key: cord-0290730-ts8ulkex authors: Morgan, A.; Noguchi, K.; Tang, A.; Heisz, J.; Thabane, L.; Richardson, J. title: High-intensity interval or circuit-based strength training effects on physical and cognitive functioning for community-dwelling older adults: A systematic review protocol. date: 2022-02-10 journal: nan DOI: 10.1101/2022.02.10.22270669 sha: 39b3cf91f954bc98d3312ec2aaf92b597e1b14b1 doc_id: 290730 cord_uid: ts8ulkex Background: High-intensity interval or circuit-based strength training utilizes brief intense periods of strengthening exercises interspersed with rest/light activity or performed in a continuous circuit. The physical and cognitive effects of this time-efficient approach in community-dwelling older adults have not been systematically reviewed. Objectives: To determine the effects of high-intensity interval or circuit-based strength training interventions on physical and cognitive functioning for community-dwelling older adults, and the associated adherence, retention, and adverse event rates. Methods: Six databases will be searched from inception to November 2021; MEDLINE, EMBASE, CINAHL, AgeLine, SPORTDiscus, and Web of Science. To assess physical and/or cognitive functioning effects, randomized and quasi-randomized controlled trials (RCTs and Q-RCTs) of high-intensity interval or circuit-based strengthening interventions in community-dwelling older adults, utilizing any comparator, will be included. The above criteria will be extended to include non-randomized study designs to assess adherence, retention, and adverse events. All screening, data extraction and risk of bias will be assessed by two independent reviewers. Risk of bias will be assessed utilizing the Cochrane RoB 2 tool for randomized and ROBINS-I for non-randomized studies. Qualitative synthesis will be used to present information on adherence, retention, and adverse event rates. Qualitative and/or quantitative synthesis will be used to present physical and cognitive functioning effects depending on which method is deemed appropriate for the various outcomes. Conclusion: This systematic review will be the first to summarize the physical and/or cognitive effects, adherence, retention, and adverse events reported in high-intensity interval and circuit-based strengthening interventions for community-dwelling older adults. Systematic review registration number: CRD42021284010 Keywords: older adults; high-intensity exercise; physical functioning; cognitive functioning Despite the recognized benefits of exercise on physical [1] [2] [3] [4] [5] and cognitive functioning [1, [6] [7] [8] for older adults, only one third of older Canadians accumulate the recommended 150 minutes of moderate to vigorous physical activity per week [9] . The World Health Organization recommends older adults perform at least 150 minutes of moderate-intensity or 75 minutes vigorous-intensity aerobic activity per week or an equivalent combination, as well as the inclusion of strengthening exercises at least two days per week [10] . High-intensity interval or circuit-based strength training may offer a time-efficient form of exercise to address these recommendations. Evidence suggests that exercise intensity may impact outcomes on physical [11] and cognitive functioning [12] in older adults. In older adults, recent systematic reviews found highintensity aerobic activity demonstrates equivalent or superior effects on cardiovascular fitness compared with moderate intensity despite its' shorter duration [11] and may facilitate greater improvements in working memory [12] . A systematic review of 56 meta-analyses of various exercise interventions for older adults reported that resistance training had the largest effect sizes overall, including for physical functioning [1] , and other reviews suggest that higher intensity resistance training is superior to low intensity for improvements in strength [2, 13] and aerobic capacity [2] . High-intensity interval training (HIIT), which combines brief intense bouts of aerobic activity combined with rest or low intensity exercise [14] is recognized as an efficient and effective mode of exercise with evidence supporting cardiovascular benefits and safety for older adults. All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 10, 2022. ; https://doi.org/10.1101/2022.02.10.22270669 doi: medRxiv preprint [11] . An analogous high-intensity interval or circuit-based format has also been applied for strengthening exercises [15] [16] [17] , employing various descriptors; including, "high intensity interval in circuit training (HIICT)"[15] "high-intensity interval resistance training (HIRT)" and "high-intensity functional training (HIFT)" [18] . Through an interval or circuit format, strengthening exercises are performed at a high-intensity (relative to ability) with no or minimal rest, thereby also offering potential aerobic benefits [18] . Randomized controlled trials of highintensity strength training using an interval or circuit-based format in older women have demonstrated improvements in walking speed [17] and speed of chair stands [16] . A 12-week quasi-randomized trial in older adults also found benefits on leg extensor strength, cardiorespiratory fitness (predicted maximal oxygen consumption [VO2max]) and reported all 18 participants in the high-intensity group completed the intervention with an overall attendance of 99% [19] . Despite the potential benefits, this type of exercise has received less attention than HIIT and the current evidence on the effects of high-intensity interval or circuit-based has not been systematically reviewed. The purpose of this review of this systematic review is to answer the following questions; Questions addressed by Systematic Review 1. What are the effects of high-intensity interval or circuit-based strength training interventions on physical and cognitive functioning for community-dwelling older adults? and, 2. What are the reported adherence, retention, and adverse event rates for these interventions? All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. To determine effects of high-intensity interval or circuit-based strength training on physical and cognitive functioning, randomized controlled trials (RCTs) and quasi-randomized controlled trials (Q-RCT; allocation method not random e.g., alternation, day of week, etc.,) [21] will be included. To assess the reported adherence, retention, and adverse event rates, other nonrandomized study designs, specifically nonrandomized controlled trial (NRCT), controlled