Int J Sports Med 2005; 26(1/02): 66-70
DOI: 10.1055/s-2004-817856
Training & Testing

© Georg Thieme Verlag KG Stuttgart · New York

Effects of Rate of Force Development on EMG Amplitude and Frequency

M. D. Ricard1 , C. Ugrinowitsch2 , 3 , A. C. Parcell2 , S. Hilton4 , M. D. Rubley5 , R. Sawyer2 , C. R. Poole2
  • 1Biomechanics Laboratory, Western Michigan University, Kalamazoo, MI, USA
  • 2Human Performance Research Center, Brigham Young University, Provo, UT, USA
  • 3Universidade de Sao Paulo, Coordenadoria de Aperfeicoamento de Pessoal de Ensino Superior (Capes), Brazil
  • 4Department of Statistics, Brigham Young University, Provo, UT, USA
  • 5Kinesiology Department, University of Nevada Las Vegas, Las Vegas, NV, USA
Further Information

Publication History

Accepted after revision: January 15, 2004

Publication Date:
30 July 2004 (online)

Abstract

The purpose of this study was to compare the amplitude and frequency of the gastrocnemius EMG during ramp and ballistic contractions in highly trained sprint athletes. Sixteen female sprinters performed ramp and ballistic isometric contractions on a Biodex dynamometer. RMS and median frequency of the gastrocnemius EMG signals were obtained at the following torque levels: 25 ± 5 %, 50 ± 5 %, 75 ± 5 %, 100 % MVC. The average rate of force development (RFD), was 610.2 ± 123.1 N · m/s and 212.3 ± 155.6 N · m/s for the ballistic and ramp contractions, respectively. In the ramp contractions the EMG amplitude increased as a function of torque. In the ballistic contractions the EMG amplitude decreased from 25 % to 100 % MVC. The highest RFD of 889.45 N · m/s was generated in ballistic contractions by a muscular activation pattern with high EMG amplitude (475.7 μV) and low frequency (116.7 Hz) at 25 % MVC. The findings suggest that the CNS utilizes different muscular activation patterns to modulate RFD in ramp and ballistic contractions. In ramp contractions the EMG amplitude increased linearly with force. In ballistic contractions a high RFD is generated with a muscular activation pattern consisting of high amplitude and low frequency at the start of the contraction.

