Cardiorespiratory fitness is a strong and consistent predictor of morbidity and mortality among adults: an overview of meta-analyses representing over 20.9 million observations from 199 unique cohort studies.

OBJECTIVE: To examine and summarise evidence from meta-analyses of cohort studies that evaluated the predictive associations between baseline cardiorespiratory fitness (CRF) and health outcomes among adults. DESIGN: Overview of systematic reviews. DATA SOURCE: Five bibliographic databases were searched from January 2002 to March 2024. RESULTS: From the 9062 papers identified, we included 26 systematic reviews. We found eight meta-analyses that described five unique mortality outcomes among general populations. CRF had the largest risk reduction for all-cause mortality when comparing high versus low CRF (HR=0.47; 95% CI 0.39 to 0.56). A dose-response relationship for every 1-metabolic equivalent of task (MET) higher level of CRF was associated with a 11%-17% reduction in all-cause mortality (HR=0.89; 95% CI 0.86 to 0.92, and HR=0.83; 95% CI 0.78 to 0.88). For incident outcomes, nine meta-analyses described 12 unique outcomes. CRF was associated with the largest risk reduction in incident heart failure when comparing high versus low CRF (HR=0.31; 95% CI 0.19 to 0.49). A dose-response relationship for every 1-MET higher level of CRF was associated with a 18% reduction in heart failure (HR=0.82; 95% CI 0.79 to 0.84). Among those living with chronic conditions, nine meta-analyses described four unique outcomes in nine patient groups. CRF was associated with the largest risk reduction for cardiovascular mortality among those living with cardiovascular disease when comparing high versus low CRF (HR=0.27; 95% CI 0.16 to 0.48). The certainty of the evidence across all studies ranged from very low-to-moderate according to Grading of Recommendations, Assessment, Development and Evaluations. CONCLUSION: We found consistent evidence that high CRF is strongly associated with lower risk for a variety of mortality and incident chronic conditions in general and clinical populations.

The effect of leisure time physical activity and sedentary behaviour on the health of workers with different occupational physical activity demands: a systematic review.

BACKGROUND: Although it is generally accepted that physical activity reduces the risk for chronic non-communicable disease and mortality, accumulating evidence suggests that occupational physical activity (OPA) may not confer the same health benefits as leisure time physical activity (LTPA). It is also unclear if workers in high OPA jobs benefit from LTPA the same way as those in sedentary jobs. Our objective was to determine whether LTPA and leisure time sedentary behaviour (LTSB) confer the same health effects across occupations with different levels of OPA. METHODS: Searches were run in Medline, Embase, PsycINFO, ProQuest Public Health and Scopus from inception to June 9, 2020. Prospective or experimental studies which examined the effects of LTPA or LTSB on all-cause and cardiovascular mortality and cardiovascular disease, musculoskeletal pain, diabetes, metabolic syndrome, arrhythmias and depression among adult workers grouped by OPA (low OPA/sitters, standers, moderate OPA/intermittent movers, high OPA/heavy labourers) were eligible. Results were synthesized using narrative syntheses and harvest plots, and certainty of evidence assessed with GRADE. RESULTS: The review includes 38 papers. Across all outcomes, except cardiovascular mortality, metabolic syndrome and atrial fibrillation, greater LTPA was consistently protective among low OPA, but conferred less protection among moderate and high OPA. For cardiovascular mortality and metabolic syndrome, higher levels of LTPA were generally associated with similar risk reductions among all OPA groups. Few studies examined effects in standers and none examined effects of LTSB across OPA groups. CONCLUSIONS: Evidence suggests that LTPA is beneficial for all workers, but with larger risk reductions among those with low compared to high OPA jobs. This suggests that, in our attempts to improve the health of workers through LTPA, tailored interventions for different occupational groups may be required. More high-quality studies are needed to establish recommended levels of LTPA/LTSB for different OPA groups. PROTOCOL REGISTRATION: PROSPERO # CRD42020191708 .

The Effect of Sedentary Behaviour on Cardiorespiratory Fitness: A Systematic Review and Meta-Analysis.

