Muscle Fiber Type And Blood Oxidative Stress Following Muscle Damaging Strength Exercise

Abstract

Acute participation in high intensity strength type exercise elicits a transient blood oxidative stress. Factors underlying the oxidative stress magnitude, however, are poorly understood. There is a rationale to suspect that muscle fiber type composition may influence the magnitude of the blood oxidative stress response to acute strength training. PURPOSE: To determine whether muscle fiber type correlates to the magnitude of blood oxidative stress following acute strength type exercise. METHODS: Eleven college aged males performed muscle damaging strength exercise which involved 3 sets of 50 eccentric-action repetitions at a rate of 30 degrees/second. Heparinized blood plasma samples taken Pre, Post, 24 hours, 48 hours, 72 hours, and 96 hours post muscle damaging exercise were assayed for comparison of muscle damage (creatine kinase - CK, and lactate dehydrogenase - LDH) and oxidative stress biomarkers (uric acid - UA, Ferric Reducing Antioxidant Power - FRAP, Trolox-Equivalent Antioxidant Capacity - TEAC, lipid hydroperoxides - LOOH, and protein carbonyls - PC). Muscle biopsies were taken of the vastus lateralis prior to the muscle damaging exercise protocol and subsequently assayed to determine the relative percentage of slow and fast type muscle fibers. Relationships between oxidative stress, muscle damage, and muscle fiber type were examined. RESULTS: A mixed fiber composition existed (Type I = 36.2 +/- 4.7%, Type IIa = 34.3 +/- 3.1, Type IIx = 29.53 +/- 2.73%; p = 0.366). Plasma CK levels peaked 24-96 hours post exercise (214%, p = 0.002) while LDH levels peaked between Post and 96 hours post (18%, p = 0.012). No elevation in Pre-to-immediately-Post sample oxidative stress biomarkers was observed. An elevation in plasma PC existed, however, 24, 48, 72, and 96 hours (p = 0.032) post strength exercise, with a peak response of 126% (p = 0.012) above baseline. No statistically significant correlations existed between muscle fiber composition and elevations in plasma markers for oxidative stress or muscle damage. CONCLUSIONS: A fiber type - oxidative stress relationship did not exist following muscle damaging strength type exercise. Further study is needed to determine whether a fiber type-oxidative stress relationship exists in individuals with fast or slow muscle fiber type predominance.