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. Author manuscript; available in PMC: 2017 Jan 1.
Published in final edited form as: Exerc Sport Sci Rev. 2016 Jan;44(1):29–36. doi: 10.1249/JES.0000000000000067

Figure 1.

Figure 1

Schematic representation of collagen fibril organization and cross-linking emphasizing the effect of APAP and exercise on rat Achilles tendon cross-linking (8). Panel A presents an example of normal tendon collagen with lysyl oxidase catalyzed cross-links connecting tropocollagen molecules. Panel B highlights the effect of chronic APAP consumption on Achilles tendon collagen cross-linking in non-exercising rats. Panel C highlights the effect of chronic exercise training on Achilles tendon collagen cross-linking. Chronic APAP consumption results in a reduction in collagen cross-linking. In contrast, chronic exercise training leads to an increase in collagen cross-linking in the Achilles tendon. Panel D highlights the combined effect of chronic exercise and APAP consumption. Effectively, the combination of exercise and APAP results in a tendon with normal levels of collagen cross-linking. APAP does not appear to blunt the effect of exercise on cross-linking. Similar effects of APAP on non-exercised skeletal muscle cross-linking have been noted (7).