title: Blood oxygenation of masseter muscle during sustained elevated muscle activity in healthy participants.
abstract: Myofascial pain associated with temporomandibular disorders has often been linked to pathological muscle hyperactivity. As a result, localised disturbances of intramuscular blood flow could lead to a lower level of oxygen distribution, hypoxia and microcirculatory changes. To assess haemodynamic changes in the masseter muscle during sustained elevated muscle activity (SEMA). Sixteen healthy participants performed thirty 1-min bouts of SEMA with intervals of 1-min 'rest' periods between the bouts on a bite force transducer device. The participants completed three sessions with different percentage of their maximal voluntary occlusal bite force (MVOBF): 0% (no task), 10% or 40% MVOBF tasks. The order of the sessions was randomised with 1- to 2-week intervals. Haemodynamic characteristics of the masseter muscle were estimated with use of a laser blood oxygenation monitor. Tissue blood oxygen saturation (StO2) during SEMA was lower than during rest (P < 0·001). The relative changes in total haemoglobin (Total-Hb) and StO2were influenced by condition (SEMA and rest) and with interactions between condition and session (0%, 10% and 40% MVOBF tasks). These results suggest that SEMA may lead to hypoxia in the masseter muscle and that the haemodynamic characteristics and muscle symptoms depend on the magnitude of muscle contractions. Overall, the present findings may help to provide better insights into relationships between jaw muscle activity, haemodynamic changes and symptom developments with implications for clinical conditions such as bruxism characterised by different levels of tooth-grinding and tooth-clenching muscle activity.
authors.affiliation: Section of Orofacial Pain and Jaw Function, Department of Dentistry and Oral Health, Health, Aarhus University, Aarhus, Denmark.|Scandinavian Center for Orofacial Neuroscience (SCON), Aarhus, Denmark.|Scandinavian Center for Orofacial Neuroscience (SCON), Malmö, Stockholm, Sweden.|Division of Oral Diagnosis and Medicine, Department of Oral Pathobiological Science, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Suzuki
authors.affiliation: Section of Orofacial Pain and Jaw Function, Department of Dentistry and Oral Health, Health, Aarhus University, Aarhus, Denmark.|Scandinavian Center for Orofacial Neuroscience (SCON), Aarhus, Denmark.|Scandinavian Center for Orofacial Neuroscience (SCON), Malmö, Stockholm, Sweden.
authors.forename: E E
authors.initials: EE
authors.lastname: Castrillon
authors.affiliation: Division of International Affairs, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Arima
authors.affiliation: Division of Oral Diagnosis and Medicine, Department of Oral Pathobiological Science, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kitagawa
authors.affiliation: Section of Orofacial Pain and Jaw Function, Department of Dentistry and Oral Health, Health, Aarhus University, Aarhus, Denmark.|Scandinavian Center for Orofacial Neuroscience (SCON), Aarhus, Denmark.|Scandinavian Center for Orofacial Neuroscience (SCON), Malmö, Stockholm, Sweden.|Department of Dental Medicine, Karolinska Institute, Stockholm, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Svensson
mesh_terms: D000328:Adult; D001732:Bite Force; D002012:Bruxism / Q000503:physiopathology*; D004576:Electromyography; D005157:Facial Pain / Q000503:physiopathology*; D005260:Female; D064368:Healthy Volunteers; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008406:Masseter Muscle / Q000098:blood supply / Q000378:metabolism / Q000503:physiopathology*; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology; D015203:Reproducibility of Results; D055815:Young Adult
keywords: blood oxygenation; masseter muscle; maximal voluntary bite force; sustained elevated muscle activity