Objectives: Premature infants in the neonatal intensive care unit (NICU) are exposed to environmental risks that may cause developmental problems i. The present study aimed to investigate the predictive effect of individual and environmental factors on the motor performance of low birth weight preterm infants. Methods: This cross-sectional study was performed in the neonatal clinic of Shahid A...

It has long been known that humans have decreased strength and muscle mass with age, but the mechanisms behind this are still not completely understood. In his review, Degens [1] discusses some potential reasons for this loss in strength with age, concluding that the hypertrophy capability of a muscle fiber does not change as one gets older, but rather that there are fewer muscle fibers. The pr...

Medial gastrocnemius surface electromyographic activity and intramuscular electromyographic activity were recorded from six individuals with chronic cervical spinal cord injury to document the recruitment order of motor units during clonus. Four subjects induced clonus that lasted up to 30 s while two subjects induced clonus that they actively stopped after 1 min. Mean clonus frequency in diffe...

During isometric contractions, the fluctuation of the force output of muscles increases as the muscle fatigues, and the contraction is sustained to exhaustion. We analyzed motor unit firing data from the vastus lateralis muscle to investigate which motor unit control parameters were associated with the increased force fluctuation. Subjects performed a sequence of isometric constant-force contra...

1. Synchronization of concurrently active motor-unit firings was studied in six human muscles performing isometric constant-force contractions at 30% of the maximal level. The myoelectric signal was detected with a quadrifilar needle electrode and was decomposed into its constituent motor-unit action-potential trains with the Precision Decomposition technique, whose accuracy has been proven pre...

Cold ambient temperature conditions are known to affect muscle performance characteristics, such as force output, power, and contraction velocity [ 11. Spectral and aniplitude characteristics of electromyogram (EMG) during inuscle contraction are modulated by the cold and hot ambient temperature [2]. Voluntary control of single motor unit action potentials (MUM') is a widely used method for inv...

The macro electromyography method was developed in the 1980s. Since then, technical modifications have been made, and a number of conditions have been explored. This study is a methodological introduction and an update of findings in some nerve–muscle disorders. The spike component of a motor unit potential (MUP) recorded by a concentric or monopolar needle electromyography (EMG) electrode is g...