Training, Detraining, Retraining and Glycemic Control in Patients With Type 2 Diabetes

• Changes from baseline in glycemic control measurements (follow-up for 21 months) at training (9 months), detraining (3 months) and retraining (9 months) [ Time Frame: Changes from baseline in HbA1C, FPG and PPG at training (9 months), detraining (11 months) and retraining (21 months) ]
  Glycemic control was evaluated by the measurement of fasting plasma glucose (FPG), postprandial glucose (PPG) and glycosylated hemoglobin (HbA1C). PPG was calculated by the mean of four values measured at the first week of every period (baseline, 9th, 12th and 21st months).
  
  

• Evaluation of body composition [ Time Frame: Changes from baseline in body composition assessment at training (9 months), detraining (3 months), retraining (9 months) ]
  Anthropometric Assessment: Body weight, height, BMI and waist circumference (WC).
  
  
• Peak oxygen consumption (VO2peak) [ Time Frame: Changes from baseline in VO2peak at training (9 months), detraining (11 months) and retraining (21 months) ]
  Measurement of Peak Oxygen Uptake: Patients underwent a symptom-limited graded exercise test on a cycle-ergometer (60 rpm). The initial load was set at 25W and increased gradually by 25W every 2-min until the patients were unable to continue. VO2peak was determined by open-circuit spirometry (E. Jaeger, IEC 601-1, Germany).
  
  
• Measurement of muscular strength in patients with type 2 diabetes [ Time Frame: Changes from baseline in muscular strength at training (9 months), detraining (11 months) and retraining (21 months) ]
  Muscle Strength: Maximum strength was measured with the one-repetition maximum (1 RM) method and total muscle strength was calculated as the sum of leg extension and bench press.
  
  

During the last decades, the positive effects of aerobic exercise in patients with type 2 diabetes have been well documented. Recently, resistance exercise has gained popularity in diabetic patients since several studies have indicated that this type of training is safe and induces favorable adaptations in physical fitness and metabolic profile. According to recent scientific evidence, a complete rehabilitation program for patients with type 2 diabetes should combine both strength and aerobic exercise; thus the American Diabetic Association in their latest guidelines recommends strength training as part of an exercise program at least two times a week.

On the contrary to the well documented effects of physical training, there is lack of data on the negative alterations of detraining in patients with type 2 diabetes. The partial or complete loss of training-induced adaptations as a consequence of training reduction or cessation is well-documented by several detraining studies in healthy subjects, older individuals and patients with coronary artery disease.

For example, the investigators know that even 6 days of physical inactivity reduces insulin action in well-trained runners which is attributed to the significant reduction in the muscle GLUT-4 level. Factors such as illness, injury, travel or vacation may interrupt the training process for longer periods, affecting the treatment in people with type 2 diabetes. For this population, it is important to quantify changes in physiological and metabolic parameters resulting from the cessation of exercise, since exercise training is a major therapeutic method.

To the best of our knowledge, there is no data concerning the loss of physiological adaptations which occurs after exercise cessation in patients with type 2 diabetes, which have previously trained for a long period of time. The current study evaluated the effects of three months of detraining after nine months of a combined strength and aerobic training program on glycemic control, body composition, peak oxygen consumption (VO2peak) and muscular strength in patients with type 2 diabetes. Further, the investigators examined the extent of the regained adaptations after the resumption of training for a period of nine months.