Submitted on October 8, 2008
Revised on November 13, 2008
Accepted on November 14, 2008
Effect of acute resistance exercise and sex on human patellar tendon structural and regulatory mRNA expression
Bridget E. Sullivan1, Chad C. Carroll2, Bozena Jemiolo1, Scott W. Trappe1, S. Peter Magnusson3, Simon Dossing4, Michael Kjaer5, and Todd A. Trappe1*
1 Ball State University
2 Midwestern University
3 Bispebjerg Hospital and Faculty of Health Sciences,
4 Bispebjerg hospital, Denmark
5 Bispebjerg Hospital and Faculty of Health Sciences, University of Copenhagen
* To whom correspondence should be addressed. E-mail: ttrappe{at}bsu.edu.
Tendon is mainly composed of collagen and an aqueous matrix of proteoglycans that are regulated by enzymes called matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). While it is known that resistance exercise (RE) and sex influence tendon metabolism and mechanical properties, it is uncertain what structural and regulatory components contribute to these responses. We measured the mRNA expression of the tendon's main fibrillar collagens (type I and type III) and the main proteoglycans(decorin, biglycan, fibromodulin, and versican), and the regulatory enzymes MMP-2, MMP-9, MMP-3, and TIMP-1 at rest and following RE. Patellar tendon biopsy samples were taken from six individuals (3M, 3F) before and 4h following a bout of RE and from a separate six individuals (3M, 3F) before and 24h following RE. Resting mRNA expression was used for sex comparisons (6M, 6F). Collagen type I, collagen type III, and MMP-2 were downregulated (P<0.05) 4h following RE, but were unchanged (P>0.05) at 24h. All other genes remained unchanged (P>0.05) following RE. Women had higher resting mRNA expression (P<0.05) of collagen type III and a trend (P=0.08) towards lower resting expression of MMP-3 compared to men. All other genes were not influenced (P>0.05) by sex. Acute RE appears to stimulate a change in collagen type I, collagen type III, and MMP-2 gene regulation in the human patellar tendon. Sex influences the structural and regulatory mRNA expression of tendon.
