Change in Submaximal Cardiorespiratory Fitness and All-Cause Mortality

Update to the 2016 American Heart Association cardiorespiratory fitness statement

In 2016 the American Heart Association published a scientific statement that summarized a large body of evidence concluding that cardiorespiratory fitness (CRF) was a powerful marker of cardiovascular disease (CVD) and CVD-mortality risk; its association with morbidity and mortality was independent of commonly obtained risk factors, and consequently, that it should be a routine measure in all health care settings. Since 2016 the interest in CRF as a prognostic for human health and performance has increased exponentially. This review will summarize a growing body of evidence that reinforces the notion that the assessment of CRF improves patient/client management. Feasible means of CRF assessment in health care settings is considered, and the expected response of CRF to exercise consistent with consensus recommendations is reviewed. The association between CRF and health care costs is also explored. The evidence reviewed will reinforce the conclusions drawn in 2016; that overwhelming evidence demands that CRF should be a routine assessment in all health care settings - a vital sign.

The Impact of Light Physical Activity, Sedentary Behavior and Cardiorespiratory Fitness in Extending Lifespan and Healthspan Outcomes: How Little is Still Significant? A Narrative Review

To describe the relationship between mortality and measures of low intensity physical activity (LIPA) as well as sedentary behavior (SB), and cardiorespiratory fitness (CRF). Study selection was performed through multiple database searches from January 1, 2000 until May 1, 2023. Seven LIPA studies, 9 SB studies, and 8 studies CRF studies were selected for primary analysis. LIPA and non-SB follow a reverse J shaped curve with mortality. The greatest benefits occur initially, and the rate of mortality reduction slows with increasing physical activity. Increasing CRF reduces mortality although the dose response curve is uncertain. For special populations such as individuals with, or at high risk of developing cardiovascular disease the benefit from exercise is heightened. LIPA, decreased SB and higher CRF lead to reductions in mortality and improved quality of life. Individualized counseling on the benefits of any amount of physical activity may increase compliance and serve as a starting point for lifestyle modifications.

Haemodynamic Gain Index Is Associated with Risk of Sudden Cardiac Death and Improves Risk Prediction: A Cohort Study

INTRODUCTION

Haemodynamic gain index (HGI) is a novel haemodynamic parameter which can be obtained from cardiopulmonary exercise testing (CPX), but its association with sudden cardiac death (SCD) is not known. We aimed to assess the association of HGI with SCD risk in a long-term prospective cohort study.

METHODS

HGI was calculated using heart rate and systolic blood pressure (SBP) responses measured in 1897 men aged 42–61 years during CPX from rest to peak exercise. Cardiorespiratory fitness (CRF) was measured using respiratory gas exchange analysis. Multivariable adjusted hazard ratios (HRs) (95% confidence intervals [CIs]) were estimated for SCD.

RESULTS

During a median follow-up of 28.7 years, 205 SCDs occurred. The risk of SCD decreased gradually with increasing HGI (p value for non-linearity = 0.63). A unit (bpm/mm Hg) higher HGI was associated with a decreased risk of SCD (HR: 0.84; 95% CI: 0.71-0.99), which was attenuated following adjustment for CRF. CRF was inversely associated with SCD, which remained after further adjustment for HGI (HR: 0.85; 95% CI: 0.77-0.94) per each unit higher CRF. Addition of HGI to a SCD risk prediction model containing established risk factors improved risk discrimination (C-index change = 0.0096; p = 0.017) and reclassification (net reclassification improvement [NRI] = 39.40%, p = 0.001). The corresponding values for CRF were (C-index change = 0.0178; p = 0.007) and (NRI = 43.79%, p = 0.001).

CONCLUSION

Higher HGI during CPX is associated with a lower SCD risk, consistent with a dose-response relationship but dependent on CRF levels. Though HGI significantly improves the prediction and classification of SCD beyond common cardiovascular risk factors, CRF remains a stronger risk indicator and predictor of SCD compared to HGI.

Temperature-dependent metabolite orchestration to acute submaximal exercise indicates cardiorespiratory fitness in humans

AIMS

Cardiorespiratory fitness (CRF), an important biomarker of human health, is impaired in cold environment compared to thermoneutral condition. The study aimed to investigate the role of metabolome response to acute exercise in regulation of CRF at different ambient temperatures.

MAIN METHODS

A total of 27 young adults were recruited, and each subject underwent a cardiopulmonary exercise test (CPET) and a constant load submaximal exercise at both room temperature (25 °C) and cold temperature (0 °C). The serum samples were collected before and immediately after constant load exercise.

