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Accordingly, we evaluated whether an exercise protocol that we have previously found to decrease structural damage kinks in fatigue damaged tendons, leads to improvement in mechanical properties. We hypothesized that exercise that promotes repair of fatigue damage will decrease apoptosis and increase the population of myofibroblasts. Rat patellar tendons underwent <jats:italic>in vivo<\/jats:italic> fatigue loading for 500 or 7200 cycles. Animals resumed cage activity for 2-weeks, then either remained cage active or began treadmill running until sacrifice at 4- or 10-weeks post-fatigue loading. Exercise following fatigue damage increased the stiffness back towards na\u00efve levels, decreased apoptosis and increased the population of myofibroblasts. Next, proteins associated with inhibition of apoptosis (Collagen VI) or activation of myofibroblast (pSmad 2\/3, fibrillin, integrin subunits \u03b1V and \u03b15) were evaluated. Data suggests that collagen VI may not be integral to inhibition of apoptosis in this context. Exercise increased pSmad 2\/3 and fibrillin in the insertion region for the 7200-cycles group. In addition, exercise decreased integrin \u03b1V and increased integrin \u03b15 in fatigue damaged tendons. Data suggests that a decrease in apoptosis and an increase in population of myofibroblasts may be integral to remodeling of fatigue damaged tendons.<\/jats:p>","DOI":"10.1038\/s41598-018-27196-5","type":"journal-article","created":{"date-parts":[[2018,6,6]],"date-time":"2018-06-06T09:42:23Z","timestamp":1528278143000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":19,"title":["A potential new role for myofibroblasts in remodeling of sub-rupture fatigue tendon injuries by exercise"],"prefix":"10.1038","volume":"8","author":[{"given":"Rebecca","family":"Bell","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"N. 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