawa, Ontario K1Y 4W7, Canada.
Dr. Prud'homme: Faculty of Health Sciences, University of Ottawa, 451 Smyth Road, Ottawa, Ontario K1H 8M5, Canada.
Dr. Fortier: School of Human Kinetics, University of Ottawa, Montpetit Hall, 125 University Avenue, Ottawa, Ontario K1N 6N5, Canada.
Dr. Reid and Ms. Tulloch: Prevention and Rehabilitation Centre, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, Ontario K1Y 4W7, Canada.
Dr. Coyle: Faculty of Health Sciences, RGN 323, 451 Smyth Road, Ottawa, Ontario K1H 8M5, Canada.
Ms. Phillips: Clinical Epidemiology Program, Ottawa Health Research Institute, 1967 Riverside Drive, 4th Floor (Diabetes Research), Ottawa, Ontario K1H 7W9, Canada.
Ms. Jennings and Mr. Jaffey: Clinical Epidemiology Program, Ottawa Health Research Institute, 1053 Carling Avenue, Ottawa, Ontario K1Y 4E9, Canada.
Author Contributions: Conception and design: R.J. Sigal, G.P. Kenny, N.G. Boulé, G.A. Wells, Denis Prud'homme, M. Fortier, R.D. Reid, D. Coyle.
Analysis and interpretation of the data: R.J. Sigal, G.P. Kenny, N.G. Boulé, G.A. Wells, Denis Prud'homme, M. Fortier, R.D. Reid, H. Tulloch, D. Coyle, J. Jaffey.
Drafting of the article: R.J. Sigal, G.P. Kenny.
Critical revision of the article for important intellectual content: R.J. Sigal, G.P. Kenny, N.G. Boulé, G.A. Wells, Denis Prud'homme, M. Fortier, R.D. Reid, H. Tulloch, D. Coyle, A. Jennings.
Final approval of the article: R.J. Sigal, G.P. Kenny, N.G. Boulé, Denis Prud'homme, M. Fortier, H. Tulloch, D. Coyle.
Provision of study materials or patients: R.J. Sigal, G.P. Kenny, R.D. Reid.
Statistical expertise: G.A. Wells, J. Jaffey.
Obtaining of funding: R.J. Sigal, G.P. Kenny, G.A. Wells, Denis Prud'homme, M. Fortier., R.D. Reid, D. Coyle
Administrative, technical, or logistic support: G.P. Kenny, P. Phillips, A. Jennings.
Collection and assembly of data: G.P. Kenny, N.G. Boulé, H. Tulloch, P. Phillips, A. Jennings.
Previous trials have evaluated the effects of aerobic training alone and of resistance training alone on glycemic control in type 2 diabetes, as assessed by hemoglobin A1c values. However, none could assess incremental effects of combined aerobic and resistance training compared with either type of exercise alone.
To determine the effects of aerobic training alone, resistance training alone, and combined exercise training on hemoglobin A1c values in patients with type 2 diabetes.
Randomized, controlled trial.
8 community-based facilities.
251 adults age 39 to 70 years with type 2 diabetes. A negative result on a stress test or clearance by a cardiologist, and adherence to exercise during a 4-week run-in period, were required before randomization.
Aerobic training, resistance training, or both types of exercise (combined exercise training). A sedentary control group was included. Exercise training was performed 3 times weekly for 22 weeks (weeks 5 to 26 of the study).
The primary outcome was the change in hemoglobin A1c value at 6 months. Secondary outcomes were changes in body composition, plasma lipid values, and blood pressure.
The absolute change in the hemoglobin A1c value in the combined exercise training group compared with the control group was −0.51 percentage point (95% CI, −0.87 to −0.14) in the aerobic training group and −0.38 percentage point (CI, −0.72 to −0.22) in the resistance training group. Combined exercise training resulted in an additional change in the hemoglobin A1c value of −0.46 percentage point (CI, −0.83 to −0.09) compared with aerobic training alone and −0.59 percentage point (CI, −0.95 to −0.23) compared with resistance training alone. Changes in blood pressure and lipid values did not statistically significantly differ among groups. Adverse events were more common in the exercise groups.
The generalizability of the results to patients who are less adherent to exercise programs is uncertain. The participants were not blinded, and the total duration of exercise was greater in the combined exercise training group than in the aerobic and resistance training groups.
Either aerobic or resistance training alone improves glycemic control in type 2 diabetes, but the improvements are greatest with combined aerobic and resistance training.
ClinicalTrials.gov registration number: NCT00195884.
