Maintaining Resistance Training in Older Prediabetic Adults

Primary Outcome Measures:

• Markers of prediabetes [ Time Frame: 15 months ] [ Designated as safety issue: No ]
  glucose tolerance and fasting glucose concentration
  
  
• Muscular Strength [ Time Frame: 15 months ] [ Designated as safety issue: No ]
  3 RM (repetition maximum - the maximum amount of weight that can be lifted three times)
  
  

Secondary Outcome Measures:

• Insulin secretion and action [ Time Frame: 15 Months ] [ Designated as safety issue: No ]
  
• Adherence to the resistance training program session schedule (twice/week sessions) [ Time Frame: 15 Months ] [ Designated as safety issue: No ]
  
• Social Cognitive Theory Measures (includes self-efficacy, self-regulation, outcome expectancies, and affect; related to resistance training) [ Time Frame: 15 Months ] [ Designated as safety issue: No ]
  
• Body Composition [ Time Frame: 15 Months ] [ Designated as safety issue: No ]
  

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 homeostasis. The overall aim is consistent with NIDDK's Behavioral/Prevention Research Program's focus on individual, family, and community-based strategies for prevention of diabetes and its complications. Resistance training is particularly applicable to older, pre-diabetic 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=180) 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 2 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 Standard intervention with 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 the 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 disabilities, 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.