Academic Journal
Effects of postural instability on diaphragm and sternocleidomastoid recruitment during a loaded-inspiratory task in healthy adults.
| Title: | Effects of postural instability on diaphragm and sternocleidomastoid recruitment during a loaded-inspiratory task in healthy adults. |
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| Authors: | Liu F; Department of Physiotherapy, School of Nursing and Health Sciences, Hong Kong Metropolitan University, Hong Kong, China; Department of Rehabilitation, Shenzhen Second People's Hospital, The First Affiliated Hospital of Shenzhen University, Health Science Centre, Shenzhen, China., On MY; Department of Physiotherapy, School of Nursing and Health Sciences, Hong Kong Metropolitan University, Hong Kong, China., Tang CK; Department of Physiotherapy, School of Nursing and Health Sciences, Hong Kong Metropolitan University, Hong Kong, China., Tung LI; Department of Physiotherapy, School of Nursing and Health Sciences, Hong Kong Metropolitan University, Hong Kong, China., Hin CC; Department of Physiotherapy, School of Nursing and Health Sciences, Hong Kong Metropolitan University, Hong Kong, China., Jones AYM; School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Australia., Tsang WWN; Department of Physiotherapy, School of Nursing and Health Sciences, Hong Kong Metropolitan University, Hong Kong, China. Electronic address: wntsang@hkmu.edu.hk. |
| Source: | Respiratory physiology & neurobiology [Respir Physiol Neurobiol] 2026 Apr; Vol. 341, pp. 104541. Date of Electronic Publication: 2025 Dec 29. |
| Publication Type: | Journal Article; Research Support, Non-U.S. Gov't |
| Language: | English |
| Journal Info: | Publisher: Elsevier Science Country of Publication: Netherlands NLM ID: 101140022 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1878-1519 (Electronic) Linking ISSN: 15699048 NLM ISO Abbreviation: Respir Physiol Neurobiol Subsets: MEDLINE |
| Imprint Name(s): | Original Publication: Amsterdam ; New York : Elsevier Science, c2002- |
| MeSH Terms: | Postural Balance*/physiology , Diaphragm*/physiology , Diaphragm*/diagnostic imaging , Recruitment, Neurophysiological*/physiology , Inhalation*/physiology , Neck Muscles*/physiology , Neck Muscles*/diagnostic imaging , Respiratory Muscles*/physiology, Humans ; Male ; Female ; Young Adult ; Adult ; Electromyography ; Ultrasonography ; Breathing Exercises ; Healthy Volunteers |
| Abstract: | Background: Inspiratory muscle training (IMT) is commonly used to improve inspiratory muscle strength. However, the relationship between postural stability and recruitment of inspiratory muscles during IMT remains unclear. Objective: To investigate the effect of concurrent seated postural instability and loaded inspiratory breathing on diaphragmatic and sternocleidomastoid (SCM) muscle recruitment activities in healthy adults. Methods: Healthy young adults performed 10 breaths with inspiratory load at 50 % Maximal Inspiratory Pressure (MIP) under four seating conditions in random order: (A) sitting on a stable surface; (B) on a balance pad with both feet on ground; (C) on a balance pad with each foot on separate balance pads; and (D) on a balance pad with both feet on a single balance pad. Right SCM and right hemidiaphragm muscle activity were recorded simultaneously using surface electromyography (sEMG) and ultrasonography, respectively. Self-perceived exertion was recorded after each task. Results: Forty-eight healthy young adults participated in this study. Diaphragmatic contraction, as reflected by the diaphragm thickening fraction (DTf), and SCM muscle activity both increased progressively with greater seated postural instability (from position A to D). Significant incremental increases in recruitment of diaphragm and SCM were observed across all positions, and the largest and statistically significant changes were found between position A and position D, with DTf increased by 40 % (P < 0.001, 95 % CI: 31-49 %) and SCM activity by 17 % (P < 0.001, 95 % CI: 14-20 %). No significant differences in self-perceived exertion levels were observed among the seated conditions. Conclusion: Postural instability during loaded inspiration significantly enhanced diaphragmatic contraction and moderately increased SCM activity in healthy adults. Incorporating postural challenges in IMT protocols may further enhance diaphragmatic training and warrants further study. (Copyright © 2025 The Authors. Published by Elsevier B.V. All rights reserved.) |
| Competing Interests: | Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. |
| Contributed Indexing: | Keywords: Diaphragm; Healthy adults; Inspiratory muscle training; Postural instability; Sternocleidomastoid muscle |
| Entry Date(s): | Date Created: 20251231 Date Completed: 20260219 Latest Revision: 20260324 |
| Update Code: | 20260324 |
| DOI: | 10.1016/j.resp.2025.104541 |
| PMID: | 41475503 |
| Database: | MEDLINE |
| ISSN: | 1878-1519 |
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| DOI: | 10.1016/j.resp.2025.104541 |