KEY FINDINGS

Acute cold exposure decreased CRF by 41 %, accompanied by a metabolic shift to anaerobic respiration. It also decreased VO₂ and increased respiratory quotient during constant load exercise. Metabolome profiling revealed that acute exercise reprogrammed serum metabolome in an ambient temperature-dependent manner. Specifically, exercise increased a cluster of fatty acids during cold exposure, possibly due to impaired fatty acid oxidation. The correlations between metabolite responses to acute exercise and exercise parameters were analyzed using partial least squares regression and machine learning, revealing that metabolite responses to acute exercise were highly correlated with exercise parameters and predictive of CRF. Among the contributors, tryptophan and its metabolites stood out as important ones.

SIGNIFICANCE

These results suggested that the metabolite responses to acute submaximal exercise unmasks the exercise performance at different ambient temperatures, highlighting the role of metabolite orchestration in the physiological regulation of CRF.

Fitness, body composition, and metabolic risk scores in children and adolescents: the UP&DOWN study

We aimed to analyse the longitudinal association between physical fitness (PF) and body composition (BC) with a metabolic risk score (Met4) in children and adolescents and to elucidate whether the association between PF and Met4 differs when using relativized or absolute fitness variables. A total of 188 children (86 females) and 195 adolescents (97 females) were included. Cardiorespiratory fitness (CRF) was determined by the 20-m shuttle run test, and muscular fitness (MF) was determined by hand grip and standing long jump tests. Height and weight were measured, and the body mass index (Kg/m²) was calculated. Triceps and subscapular skinfolds were assessed to compute body fat percentage. Met4 was computed from systolic blood pressure, triglycerides, high-density lipoprotein cholesterol, and glucose levels. Relative CRF was longitudinally and negatively associated with Met4 in female children (β =  -0.031, p = 0.025), while absolute CRF was positively associated with Met4 in male children and adolescents (β = 0.000, p < 0.05). Relative upper and lower-body MF were longitudinally and negatively associated with Met4 in female adolescents (β =  -1.347, β =  -0.005, p < 0.05), while absolute lower-body MF was positively associated with Met4 in male children (β = 0.000, p = 0.019). BC was longitudinally and positively associated with Met4 in male children (β-ranging from 0.011 to 0.055, all p < 0.05) and male adolescents (β-ranging from 0.011 to 0.046, all p < 0.05).  Conclusion: BC is more strongly associated with Met4 than PF in children and adolescents. An optimal body weight status should be considered the main objective of health-promoting programs at childhood and adolescence. Furthermore, the way of expressing the fitness variables determines the direction of the association with Met4. What is Known: • Physical fitness is an important health indicator in children and adolescents, with great amount of previous evidence supporting the preventive role of maintaining optimal levels of both cardiorespiratory and muscular fitness for future cardiometabolic issues. What is New: • The way of reporting physical fitness variables can affect the associations between physical fitness features and cardiometabolic outcomes. Since body composition variables have a great impact on both physical fitness and cardiometabolic health, relativizing physical fitness performance by body composition could lead to erroneous conclusions.

Percentage of Age-Predicted Cardiorespiratory Fitness and Risk of Incident Hypertension: A PROSPECTIVE COHORT STUDY

PURPOSE

There are inverse and independent associations between cardiorespiratory fitness (CRF) and several adverse cardiometabolic outcomes including hypertension (HTN). The prospective relationship between percentage of age-predicted CRF and risk of HTN has not been previously investigated. We aimed to assess the association of percentage of age-predicted CRF with incident HTN in a long-term prospective cohort study.

METHODS

Cardiorespiratory fitness, as measured by peak oxygen uptake, was assessed using the gold standard respiratory gas exchange analyzer in 1602 men who underwent cardiopulmonary exercise testing. The age-predicted CRF estimated from a regression equation for age was converted to percentage of age-predicted CRF ([achieved CRF/age-predicted CRF] × 100). The HR with 95% CI were estimated for HTN.

RESULTS

During a median follow-up of 26.8 yr, 308 HTN cases were recorded. There was a linear relationship between age-predicted CRF and incident HTN (P value for nonlinearity = .68). A 1-SD increase in percentage of age-predicted CRF was associated with a decreased risk of HTN in analysis adjusted for established risk factors (HR = 0.79: 95% CI, 0.69-0.90), which remained consistent on further adjustment for several other potential confounders including alcohol consumption, physical activity, socioeconomic status, and inflammation (HR = 0.83: 95% CI, 0.72-0.95). The corresponding adjusted HRs were 0.55 (95% CI, 0.38-0.80) and 0.63 (95% CI, 0.43-0.91), respectively, when comparing extreme quartiles of percentage of age-predicted CRF levels.

