Paper
EMG signal amplitude normalization technique in stretch-shortening cycle movements

https://doi.org/10.1016/1050-6411(93)90013-MGet rights and content

Abstract

Analysis of functional movements using surface electromyography (EMG) often involves recording both eccentric and concentric muscle activity during a stretch-shorten cycle (SSC). The techniques used for amplitude normalization are varied and are independent of the type of muscle activity involved. The purpose of this study was: (i) to determine the effect of 11 amplitude normalization techniques on the coefficient of variation (CV) during the eccentric and concentric phases of the SSC; and (ii) to establish the effect of the normalization techniques on the EMG signal under variable load and velocity. The EMG signal of the biceps brachii of eight normal subjects was recorded under four SSC conditions and three levels of isometric contraction. The 11 derived normalization values were total rms, mean rms and peak rms (100 ms time constant) for the isometric contractions and the mean rms and peak rms values of the ensemble values for each set of isotonic contractions. Normalization using maximal voluntary isometric contractions (MVIC), irrespective of rms processing (total, mean or peak), demonstrated greater CV above the raw data for both muscle actions. Mean ensemble values and submaximal isometric recordings reduced the CV of concentric data. No amplitude normalization technique reduced the CV for eccentric data under loaded conditions. An ANOVA demonstrated significant (P < 0.01) main effects for load and velocity on concentric raw data and an interaction (P < 0.05) for raw eccentric data. No significant effects were demonstrated for changes in velocity when the data were normalized using mean rms values. The reduction of the CV should not be at the expense of true biological variance and current normalization techniques poorly serve the analysis of eccentric muscle activity during the SSC.

References (17)

  • AB Arsenault et al.

    Characteristics of muscular function and adaptation in gait: a literature review

    Physiotherapy Canada

    (1987)
  • A Gollhofer et al.

    Fatigue during stretch-shortening cycle exercises: Changes in mechanical performance of human skeletal muscle

    Int J Sports Med

    (1987)
  • A Gollhofer et al.

    Fatigue during stretch-shortening cycle exercises. II. Changes in neuromuscular activation patterns of human skeletal muscle

    Int J Sports Med

    (1987)
  • PV Komi et al.

    EMG activity of the leg extensor muscle with special reference to mechanical efficiency in concentric and eccentric exercise

    Int J Sports Med

    (1987)
  • PV Komi

    Stretch-shortening cycle

  • MP Kadaba et al.

    Repeatability of kinematic kinetic, and electromyographic data in normal adult gait

    J Orthopaed Res

    (1989)
  • HIC Dubo et al.

    Electromyographic temporal analysis of gait: normal human locomotion

    Arch Phys Med Rehab

    (1976)
  • M Peat et al.

    Electromyographic temporal analysis of gait: Hemiplegic locomotion

    Arch Phys Med Rehab

    (1976)
There are more references available in the full text version of this article.

Cited by (0)

View full text