Acoustic and electrical activities during voluntary isometric contraction of biceps brachii muscles in patients with spastic cerebral palsy

Abstract

This study was designed to compare electromyogram (EMG) and acoustic myogram (AMG) recordings of biceps brachii muscles in patients with spastic cerebral palsy (CP). The maximal voluntary contraction (MVC) in the CP group was approximately one half of that of the normal group even after being normalized by the muscle cross‐sectional area (CSA) (18.6 ± 5.9 kNm/m2 in CP, 37.3 ± 2.9 kNm/m2 in normal). Both CP and normal groups demonstrated a progressive increase in the root mean squared values per unit muscle CSA in the EMG (RMSEMG/CSA) as well as in the AMG (RMSAMG/CSA) with increasing force up to 50% MVC. The increasing magnitude of the RMSEMG/CSA with force was not significantly different between two subject groups. However, all the levels of force resulted in significantly smaller RMSAMG/CSA in the CP group compared to the normal group. The ratios of RMSAMG to RMSEMG in the CP group (0.75 ± 0.03 m/s2/mV) were significantly smaller than those in the normal group (1.37 ± 0.07 m/s2/mV) at force levels above 30% MVC. These results suggest that motor disabilities in CP patients are caused not only by primary neural impairment but also by secondary deterioration in muscular contractile properties, probably resulting from muscle fiber atrophy. This appears to be more selective in fast twitch fibers. © 1996 John Wiley & Sons, Inc.

Cross-fuzzy entropy: A new method to test pattern synchrony of bivariate time series

“…The EMG signal is the electrical manifestation of the neuromuscular activation associated with muscle contraction [2,25] while the MMG signal records and quantifies the low-frequency lateral oscillations of active skeletal muscle, which reflects the ''mechanical counterpart" of the motor unit electrical activity as measured by EMG [20,24,36,37]. Simultaneous measurements of EMG and MMG have been used to examine muscle fatigue [34], age-related muscle performance [6], neuromuscular disease [3] and athletic training programs [7]. However, previous studies were mostly based on spectral or statistical methods, such as analysis of EMG and MMG mean frequency, median frequency, root mean square of time, correlation coefficient and cross-spectrum.…”

Influence of subcutaneous fat on mechanomyographic signals at three levels of voluntary effort

“…Isometric contraction was employed to measure the force (Neering et al, 1991;Akataki et al, 1996;Akataki et al, 2001;Alves and Chau, 2008;Krueger et al, 2013).…”

Mechanomyographic and electromyographic responses during fatigue in humans: influence of muscle length

“…In addition, it may be used to dierentiate among muscles containing dierent types of ®bers (Marchetti et al 1992;Mealing et al 1996; and healthy from diseased muscle (Akataki et al 1996; Barry et al 1990;Orizio et al 1997;Rhatigan et al 1986;Rodriquez et al 1996). Several studies have examined muscle fatigue responses in MMG signals (Barry et al 1985;Dalton et al 1992;Goldenberg et al 1991;Herzog et al 1994;Orizio et al 1989aRodriquez et al 1996;Stokes and Dalton 1991b;Zwarts and Keidel 1991) and these fatigue related changes in the MMG signal may also re¯ect changes in motor unit recruitment and ®ring rate (Goldenberg et al 1991).…”