SEX-BASED DIFFERENCES IN ACHILLES TENDON RELEASE OF MATRIX METALLOPROTEINASES AND GROWTH FACTORS AFTER ACUTE RESISTANCE EXERCISE

IntroductionTendon cross-sectional area (CSA) and stiffness increase in men during chronic exercise. The increase in tendon CSA and stiffness is not evident in women. In men, exercise increases tendon production of MMPs, IGF-1, and IL-6, which presumably contribute to tendon remodeling during chronic exercise. The purpose of this study was to determine if exercise-induced production of MMPs, IGF-1, and IL-6 are limited in women when compared to men.Materials and MethodsYoung men (n=9, 27±1 y) and women (n=8, 26±1 y) performed a single bout of calf press exercise (8 sets of 15 repetitions at 70% of 15-RM). A microdialysis fiber (3000 kDa cut-off) was inserted into the space anterior to the Achilles tendon immediately after exercise and during a control experiment. All proteins were evaluated with ELISA kits.ResultsIn men IGF-I increased with exercise at 3 (p<0.05) but not 4 hrs. IGF-1 was not elevated at any measured time points in women. IL-6 increased with exercise to a similar extent in men and women at...