before-and-after (CBA), and before and after (BA) studies [21] will also be included. Nonrandomized studies are prone to greater bias than RCTs but can be particularly useful in providing information regarding harms, especially when evidence from RCTs may be limited [22] [23] [24] . Grey literature will not be included. Eligible participants will be community-dwelling older adults. Study samples must have a mean or median age of 60 years or older. Studies focused on samples of older adults with moderate/severe cognitive impairment (clinical diagnosis of dementia or Alzheimer's disease or indicated by cognitive screening tool such as Montreal Cognitive Assessment or Mini Mental State Exam), a neurological condition or pre-or post-surgery will be excluded. Studies with mixed populations of older adults will be excluded if > 50% of the sample includes individuals All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 10, 2022. ; https://doi.org/10.1101/2022.02.10.22270669 doi: medRxiv preprint with moderate/severe cognitive impairment (see previous criteria previously), a neurological condition or are pre-or post-surgery. Eligible interventions will be ≥ 4 weeks in total duration. Eligible interventions will involve strengthening exercises (including body weight and external resistance) that are performed in a continuous circuit (i.e., several exercises performed sequentially with no/minimal rest between exercises, may have rest between circuits)[25-27] or interval format (alternating periods of time performing high intensity exercise with periods of low intensity activity or rest[28]). Highintensity must be defined using prespecified target criteria (e.g., rating of perceived exertion, percentage of heart rate or one-repetition maximum). Acceptable criteria may include; least "hard" using another scale). Inclusion of a familiarization period (not meeting highintensity criteria) is acceptable; however, this duration should not exceed 1/3 of the total intervention duration. Interventions which combine high-intensity interval or circuit-based strength training with other additional interventions likely to impact physical and/or cognitive functioning (e.g., cognitive training, other forms of exercise) will be excluded. 'Other forms of exercise' will be considered the inclusion of exercise components beyond a warm-up and cooldown period (e.g., high-intensity strength circuit followed by 30 minutes stationary cycling). To assess effects on the intervention on physical and/or cognitive functioning, studies comparing interval or circuit-based high-intensity strength training to a control group or intervention that All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 10, 2022. ; https://doi.org/10.1101/2022.02.10.22270669 doi: medRxiv preprint does not include interval or circuit-based high-intensity strength training will be included. To assess adherence, retention, and adverse event rates, studies utilizing any or no comparator intervention will be included. Eligible studies will be included if effects of the intervention on any specified physical or cognitive functioning outcome are included. Physical functioning outcomes will include measures of both physiological impairment; specifically measures assessing muscle strength or cardiorespiratory fitness, and measures of mobility and performance capacity [33] (e.g., selfreport questionnaires, performance of functional tasks including walking and sit to stands). Cognitive functioning outcomes will include any measures which assess general cognition or specific domains/functions. Studies which only report acute effects (immediately after a single bout of exercise) will be excluded. Any setting will be included provided the older adults are living in the community. Studies published in English will be included. Six databases will be searched with no date restrictions to October 2021: Ovid MEDLINE, Ovid EMBASE, EBSCOhost CINAHL, EBSCOhost AgeLine, EBSCOhost SPORTDiscus, and Clarivate Web of Science. A McMaster University research librarian assisted in the development and refinement of the MEDLINE search strategy which can be found in Appendix II. This strategy with feedback from the research librarian was adapted for each database listed above. Searches will be re-run in all databases in November 2021 to identify any All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 10, 2022. ; https://doi.org/10.1101/2022.02.10.22270669 doi: medRxiv preprint additional studies. Finally, the references list of relevant studies will be hand-searched to identify additional studies. Titles and abstracts of eligible articles will be uploaded to Covidence systematic review management software [34] for screening. After initial title and abstract screening, full text for eligible articles will be retrieved and uploaded into Covidence to assess against inclusion and exclusion criteria. The final data extraction phase will utilize Microsoft Excel software [35] . Detailed inclusion and exclusion criteria will be provided to reviewers, titles and abstracts of articles will be screened independently by two reviewers (AM and KN), after a calibration period. This period will involve both reviewers independently screening 20 titles and abstracts to ensure inclusion and exclusion is understood. Articles that appear to meet inclusion criteria or are uncertain will be included at this stage. These articles will be retrieved in full text and will be screened independently by two reviewers (AM and KN) after a similar calibration period. Any disagreement will be resolved through discussion or consultation with a third reviewer (JR). Additional information will be sought from authors as needed. Reviewers will not be blind to study title or author(s). Piloted standardized data extraction forms will be used to extract data from each eligible article by two independent reviewers (AM and KSN). The data extraction forms found in Appendix III detail the variables for which data will be sought and these forms will be pilot tested with at least five articles to ensure completeness and clarity. All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. tool. Non-randomized studies will be assessed using the Risk Of Bias in Non-randomised Studies-of Interventions (ROBINS-I) [37] . Two independent reviewers (AM and KSN) will conduct risk of bias assessments, with any disagreements resolved through discussion or consultation with a third reviewer (JR). Reviewers will not be blinded to article title or author(s). The study characteristics