Abstract
Mixed and collagen protein synthesis is elevated for as many as 3 days following exercise. Immediately after exercise, enhanced amino acid availability increases synthesis of mixed muscle protein, but not muscle collagen protein. However, the potential for synergic effects of amino acid ingestion with exercise on both mixed and collagen protein synthesis remains unclear. We investigated muscle collagen protein synthesis in rats following post-exercise ingestion of leucine-enriched essential amino acids. We determined fractional protein synthesis rates (FSR) at different time points following exercise. Mixed protein and collagen protein FSRs in skeletal muscle were determined by measuring protein-bound enrichments of hydroxyproline and proline, and by measuring the intracellular enrichment of proline, using injections of flooding d3-proline doses. A leucine-enriched mixture of essential amino acids (or distilled water as a control) was administrated 30 min or 1 day post-exercise. The collagen protein synthesis in the vastus lateralis was elevated for 2 days after exercise. Although amino acid administration did not increase muscle collagen protein synthesis, it did lead to augmented mixed muscle protein synthesis 1 day following exercise. Thus, contrary to the regulation of mixed muscle protein synthesis, muscle collagen protein synthesis is not affected by amino acid availability after damage-inducing exercise.
Highlights
Collagen protein, the major protein of the extracellular matrix of skeletal muscle, has crucial roles in mechanical strength, and transmission of forces generated by muscle contractions [1]
Through measuring the enrichment of hydroxyproline in protein-bound fractions following flooding doses of intravenous d3 -proline, we found that muscle collagen protein synthesis is elevated and peaks at 1 day after downhill exercise, consistent with reported changes in collagen gene expression [23]
Leucine-enriched essential amino acids do not affect muscle collagen protein synthesis 1 h or 1 day after exercise, while the amino acids induce a further increase in mixed muscle protein synthesis 1 day after exercise compared with control
Summary
The major protein of the extracellular matrix of skeletal muscle, has crucial roles in mechanical strength, and transmission of forces generated by muscle contractions [1]. The muscle collagen network provides a structural framework for skeletal muscle cells and should grow with muscle hypertrophy. Collagen content can be increased by endurance training [2] or experimental compensatory hypertrophy [3]. Lengthening contractions result in muscle damage that involves muscle fibers and the extracellular matrix [4]. Failure in the re-organization of the extracellular matrix after exercise leads to accumulation of connective tissue, which may interfere with tissue repair and functional recovery [5]. Post-exercise re-organization of the skeletal muscle extracellular matrix is necessary for recovery from muscle damage
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