CONCLUSIONS

Percentage of age-predicted CRF is linearly, inversely, and independently associated with risk of incident HTN, and it is comparable to absolute CRF as a risk indicator for HTN in a general population of middle-aged men.

The Metabolic Signature of Cardiorespiratory Fitness: A Systematic Review

Background

Cardiorespiratory fitness (CRF) is a potent health marker, the improvement of which is associated with a reduced incidence of non-communicable diseases and all-cause mortality. Identifying metabolic signatures associated with CRF could reveal how CRF fosters human health and lead to the development of novel health-monitoring strategies.

Objective

This article systematically reviewed reported associations between CRF and metabolites measured in human tissues and body fluids.

Methods

PubMed, EMBASE, and Web of Science were searched from database inception to 3 June, 2021. Metabolomics studies reporting metabolites associated with CRF, measured by means of cardiopulmonary exercise test, were deemed eligible. Backward and forward citation tracking on eligible records were used to complement the results of database searching. Risk of bias at the study level was assessed using QUADOMICS.

Results

Twenty-two studies were included and 667 metabolites, measured in plasma (n = 619), serum (n = 18), skeletal muscle (n = 16), urine (n = 11), or sweat (n = 3), were identified. Lipids were the metabolites most commonly positively (n = 174) and negatively (n = 274) associated with CRF. Specific circulating glycerophospholipids (n = 85) and cholesterol esters (n = 17) were positively associated with CRF, while circulating glycerolipids (n = 152), glycerophospholipids (n = 42), acylcarnitines (n = 14), and ceramides (n = 12) were negatively associated with CRF. Interestingly, muscle acylcarnitines were positively correlated with CRF (n = 15).

Conclusions

Cardiorespiratory fitness was associated with circulating and muscle lipidome composition. Causality of the revealed associations at the molecular species level remains to be investigated further. Finally, included studies were heterogeneous in terms of participants’ characteristics and analytical and statistical approaches.

PROSPERO Registration Number

CRD42020214375.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40279-021-01590-y.

Cardiorespiratory optimal point during exercise testing and sudden cardiac death: A prospective cohort study

BACKGROUND

Cardiorespiratory optimal point (COP) during exercise, a potentially useful submaximal cardiopulmonary exercise testing (CPET) variable, may be an independent risk factor for cardiovascular disease outcomes. However, the relationship of COP with risk of sudden cardiac death (SCD) has not been previously investigated. We sought to evaluate the association between COP during exercise and SCD risk and determine whether COP improves SCD risk prediction.

METHODS

COP, the minimum value of the ventilatory equivalent for oxygen (VE/VO2) in a given minute of a CPET, was ascertained in 2190 men who underwent clinical exercise testing. Hazard ratios (HRs) (95% confidence intervals [CIs]) and measures of risk discrimination for SCD were calculated.

RESULTS

A total of 240 SCDs death occurred during a median follow-up of 28.8 years. COP was linearly associated with SCD in a dose-response manner. In a multivariable model comprising several established and emerging CVD risk factors, the HR (95% CI) for SCD was 2.51 (1.36-4.62) per standard deviation increase in COP. This was minimally attenuated to 2.36 (1.27-4.37) on further adjustment for high sensitivity C-reactive protein. The association did not vary importantly in several relevant clinical subgroups. Addition of COP to a SCD risk score was associated with a C-index change of 0.0086 (0.0005 to 0.0167; p = .038) and difference in -2 log likelihood (p = .017).

CONCLUSIONS

COP during exercise is strongly, inversely and independently associated with SCD in a graded fashion. COP during exercise may potentially be used for the prediction of the long-term risk for SCD beyond established CVD risk factors.

Fitness and Mortality Among Persons 70 Years and Older Across the Spectrum of Cardiovascular Disease Risk Factor Burden: The FIT Project

OBJECTIVE

To determine whether fitness could improve mortality risk stratification among older adults compared with cardiovascular disease (CVD) risk factors.

METHODS

We examined 6509 patients 70 years of age and older without CVD from the Henry Ford ExercIse Testing Project (FIT Project) cohort. Patients performed a physician-referred treadmill stress test between 1991 and 2009. Traditional categorical CVD risk factors (hypertension, hyperlipidemia, diabetes, and smoking) were summed from 0 to 3 or more. Fitness was grouped as low, moderate, and high (<6, 6 to 9.9, and ≥10 metabolic equivalents of task). All-cause mortality was ascertained through US Social Security Death Master files. We calculated age-adjusted mortality rates, multivariable adjusted Cox proportional hazards, and Kaplan-Meier survival models.

