Neural inhibition during maximal eccentric and concentric quadriceps contraction: effects of resistance training

• Published in: Journal of applied physiology (1985) Vol. 89; no. 6; pp. 2249 - 2257
• Main Authors: Aagaard, P, Simonsen, E. B, Andersen, J. L, Magnusson, S. P, Halkjar-Kristensen, J, Dyhre-Poulsen, P
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.12.2000; American Physiological Society
• Subjects: Adult; Biological and medical sciences; Electromyography; Fundamental and applied biological sciences. Psychology; Humans; Leg; Male; Muscle Contraction - physiology; Muscle, Skeletal - physiology; Muscular system; Neural Inhibition - physiology; Neurology; Neuromuscular Junction - physiology; Physical Education and Training; Physical training; Striated muscle. Tendons; Time Factors; Vertebrates: osteoarticular system, musculoskeletal system; Weight Lifting - physiology; Weightlifting; Human; Vastus lateralis muscle; Physical training; Electrophysiology; Quadriceps muscle; Activation; Electromyography; Inhibition; Striated muscle; Neuromuscular transmission; Muscle contraction
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.2000.89.6.2249

1  Department of Neurophysiology, Institute of Medical Physiology, and 2  Anatomy Department C, Panum Institute, 3  Copenhagen Muscle Research Centre, 4  Department of Medical Orthopaedics 7111 Rigshospitalet, and 5  Team Danmark Testcentre, Sports Medicine Research Unit, Bispebjerg Hospital, University of Copenhagen, DK-2200 Copenhagen, Denmark Despite full voluntary effort, neuromuscular activation of the quadriceps femoris muscle appears inhibited during slow concentric and eccentric contractions. Our aim was to compare neuromuscular activation during maximal voluntary concentric and eccentric quadriceps contractions, hypothesizing that inhibition of neuromuscular activation diminishes with resistance training. In 15 men, pretraining electromyographic activity of the quadriceps muscles [vastus medialis (VM), vastus lateralis (VL), and rectus femoris (RF)] was 17-36% lower during slow and fast (30 and 240°/s) eccentric and slow concentric contractions compared with fast concentric contractions. After 14 wk of heavy resistance training, neuromuscular inhibition was reduced for VL and VM and was completely removed for RF. Concurrently, electromyographic activity increased 21-52, 22-29, and 16-32% for VL, VM, and RF, respectively. In addition, median power frequency decreased for VL and RF. Eccentric quadriceps strength increased 15-17%, whereas slow and fast concentric strength increased 15 and 8%, respectively. Pre- and posttraining median power frequency did not differ between eccentric and concentric contractions. In conclusion, quadriceps motoneuron activation was lower during maximal voluntary eccentric and slow concentric contractions compared with during fast concentric contraction in untrained subjects, and, after heavy resistance training, this inhibition in neuromuscular activation was reduced. neuromuscular activation; muscle strength; neural efferent drive; eccentric activation deficiency; force inhibition