BACKGROUND: Cardiorespiratory fitness (CRF) is an important indicator of current and future health. While the impact of habitual physical activity on CRF is well established, the role of sedentary behaviour (SB) remains less understood. OBJECTIVE: We aimed to determine the effect of SB on CRF. METHODS: Searches were conducted in MEDLINE, Embase, PsycINFO, CINAHL and SPORTDiscus from inception to August 2022. Randomised controlled trials, quasi-experimental studies and cohort studies that assessed the relationship between SB and CRF were eligible. Narrative syntheses and meta-analyses summarised the evidence, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) certainty was based on evidence from randomised controlled trials. RESULTS: This review included 18 studies that focused on youth (four randomised controlled trials, three quasi-experimental studies, 11 cohort studies) and 24 on adult populations (15 randomised controlled trials, five quasi-experimental studies, four cohort studies). In youth and adults, evidence from randomised controlled trials suggests mixed effects of SB on CRF, but with the potential for interventions to improve CRF. Quasi-experimental and cohort studies also support similar conclusions. Certainty of evidence was very low for both age groups. A meta-analysis of adult randomised controlled trials found that interventions targeting reducing SB, or increasing physical activity and reducing SB, had a significant effect on post-peak oxygen consumption (mean difference = 3.16 mL.kg-1.min-1, 95% confidence interval: 1.76, 4.57). CONCLUSIONS: Evidence from randomised controlled trials indicates mixed associations between SB and CRF, with the potential for SB to influence CRF, as supported by meta-analytical findings. Further well-designed trials are warranted to confirm the relationship between SB and CRF, explore the effects of SB independent from higher intensity activity, and investigate the existence of such relationships in paediatric populations. CLINICAL TRIAL REGISTRATION: PROSPERO CRD42022356218.

Examining the state, quality and strength of the evidence in the research on built environments and physical activity among children and youth: An overview of reviews from high income countries.

BACKGROUND: Built environments have shown to be associated with health, with physical activity (PA) considered one of the critical pathways for achieving benefits. Navigating available evidence on the built environment and PA is challenging given the number of reviews. OBJECTIVE: Examine the current state and quality of research looking at associations between built environments and total PA and domains of PA (i.e., leisure/recreation, transportation, school) among children and youth (1-18 years). METHODS: We systematically searched the grey literature and six bibliographic databases from January 2000 to May 2020. Review quality was assessed using the AMSTAR2. Results by age group were synthesized using narrative syntheses and harvest plots, and certainty of the evidence was assessed using a modified GRADE approach. RESULTS: This overview included 65 reviews. Most reviews were of very low-to-low quality. High certainty was found for positive associations between transportation PA and walking/cycling/active transportation (AT) infrastructure. There was high certainty for positive associations between streets/play streets and total PA, alongside lower certainty for transportation and leisure PA. Very low-to-moderate certainty supports schoolyards designed to promote PA were positively associated with total PA, but mixed for school PA (except children). Less consistent positive associations were found for forests/trees, greenspace/open space, recreation facilities, street lighting, traffic safety, population/residential density, proximity/access to destinations, neighbourhood characteristics, and home environments. There is very low-to-moderate certainty for negative associations between greater distance to school and traffic volume and domains of PA. Generally, null or mixed associations were observed for aesthetics, parks, AT comfort infrastructure, land-use mix, street connectivity, urban/rural status, and public transit. DISCUSSION: There remains a need for high quality systematic reviews and studies to evaluate the effects of environmental changes across the pediatric age spectrum and using a PA domain approach. Given the global physical inactivity crisis the built environment remains and important means to promote PA among children/youth.

Examining the state, quality and strength of the evidence in the research on built environments and physical activity among adults: An overview of reviews from high income countries.

BACKGROUND: Built environments have been implicated in the development of chronic disease, with physical activity (PA) considered one of the critical mechanisms for this relationship. Substantial growth in research on built environments and PA makes navigating the available evidence challenging. OBJECTIVE: To examine and describe the current state, strength and quality of research investigating the associations between built environments and PA domains of active living (i.e., leisure, transportation, occupational) and total PA among adults (≥18 years) from high-income OECD countries. METHODS: We conducted an overview of systematic reviews. A systematic search of six bibliographic databases and grey literature from January 2000 to May 2020. Review quality was assessed with the AMSTAR2. Results by age group were synthesized narratively and direction of association displayed using harvest plots. Certainty of the evidence was assessed using a modified GRADE approach. RESULTS: The overview included 116 systematic reviews. Most evidence was cross-sectional and of low-to-very low quality. Moderate-to-high certainty of evidence supported positive associations between environments that support active transportation (e.g., walkability, walking infrastructure, street connectivity, land-use mix) and transportation PA among adults/working-aged adults. Across all age groups, there was very low-to-moderate certainty for consistent positive associations between point of decision prompts (e.g., signs in stairwells and along paths) and all PA. Evidence from older adults was of very low certainty and largely equivocal. There was little-to-no evidence for young and middle-aged adults and occupational PA. DISCUSSION: While there has been an increase in evidence from observational and natural experiment studies, most has been related to active transportation infrastructure and point of decision prompts. There remains a need for these studies to evaluate built environments for leisure and occupational PA and among younger and older adults, and for high quality reviews to summarize this evidence. Interventions that target changes to the built environment show promise for promoting PA among adults, providing an important means to combat the global physical inactivity crisis.