This study provides preliminary evidence that autonomic function is dysregulated following mTBI within the initial 72 hours of injury.

Finding sensitive and specific markers for sports-related concussion is both challenging and clinically important. Such biomarkers might be helpful in the management of patients with concussion (i.e. diagnosis, monitoring and risk prediction). Among many parameters, blood flow-pressure metrics and heart rate variability (HRV) have been used to gauge concussion outcomes. Reports on the relation between HRV and both acute and prolonged concussion recovery are conflicting. While some authors report on differences in the low-frequency (LF) component of HRV during postural manipulations and postexercise conditions, others observe no significant differences in various HRV measures. Despite the early success of using the HRV LF for concussion recovery, the interpretation of the LF is debated. Recent research suggests the LF power is a net effect of several intrinsic modulatory factors from both sympathetic and parasympathetic branches of the autonomic nervous system, vagally mediated baroreflex and even some respiratory influences at lower respiratory rate. There are only a few well-controlled concussion studies that specifically examine the contribution of the autonomic nervous system branches with HRV for concussion management. This study reviews the most recent HRV- concussion literature and the underlying HRV physiology. It also highlights cerebral blood flow studies related to concussion and the importance of multimodal assessment of various biological signals. It is hoped that a better understanding of the physiology behind HRV might generate cost-effective, repeatable and reliable protocols, all of which will improve the interpretation of HRV throughout concussion recovery.

Monitoring cerebral oxygenation changes is a viable biomarker to assess the physiological state of the brain following concussion.

Introduction: The prevalence and incidence of sport-related concussion have continued to increase over the past decade, and researchers from various backgrounds strive for evidenced-based clinical assessment and management. When diagnosing and managing a concussion, a battery of tests from several domains (e.g., symptom reporting, neurocognitive, physiology) must be used. In this study, we propose and develop an objective, evidence-based protocol to assess the pathophysiology of the brain by using non-invasive methods. Methods: Contact sport athletes (n = 300) will be assessed at the beginning of the season in a healthy state to establish baseline values, and then prospectively followed if a mild traumatic brain injury (mTBI) occurs on approximately days 1–2, 3–5, 7–10, 21, 30, and subsequently thereafter, depending on the severity of injury. The protocol includes spontaneous measurements at rest, during head postural change, controlled breathing maneuvers for cerebrovascular reactivity, a neurovascular coupling stimuli, and a baroreflex/autoregulation maneuver. Physiological data collection will include cerebral blood flow velocity, cerebral oxygenation, respiratory gases for end-tidal oxygen and carbon dioxide, finger photoplethysmography for blood pressure, seismocardiography for cardiac mechanics, and electrocardiography. Conclusion, Limitations, and Ethics: The protocol will provide an objective, physiological evidence-based approach in an attempt to better diagnose concussion to aid in return-to-play or -learn. Ethics approval has been granted by the University Research Ethics Board.

Background and purpose: Total knee arthroplasty (TKA) is one of the most frequently performed orthopaedic procedures in Canada. Despite the frequency at which TKAs are performed, few studies have examined the association between postoperative outcomes and long-term functional outcomes following group-based rehabilitation in Canada. The primary objective of the present study was to examine changes in flexion and extension from intake to discharge from rehabilitation in patients in Saskatchewan, Canada. A secondary objective was to explore the demographic and medical predictors of range of motion in TKA patients, and treatment duration.Methods: A retrospective chart review from an outpatient rehabilitation clinical database was conducted between September 2014 and December 2016, and assessed demographic and medical variables.Results: A total of 672 patient charts were included in the study. Significant improvements (p < 0.001) were noted from intake to discharge from rehabilitation for flexion and extension. Right-side TKA, flexion at intake and the length of treatment predicted flexion at discharge from rehabilitation (R 2 = 0.23). Gender, right side TKA, extension at intake and the length of treatment predicted extension at discharge from rehabilitation (R 2 = 0.23). Lastly, age, flexion at intake and extension at intake predicted length of treatment in the rehabilitation programme (R 2 = 0.21). Conclusions:Patients who participated in rehabilitation following TKA experienced improvements in flexion and extension. Those with decreased flexion and extension after TKA may be less likely to experience a desirable range of motion, indicating a need for more intensive targeted rehabilitation in this group, and adjustments in hospital and community care.