Changes in the human muscle force-velocity relationship in response to resistance training and subsequent detraining

• Published in: Journal of applied physiology (1985) Vol. 99; no. 1; pp. 87 - 94
• Main Authors: Andersen, Lars L, Andersen, Jesper L, Magnusson, S. Peter, Suetta, Charlotte, Madsen, Jorgen L, Christensen, Lasse R, Aagaard, Per
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.07.2005; American Physiological Society
• Subjects: Adaptation, Physiological - physiology; Adult; Biological and medical sciences; Exercise; Exercise - physiology; Fundamental and applied biological sciences. Psychology; Human subjects; Humans; Knee Joint - physiology; Male; Movement - physiology; Muscle Contraction - physiology; Muscle, Skeletal - anatomy & histology; Muscle, Skeletal - physiology; Muscles; Muscular system; Myosin Heavy Chains - metabolism; Physical Exertion - physiology; Physical Fitness - physiology; Physical training; Stress, Mechanical; Human; myosin heavy chain; Vertebrata; Heavy peptide chain; Physical training; Mammalia; twitch; Force; Myosin; Striated muscle; Velocity
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00091.2005

1 Institute of Sports Medicine Copenhagen/Team Danmark Testcenter, Bispebjerg Hospital, and 2 Copenhagen Muscle Research Center, Rigshospitalet, Copenhagen, Denmark Submitted 26 January 2005 ; accepted in final form 22 February 2005 Previous studies show that cessation of resistance training, commonly known as "detraining," is associated with strength loss, decreased neural drive, and muscular atrophy. Detraining may also increase the expression of fast muscle myosin heavy chain (MHC) isoforms. The present study examined the effect of detraining subsequent to resistance training on contractile performance during slow-to-medium velocity isokinetic muscle contraction vs. performance of maximal velocity "unloaded" limb movement (i.e., no external loading of the limb). Maximal knee extensor strength was measured in an isokinetic dynamometer at 30 and 240°/s, and performance of maximal velocity limb movement was measured with a goniometer during maximal unloaded knee extension. Muscle cross-sectional area was determined with MRI. Electromyographic signals were measured in the quadriceps and hamstring muscles. Twitch contractions were evoked in the passive vastus lateralis muscle. MHC isoform composition was determined with SDS-PAGE. Isokinetic muscle strength increased 18% ( P < 0.01) and 10% ( P < 0.05) at slow and medium velocities, respectively, along with gains in muscle cross-sectional area and increased electromyogram in response to 3 mo of resistance training. After 3 mo of detraining these gains were lost, whereas in contrast maximal unloaded knee extension velocity and power increased 14% ( P < 0.05) and 44% ( P < 0.05), respectively. Additionally, faster muscle twitch contractile properties along with an increased and decreased amount of MHC type II and MHC type I isoforms, respectively, were observed. In conclusion, detraining subsequent to resistance training increases maximal unloaded movement speed and power in previously untrained subjects. A phenotypic shift toward faster muscle MHC isoforms (I IIA IIX) and faster electrically evoked muscle contractile properties in response to detraining may explain the present results. myosin heavy chain; twitch Address for reprint requests and other correspondence: L. L. Andersen, Institute of Sports Medicine Copenhagen/Team Danmark Testcenter, Bispebjerg Hospital, Build. 8, 2nd floor, DK-2400 Copenhagen (E-mail: ll_andersen{at}yahoo.dk )