Expose the electromyography and spirometry relationship and the chronology of the contraction of Scalene and Rectus abdominis in physiological breathing and understand the physiology of respiratory muscles by analysis of EMG signals of inspiratory and expiratory muscles.
Methods: 128 electromyographic tests were performed during the respiratory cycle on 43 healthy adults. EMG signals of Scalene (inspiratory muscle), Rectus abdominis (forced expiratory muscle) were recorded by using LabView system. The breathing was recorded by using a spirometer (vernier®). the test of 15 seconds was repeated 3 times for each subject.
Results: The duration of the contraction of Scalene are superior to Rectus abdominis 82% p-value = 0.000058, the amplitude of Scalene is superior of Rectus abdominis, p-value = 0.000000073. 109 tests of Scalene contraction begin before that of Rectus abdominis (63.74%), p-value = 0.000012. RMS is 0.02 ± 0.011 μv for Rectus abdominis and 0.04 ± 0.021 μv for Scalene, p-value = 6.76591E-06. Duration of inspiration is 1.25 s ± 0.19, the expiration is 1.04 s ± 0.19. The mean frequency of Rectus abdominis is 54.19 Hz ± 6.35, it is 57.21 Hz ± 7.08 for Scalene, p-value is 9.84081E-08. The median frequency of Rectus abdominis is 51.05 Hz ± 6.51, it is 52.72 Hz ± 6.94 for Scalene, p-value is 0.0098. The muscle fatigue of Rectus abdominis decreased from 60.40 ± 0.45 to 19.98 ± 4.32. For Scalene it decreased from 60.41 ± 0.4 to 23.52 ± 4.41.
There is a synergistic - antagonism relationship between the Scalene (inspiratory muscle) and Rectus abdominis (forced expiratory muscle) during respiration. Scalene is a main inspiratory muscle, its contraction is important in amplitude, duration and frequency. the Rectus abdominis participate to the inspiration phases and it's contraction is less important in duration, amplitude and frequency. Both muscles are fatigable during the inspiratory cycle.