Muscle strain injuries are a particularly frequent type of sports injury in soccer, athletics, badminton/ tennis and cross-fit fitness, thereby affecting a broad range of popular leisure time activities. Depending on severity, sports-active individuals may experience long-term functional impairment and pain. Additionally, individuals having sustained one strain injury have a substantially increased risk of injuring the same muscle again. Strain injuries lead to long-term, potentially permanent, loss of muscle mass, thereby weakening the muscle. Muscle atrophy is likely a major factor in the high re-injury risk. Further, strain injuries are associated with a long-term inflammatory response. In the current study, the investigators seek to study interventions to prevent the loss of muscle mass and elaborate on strategies to address the prolonged inflammation observed at the site of the injured muscle. The primary aim of this study is to investigate the effect of protein supplementation on the reduction of muscle atrophy following a severe muscle strain injury in comparison to a carbohydrate supplement. As a second purpose, this study aims to elaborate on findings of prolonged inflammation intra-/ intermuscular by large-scale protein analysis and the characterization of cells active at the site of injury. The study includes the following hypotheses: 1. Protein supplementation administered in combination with a gradually increasing loading regime (rehabilitation with weekly progression in load/ intensity) will be effective in reducing the injury-related loss of muscle mass. 2. The environment at the site of injury is not only pro-inflammatory, but contains proteins associated with proteolysis. 3. Cells belonging to the group of fibro-adipogenic progenitors will be accumulating intra- and inter-muscularly.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
50
Daily dose of 40 g whey protein for 3 months
Daily dose of 40 g maltodextrin for 3 months
Progressive rehabilitation following a muscle strain injury for 3 months
Institute of Sports Medicine Copenhagen, Bispebjerg Hospital, Nielsine Nielsen Vej 11, Building 8
Copenhagen, Denmark
Muscle volume
Change in muscle volume in the injured muscle comparing immediate post injury scan with 3 months post scan plus comparison of change with healthy, contralateral muscle over the same time span.
Time frame: 3 months post injury
Muscle volume
Change in muscle volume in the injured muscle comparing immediate post injury scan with 12 months post scan plus comparison of change with healthy, contralateral muscle over the same time span.
Time frame: 12 months post injury
Isokinetic muscle strength
Change in muscle strength in the injured leg compared to muscle strength in healthy, contralateral muscle
Time frame: 3 months post injury
Isokinetic muscle strength
Change in muscle strength in the injured leg compared to muscle strength in healthy, contralateral muscle
Time frame: 6 months post injury
Isokinetic muscle strength
Change in muscle strength in the injured leg compared to muscle strength in healthy, contralateral muscle
Time frame: 12 months post injury
Fat infiltration
Assessment of fat content in the injured muscle comparing immediate post injury scan with 3 months post scan plus comparison of change with healthy, contralateral muscle over same time range
Time frame: 3 months post injury
Fat infiltration
Assessment of fat content in the injured muscle comparing immediate post injury scan with 12 months post scan plus comparison of change with healthy, contralateral muscle over same time range
Time frame: 12 months post injury
Injury screening Questionnaire
Assessment of subjective symptoms and pain during sports and daily activities
Time frame: 3 months post
Injury screening Questionnaire
Assessment of subjective symptoms and pain during sports and daily activities
Time frame: 6 months post
Injury screening Questionnaire
Assessment of subjective symptoms and pain during sports and daily activities
Time frame: 12 months post
Ultrasound images
Fascicle length measurement, pennation angle, mechanical properties of the muscle (- tendon unit) in the injured and healthy, contralateral muscle
Time frame: Baseline (Acute post injury)
Ultrasound images
Fascicle length measurement, pennation angle, mechanical properties of the muscle (- tendon unit) in the injured and healthy, contralateral muscle
Time frame: 3 months post injury
Ultrasound images
Fascicle length measurement, pennation angle, mechanical properties of the muscle (- tendon unit) in injured and healthy, contralateral muscle
Time frame: 6 months post injury
Ultrasound images
Fascicle length measurement, pennation angle, mechanical properties of the muscle (- tendon unit) in the injured and healthy, contralateral muscle
Time frame: 12 months post injury
Assessment injury exudate
Assessment and characterization of cells and soluble factors released after a strain injury into the intra-/ intermuscular space
Time frame: Within 7 days post injury
Assessment injury exudate
Assessment and characterization of cells and soluble factors released after a strain injury into the intra-/ intermuscular space
Time frame: <1 week post injury -12 weeks post injury
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