The aim of this Phase II Clinical Trial is to demonstrate the efficacy of social cognitive theory (SCT) based intervention for initiating, and most importantly, maintaining resistance training in older adults with pre-diabetes (i.e., impaired glucose tolerance or impaired fasting glucose) to improve glucose homeostatis. The overall aim is consistent with NIDDK's Behavioral/Prevetion Research Program's forcus on individual, family, and community-based strategies for prevention of diabetes and its complications. Resistance training is particularly applicable to older, prediabeteic adults given the loss of lean body mass and worsening of glucose tolerance with aging. The proposed research program evaluates a 15-month SCT based intervention for maintenance of resistance training with older adults. Men and women 50-69 (N=220) with pre-diabetes, defined as exhibiting either impaired glucose tolerance (IGT;2-h glucose 140-199 mg/dl) or impaired fasting glucose (IFG;100-125 mg/dl), will first follow the same standard, supervised 3-month initiation period with resistance training. All people completing the Initial Phase will be randomly assigned to 1 of 3 maintenance conditions: 1. a long-term SCT based, ASPIRE intervention, emphasizing self-regulation and other SCT strategies to optimize training, with faded contact;2. a long-term Generic intervention lacking a number of SCT components but with the same faded contact, or, 3. a Standard intervention with more minimal contact. The primary outcome measures are indices of pre-diabetes (glucose tolerance and fasting glucose concentration) and strength. Secondary measures include adherence;ss-cell responsivity, insulin sensitivity, and disposition index, as determined by the oral glucose and C-peptide minimal model;fat free mass, other indicators of health and metabolic fitness, and SCT measures. Assessments will occur at baseline, at the end of the Initiation Phase (3 months), at the end of the different interventions (9 months) and 6 months after all contact has ended (15 months from baseline). It is hypothesized that SCT based resistance training with faded contact will produce better outcomes than Generic based training with faded contact, which in turn, will produce better outcomes than Standard-based resistance training at 9 month and 15 month assessments. It also is hypothesized that improvements in glucose homeostasis and in strength from resistance training will be mediated by adherence, self-efficacy, and use of self-regulation strategies. Resistance training has become an important component in the treatment and prevention of diseases and disabilites, and especially so for Type 2 diabetes. Critical to public health and a focus of NIDDK are theory-based interventions that enable, effective long-term resistance training with minimal supervision after an initiation phase and where improvements in adherence and outcomes are facilitated by theoretical constructs.
Pre-diabetes is present is more than half of adults aged 60-74 years. Resistance (strength) training appears to be another modality besides weight loss and physical activity that is effective for pre-diabetes prevention. Even though these health benefits can be accrued from a limited time investment, only 10-15 percent of people over 55 report performing any strengthening activities. Prior work suggests that resistance training (RT) can be effectively initiated in well-supervised settings, however there are very few theory-based studies showing effective maintenance of RT in minimally supervised settings. In the absence of such theoretically based efficacy studies on long-term maintenance, it is likely that although people such as those with pre-diabetes will initiate RT, a high percentage will soon discontinue RT. Therefore, we propose to demonstrate the efficacy of a social cognitive theory-based intervention for initiating and maintaining RT in older adults with pre-diabetes to improve glucose homeostasis.
