Firstly, the investigators aim to study the biochemical, structural and functional changes associated with acute muscle strain injury in the acute phase and during rehabilitation in vivo. Specific factors present after the injury and their effects on connective tissue cells will be examined in vitro. Secondly, the investigators will investigate individuals with chronic pain, scar tissue and inferior function after a previous muscle strain injury and test a specific rehabilitation program to alleviate pain and disabilities associated with the preceding muscle injury. The investigators have the following hypotheses: 1. Humoral growth factors and pro-inflammatory macrophages released into the injured area post strain injury stimulate formation of connective tissue in vitro. 2. Early onset of rehabilitation will be superior to a delayed start of rehabilitation for the healing process, in regards to structural improvement of tissue and better clinical function. 3. Scar tissue following a muscle strain injury is characterized by disorganized structure of connective tissue. 4. Mechanical loading in the form of heavy eccentric muscle activity for 12 weeks will lead to a local re-modeling of scar tissue, and result in improved function and reduced symptoms in patients with chronic pain and impaired function after a previous muscle injury.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
85
Early onset of rehabilitation
Delayed onset of rehabilitation
Exercise
Control
Institute of Sports Medicine Copenhagen, Bispebjerg Hospital, Bispebjerg Bakke 23, Building 8
Copenhagen, Denmark
Return to full physical activity
First time the subject is fully fit to take part in all types of physical activity post injury;
Time frame: Baseline; Up to 30 weeks (estimated time frame maximum)
Magnetic resonance images
Size of injured tissue; Size and location of hematoma; Measurement of muscle perfusion (indication of metabolic activity)
Time frame: Baseline, 4 weeks, 6 weeks, 12 weeks, 6 months
Ultrasound images
Size and location of injury
Time frame: Baseline, 7-14 days, 4 weeks, 6 weeks, 12 weeks, 6 months
Ultrasound images
Volume of hematoma
Time frame: Baseline, 1 week, 2 weeks
Strength measurements
Strength tests of injured muscle group compared to healthy muscle group on contralateral leg
Time frame: Baseline, 4 weeks, 6 weeks, 9 weeks, 12 weeks, 6 months
Structural changes of tissue
Evaluation of tissue samples from injured muscle before and after rehabilitation program
Time frame: Baseline, 12 weeks
Aspiration and characterization of inter-/ intramuscular fluid in the injured muscle
The aspirated fluid (hematoma/exudate) will be analyzed for released humoral factors, cell types present and its effect on human fibroblast proliferation
Time frame: Baseline, 3 -14 days
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