OBJECTIVE: To determine the effects of low- vs. high-intensity aerobic and resistance training on motor and cognitive function, brain activation, brain structure, and neurochemical markers of neuroplasticity and the association thereof in healthy young and older adults and in patients with multiple sclerosis, Parkinson's disease, and stroke. DESIGN: Systematic review and robust variance estimation meta-analysis with meta-regression. DATA SOURCES: Systematic search of MEDLINE, Web of Science, and CINAHL databases. RESULTS: Fifty studies with 60 intervention arms and 2283 in-analyses participants were included. Due to the low number of studies, the three patient groups were combined and analyzed as a single group. Overall, low- (g=0.19, p = 0.024) and high-intensity exercise (g=0.40, p = 0.001) improved neuroplasticity. Exercise intensity scaled with neuroplasticity only in healthy young adults but not in healthy older adults or patient groups. Exercise-induced improvements in neuroplasticity were associated with changes in motor but not cognitive outcomes. CONCLUSION: Exercise intensity is an important variable to dose and individualize the exercise stimulus for healthy young individuals but not necessarily for healthy older adults and neurological patients. This conclusion warrants caution because studies are needed that directly compare the effects of low- vs. high-intensity exercise on neuroplasticity to determine if such changes are mechanistically and incrementally linked to improved cognition and motor function.

Center for Human Movement Sciences University of Groningen Medical Center Groningen the Netherlands; Somogy County Kaposi Mór Teaching Hospital Kaposvár Hungary; Department of Sport Biology Institute of Sport Sciences and Physical Education University of Pécs Hungary; Division of Training and Movement Sciences Research Focus Cognition Sciences University of Potsdam Potsdam Germany; Hungarian University of Sports Science Department of Kinesiology Budapest Hungary

Department of Biomedical Sciences University of Sassari Sassari Italy

Department of Biomedical Sciences University of Sassari Sassari Italy; Unit of Endocrinology Nutritional and Metabolic Disorders AOU Sassari Sassari Italy

Department of Computer Science and Applied Mathematics Weizmann Institute of Science Rehovot Israel

Department of Neurobiology Care Sciences and Society Division of Physiotherapy Karolinska Institutet Stockholm Sweden; Women's Health and Allied Health Professionals Theme Medical Unit Occupational Therapy and Physiotherapy Karolinska University Hospital Stockholm Sweden

Department of Physical Therapy Faculty of Medicine University of British Columbia Vancouver Canada; Djavad Mowafaghian Centre for Brain Health University of British Columbia Vancouver Canada

Department of Sport Biology Institute of Sport Sciences and Physical Education University of Pécs Hungary

Division of Training and Movement Sciences Research Focus Cognition Sciences University of Potsdam Potsdam Germany

Faculty of Physical Education and Sport Charles University Prague Czech Republic

Neurovascular Research Unit Department of Neurology Herlev Gentofte Hospital University of Copenhagen Copenhagen Denmark

Research Center of Molecular Exercise Science Hungarian University of Sport Science Budapest Hungary

References provided by Crossref.org

Managing multiple sclerosis in individuals aged 55 and above: a comprehensive review