THE INFLUENCE OF THE TRUNK MUSCLE ACTIVATION ON OCCLUSION PRESSURE AND RESPIRATORY MUSCLE STRENGTH IN HEALTHY PARTICIPATIONS: RANDOMISED CONTROLLED TRIAL

W. Rosa¹, A. Śliwka¹, R. Piliński¹, R. Nowobilski¹

Background: The dual function of the diaphragm has been confirmed by studies indicating is postural and ventilatory function. The stabilizing function of the diaphragm has been investigated by many authors. A correlation between the activity of the diaphragm and the mechanical stabilization of the trunk, at the same time as the diaphragm performs its ventilation function, has also been demonstrated. Ultrasound is the most frequently used method of examination to assess the inspiratory and expiratory position of the diaphragm and its thickness. Another way to assess the efficiency of the diaphragm is to measure the respiratory drive.  
The research questions were:

1. Does the trunk muscle activation affect the occlusion pressure (P0.1)?
2. Does the trunk muscle activation affect the respiratory muscle strength (PImax, PEmax, P0.1max)?

Purpose: The aim of this study was to evaluate the influence of trunk stability muscle activation and the correction of trunk alignment on variables of respiratory drive including: occlusion pressure (P0.1), maximum occlusion pressure (P0.1max), maximum inspiratory (PImax) and expiratory pressures (PEmax).

Methods: Design: Randomised controlled-trial. Between-subjects design.
Participants: Seventy-four healthy volunteers, aged 20-26 years, were recruited from medical students, randomly assigned to an experimental or a control group.
Intervention: The intervention in the experimental group was based on the Bobath concept. The control group participated in a lecture on the importance of trunk muscle stability and an adequate diaphragm position for its respiratory work
Outcome measures: The subjects underwent two assessments of the following variables of occlusion pressure: P0.1 and of the respiratory muscle strength: maximal inspiratory pressure (PImax), maximal expiratory pressure (PEmax), maximal occlusion pressure (P0.1max) with the use of MasterScope Spirometer. In experimental group, the physiotherapy assessment was carried out before intervention.

Results: As a result of the applied intervention, P0.1 in the experimental group increased (p = 0.001; 82,45 vs 103.73).  This was not observed in the control group (88,95 vs 85.83). The intervention did not change the results of all other outcomes including P0.1 max; PImax and PE max.

Conclusion(s): The activation of trunk muscles such as transversus abdominis, multifidius and muscles of the pelvic floor was found to improve the effectiveness of diaphragmatic work during tidal breathing as measured with P0.1 values. Established abdominal pressure, which stabilizes the trunk and prevents chest mobility might be the reason why forced measurements (PImax, PEmax, P.01 max) remain unchanged.

Implications: The results of this study may be the beginning of further experiments including assessing the influence of central stabilization muscle activation on patients with respiratory system diseases, neurological disorders or postural control disorders resulting from pain or diseases of the musculoskeletal system.

Funding, acknowledgements: Funding Acknowledgements from the Jagiellonian University Medical College

Keywords: diaphragm, respiratory drive, respiratory muscle strength

Topic: Cardiorespiratory

Did this work require ethics approval? Yes

Institution: The Jagiellonian University

Committee: The Jagiellonian University's Bioethical Committee

Ethics number: 1072.6120.19.2019