Effects of Heavy Resistance Exercise on Skeletal Muscle IL-6 and Serum IL-10 Expression.

Abstract

0589 Interleukin-6 (IL-6) is produced in skeletal muscle during exercise involving bicycling or eccentric contractions; however, little is known about the effects of heavy resistance training on skeletal muscle IL6 and IL-6 receptor expression. In addition, the effects of resistance training on serum IL-6 and IL-10 levels are also unclear. PURPOSE: The purpose of this study was to determine the effects of three sequential bouts of lowerbody heavy resistance exercise on the mRNA and protein expression of skeletal muscle IL-6 and IL-6 receptor, along with the levels of serum IL-6 and IL-10. METHODS: Seven untrained males (n = 7, age = 18.43 ± 1.13 years, height = 180.25 ± 8.25 cm, body mass = 84.79 ± 20.39 kg) performed three sequential bouts of heavy resistance exercise within a 5-d period; each bout was separated by 48 hr. All three bouts consisted of the barbell squat, leg press, and leg extension exercises and each was performed for 3 sets of 8–10 repetitions with a relative intensity of 75%–80% of the one-repetition maximum. A total of six blood and four biopsy samples were obtained across the three bouts (with a final sample taken 48 hr following the third bout). The relative expression of skeletal muscle IL-6 mRNA was determined with RT-PCR and the contents of IL-6 and IL-6 receptor, along with the serum IL-6 and IL-10 were determined with an enzyme-linked immunoabsorbent assay. Results were analyzed with separate one-way ANOVA with repeated measures (p<0.05). RESULTS: The three exercise bouts were completed with an average of 8.98 repetitions and a relative intensity of 75.4% for all three exercises. The mRNA expression of skeletal muscle IL-6 and IL-6 receptor underwent peak increases of 89% and 91% (P<0.05), respectively, 48 hr after the second exercise bout. However, the content of skeletal muscle IL-6 and IL-6 receptor underwent peak increases of 98% and 126% (P<0.05), respectively, 48 hr after the fourth exercise bout. Serum IL-6 and IL-10 reached peak increases of 17% and 52% (P<0.05) 48 hr after the second and third exercise bout, respectively. CONCLUSIONS: Three sequential bouts of heavy lower-body resistance training bouts, all within a 5-d period, were sufficient to up-regulate skeletal muscle IL-6 and IL-6 receptor gene and protein expression. In addition, increases in serum IL-6 levels occurred concomitant with IL-10.