Study of Muscle Repair Following Exercise in Young and Elderly People
Condition: Healthy
Study type: Interventional

Summary: 
      The aim of this study is to understand how healthy muscle repairs in response to eccentric
      exercise by evaluating functional, metabolic and molecular measures. Furthermore, this study
      will aim to understand the repair mechanisms in elderly healthy muscle following eccentric
      exercise by evaluating the same measures and highlighting age-related differences in repair
      mechanisms which may account for the age-related loss in muscle mass. It is hypothesised that
      elderly muscle will have a lesser/ blunted repair process compared to young muscle.

      To meet the aims of this study and to answer the hypothesis, this study protocol is as
      follows:

      Baseline functional, metabolic and molecular values are obtained via functional testing and a
      muscle biopsy. Participants then perform eccentric exercise designed to induce functional
      decline and muscle soreness and the contralateral leg performs concentric exercise which
      isn't designed to induce soreness or functional decline. Using a time-course, various
      metabolic and molecular measures are taken prior to and up to 7 days post exercise to
      understand the mechanisms underlying muscle repair. In addition the use of a novel amino acid
      tracer (D2O) will allow for synthesis measures over the duration of the study rather than the
      typical tracer techniques which only capture ~12 hours of synthesis.
    

Detailed description: 
      Participation in this study requires participants to attend the laboratory fasted on 5
      occasions spread over a period of 12 days.

      Participants will report to the laboratory on the first visit for a blood sample and muscle
      biopsy. In order to measure muscle metabolism participants will also consume 'heavy water',
      which will also require participants to provide daily saliva swabs.

      After 96 hours participants will be asked to arrive at the laboratory to perform a bout of
      heavy exercise on one leg to induce sensations of muscle soreness in the days following
      exercise. Investigators will then collect a blood sample and muscle biopsy from the exercised
      leg and do exercise tests. After this, participants will perform another bout of exercise on
      the other leg that will also be followed immediately by a blood sample, muscle biopsy and
      exercise tests. This second exercise bout is not designed to induce sensations of muscle
      soreness. After 5 hours , exercise tests will be performed and a further blood sample and
      biopsies from both legs will be collected.

      Approximately, 21 hours after exercise (visit 3) participants will be asked to return to the
      lab for a short infusion (2.5 hour duration) of 2-deoxyglucose (2DOG), which allows
      investigators to measure glucose uptake. After the infusion, a blood and a muscle biopsy will
      be taken from each leg followed by exercising testing. Participants will then report back to
      the laboratory for exercise testing, a blood sample and a single muscle biopsy from both legs
      at 72 (visit 4) and 168 hours (visit 5) after the initial exercise session.
    

Intervention name(s): Exercise
Intervention type(s): Other
Intervention description(s): One leg eccentric exercise: 7 sets of 10 repetitions at 80% 1 repetition maximum Contralateral leg concentric exercise: 7 sets of 10 repetitions at 80% 1 repetition maximum
2 mins rest between sets
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)