reported in included studies will be summarized and compared to determine where synthesis may be appropriate. Study authors will be contacted to obtained insufficient or missing information. Information on the effects of the intervention on physical and cognitive outcomes will be collected from RCTs and quasi-RCTs. Information on adherence, retention, and adverse events will also be collected from the additional non-randomized designs specified in the inclusion criteria. Randomized controlled trials will not be combined with nonrandomized study designs for synthesis. Qualitative synthesis, utilizing text and tables, will be used to present information on adherence, retention, and adverse event rates and intervention characteristics (e.g., exercise parameters, duration). Data on the effects on physical and cognitive functioning outcomes will be grouped according to shared outcomes (e.g., muscle strength, gait speed, general cognition, etc.,) and presented using qualitative and/or quantitative synthesis depending on which method is deemed appropriate for the various outcomes. Quantitative synthesis (meta-analysis) will be conducted based on considerations of clinical, methodological, and statistical heterogeneity. Clinical heterogeneity considers variability in the intervention and comparators, population characteristics, outcomes and followup duration[38] while methodological heterogeneity considers study design, measurement tools, and risk of bias. Clinical and methodological heterogeneity will impact statistical heterogeneity All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 10, 2022. ; https://doi.org/10.1101/2022.02.10.22270669 doi: medRxiv preprint (variability in intervention effects). For those studies deemed suitable to combine based on clinical and methodological considerations; statistical heterogeneity will be quantified using the chi squared and I² tests. An I² statistic of 50-90% may represent substantial, and 75-100% considerable heterogeneity [38] . Combined studies with an I² statistic of ≥ 75% will not be combined and those with 50-75% will consider the size and direction and effects and the strength of the evidence for heterogeneity (e.g., confidence interval for I², p-value from chi-squared test) [38]. If appropriate, meta-analysis will be conducted using the mean difference for outcomes utilizing the same scale and standardized mean difference for those utilizing different scales [38]. Results will be presented with 95% confidence intervals. Missing standard deviation values will be estimated using standard errors, confidence intervals, t values, and/or P values based on the recommendations from the Cochrane handbook [38]. Data will be used from intention-to-treat analysis data if available. A random effects model will be used for any meta-analyses. If deemed appropriate for combination, subgroup analyses will be conducted based on intervention (criteria utilized for "high-intensity"; duration <12 weeks, ≥ 12 weeks) and sample characteristics (clinical conditions, sex). Credibility of subgroup analyses will be assessed using the Instrument to assess the Credibility of Effect Modification Analyses (ICEMAN) [39] . Sensitivity analysis will be conducted removing studies with high risk of bias. The certainty of findings for intervention effects on physical and cognitive outcomes will be assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) [40] approach resulting a rating of high, moderate, low, or very low quality. GRADE summary of findings (SoF) tables will be used to summarize the results. The recommendations All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 10, 2022. ; https://doi.org/10.1101/2022.02.10.22270669 doi: medRxiv preprint from the GRADE working group will be followed regarding the evaluation and incorporation of non-randomized studies into rating the certainty of a body of evidence[41], including rating the certainty of evidence for RCTs and quasi-RCTs separately. High-intensity interval or circuit-based strength training may offer a time-efficient approach to exercise. However, existing evidence on the effects on community-dwelling older adults' physical and cognitive functioning has yet to be systematically reviewed. Information summarizing the retention, adherence, and adverse events rates for interventions employing this type of training in older adult populations is also required. The results of this review will present valuable considerations for alternative training approaches and optimizing exercise prescription for community-dwelling older adults. High-intensity strength training using an interval or circuitbased format is an emerging area of research and this review will summarize the current evidence and recommend important future directions. Funding details: This works was not supported by any funding or grant-awarding bodies. The authors report there are no competing interests to declare. All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 10, 2022. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 10, 2022. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 10, 2022. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 10, 2022. All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 10, 2022. ; https://doi.org/10.1101/2022.02.10.22270669 doi: medRxiv preprint Appendix I: PRISMA-P checklist (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. A P P E N D I X I I S t u d y r e c o r d s : D a t a m a n a g e m e n t 1 1 a D e s c r i b e t h e m e c h a n i s m ( s ) t h a t w i l l b e u s e d t o m a n a g e r e c o r d s a n d d a t a t h r o u g h o u t t h e r e v i e All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 10, 2022. ; https://doi.org/10.1101/2022.02.10.22270669 doi: medRxiv preprint Exercise interventions for older adults: A systematic review of meta-analyses Progressive resistance strength training for improving physical function in older adults Copenhagen Consensus statement 2019: Physical activity and ageing Systematic review of functional training on muscle strength, physical functioning, and activities of daily living in older adults The effects of exercise on muscle strength, body composition, physical functioning and the inflammatory profile of older adults: A systematic review Exercise for cognitive brain health in aging: A systematic review for an evaluation of dose Effects of Exercise on Cognitive Performance in All rights reserved. No reuse allowed without permission.(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.