The benefits of exercise in improving glycemic control in patients with type 2 diabetes are well documented. Previous studies have examined aerobic or resistance exercise alone but not in combination.
This randomized, controlled trial showed better reduction in hemoglobin A1c values in patients who followed a combined aerobic exercise and resistance training program 3 times weekly than in patients who followed a program of either exercise type alone.
Patients in the combined exercise group had a longer duration of exercise than those in the other exercise groups; the study thus does not permit definitive conclusions about whether the benefits were due to longer exercise duration or to the combined exercise training.
Study flow diagram.
Table 1. Baseline Characteristics
Table 2. Changes in Hemoglobin A1c, Blood Pressure, and Lipid Values
Appendix Table 1. Changes in Hemoglobin A1c Value
Appendix Table 2. Changes to Medication Regimens
Table 3. Changes in Body Composition
Appendix Table 3. Changes in Nutritional Variables
Table 4. Adverse Events
Appendix Table 4. Exercise Program during the Run-in and Intervention Phases
Appendix Table 5. Resistance Training Regimens
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A randomized control trial found that both aerobic exercise and resistance exercise improved glycemic/blood sugar control in people with type 2 diabetes.
Milo A Puhan
Horten Centre for patient-oriented research, University of Zurich, Switzerlan
October 1, 2007
No patient-important outcomes?
Dr Sigal and colleagues showed in their randomized trial impressive reductions in HbA1c in patients with type 2 diabetes after supervised exercise sessions over a period of 22 weeks.(1) It is, however, a limitation that only surrogate parameters were presented as outcomes. HbA1c is associated with clinically relevant events in the future (microvascular complications and cardiovascular events) but it does not reflect treatment effects that are of immediate importance to the patient. A great advantage of physical exercise in the treatment of chronic diseases is that it often combines benefits on the patients' current health status and on prognosis. Without the use of patient-important endpoints, clinically relevant effects of physical exercise on the patients' symptoms, limitations and health-related quality of life may have been missed. To know about these effects is also important to inform patients about potential benefits of physical exercise. Just informing patients about potential preventative effects might not convince them to start an exercise program. It would be important to learn whether the investigators used any patient- important outcomes that are going to be reported elsewhere. If such outcomes were not included, it would be important to know the reason for not investigating this important aspect.
(1) Sigal RJ et al: Effects of aerobic training, resistance training, or both on glycemic control in type 2 diabetes: a randomized trial. Ann Intern Med. 2007 Sep 18;147(6):357-69.
Young Kwang Chae
Johns Hopkins University
October 10, 2007
Effect of Aerobic Exercise versus Resistance Exercise
In their well-designed clinical trial, Signal and colleagues  reported the favorable effect of both aerobic and resistance exercise in the type 2 diabetes patients. I agree with their discussion in the article that the effect of aerobic training and resistance training was about equal. Indeed, the fact that the effect of combined exercise training was twice that of either type of exercise alone alludes to the notion that both types of excise are of similar benefit to type 2 diabetes patients, regardless of their difference in physiological effects. However, it seems that aerobic exercise actually helped to achieve a significantly lower level of hemoglobin A1c much faster than resistance excise, comparing 3 month results versus 6 month (Table 2). Moreover, the effect of aerobic exercise seems much greater among patients whose baseline hemoglobin A1c levels were above 7.5 percentage point (Appendix Table 1). In the same group of patients, only the added effect of aerobic exercise, not resistance exercise, was shown to be statistically significant (combined excise vs. aerobic, and resistance exercise alone, Appendix Table 1). These additional observations may suggest that aerobic exercise may provide greater benefit to type 2 diabetes patients, at least to those with worse glycemic control.
Reference: 1. Sigal RJ, Kenny GP, Boule NG, Wells GA, Prud'homme D, Fortier M, Reid RD, Tulloch H, Coyle D, Phillips P, Jennings A, Jaffey J. Effects of Aerobic Training, Resistance Training, or Both on Glycemic Control in Type 2 Diabetes: A Randomized Trial. Ann Intern Med. 2007; 147: 357-69.
Sigal RJ, Kenny GP, Boulé NG, Wells GA, Prud'homme D, Fortier M, et al. Effects of Aerobic Training, Resistance Training, or Both on Glycemic Control in Type 2 Diabetes: A Randomized Trial. Ann Intern Med. ;147:357–369. doi: 10.7326/0003-4819-147-6-200709180-00005
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Published: Ann Intern Med. 2007;147(6):357-369.
Cardiology, Coronary Risk Factors, Diabetes, Endocrine and Metabolism.
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