• Mikhail J
• Funabashi M
• Descarreaux M
• Pagé I

• Affiliation / Canadian Memorial Chiropractic College (CMCC). Division of Research and Innovation
• Affiliation / Center for Interdisciplinary Research in Rehabilitation and Social Integration (CIRRIS)
• Affiliation / Université du Québec à Trois-Rivières (UQTR). Département de chiropratique
• Affiliation / Université du Québec à Trois-Rivières (UQTR). Département des sciences de l'activités physique
• Affiliation(G) / Canada / Ontario / Toronto
• Affiliation(G) / Canada / Quebec / Quebec
• Affiliation(G) / Canada / Quebec / Trois-Rivières
• Chiropractic / methods
• Kinetics
• Manipulation, Spinal
• Mobilization / methods
• Open Access Document
• Osteoarthritis, Spine

Background: Spinal manipulative therapy (SMT) and mobilization (MOB) effects are believed to be related to their force characteristics. Most previous studies have either measured the force at the patient-table interface or at the clinician-patient interface. The objectives of this study were to determine 1) the difference between the force measured at the patient-table interface and the force applied at the clinician-patient interface during thoracic SMT and MOB, and 2) the influence of the SMT/MOB characteristics, participants’ anthropometry and muscle activity (sEMG) on this difference.

Methods: An apparatus using a servo-linear motor executed 8 SMT/MOB at the T7 vertebrae in 34 healthy adults between May and June 2019. SMT and MOB were characterized by a 20 N preload, total peak forces of 100 N or 200 N, and thrust durations of 100 ms, 250 ms, 1 s or 2 s. During each trial, thoracic sEMG, apparatus displacement as well as forces at the patient-table interface and the clinician-patient interface were recorded. The difference between the force at both interfaces was calculated. The effect of SMT/MOB characteristics on the difference between forces at both interfaces and correlations between this difference and potential influencing factors were evaluated.

Results: Force magnitudes at the patient-table interface were, in most trials, greater than the force at the clinician-patient interface (up to 135 N). SMT/MOB characteristics (total peak force, thrust duration and rate of force application) affected the difference between forces at both interfaces (all p-values< 0.05). No factor showed significant correlations with the difference between forces at both interfaces for the 8 SMT/MOB.

Conclusions: The results revealed that the force measured at the patient-table interface is greater than the applied force at the clinician-patient interface during thoracic SMT and MOB. By which mechanism the force is amplified is not yet fully understood.

Author keywords: Force — Kinetics —  Spinal manipulative therapy —  Thoracic spine

Author affiliations: JM, MF, IP: Department of Chiropractic, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada; MF: Division of Research and Innovation, Canadian Memorial Chiropractic College, Toronto, Ontario, Canada; MD: Department of Human Kinetics, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada; IP: Center for Interdisciplinary Research in Rehabilitation and Social Integration (CIRRIS), Québec, Québec, Canada 

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