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Research Reports |
LL Andersen, PhD Stud, MSc, is Exercise Physiologist and Researcher, National Institute of Occupational Health, Lersø Parkalle 105, DK 2100 Copenhagen Ø, Denmark, and Institute of Sports Medicine Copenhagen, Bispebjerg Hospital, 2400 Copenhagen NV, Denmark
SP Magnusson, PT, DSc, is Associate Professor, Institute of Sports Medicine Copenhagen, Bispebjerg Hospital
M Nielsen, PT, is Physical Therapist, Institute of Sports Medicine Copenhagen, Bispebjerg Hospital, and School of Physiotherapy, University College South, Copenhagen, Denmark
J Haleem, PT, is Physical Therapist, Institute of Sports Medicine Copenhagen, Bispebjerg Hospital, and School of Physiotherapy, University College South
K Poulsen, PT, is Physical Therapist, Institute of Sports Medicine Copenhagen, Bispebjerg Hospital, and School of Physiotherapy, University College South
P Aagaard, PhD, is Professor and Researcher, Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
(ll_andersen{at}yahoo.dk). Address all correspondence to Dr Andersen
Background and Purpose. Central activation failure and muscular atrophy are common after knee joint injury. Thus, exercises that aim to stimulate muscular hypertrophy and increase neural drive to the muscle fibers should be used during rehabilitation. This study examined the level of knee joint neuromuscular activation during 4 conventional therapeutic exercises (quadriceps femoris muscle setting, manual lateralization of the patella, rhythmic stabilization, and the pelvic bridging exercise) and 4 heavy resistance exercises (free-weight squat with a barbell, horizontal seated leg press, isolated knee extension with a cam mechanism, and isolated hamstring muscle curl) in young, untrained men who were healthy.
Subjects. Thirteen male subjects (mean age=25.3 years, SD=3.0) with no previous history of knee injury participated in the study.
Methods. Neuromuscular activation during the exercises was defined as the root-mean-square (RMS) electromyographic (EMG) signal normalized to the peak RMS EMG signal of a maximal isometric muscle contraction.
Results. Low levels of neuromuscular activation were found during all conventional exercises (<35%). A limitation may be that only a few of many different conventional exercises were investigated. The highest level of neuromuscular activation (67%–79%) was observed during the open kinetic chain resistance exercises (isolated knee extension and hamstring muscle curl). None of the conventional exercises or heavy resistance exercises were found to preferentially activate the vastus medialis muscle over the vastus lateralis muscle.
Discussion and Conclusion. The results indicate that heavy resistance exercises should be included in rehabilitation programs to induce sufficient levels of neuromuscular activation to stimulate muscle growth and strength.
Key Words: Electromyography • Neuromuscular activation • Neural drive • Physical therapy • Rehabilitation • Resistance exercise • Strength • Training
This article has been cited by other articles:
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  L. L Andersen, M. Kjaer, C. H Andersen, P. B Hansen, M. K Zebis, K. Hansen, and G. Sjogaard Muscle Activation During Selected Strength Exercises in Women With Chronic Neck Muscle Pain Physical Therapy, June 1, 2008; 88(6): 703 - 711. [Abstract] [Full Text] [PDF]
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M.-H. Jan, J.-J. Lin, J.-J. Liau, Y.-F. Lin, and D.-H. Lin Investigation of Clinical Effects of High- and Low-Resistance Training for Patients With Knee Osteoarthritis: A Randomized Controlled Trial Physical Therapy, April 1, 2008; 88(4): 427 - 436. [Abstract] [Full Text] [PDF]
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