RESULTS

Patients had a mean age of 75±4 years, and 3385 (52%) were women; during a mean follow-up of 9.4 years, there were 2526 deaths. A higher fitness level (P<.001), not lower CVD risk factor burden (P=.31), was associated with longer survival. The age-adjusted mortality rate per 1000 person-years was 56.7 for patients with low fitness and 0 risk factors compared with 24.9 for high fitness and 3 or more risk factors. Among patients with 3 or more risk factors, the adjusted mortality hazard was 0.68 (95% CI, 0.61 to 0.76) for moderate and 0.51 (95% CI, 0.44 to 0.60) for high fitness compared with the least fit.

CONCLUSION

Among persons aged 70 years and older, there was no significant difference in survival of patients with 0 vs 3 or more risk factors, but a higher fitness level identified older persons with good long-term survival regardless of CVD risk factor burden.

Cardiorespiratory optimal point during exercise testing is related to cardiovascular and all-cause mortality

Cardiorespiratory optimal point (COP) during exercise may be a potentially clinically useful cardiopulmonary exercise testing (CPET) variable, but its prognostic relevance for adverse cardiovascular disease (CVD) outcomes is unknown. We aimed to assess the association of COP during exercise with fatal mortality outcomes and the extent to which COP could improve the prediction of CVD mortality. Cardiorespiratory optimal point, the minimum value of the ventilatory equivalent for oxygen (VE/VO2) in a given minute of a CPET, was defined in 2,205 men who underwent CPET. Hazard ratios (HRs) (95% confidence intervals [CIs]) for outcomes and measures of risk discrimination for CVD mortality were calculated. During a median follow-up of 28.8 years, 402 fatal CHDs, 607 fatal CVDs, and 1,348 all-cause mortality events occurred. COP was continually associated with each outcome in a dose-response manner. On adjustment for established and emerging risk factors, the HRs (95% CIs) for fatal CHD, fatal CVD, and all-cause mortality were 3.05 (1.94-4.81), 2.82 (1.91-4.18) and 2.46 (1.85-3.27), respectively, per standard deviation increase in COP. After further adjustment for high sensitivity C-reactive protein, the HRs were 2.82 (1.78-4.46), 2.57 (1.73-3.81), and 2.27 (1.70-3.02), respectively. Addition of COP to a CVD mortality risk prediction model containing established risk factors was associated with a C-index change of 0.0139 (0.0040 to 0.0238; p = 0.006) at 25 years. COP during exercise is directly associated with fatal cardiovascular and all-cause mortality events in dose-response fashions. COP during exercise may improve the prediction of the long-term risk for CVD mortality.

Fitness vs. fatness as determinants of survival in non-institutionalized older adults: The EXERNET multi-center study

BACKGROUND

Physical fitness and body composition are important health indicators, nevertheless their combined pattern inter-relationships and their association with mortality are poorly investigated.

METHODS

This longitudinal study is part of the Spanish EXERNET-Elder project. Person-months follow-up were calculated from the interview date, performed between June 2008 and November 2009, until date of death or censoring on March 2018 (whichever came first). In order to be included, participants had to fulfill the following criteria: 1) be over 65 years old, 2) live independently at home, 3) not suffer dementia and/or cancer and 4) have a BMI above 18.5. Body fat and weight were assessed by a bioelectrical impedance analyzer. Fitness was measured with the Senior Fitness and the one leg static balance tests. The Spanish Death Index was consulted for the death's identification. Cluster analysis was performed to identify Fat-Fit patterns and traditional cut points and percentiles to create the Fat-Fit groups. Cox proportional hazards regression models were used to calculate the hazard ratios of death in clustered Fat-Fit patterns and in traditional Fat-Fit groups.

RESULTS

A total of 2299 older adults (76.8% of women) were included with a baseline mean age of 71.9 ± 5.2 years. A total of 196 deaths (8.7% of the sample) were identified during the 8 years of follow up. Four clustered Fat-Fit patterns (Low fat-Fit, Medium fat-Fit, High fat-Unfit and Low fat-Unfit) and nine traditional Fat-Fit groups emerged. Using the Low fat-Fit pattern as the reference, significantly increased mortality was noted in High fat-Unfit (HR: 1.68, CI: 1.06 - 2.66) and Low fat-Unfit (HR: 2.01, CI: 1.28 - 3.16) groups. All the traditional Fit groups showed lower mortality risk when compared to the reference group (obese-unfit group).

