Dietary Protease Supplementation Attenuates Eccentric-exercise Induced Force Production Decrements By Regulating Leukocyte Activity

Dietary protease supplementation has been purported to reduce the damaging effects of eccentric exercise and accelerate recovery of muscle function, possibly by regulating local inflammation. PURPOSE: To determine the effectiveness of prophylactic protease supplementation in attenuating eccentric-exercise induced skeletal muscle damage and inflammation. METHODS: Following standard physical and hemodynamic assessment subjects donated fasting venous blood samples. Subjects then performed isokinetic extension/flexion of the quadriceps group on a Biodex isokinetic dynamometer at 60°/s, followed by VO2max testing. Subjects were randomly assigned to consume 5.83g daily of either a cellulose placebo (N= 15; 22.27+3.33 yr, 71.17+2.91 in, 179.4+24.05 lb, 50.55+5.66 ml/kg/min) or a proteolytic supplement containing fungal proteases, bromelain, and papain (N= 14; 22.85+5.9 yr, 70.0+2.67 in, 173.11+29.94 lb, 49.69+6.15 ml/kg/min) for a period of 21 days. Following the supplementation period, subjects donated blood samples prior to performing a 45 minute downhill (-17.5%) treadmill protocol at 60% of VO2max. An additional 4 blood draws and 3 muscle function tests were performed over the next 48h. Blood was analyzed using standard hematology and clinical chemistry, ELISA, and bead-array. Blood data were analyzed using MANOVA with repeated measures, while Biodex data were analyzed using MANOVA on %D values. RESULTS: Significant group differences (T1-T3, p= 0.033; T1-T4, p= 0.043) and another strong trend (T1-3h, p= 0.055) were observed for flexion peak torque %D at 60°/s. No significant differences were observed for extension. Following eccentric exercise, muscle force in the protease group actually increased (T1-3h: 4.73%, T1-T3: 3.01%, T1-T4: 6.44%), while the placebo group experienced significant force decrements (T1-3h: -19.54%, T1-T3: -27.94%, T1-T4: -25.87%). Significant group x time interactions (p < 0.05) for the protease group were observed with increases in circulating eosinophils, basophils, and decreases in serum COX2, IL-6, and IL-12. CONCLUSION: Protease supplementation appears to attenuate muscle strength loss following eccentric exercise by altering leukocyte activity and inflammatory responses. Funded by Transformation Enzyme Corp. (Houston, TX) & ACSM Texas Chapter.