Practical Approaches for Interrupting Prolonged Sitting to Improve Postprandial Glucose and Protein Metabolism
Condition: Healthy Adults
Study type: Interventional

Summary: 
      The present study will determine the impact of interrupting prolonged sitting with short,
      2-minute walks or body-weight squats on: i) postprandial glycemia and insulinemia, and; ii)
      postprandial utilization of dietary amino acids. We hypothesize that postprandial glycemia
      and insulinemia will be similarly improved by interrupting prolonged sitting with short walks
      or body-weight squats, whereas postprandial utilization of dietary amino acids will only be
      improved by interrupting prolonged sitting with body-weight squats.
    

Detailed description: 
      Sedentary behavior is an independent risk factor for chronic disease and premature mortality.
      Despite a growing awareness of the health risks associated with prolonged sitting, Americans
      spend upwards of 10 hours per day in a sedentary state. Many leisure-time activities and
      careers of modern society involve prolonged sitting, necessitating an urgent need to identify
      strategies that mitigate the health consequences of these behaviors. Recent evidence suggests
      that interrupting prolonged periods of sitting with short breaks of walking or cycling
      improve postprandial glucose and lipid handling throughout the day. Thus, relatively small
      quantities of movement represent an efficacious strategy for improving indices of metabolic
      health. However, more cost-effective and practical interventions that do not require extra
      space (i.e. walking) or equipment (i.e. cycling or a treadmill desk) beyond one's immediate
      sedentary space (e.g. office, desk) would help reduce real and/or perceived barriers of
      adopting this efficacious disease risk-reduction behavior. A currently understudied
      consequence of prolonged sitting may also be a desensitization of skeletal muscle's ability
      to use ingested protein, which overtime can result in detriments to the quantity and quality
      of this important tissue. Body-weight resistance exercise (RE) can augment the body's ability
      to use ingested protein to support the maintenance of skeletal muscle mass, and therefore may
      represent a novel exercise mode to minimize consequences of prolonged sitting. The proposed
      research will be the first to investigate the influence of interrupting prolonged sitting
      with short breaks of body-weight resistance exercise (RE) on postprandial glucose and protein
      metabolism. Importantly, the efficacy of this approach will be directly compared to short
      breaks of walking, which has previously been reported to improve postprandial glycemia in
      healthy adults.
    

Intervention name(s): Mixed-macronutrient meal
Intervention type(s): Dietary Supplement
Intervention description(s): Participants will be provided a mixed-macronutrient meal (liquid drink) at hours "0" and "3", mimicking the energy and macronutrient composition of breakfast and lunch in Western society (38). 20% of daily energy intake will be provided as "breakfast" and 30% at lunch. Macronutrient composition will reflect a diet providing 55% energy needs from carbohydrate (CHO) and 1.2g/kg/d protein. The remaining energy requirements, as determined by total energy intake, will be met with dietary fat (estimated to be ~0.2 and 0.3g/kg fat for breakfast and lunch, respectively), similar to previous liquid mixed-meal approaches.
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Fourteen men and women will visit the lab on three separate occasions and will remain seated at a desk all-day (Visit 1) or interrupt this sitting every 30-minutes with either 2-minute walking-breaks (Visit 2) or with 15 body-weight squats (repeatedly rising from a chair and onto tip-toes, Visit 3).
Masking: None (Open Label)
Primary purpose: Treatment