Resistance Exercise and Muscle Protein Synthesis in Obese Adults
Condition: Obesity
Study type: Interventional

Summary: 
      Obesity has numerous comorbidities that are associated with exceedingly high healthcare
      costs. In addition to well- characterized impairments in lipid and glucose metabolism,
      obesity is associated with altered protein metabolism. We have recently observed that obese
      individuals are essentially nonresponsive to protein ingestion with respect to myofibrillar
      protein synthesis. This suggests that skeletal muscle remodeling in obese individuals is
      impaired possibly contributing to a poor metabolic quality of muscle. Resistance exercise is
      known to strongly augment muscle protein synthesis in response to protein ingestion. The
      purpose of this research is to determine the muscle protein synthetic response during
      post-exercise recovery in obese individuals. Using stable isotope methodology, we will
      determine the postprandial muscle protein synthetic response in 14 male and female obese
      adults (Age: 20-45, BMI: 30-39.9 kg/m2) immediately after an acute bout of resistance
      exercise. Participants will be sedentary (< 60 min exercise/ week) and weight stable for a
      minimum of 6 months. During the testing blood and muscle samples will be collected. In
      addition participants will be asked to perform moderate intensity resistance exercise.
      Completion of the proposed research will identify the role of resistance exercise in the
      maintenance of skeletal muscle tissue after the consumption of a protein-dense meal in obese
      people.
    

Detailed description: 
      Baseline procedures:

      A parallel group design will be used for this study. Prior to the infusion trial,
      participants will reported to the laboratory on two separate occasions in the morning. On the
      first visit, we will determine participants' body weight and height as well as body
      composition by dual-energy X-ray absorptiometry. Finally, participants will be familiarized
      with unilateral leg extension and the ten repetition maximum (10RM) procedure. On a separate
      occasion, each subject will arrive to the lab after an overnight fast for the determination
      of oral glucose tolerance in response to the consumption of 75 g glucose dissolved in 500 mL
      of water. At the end of this visit, we will assess participant's unilateral 10RM for leg
      extension. In addition, participants will be instructed to refrain from vigorous physical
      activity and alcohol for three days prior to the tracer infusion.

      Infusion protocol On the day of the infusion trial, participants will report to the
      laboratory at ~0700 h after a 10 h fast. An intravenous catheter will be inserted into an
      antecubital vein for baseline blood sample collection, after which a primed (2 μmol·kg-1),
      continuous infusion (0.05 μmol·kg Lean Body Mass-1·min-1) of L-[ring-13C6]phenylalanine will
      be initiated (t=-180 min) and maintained until the end of the trial. A second intravenous
      catheter placed in a contralateral dorsal hand vein will be placed in a heated blanket for
      repeated arterialized blood sampling. In the post-absorptive state, muscle biopsies of the
      vastus lateralis are to be collected at 0 min of infusion from a non-exercised control leg
      (CON). Subsequently, participants will perform moderate intensity unilateral leg extension
      exercise. Upon completion, participants will consume 170 g of lean ground pork (36 g
      protein). Additional muscle biopsies will be collected from both the exercised (EX) and CON
      legs at 120 and 300 min after pork ingestion. Arterialized blood samples will be collected
      every 30 or 60 min during the post-absorptive and postprandial-states and placed in
      pre-chilled EDTA tubes.
    

Intervention name(s): Resistance Exercise
Intervention type(s): Other
Intervention description(s): Participants will perform 4 sets of 12 repetitions of moderate intensity leg extension
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Basic Science