Synergy Relationship Between The Scalene And The Rectus Abdominis During The Respiratory Cycle In Healthy Subjects

This study aims to reveal the electromyography and spirometry relationship of the respiratory cycle, and to establish the chronology of the contraction between the Scalene and the Rectus abdominis. Purpose: Expose the electromyography and spirometry relationship and establish the chronology of the contraction of Scalene and Rectus abdominis which works together in synergy antagonism in physiological breathing.In our study 128 electromyographic tests were performed during the respiratory cycle on 43 healthy adults. EMG signals of Scalene, Rectus abdominis were recorded. The breathing was recorded by using a spirometer (vernier®).The obtained results showed that the duration of the contraction of Scalene is superior to Rectus abdominis 82% p-value=0.000058, the amplitude of Scalene is superior to 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. The 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, the 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, the p-value is 0.0098. The muscle fatigue of the 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.As Conclusion, there is a synergistic-antagonism relationship between Scalene and Rectus abdominis during respiration. Scalene is a main inspiratory muscle, its contraction is important in amplitude, duration, and frequency. Both muscles are fatigable during the inspiratory cycle.