Sex-based difference in Achilles peritendinous levels of matrix metalloproteinases and growth factors after acute resistance exercise

Several recent investigations have demonstrated that the ability of various tendons to alter structural and functional properties in response to exercise are muted in women when compared to men. We hypothesize that this disparity between men and women may be due to a reduced tendon production of key mediators of tendon extracellular matrix (ECM) remodeling in response to mechanical loading, e.g. exercise. Using microdialysis before and after an acute bout of resistance exercise, we evaluated Achilles peritendinous levels of insulin-like growth factor-1 (IGF-1) and interleukin-6 (IL-6), which have both been shown to increase tendon collagen synthesis. Additionally, the matrix remodeling enzymes matrix metalloproteinase-2 (MMP-2), MMP-9, and tissue inhibitor of metalloproteinase-1 (TIMP-1) were also evaluated. IGF-1 levels were elevated (p<0.05) to a similar extent in men and women after 3-hours of exercise but remained elevated at 4-hours in only women. IL-6 levels were ~4-fold greater after exercise in both men and women (p<0.05). MMP-2 levels increased to a similar extent (~2-3-fold) in men and women (p<0.05). In contrast, MMP-9 increased with exercise but only in men (p<0.05). Lastly, TIMP-1 levels also increased (p<0.05) with exercise in men and women but the increase was more prolonged in women. In conclusion, we observed modest sex-differences in tendon release of MMP-9, TIMP-1, and IGF-1 after acute resistance exercise. If such differences persist throughout a chronic exercise training, they may contribute to the reduced ability of women to adapt to exercise when compared to men.

from Physiology via xlomafota13 on Inoreader http://ift.tt/2gnONqO
via IFTTT