Abstract
BackgroundWhile current recommendations on exercise type and volume have strong experimental bases, there is no clear evidence from large-sized studies indicating whether increasing training intensity provides additional benefits to subjects with type 2 diabetes.ObjectiveTo compare the effects of moderate-to-high intensity (HI) versus low-to-moderate intensity (LI) training of equal energy cost, i.e. exercise volume, on modifiable cardiovascular risk factors.DesignPre-specified sub-analysis of the Italian Diabetes and Exercise Study (IDES), a randomized multicenter prospective trial comparing a supervised exercise intervention with standard care for 12 months (2005–2006).SettingTwenty-two outpatient diabetes clinics across Italy.PatientsSedentary patients with type 2 diabetes assigned to twice-a-week supervised progressive aerobic and resistance training plus exercise counseling (n = 303).InterventionsSubjects were randomized by center to LI (n = 142, 136 completed) or HI (n = 161, 152 completed) progressive aerobic and resistance training, i.e. at 55% or 70% of predicted maximal oxygen consumption and at 60% or 80% of predicted 1-Repetition Maximum, respectively, of equal volume.Main Outcome Measure(s)Hemoglobin (Hb) A1c and other cardiovascular risk factors; 10-year coronary heart disease (CHD) risk scores.ResultsVolume of physical activity, both supervised and non-supervised, was similar in LI and HI participants. Compared with LI training, HI training produced only clinically marginal, though statistically significant, improvements in HbA1c (mean difference −0.17% [95% confidence interval −0.44,0.10], P = 0.03), triglycerides (−0.12 mmol/l [−0.34,0.10], P = 0.02) and total cholesterol (−0.24 mmol/l [−0.46, −0.01], P = 0.04), but not in other risk factors and CHD risk scores. However, intensity was not an independent predictor of reduction of any of these parameters. Adverse event rate was similar in HI and LI subjects.ConclusionsData from the large IDES cohort indicate that, in low-fitness individuals such as sedentary subjects with type 2 diabetes, increasing exercise intensity is not harmful, but does not provide additional benefits on cardiovascular risk factors.Trial Registration www.ISRCTN.org ISRCTN-04252749.
Highlights
Adverse event rate was similar in high intensity (HI) and low-to-moderate intensity (LI) subjects
A large body of evidence indicates that physical activity (PA) is associated with reduced cardiovascular disease (CVD) and all-cause mortality in the general population [1,2] and in subjects with type 2 diabetes [3,4]
The large Italian Diabetes and Exercise Study (IDES) demonstrated that twice-weekly supervised, facility-based, aerobic and resistance training on top of exercise counseling is superior to counseling alone in promoting PA, improving physical fitness, hemoglobin (Hb) A1c and CVD risk profile, and reducing medication number and/or dosage in sedentary patients with type 2 diabetes [9]
Summary
A large body of evidence indicates that physical activity (PA) is associated with reduced cardiovascular disease (CVD) and all-cause mortality in the general population [1,2] and in subjects with type 2 diabetes [3,4]. Combined aerobic and resistance exercise was reported to be more effective than either one alone on glycemic control in two other large trials [11,12], though a systematic review and meta-analysis including these studies [13] showed that structured exercise training, either aerobic, resistance, or both, is associated with HbA1c reduction in patients with type 2 diabetes, especially if of more than 150 minutes per week and when combined with dietary advice. While current recommendations on exercise type and volume have strong experimental bases, there is no clear evidence from large-sized studies indicating whether increasing training intensity provides additional benefits to subjects with type 2 diabetes
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