CONCLUSIONS

Physical fitness is a determinant factor in terms of survival in community-dwelling older adults, independently of adiposity levels.

The metabolic signature of cardiorespiratory fitness: a protocol for a systematic review and meta-analysis

INTRODUCTION

A low cardiorespiratory fitness (CRF) is a strong and independent predictor of cardiometabolic, cancer and all-cause mortality. To date, the mechanisms linking CRF with reduced mortality remain largely unknown. Metabolomics, which is a powerful metabolic phenotyping technology to unravel molecular mechanisms underlying complex phenotypes, could elucidate how CRF fosters human health.

METHODS AND ANALYSIS

This study aims at systematically reviewing and meta-analysing the literature on metabolites of any human tissue sample, which are positively or negatively associated with CRF. Studies reporting estimated CRF will not be considered. No restrictions will be placed on the metabolomics technology used to measure metabolites. PubMed, Web of Science and EMBASE will be searched for relevant articles published until the date of the last search. Two authors will independently screen full texts of selected abstracts. References and citing articles of included articles will be screened for additional relevant publications. Data regarding study population, tissue samples, analytical technique, quality control, data processing, metabolites associated to CRF, cardiopulmonary exercise test protocol and exercise exhaustion criteria will be extracted. Methodological quality will be assessed using a modified version of QUADOMICS. Narrative synthesis as well as tabular/charted presentation of the extracted data will be included. If feasible, meta-analyses will be used to investigate the associations between identified metabolites and CRF. Potential sources of heterogeneity will be explored in meta-regressions.

ETHICS AND DISSEMINATION

No ethics approval is required. The results will be published in a peer-reviewed journal and as conference presentation.

PROSPERO REGISTRATION NUMBER

CRD42020214375.

Accuracy of Exercise-based Equations for Estimating Cardiorespiratory Fitness

Equations are often used to predict cardiorespiratory fitness (CRF) from submaximal or maximal exercise tests. However, no study has comprehensively compared these exercise-based equations with directly measured CRF using data from a single, large cohort.

PURPOSE

This study aimed to compare the accuracy of exercise-based prediction equations with directly measured CRF and evaluate their ability to classify an individual's CRF.

METHODS

The sample included 4871 tests from apparently healthy adults (38% female, age 44.4 ± 12.3 yr (mean ± SD)). Estimated CRF (eCRF) was determined from 2 nonexercise equations, 3 submaximal exercise equations, and 10 maximal exercise equations; all eCRF calculations were then compared with directly measured CRF, determined from a cardiopulmonary exercise test. Analysis included Pearson product-moment correlations, standard error of estimate values, intraclass correlation coefficients, Cohen κ coefficients, and the Benjamini-Hochberg procedure to compare eCRF with directly measured CRF.

RESULTS

All eCRF values from the prediction equations were associated with directly measured CRF (P < 0.01), with intraclass correlation coefficient estimates ranging from 0.07 to 0.89. Although significant agreement was found when using eCRF to categorize participants into fitness tertiles, submaximal exercise equations correctly classified an average of only 51% (range, 37%-58%) and maximal exercise equations correctly classified an average of only 59% (range, 43%-76%).

CONCLUSIONS

Despite significant associations between exercise-based prediction equations and directly measured CRF, the equations had a low degree of accuracy in categorizing participants into fitness tertiles, a key requirement when stratifying risk within a clinical setting. The present analysis highlights the limited accuracy of exercise-based determinations of eCRF and suggests the need to include cardiopulmonary measures with maximal exercise to accurately assess CRF within a clinical setting.

Prognostic Relevance of Cardiorespiratory Fitness as Assessed by Submaximal Exercise Testing for All-Cause Mortality: A UK Biobank Prospective Study

OBJECTIVE

To investigate whether the inverse associations of cardiorespiratory fitness (CRF) with all-cause and cardiovascular mortality in the general population vary among individuals who are at different levels of pretest risk.

PATIENTS AND METHODS

Cardiorespiratory fitness was assessed through submaximal bicycle tests in 58,892 participants aged 40 to 69 years who completed baseline questionnaires between January 1, 2006, and December 31, 2010, in the UK Biobank Prospective Study. Participants were categorized into risk categories, which determined allocation to an individualized bicycle protocol. The groups at minimal risk (category 1), small risk (category 2), and medium risk (category 3) were tested at 50%, 35% of the predicted maximal workload, and constant level, respectively. We investigated associations of CRF with mortality across different levels of pretest risk and determined whether CRF improves risk prediction.