References

  • 1 Bigland-Ritchie B, Johansson R, Lippold O C, Smith S, Woods J J. Changes in motoneurone firing rates during sustained maximal voluntary contractions.  J Physiol. 1983;  340 335-346
  • 2 Bilodeau M, Arsenault A B, Gravel D, Bourbonnais D. EMG power spectra of elbow extensors during ramp and step isometric contractions.  Eur J Appl Physiol Occup Physiol. 1991;  63 24-28
  • 3 Bilodeau M, Cincera M, Arsenault A B, Gravel D. Normality and stationarity of EMG signals of elbow flexor muscles during ramp and step isometric contractions.  J Electromyogr Kinesiol. 1997;  7 87-96
  • 4 Bilodeau M, Goulet C, Nadeau S, Arsenault A B, Gravel D. Comparison of the EMG power spectrum of the human soleus and gastrocnemius muscles.  Eur J Appl Physiol Occup Physiol. 1994;  68 395-401
  • 5 Broman H, Bilotto G, De Luca C J. Myoelectric signal conduction velocity and spectral parameters: influence of force and time.  J Appl Physiol. 1985;  58 1428-1437
  • 6 Celichowski J. Mechanisms underlying the regulation of motor unit contraction in the skeletal muscle.  J Physiol Pharmacol. 2000;  51 17-33
  • 7 Clamann H P, Schelhorn T B. Nonlinear force addition of newly recruited motor units in the cat hindlimb.  Muscle Nerve. 1988;  11 1079-1089
  • 8 Daniels M J, Zhao Y D. Modelling the random effects covariance matrix in longitudinal data.  Stat Med. 2003;  22 1631-1647
  • 9 De Luca C J, Foley P J, Erim Z. Motor unit control properties in constant-force isometric contractions.  J Neurophysiol. 1996;  76 1503-1516
  • 10 Henneman E, Somjen G, Carpenter D O. Functional significance of cell size in spinal motoneurons.  J Neurophysiol. 1965;  28 560-580
  • 11 Hermens H J, Bruggen v T AM. Baten CTM, Rutten WLC, Boom HBK. The median frequency of the surface EMG power spectrum in relation to motor unit firing and action potential properties.  J Electromyogr Kinesiol. 1992;  2 15-25
  • 12 Kleine B U, Stegeman D F, Mund D, Anders C. Influence of motoneuron firing synchronization on SEMG characteristics in dependence of electrode position.  J Appl Physiol. 2001;  91 1588-1599
  • 13 Krogh-Lund C, Jorgensen K. Modification of myo-electric power spectrum in fatigue from 15 % maximal voluntary contraction of human elbow flexor muscles, to limit of endurance: reflection of conduction velocity variation and/or centrally mediated mechanisms?.  Eur J Appl Physiol Occup Physiol. 1992;  64 359-370
  • 14 Littell R C, Pendergast J, Natarajan R. Modelling covariance structure in the analysis of repeated measures data.  Stat Med. 2000;  19 1793-1819
  • 15 MacIsaac D, Parker P A, Scott R N. The short-time Fourier transform and muscle fatigue assessment in dynamic contractions.  J Electromyogr Kinesiol. 2001;  11 439-449
  • 16 Milner-Brown H S, Stein R B, Lee R G. Synchronization of human motor units: possible roles of exercise and supraspinal reflexes.  Electroencephalogr Clin Neurophysiol. 1975;  38 245-254
  • 17 Monti R J, Roy R R, Edgerton V R. Role of motor unit structure in defining function.  Muscle Nerve. 2001;  24 848-866
  • 18 Moritani T, Muro M. Motor unit activity and surface electromyogram power spectrum during increasing force of contraction.  Eur J Appl Physiol. 1987;  56 260-265
  • 19 Moritani T, Muro M, Ishida K, Taguchi S. Electromyographic analyses of the effects of muscle power training.  J Sports Med Sci (Japan). 1987;  1 23-32
  • 20 Mortiani T, Yoshitake Y. The use of electromyography in applied physiology.  J Electromyogr Kinesiol. 1998;  8 361-381
  • 21 Muro M, Nagata A, Moritani T. Analysis of myoelectric signals during dynamic and isometric contractions. Matsui H, Kobayashi K Biomechanics VIII-A. Champaign; Human Kinetics 1983: 423-439
  • 22 Nordstrom M A, Fuglevand A J, Enoka R M. Estimating the strength of common input to human motoneurons from the cross-correlogram.  J Physiol. 1992;  453 547-574
  • 23 Park T, Park J K, Davis C S. Effects of covariance model assumptions on hypothesis tests for repeated measurements: analysis of ovarian hormone data and pituitary-pteryomaxillary distance data.  Stat Med. 2001;  20 2441-2453
  • 24 Powers R K, Binder M D. Summation of motor unit tensions in the tibialis posterior muscle of the cat under isometric and nonisometric conditions.  J Neurophysiol. 1991;  66 1838-1846
  • 25 Semmler J G. Motor unit synchronization and neuromuscular performance.  Exer Sport Sci Rev. 2002;  30 8-14
  • 26 Semmler J G, Nordstrom M A. Motor unit discharge and force tremor in skill- and strength-trained individuals.  Exp Brain Res. 1998;  119 27-38
  • 27 Thomas C K, Johansson R S, Bigland-Ritchie B. Pattern of pulses that maximize force output from single human thenar motor units.  J Neurophysiol. 1999;  82 3188-3195
  • 28 Van Cutsem M, Duchateau J, Hainaut K. Changes in single motor unit behaviour contribute to the increase in contraction speed after dynamic training in humans.  J Physiol. 1998;  513 295-305
  • 29 Yao W, Fuglevand R J, Enoka R M. Motor-unit synchronization increases EMG amplitude and decreases force steadiness of simulated contractions.  J Neurophysiol. 2000;  83 441-452

M. D. Ricard

Biomechanics Laboratory 1060 SRC · Western Michigan University

1903 West Michigan Avenue

Kalamazoo, MI 49008

USA

Phone: + 2693872546

Fax: + 26 93 87 27 04

Email: Mark.Ricard@wmich.edu

    >