Heat-induced Extracellular HSP72 Release is Blunted in Elderly Diabetic People in Comparison With Healthy Middle-aged and Older Adults But is Partially Restored by Strength Training

The aim of this study was to compare the heat shock response (HSR) between healthy middle-aged adults, healthy elderly adults and type 2 diabetic elderly people. In addition, considering the effects of strength exercise in promoting health, we aimed to test the effects of strength training over the HSR in diabetic elderly people. Thirty (19 females and 11 males) sedentary non-smoking participants volunteered for this study (11 healthy middle-age adults, 7 healthy old adults and 12 diabetic old subjects, previously diagnosed by their personal physicians).

Firstly, venous blood samples were obtained from all participants to test the HSR. They were divided in three groups: healthy middle-age adults (45-59 y.o.), healthy elderly adults and elderly diabetic (> 60 y.o.). As we identify that diabetic people presented a poor HSR, we submit the diabetic group to a twelve-week resistance exercise training to verify if this intervention could improve the HS response.

Diabetic subjects were randomly (1:1 block randomization) allocated in one of the two groups: Trained and Control (no training). Strength training was performed three times per week while the control group performed a "placebo" stretching/relaxing session once a week (for adherence purposes). Both interventions had twelve weeks of duration. To avoid any significant adaptation, all stretching exercises (for large muscle groups only) were performed at very low intensity without any significant discomfort.

Supervised (by qualified sport and exercise scientists) exercise was performed in a gym on three non-consecutive days of the week. Each session lasted ~60 min and consisted of a warm up, the resistance exercise training and a cool down. The training programme consisted of a combination of upper and lower body exercises using gym equipments, free weights and body weight as the primary resistance. The twelve weeks of strength training were divided into three mesocycles of four weeks each. Exercises included leg press, knee extensions and leg curls, biceps curls, triceps extensions, lat pull-downs, shoulder press, bench press and abdominal crunch. Before the start of the training period, subjects completed a familiarization session to practice the exercises they would further perform during the training sessions, where the exercise load was individually tested. The resistance training was performed using two to three sets per exercise at intensities between 12-15 repetition maximum-RM.