RESULTS

During a median follow-up of 5.8 years, 936 deaths occurred. Cardiorespiratory fitness was linearly associated with mortality risk. Comparing extreme fifths of CRF, the multivariable-adjusted hazard ratios (95% CIs) for mortality were 0.63 (0.52-0.77), 0.54 (0.36-0.82), 0.81 (0.46-1.43), and 0.58 (0.48-0.69) in categories 1, 2, and 3 and overall population, respectively. The addition of CRF to a 5-year mortality risk score containing established risk factors was associated with a C-index change (0.0012; P=.49), integrated discrimination improvement (0.0005; P<.001), net reclassification improvement (+0.0361; P=.005), and improved goodness of fit (likelihood ratio test, P<.001). Differences in 5-year survival were more pronounced across levels of age, smoking status, and sex.

CONCLUSION

Cardiorespiratory fitness, assessed by submaximal exercise testing, improves mortality risk prediction beyond conventional risk factors and its prognostic relevance varies across cardiovascular risk levels.

Bidirectional associations between fitness and fatness in youth: A longitudinal study

The aim was to examine the bidirectional association between cardiorespiratory fitness (CRF) and fatness in a 2-year longitudinal study conducted in young people. A total of 1082 children (512 females) and 727 adolescents (342 females) with complete data at baseline and follow-up were included. CRF was determined by the 20-m shuttle run test. Height and weight were measured, and body mass index and fat mass index (kg/m² ) were calculated. Triceps and subscapular skinfolds were assessed to compute body fat percentage. Bidirectionality was tested by including CRF and each fatness index as exposures and outcomes, alternatively, in different regression models. CRF was prospectively associated with fatness index levels (ß from -0.186 to -0.528; P < .001), remaining significant in children after adjusting for baseline fatness indices. Fatness indices were prospectively associated with CRF (ß from -0.207 to -0.479; P < .001), with no substantial changes observed in children and female adolescents when baseline CRF was considered. Changes in CRF were prospectively associated with several fatness indices, regardless of body fatness at baseline (ß from -0.062 to -0.220; P < .05). Body fatness changes were associated with future CRF levels, independently of baseline CRF, especially in children of both sexes and male adolescents (ß from -0.079 to -0.260; P < .05). Overall, a bidirectional association was observed between CRF and fatness in children and adolescents. The attainment of optimal CRF and fatness levels in early ages should be promoted since it could result in favorable future fatness and CRF levels, respectively, which are two key determinants of health status.

Development of Global Reference Standards for Directly Measured Cardiorespiratory Fitness: A Report From the Fitness Registry and Importance of Exercise National Database (FRIEND)

OBJECTIVE

To begin the process of developing global reference standards for adults from directly measured cardiorespiratory fitness (CRF).

METHODS

Percentiles of maximal oxygen consumption (VO₂max) for men and women were determined for each decade from 20 through 79 years of age using International data from the Fitness Registry and Importance of Exercise: A National Database (FRIEND-I) along with previously published data from seven studies. FRIEND-I data from January 1, 2014, through January 1, 2019, included 11,678 maximal treadmill tests from three countries, whereas the previously published reports included 32,329 maximal treadmill tests from six countries.

RESULTS

FRIEND-I data revealed significant differences between sex and age groups for VO₂max (P<0.01). For the 20- to 29-years of age group, the 50^th percentile VO₂max in men and women were 49.5 mLO₂⋅kg^-1⋅min^-1 and 40.6 mLO₂⋅kg^-1⋅min^-1, respectively. VO₂max declined an average of 9% per decade with the 50^th percentile for the 70- to 79-years of age group having a VO₂max of 30.8 mLO₂⋅kg^-1⋅min^-1 in men and 25.0 mLO₂⋅kg^-1⋅min^-1 in women. These results were similar in magnitude and direction to the previously published literature. Within both the FRIEND-I and previously published data there were CRF differences between countries.

CONCLUSION

This report begins to establish global reference standards for CRF. Continued development of FRIEND-I will increase global representation providing an improved ability to identify and stratify CRF risk categories.

Aerobic capacity is associated with disease activity and cardiovascular risk factors in early rheumatoid arthritis

Objectives

The aim of this study was to investigate aerobic capacity and its associations with disease activity and risk factors for cardiovascular disease (CVD) in early rheumatoid arthritis (RA).

