The study includes healthy young habitually active subjects. All subjects are subjected to two weeks of immobilization of one leg followed by four weeks of training of both legs. The subjects are randomized to either one-leg training of the non-immobilized leg during the two-week immobilization period or to no training of the non-immobilized leg during the immobilization period. Measures include skeletal muscle morphology, markers of angiogenesis and apoptosis, muscle metabolic markers, vascular function, vascular proteins and performance.
One leg of young healthy subjects will be immoblized for two weeks. Changes in angiogenic proteins and markers of apoptosis in muscle tissue and muscle extracellular fluid will be determined in both legs and in parallel the functional consequences of immobilization will be assessed. Vascular function and vascular proteins will also be determined. In order to understand how the oxidative capacity of the muscle is altered in parallel with changes in capillarization, markers of mitochondria will be measured .Half of the subjects will be randomized to single-leg training during the immobilization period to assess whether simultaneous training reduces the loss of capillaries, muscle function and vascular function in the immobilized leg. After the immobilization period the study participants will train the immobilized leg and the control leg for four weeks by moderate to intense interval cycle training and the same parameteres as during immobilization will be assessed in both legs. The study will also include measurements of circulating compounds and platelets in blood.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
12
Full length cast of one leg R/L randomized
Exercise training will be conducted with the non-immobilized leg during the immobilization period of two weeks
Exercise training will be conducted regularly on a cycle ergometer during a four week period
University of Copenhagen
Copenhagen, Denmark
Angiogenesis
Skeletal muscle capillarization-comparison between legs
Time frame: Change from baseline to after 2 weeks of immobilization
Vascular function
Measurements of skeletal muscle blood flow by ultrasound doppler in response to infusion of vasodilators/constrictors-comparison between legs
Time frame: Change from baseline to after 2 weeks of immobilization
Angiogenesis
Skeletal muscle capillarization-comparison between legs
Time frame: Change from after immobilization to after 4 weeks of training
Vascular function
Measurements of skeletal muscle blood flow by ultrasound doppler in response to infusion of vasodilators/constrictors-comparison between legs
Time frame: Change from after immobilization to after 4 weeks of training
Vascular and metabolic proteins
Proteins of importance for vascular function and muscle metabolism measured in muscle biopsy samples, skeletal muscle interstitial fluid and plasma-comparison between legs
Time frame: Change from baseline to after 2 weeks of immobilization and from after immobilization to after 4 weeks of training
Arterial blood pressure
Measured by sphygmomanometer and intra-arterially
Time frame: Change from baseline to after 2 weeks of immobilization and from after immobilization to after 4 weeks of training
Knee extensor performance
Measurements of maximal power and endurance-comparison between legs
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Time frame: Change from baseline to after 2 weeks of immobilization and from after immobilization to after 4 weeks of training
Maximal oxygen uptake
Measured by gas analysis during an incremental ergometer cycle protocol
Time frame: Change from baseline to after 2 weeks of immobilization and from after immobilization to after 4 weeks of training
Body composition
Measurements by dual energy x-ray absorptiometry
Time frame: Change from baseline to after 2 weeks of immobilization and from after immobilization to after 4 weeks of training
Skin microcirculation
Measurements of skin blood flow and morphology and relevant proteins in skin biopsies
Time frame: Change from baseline to after 2 weeks of immobilization and from after immobilization to after 4 weeks of training
Markers of bone metabolism
Measurements of bone markers in plasma
Time frame: Change from baseline to after 2 weeks of immobilization and from after immobilization to after 4 weeks of training
Markers of angiogenesis
Measurement of angiogenic and apoptotic factors-comparison between legs
Time frame: Change from baseline to after 2 weeks of immobilization and from after immobilization to after 4 weeks of training
Vascular function-non-invasive
Measurements of skeletal muscle blood flow at rest, during passive movement, during exercise, after five min of occlusion and during infusion of vasodilators and constrictors-comparison between legs
Time frame: Change from baseline to after 2 weeks of immobilization and from after immobilization to after 4 weeks of training