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Jordi P.D. Kleinloog, Kevin M.R. Nijssen, Ronald P. Mensink, and Peter J. Joris

The aim of this systematic review was to examine the effects of physical exercise training on cerebral blood flow (CBF), which is a physiological marker of cerebrovascular function. Relationships between training-induced effects on CBF with changes in cognitive performance were also discussed. A systematic search was performed up to July 2022. Forty-five intervention studies with experimental, quasi-experimental, or pre–post designs were included. Sixteen studies (median duration: 14 weeks) investigated effects of physical exercise training on CBF markers using magnetic resonance imaging, 20 studies (median duration: 14 weeks) used transcranial Doppler ultrasound, and eight studies (median duration: 8 weeks) used near-infrared spectroscopy. Studies using magnetic resonance imaging observed consistent increases in CBF in the anterior cingulate cortex and hippocampus, but not in whole-brain CBF. Effects on resting CBF—measured with transcranial Doppler ultrasound and near-infrared spectroscopy—were variable, while middle cerebral artery blood flow velocity increased in some studies following exercise or hypercapnic stimuli. Interestingly, concomitant changes in physical fitness and regional CBF were observed, while a relation between training-induced effects on CBF and cognitive performance was evident. In conclusion, exercise training improved cerebrovascular function because regional CBF was changed. Studies are however still needed to establish whether exercise-induced improvements in CBF are sustained over longer periods of time and underlie the observed beneficial effects on cognitive performance.

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Michael J. Rose, Michael P. LaValley, S. Reza Jafarzadeh, Kerry E. Costello, Nirali Shah, Soyoung Lee, Belinda Borrelli, Stephen P. Messier, Tuhina Neogi, and Deepak Kumar

Objective: To examine changes in physical activity, sleep, pain, and mood in people with knee osteoarthritis during the ongoing COVID-19 pandemic by leveraging an ongoing randomized clinical trial. Methods: Participants enrolled in a 12-month parallel two-arm randomized clinical trial (NCT03064139) interrupted by the COVID-19 pandemic wore an activity monitor (Fitbit Charge 3) and filled out custom weekly surveys rating knee pain, mood, and sleep as part of the study. Data from 30 weeks of the parent study were used for this analysis. Daily step count and sleep duration were extracted from activity monitor data, and participants self-reported knee pain, positive mood, and negative mood via surveys. Metrics were averaged within each participant and then across all participants for prepandemic, stay-at-home, and reopening periods, reflecting the phased reopening in the state of Massachusetts. Results: Data from 28 participants showed small changes with inconclusive clinical significance during the stay-at-home and reopening periods compared with prepandemic for all outcomes. Summary statistics suggested substantial variability across participants with some participants showing persistent declines in physical activity during the observation period. Conclusion: Effects of the COVID-19 pandemic on physical activity, sleep, pain, and mood were variable across individuals with osteoarthritis. Specific reasons for this variability could not be determined. Identifying factors that could affect individuals with knee osteoarthritis who may exhibit reduced physical activity and/or worse symptoms during major lifestyle changes (such as the ongoing pandemic) is important for providing targeted health-care services and management advice toward those that could benefit from it the most.