Methods

This cross‐sectional study included 67 patients with early RA. Aerobic capacity was estimated with the Åstrand submaximal test adjusted according to the Nord‐Tröndelag Health Study formula. The following were also assessed: subclinical atherosclerosis by carotid intima‐media thickness and pulse wave analysis; body composition by dual X‐ray absorptiometry; estimated CVD mortality risk by the Systematic Coronary Risk Evaluation; disease activity by the Disease Activity Score 28, C‐reactive protein and erythrocyte sedimentation rate; blood lipids by total cholesterol, low‐density lipoproteins, high‐density lipoproteins, and triglycerides; and functional ability by the Stanford health assessment questionnaire. Univariate and multiple linear regression analyses were performed to explore the associations between variables.

Results

The mean (SD) aerobic capacity was 31.6 (8.7) ml O₂⁻¹ kg min⁻¹. Disease activity and risk factors for CVD were more favourable for patients with aerobic capacity above the median value. Aerobic capacity was associated with ESR and several CVD risk factors, independent of age and sex. In a multiple regression model that was adjusted for age and sex, aerobic capacity was significantly associated with per cent body fat (β = −0.502, 95% CI [−0.671, −0.333]) and triglycerides (β = −2.365, 95% CI [−4.252, −0.479]).

Conclusions

Disease activity and risk factors for CVD were in favour for patients with a higher aerobic capacity. Aerobic capacity was associated with disease activity and several risk factors for CVD, independent of age and sex. In RA, these findings may provide insights into the benefits of using aerobic capacity as a marker to prevent CVD.

The Influence of Change in Cardiorespiratory Fitness With Short-Term Exercise Training on Mortality Risk From The Ball State Adult Fitness Longitudinal Lifestyle Study

OBJECTIVE

To assess the influence of changes in cardiorespiratory fitness (CRF) after exercise training on mortality risk in a cohort of self-referred, apparently healthy adults.

PATIENTS AND METHODS

A total of 683 participants (404 men, 279 women; mean age: 42.7±11.0 y) underwent two maximal cardiopulmonary exercise tests (CPX) between March 20, 1970, and December 11, 2012, to assess CRF at baseline (CPX1) and post-exercise training (CPX2). Participants were followed for an average of 29.8±10.7 years after their CPX2. Cox proportional hazards models were performed to determine the relationship of CRF change with mortality, with change in CRF as a continuous variable, as well as a categorical variable. A Wald chi-square test was used to compare the coefficients estimating the relationship of peak oxygen consumption (VO_2peak) at CPX1 with VO_2peak measured at CPX2 with time until death for all-cause mortality.

RESULTS

During the follow-up period there were 180 deaths. When assessed independently, there were 20% (95% CI, 10-49%) and 38% (95% CI, 7-66%) lower mortality risks per 1 metabolic equivalent improvement in CRF (P<.01) in men and women, respectively, after multivariable adjustment. Those that remained unfit had ∼2-fold higher risk for all-cause mortality compared with those that remained fit and CRF at CPX2 was a stronger predictor of all-cause mortality than at CPX1 (P=.02).

CONCLUSION

Improving CRF through exercise training lowers mortality risk. Clinicians should encourage individuals to participate in exercise training to improve CRF to lower risk of mortality.

A Systematic Review of Fitness Apps and Their Potential Clinical and Sports Utility for Objective and Remote Assessment of Cardiorespiratory Fitness

BACKGROUND

Cardiorespiratory fitness (CRF) assessment provides key information regarding general health status that has high clinical utility. In addition, in the sports setting, CRF testing is needed to establish a baseline level, prescribe an individualized training program and monitor improvement in athletic performance. As such, the assessment of CRF has both clinical and sports utility. Technological advancements have led to increased digitization within healthcare and athletics. Nevertheless, further investigation is needed to enhance the validity and reliability of existing fitness apps for CRF assessment in both contexts.

OBJECTIVES

The present review aimed to (1) systematically review the scientific literature, examining the validity and reliability of apps designed for CRF assessment; and (2) systematically review and qualitatively score available fitness apps in the two main app markets. Lastly, this systematic review outlines evidence-based practical recommendations for developing future apps that measure CRF.

DATA SOURCES

The following sources were searched for relevant studies: PubMed, Web of Science®, ScopusTM, and SPORTDiscus, and data was also found within app markets (Google Play and the App Store).

STUDY ELIGIBILITY CRITERIA

Eligible scientific studies examined the validity and/or reliability of apps for assessing CRF through a field-based fitness test. Criteria for the app markets involved apps that estimated CRF.

