Abstract
The present study investigated the applicability of magnetic stimulation (MS) for estimating activation capacity. Ten men performed isometric knee extensions at 95% of maximum voluntary contraction level on two testing sessions. MS and electrical stimulation (ES) were applied by placing the coil and stimulating electrodes, respectively, on the quadriceps muscle group. In session 1, MS and ES were applied to allow a comparison between the two stimulating devices. During session 2, MS was applied again to assess the reproducibility of MS measurements. Activation level was estimated with the interpolated twitch technique (ITT) and the central activation ratio (CAR). Activation level determined with MS was highly repeatable, but was only comparable to ES when using ITT (standard error < 1.45%, mean difference < 0.63%, for all). MS with CAR overestimated activation by 3% compared to ES (standard error = 1.13%, mean difference = 2.76%) because the power of the magnetic field was limited. These results indicate that MS is a promising tool for reliable and valid quantification of activation levels when using the ITT approach and potentially suitable for studies involving children or other subjects where the pain of conventional ES is a problem.
Similar content being viewed by others
References
Babault N, Desbrosses K, Fabre MS, Michaut A, Pousson M (2006) Neuromuscular fatigue development during maximal concentric and isometric knee extensions. J Appl Physiol 100:780–785. doi:10.1152/japplphysiol.00737.2005
Bampouras TM, Reeves ND, Baltzopoulos V, Maganaris CN (2006) Muscle activation assessment: effects of method, stimulus number, and joint angle. Muscle Nerve 34:740–746. doi:10.1002/mus.20610
Barker AT, Freeston IL, Jalinous R, Jarratt JA (1987) Magnetic stimulation of the human brain and peripheral nervous system: an introduction and the results of an initial clinical evaluation. Neurosurgery 20:100–109. doi:10.1097/00006123-198701000-00024
Behm D, Power K, Drinkwater E (2001) Comparison of interpolation and central activation ratios as measures of muscle inactivation. Muscle Nerve 24(7):925–934. doi:10.1002/mus.1090
Behm DG, Whittle J, Button D, Power K (2002) Intermuscle differences in activation. Muscle Nerve 25(2):236–243. doi:10.1002/mus.10008
Bland M, Altman D (1986) Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1:307–310
Harridge SD, Kryger A, Stensgaard A (1999) Knee extensor strength, activation, and size in very elderly people following strength training. Muscle Nerve 22:831–839. doi:10.1002/(SICI)1097-4598(199907)22:7<831::AID-MUS4>3.0.CO;2-3
Harris ML, Polkey MI, Bath PM, Moxham J (2001) Quadriceps muscle weakness following acute hemiplegic stroke. Clin Rehabil 15(3):274–281. doi:10.1191/026921501669958740
Kremenic IJ, Ben-Avi SS, Leonhardt D, McHugh MP (2004) Transcutaneous magnetic stimulation of the quadriceps via the femoral nerve. Muscle Nerve 30:379–381. doi:10.1002/mus.20091
Newman SA, Jones G, Newham DJ (2003) Quadriceps voluntary activation at different joint angles measured by two stimulation techniques. Eur J Appl Physiol 89:496–499. doi:10.1007/s00421-003-0836-0
Onambele GL, Narici MV, Constantinos CN, Maganaris N (2006) Calf muscle-tendon properties and postural balance in old age. J Appl Physiol 100:2048–2056. doi:10.1152/japplphysiol.01442.2005
Pap G, Machner A, Awiszus F (2004) Strength and voluntary activation of the quadriceps femoris muscle at different severities of osteoarthritic knee joint damage. J Orthop Res 22:96–103. doi:10.1016/S0736-0266(03)00128-1
Polkey MI, Kyroussis D, Hamnegard CH, Mills GH, Green M, Moxham J (1996) Quadriceps strength and fatigue assessed by magnetic stimulation of the femoral nerve in man. Muscle Nerve 19:549–555. doi:10.1002/(SICI)1097-4598(199605)19:5<549::AID-MUS1>3.0.CO;2-B
Reeves ND, Narici MV, Maganaris CN (2004) In vivo human muscle structure and function: adaptations to resistance training in old age. Exp Physiol 89(6):675–689. doi:10.1113/expphysiol.2004.027797
Rutherford OM, Jones DA, Newham DJ (1986) Clinical and experimental application of the percutaneous twitch superimposition technique for the study of human muscle activation. J Neurol Neurosurg Psychiatry 49:1288–1291
Scaglioni G, Ferri A, Minetti AE, Martin A, Van Hoecke J, Capodaglio P et al (2002) Plantar flexor activation capacity and H reflex in older adults: adaptations to strength training. J Appl Physiol 92:2292–2302
Similowski T, Duguet A, Straus C, Attali V, Boisteanu D, Derenne JP (1996) Assessment of the voluntary activation of the diaphragm using cervical and cortical magnetic stimulation. Eur Respir J 9(6):1224–1231. doi:10.1183/09031936.96.09061224
Suter E, Herzog W, Bray RC (1998) Quadriceps inhibition following arthroscopy in patients with anterior knee pain. Clin Biomech (Bristol, Avon) 13:314–319. doi:10.1016/S0268-0033(98)00098-9
Todd G, Taylor JL, Gandevia SC (2003) Measurement of voluntary activation of fresh and fatigued human muscles using transcranial magnetic stimulation. J Physiol 551:661–671. doi:10.1113/jphysiol.2003.044099
Todd G, Taylor JL, Gandevia SC (2004) Reproducible measurement of voluntary activation of human elbow flexors with motor cortical stimulation. J Appl Physiol 97:236–242. doi:10.1152/japplphysiol.01336.2003
Zipp P (1982) Recommendations for the standardization of lead positions in surface electromyography. Eur J Appl Physiol Occup Physiol 50:41–54. doi:10.1007/BF00952243
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
O’Brien, T.D., Reeves, N.D., Baltzopoulos, V. et al. Assessment of voluntary muscle activation using magnetic stimulation. Eur J Appl Physiol 104, 49–55 (2008). https://doi.org/10.1007/s00421-008-0782-y
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00421-008-0782-y