Comparison of effects of aerobic and resistance trainingin subjects with type 2 diabetes

Project 1. Effects of Aerobic training and Resistance training in type 2 Diabetes. ClinicalTrials.gov Identifier Number: NCT01182948 Background. Exercise is considered a fundamental issue in the management of subjects with type 2 diabetes (T2DM). The most recent guidelines recommend both aerobic and strength exercise in these subjects, as this strategy may have greater beneficial effects on glucose control. However, it still remains unclear which differences and similarities exist between the effects of these two training protocols on the different factors contributing to metabolic control in subjects with T2DM. This is of great speculative interest and could help in programming a more appropriate combination of different exercise modalities. Our study aimed at exploring this crucial issue. Subjects and Methods. 40 T2DM subjects, 12 females and 28 males (mean±SD: age 56±7 years, BMI 29.4±4.6 kg/m2, HbA1c 7.3±0.7%) were randomized to aerobic (AER, n=20) or resistance (RES, n=20) training. In both groups exercise was performed 3 times weekly, for 4 months. The AER group exercised for 60 minutes at 60-65% heart rate reserve. The RES group performed 3 series of 8-10 repetitions of 8 different exercises on weight machines each session, at 70-80% 1RM. Before and after the intervention the following were assessed: HbA1c and other metabolic features, weight, waist circumference, caloric intake and overall physical activity (through questionnaires), peak oxygen uptake (VO2peak), leg and arm muscle 1RM tests (leg extension and chest press), fat mass and fat free mass (DEXA Total Body), insulin sensitivity (euglycemic hyperinsulinemic clamp), β-cell function (OGTT and mathematical models), metabolic flexibility (calorimetry), subcutaneous (SAT) and visceral abdominal adipose tissue (VAT), and hepatic and skeletal muscle fat content (Magnetic Resonance Imaging). In addition, continuous plasma glucose monitoring for 48 h was carried out and changes in antidiabetic therapy and adverse events were recorded. Some additional investigations were also carried out (expression of relevant genes and measurement of mitochondrial DNA in fine needle aspirates of vastus lateralis muscle; tissue oxygen extraction during exercise test; baroreceptor function; venoarteriolar response; spectral analysis of autonomic system function; oxidative stress measurement). However, these data are not yet available and therefore these aspects have not been included in the thesis. Results. The two groups had similar baseline characteristics. After 4 months of training, changes in VO2peak and strength showed significant differences between the AER and RES groups (VO2peak 15±10 vs 8±10%, p=0.04; Leg extension performance 4±11 vs 19±10%, p<0.0001, respectively). HbA1c was similarly reduced in the two groups (from 7.23±0.64 to 6.83±0.38; and from 7.34±0.69 to 6.99±0.64%, respectively in the AER and RES groups). BMI, waist, fat mass, truncal fat, limbs lean mass, SAT and VAT were also significantly reduced in both groups, with no statistically significant differences between the two groups. Insulin sensitivity was significantly increased in both groups (by 30% and 15%, respectively), while β-cell function and metabolic flexibility did not change in the two groups. AER and RES groups showed similar reductions in hepatic and skeletal muscle fat. During the 60 min of supervised training, blood glucose, measured by a continuous glucose monitoring system, showed a reduction in both groups. However, reduction was significantly greater in the AER than in the RES group (p<0.001). Differences between groups were also found in the comparison of blood glucose values recorded during the night following the training session. After 4 months of training there was no significant change in antidiabetic medications and no relevant adverse events were reported. In the entire cohort of subjects, reduction after training of HbA1c was significantly associated with changes in total body fat, truncal fat, VO2peak, maximal workload and leg extension performance. Changes in insulin sensitivity, as measured by the glucose clamp, were significantly associated with changes in VAT and VAT/SAT ratio, as well as with changes in VO2peak. In multiple regression analyses, change after intervention in HbA1c was independently predicted by HbA1c at baseline and changes in VO2peak, leg extension performance and truncal fat (overall variance explained 65%). Change after intervention in insulin sensitivity was independently predicted by changes in VAT and VO2peak, whereas changes of leg extension performance and limb lean mass were of borderline significance (variance explained 66%). Conclusions. These data show that aerobic and resistance training can exert similar beneficial effects on glucose control in type 2 diabetes subjects, despite their different effects on functional capacity. Post-exercise acute blood glucose reduction is greater after aerobic training than after resistance training, suggesting an increased risk of post-exercise hypoglycemia after an aerobic exercise session. Exercise-induced improvement of insulin sensitivity is independently predicted by the increase in cardiorespiratory fitness and reduction in visceral fat. Project 2. Supervised walking groups to increase physical activity in type 2 diabetes patients. ClinicalTrials.gov Identifier Number: NCT01115205 Background. Previous studies reported that self-paced walking is inadequate to obtain metabolic improvement in patients with type 2 diabetes (T2DM). The aims of this study were to evaluate the compliance of T2DM patients with an exercise programme organized into supervised walking groups; and to assess the impact of this model on metabolic control and overall physical activity. Subjects and Methods. 59 T2DM subjects were randomized, with a 1:2 ratio, to a control group or an intervention group. The control group received standard recommendations to increase physical activity. Intervention was based on supervised walking groups and counselling. Progressive training sessions were scheduled 3 times weekly for 4 months. Before and at the end of the study, haemoglobin (Hb)A1c (primary outcome), fasting glucose, serum lipids, weight, and blood pressure were measured. Functional capacity was assessed by a 6 minute walk test. Changes in prescription of antidiabetic medications and overall physical activity were also recorded. Results. At baseline, the two groups were similar. At the end of the study, functional capacity and overall physical activity were higher in the intervention group, whereas changes in metabolic parameters did not show significant differences between the groups. However, in subjects of the intervention group who attended at least 50% of scheduled walking, changes in HbA1c and fasting glucose were greater than in controls. Discontinuation or reduction of antidiabetic drugs occurred in 33% of these patients vs 5 % in the control group (p<0.05). Conclusions. Supervised walking may be beneficial in diabetic subjects, but metabolic improvement requires adequate compliance.