Disuse Atrophy (Muscle) of Lower Leg, Muscle Atrophy
Conditions
Keywords
Muscle Hypertrophy, Muscle Atrophy, Resistance Training, Immobilization
Brief summary
It is well known that periods of weight training lead to increases in skeletal muscle size and strength. In contrast, periods of inactivity such as bed rest or immobilization result in losses of skeletal muscle size and strength. However, individuals experience variable magnitudes of muscle size change in response to changes in mechanical tension, such that certain individuals experience large changes in muscle mass whereas others do not. What is not currently known, and will be the primary goal of the present investigation, is to determine whether individuals who gain the most muscle mass with exercise training also lose the most muscle when they are immobilized. The investigators hypothesize that individuals who gain the most muscle with training will also lose the most with immobilization.
Detailed description
Resistance exercise, paired with protein ingestion, leads to the accretion of muscle proteins that over time results in the augmentation of muscle size and muscle strength. By virtue of its ability to stimulate increases in muscle size and strength, resistance exercise is an effective method that can be used by healthcare practitioners to promote the recovery of lost muscle mass resulting from a period of immobilization (resulting from broken bones, elective surgery, etc.). However, while exercise in general is an effective therapeutic strategy to combat muscle loss and frailty, the extent to which individuals respond to resistance exercise is highly variable. Some individuals exhibit large changes in muscle size (high responders) whereas other exhibit little to no change (low responders). Thus, where as one resistance exercise program might be an appropriate treatment for one individual following disuse, another individual might require a greater stimulus and/or pharmaceutical assistance in order to fully recover. What is currently unknown is whether individuals who experience the most profound increases in skeletal muscle mass following resistance exercise also lose the most muscle upon limb immobilization. Answering this gap in our knowledge will be the primary goal of this study. The procurement of this knowledge will hopefully permit the development of individualized exercise programs that can be used to influence the recovery of skeletal muscle that is lost with inactivity and immobilization.
Interventions
Unilateral Resistance exercise will include training three days per week and each session will include 3 sets of leg extension and 3 sets of leg press. In each set, the participant will complete a maximum of 12 repetitions.
PROCEDUREImmobilization
During the last two weeks of the study (week 8-10), a Don Joy adjustable knee brace will be applied to the participant's leg randomized to immobilization. The brace will be applied at a 40 degree angle relative to complete extension.
Sponsors
McMaster University
Study design
Allocation
RANDOMIZED
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Masking description
Investigators and participants will have knowledge or which leg will be undergoing resistance training and which will be immobilized.
Intervention model description
The model will be a within-subject intervention. Each subject will have one leg randomized to unilateral resistance exercise (for 10 weeks) and the other to immobilization (for the last 2 weeks of the study).
Eligibility
Sex/Gender
MALE
Age
18 Years to 30 Years
Healthy volunteers
Yes
Inclusion criteria
* Healthy * Non-Smoker * Do not heavily consume alcohol
Exclusion criteria
* Female * Younger than 18, or older than 30 years * use of anti-inflammatory or analgesic medication * history of neuromuscular disorders * family history of deep vein thrombosis * regularly take part in structured physical exercise (greater than 2 days per week) * take any medications known to influence protein metabolism
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Muscle Cross Sectional Area | May 2017 - Dec 2017 | The changes in muscle cross sectional area will be assessed pre-training (week 0) and post training/immobilization (week 10) using magnetic resonance imaging (MRI). Muscle cross-sectional area will be assessed over a continuous period of 7 months. |
| Leg Lean Mass | May 2017 - Dec 2017 | The changes in leg lean mass will be assessed pre-training (week 0) and post-training/immobilization using dual energy x-ray absorptiometry. Leg lean mass measurements will be made over a continuous period of 7 months. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Skeletal Muscle Gene Expression | May 2017 - Dec 2017 | Gene expression will be quantified pre-training (week 0) and post-training/immobilization from muscle tissue samples obtained via muscle biopsies in both legs. Gene expression assessment will take place over a continuous period of 7 months. |
Countries
Canada
Outcome results
None listed