title: The effects of short-term exercise training on peak-torque are time- and fiber-type dependent.
abstract: We examined the susceptibility of fast and slow twitch muscle fibers in the quadriceps muscle to eccentric exercise-induced muscle damage. Nine healthy men (age: 22.5 ± 1.6 years) performed maximal eccentric quadriceps contractions at 120°·s-1 over a 120° of knee joint range of motion for 6 consecutive days. Biopsies were taken from the vastus lateralis muscle before repeated bouts of eccentric exercise on the third and seventh day. Immunohistochemical procedures were used to determine fiber composition and fibronectin activity. Creatine kinase (CK) and lactate dehydrogenase (LDH) were determined in serum. Average torque was calculated in each day for each subject. Relative to baseline, average torque decreased 37.4% till day 3 and increased 43.0% from the day 3 to day 6 (p < 0.001). Creatine kinase and LDH were 70.6 and 1.5 times higher on day 3 and 75.5 and 1.4 times higher on day 6. Fibronectin was found in fast fibers in subjects with high CK level on day 3 and 7 after exercise, but on day 7, fibronectin seemed in both slow and fast fibers except in muscles of 2 subjects with high fast fiber percentage. Peak torque and muscle fiber-type composition measured at baseline showed a strong positive association on day 3 (r = 0.76, p < 0.02) and strong negative association during recovery between day 3 and day 6 (r = -0.76, p < 0.02), and day 1 and day 6 (r = 0.84, p < 0.001). We conclude that the damage of fast fibers preceded the damage of slow fibers, and muscles with slow fiber dominance were more susceptible to repeated bouts of eccentric exercise than fast fiber dominance muscles. The data suggest that the responses to repeated bouts of eccentric exercise are fiber-type-dependent in the quadriceps muscle, which can be the basis for the design of individualized strength training protocols.
authors: 1Department of Biomechanics, Kinesiology and Informatics, Faculty of Physical Education, and Sport Sciences, Semmelweis University, Budapest, Hungary; 2Department of Physical Education, Faculty of Pedagogy, Kaposvár University, Kaposvár, Hungary; 3Institute of Human Physiology and Clinical Experimental Research, Faculty of Medicine, Semmelweis University, Budapest, Hungary; and 4Center for Human Movement Sciences, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
authors: Dóra
authors: D
authors: Ureczky
authors: Gabriella
authors: G
authors: Vácz
authors: Andreas
authors: A
authors: Costa
authors: Bence
authors: B
authors: Kopper
authors: Zsombor
authors: Z
authors: Lacza
authors: Tibor
authors: T
authors: Hortobágyi
authors: József
authors: J
authors: Tihanyi
mesh_terms: D003402:Creatine Kinase / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005353:Fibronectins / Q000032:analysis; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000097:blood; D008297:Male; D009119:Muscle Contraction; D018656:Muscle Fibers, Fast-Twitch / Q000737:chemistry* / Q000502:physiology; D018657:Muscle Fibers, Slow-Twitch / Q000737:chemistry* / Q000502:physiology; D063806:Myalgia / Q000503:physiopathology; D052097:Quadriceps Muscle / Q000737:chemistry* / Q000473:pathology / Q000503:physiopathology*; D013997:Time Factors; D019415:Torque; D055815:Young Adult
chemical_list: D005353:Fibronectins; D007770:L-Lactate Dehydrogenase; D003402:Creatine Kinase