Disuse Atrophy, Sarcopenia, Skeletal Muscle Atrophy
Conditions
Brief summary
This is a 10-week human study involving 24 younger (20-35 y) and 24 older (65-85 y) healthy individuals. All participants will undergo unilateral immobilization of a knee for 7-10 days, followed by 4 weeks of heavy resistance exercise training (HReT). Half of the participants (12 younger and 12 older) will also undergo 4 weeks HReT prior to the immobilization. Prehabilitative exercise may confer protective effects on subsequent immobilization, and the various underlying mechanisms involved
Interventions
OTHERPrehabilitative exercise
3-4 weeks of heavy resistance exercise
Sponsors
Bispebjerg Hospital
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
20 Years to 85 Years
Healthy volunteers
Yes
Inclusion criteria
* Age: Between 20-35 years old or between 65-85 years old. * BMI: Between 18.5 and 35 kg/m2. * Healthy and well, with normal dietary habits (not vegan).
Exclusion criteria
* More than one muscle biopsy previously taken from both vastus lateralis muscles. * Smoking. * Pregnancy. * Past or present substance or alcohol abuse. * Medical/surgical conditions that are assessed to affect protein synthesis or the participant's involvement in the trial. * Knee pain that could affect the completion of the training intervention. * High intake of supplements that increase the risk of bleeding during muscle biopsy (such as fish oil and ginger). * Participation in regular strength training within the past year. * Regular participation in structured sports. * Current use of blood-thinning medication. * Previous participation in trials involving oral intake of heavy water. * Metal in the body preventing MRI scanning. * For the older group, not having gone through menopause, and for the younger group, not having a regular menstrual cycle.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Quadriceps cross-sectional area | From pre (week 0) to post immobilization (week 5) | Quadriceps cross-sectional area measured by MRI |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Denervated muscle fibers | From pre (week 0) to post immobilization (week 5) and post retraining (week 10) | Assessment denervated fibers using histochemical stainings |
| Muscle protein synthesis | From pre immobilization (week 4) to post immobilization (week 5) | Muscle protein synthesis assessed using deuterium (heavy water) |
| Muscle gene expression | From pre (week 0) to post immobilization (week 5) and post retraining (week 10) | Muscle gene expression assessed by RNA sequencing |
| Brain structure | From pre (week 0) to post immobilization (week 5) and post retraining (week 10) | Brain structure measured by MRI |
| Brain function | From pre (week 0) to post immobilization (week 5) and post retraining (week 10) | Brain function measured by MRI |
| Muscle fiber size | From pre (week 0) to post immobilization (week 5) and post retraining (week 10) | Muscle fiber size assessed by histochemical stainings |
| Tendon ultrastructure | From pre immobilization (week 4) to post immobilization (week 5) | Tendon tissue analysed by molecular analyses |
| Lean-body mass | From pre (week 0) to post immobilization (week 5) and post retraining (week 10) | Whole-body and thigh lean-body mass assessed using DEXA-scans |
| Muscle strength | From pre (week 0) to post immobilization (week 5) and post retraining (week 10) | Muscle strength during knee extension assessed using isokinetic and isometric dynamometers |
| Balance | From pre (week 0) to post immobilization (week 5) and post retraining (week 10) | One-legged balanced assessed using a force platform |
| Force variability | From pre (week 0) to post immobilization (week 5) and post retraining (week 10) | Force variability during knee extension assessed using submaximal isometric contractions |
| Tendon structure | From pre (week 0) to post immobilization (week 5) | Tendon structure measured by MRI |
Countries
Denmark
Outcome results
None listed