A new technique for simultaneously recording EMG and movements in experimental animals

In this protocol a new system is presented fur recording EMG signals from leg and trunk muscles along with video-recording of leg and trunk movements. The system comprises a front-end amplifier consisting of a reference amplifier, a differential amplifier with a filter combination and an analog to digital converter (ADC). A fiber optic transmitter connects the front end amplifier via a fiber cable to a receiver board placed in a personal computer (PC). A dedicated software programme (POLY) was written to process the physiological signals on the PC. The physiological recordings can be synchronized to video-recordings and the principles of this technique are given. The system allows to record artifact-free physiological signals and also to link activation patterns in muscles with kinematic aspects of movements. (C) 2001 Elsevier Science B.V. All rights reserved

Different breathing patterns in healthy and asthmatic children:Responses to an arithmetic task

Asthma patients have been reported to be sensitive to breathlessness, independent of the degree of airway obstruction. Paying attention and task performance may induce changes in breathing pattern and these in turn may mediate such a feeling. The present experiment investigates whether strained breathing induced by an arithmetic task was different in children with asthma compared to healthy children. Methods: Seven healthy and eight asthmatic but symptom-free school children were equipped with electrodes for surface electromyographic (EMG) measurements of diaphragm, abdominal and intercostal (IC) muscles and with a strain gauge to monitor the pattern of breathing at rest and during an arithmetic task. The relative duration of exhalation and the relative speed of exhalation are used as measures of straining. The phase angle of maximal. respiratory muscle activities relative to the maximal. chest extension (MCE) are additional discriminating parameters. Results: Asthmatic children breathed more slowly and already at rest the phase of their respiratory muscle activity appears to be different. While in healthy children the maximal activity of the (left)abdominal muscles occurred 5 +/- 29% later than the MCE, in children with asthma the maximal. activity occurred 26 +/- 30% of the cycle earlier than MCE. In children with asthma the activity of the IC muscles starts weaning already at 10 +/- 30% before MCE, in contrast to the healthy children in which intercostal muscle weaning starts only at 1 +/- 24% after MCE. During arithmetic, the significant difference between the groups in this respect disappeared. Conclusion: Children with asthma show, even at rest, signs of respiratory muscle straining, probably in order to keep close control over the airflow in a similar way as healthy children during mental tasks. Such a 'careful' breathing pattern may work to prevent airway irritation also when they are free of symptoms. (c) 2005 Published by Elsevier Ltd