STUDY APPRAISAL AND SYNTHESIS METHODS

The scientific literature search included four major electronic databases and the timeframe was set between 01 January 2000 and 31 October 2018. A total of 2796 articles were identified using a set of fitness-related terms, of which five articles were finally selected and included in this review. The app market search was undertaken by introducing keywords into the search engine of each app market without specified search categories. A total of 691 apps were identified using a set of fitness-related terms, of which 88 apps were finally included in the quantitative and qualitative synthesis.

RESULTS

Five studies focused on the scientific validity of fitness tests with apps, while only two of these focused on reliability. Four studies used a sub-maximal fitness test via apps. Out of the scientific apps reviewed, the SA-6MWTapp showed the best validity against a criterion measure (r = 0.88), whilst the InterWalk app showed the highest test-retest reliability (ICC range 0.85-0.86).

LIMITATIONS

Levels of evidence based on scientific validity/reliability of apps and on commercial apps could not be robustly determined due to the limited number of studies identified in the literature and the low-to-moderate quality of commercial apps.

CONCLUSIONS

The results from this scientific review showed that few apps have been empirically tested, and among those that have, not all were valid or reliable. In addition, commercial apps were of low-to-moderate quality, suggesting that their potential for assessing CRF has yet to be realized. Lastly, this manuscript has identified evidence-based practical recommendations that apps might potentially offer to objectively and remotely assess CRF as a complementary tool to traditional methods in the clinical and sports settings.

Screening for unhealthy diet and exercise habits: The electronic health record and a healthier population

The US spends more money than any other country in the world on health care but does not have the best health outcomes. Most healthcare dollars are spent on treatment of preventable chronic conditions including heart disease, hypertension, diabetes, hypertension, and obesity. Many recent studies have shown that a poor diet and low cardiorespiratory fitness are associated with significant morbidity and an increased risk of all-cause mortality. There is evidence that those with higher cardiorespiratory fitness have lower annual healthcare costs. Despite continued research on the essential role of diet and exercise in optimal health, these vital health behaviors have been slow to change in the US population and do not receive adequate attention. We propose more objective screening, visible and monitored in the Electronic Health Record, to improve awareness, help educate patients, and monitor their progress over time. It would also help identify those individuals that would benefit from referral to interventional behavioral resources in the clinic and community. With an increased focus on preventive and population health measures, now is an ideal time to include both exercise and diet in health metrics. A few relatively simple changes could prompt providers to assess and educate patients about nutrition and fitness and promote a healthier population.

Exercise Testing in Sports Medicine

BACKGROUND

Bicycle and treadmill exercise tests are used in sports medicine and occupational medicine to detect latent disease, to monitor treatment, and to measure patients' physical performance ability and reserve. In this review, we describe the indications, contraindications, and manner of performance of these tests, along with the variables tested, criteria for evaluation, (sub)maximal stress, and the factors that affect these tests, including age, sex, and medications.

METHODS

This review is based on pertinent articles retrieved by a selective literature search and on the ergometry guidelines of four medical specialty societies.

RESULTS

The proper performance of ergometric stress tests calls for preparation and monitoring by qualified staff as well as standardized testing conditions. Ergometric studies are indispensable as a clinical diagnostic method for the early recognition of disease, for follow-up over time, and for individual counseling. The patient's maximal achievable performance is a predictor of morbidity and mortality. Among the variables that can be measured in the submaximal performance range, the respiratory rate, heart rate, and lactate performance curves are more accurate prognostic predictors than the so-called threshold values (physical working capacity, anaerobic-aerobic threshold). Ergometric stress tests can be used to detect (among other conditions) latent hypertension, pulmonary diseases (e.g., exertional asthma), pabnormal ECG changes, and cardiovascular disorders (e.g., ischemia, arrhythmia, congestive heart failure). The ergometric findings are influenced by the choice of stress-inducing protocol. They provide important information for the planning and monitoring of exercise training and for the treatment of persons suffering from diverse physical conditions, as well as for leisure-time athletes. They are less suit- able for use in the design of training programs for high-performance athletes.

CONCLUSION

Ergometric stress tests provide important data in clinical and preventive medicine. The findings are often difficult to interpret because of the wide range of normal findings, the use of different stress-inducing protocols, and the lack of gen- erally accepted reference values. The establishment of a nationwide fitness and health registry for ergometric data would be very helpful for the individualized inter- pretation of test findings and for the monitoring of exercise training and therapy.