Longitudinal cardiorespiratory fitness algorithms for clinical settings

Estimating cardiorespiratory fitness in older adults using the international physical activity questionnaire

Introduction

Non-exercise estimates of cardiorespiratory fitness hold great utility for epidemiological research and clinical practice. Older adults may yield the greatest benefit from fitness estimates due to limited capacity to undergo strenuous maximal exercise testing, however, few of the previously developed non-exercise equations are suitable for use in older adults. Thus, the current study developed a non-exercise equation for estimating cardiorespiratory fitness in older adults derived from the widely used International Physical Activity Questionnaire (IPAQ).

Methods

This study was a secondary analysis of baseline data from a randomized controlled trial. Participants were community-dwelling, cognitively unimpaired older adults aged 60-80 years (n = 92). They completed the IPAQ and underwent maximal exercise testing on a cycle ergometer. Stepwise linear regression was used to determine the equation in a randomly selected, sex-balanced, derivation subset of participants (n = 60), and subsequently validated using a second subset of participants (n = 32).

Results

The final equation included age, sex, body mass index and leisure time activity from the IPAQ and explained 61% and 55% of the variance in the derivation and validation groups, respectively (standard error of estimates = 3.9, 4.0). Seventy-seven and 81% of the sample fell within ±1SD (5.96 and 6.28 ml·kg-1·min-1) of measured VO2peak for the derivation and validation subgroups. The current equation showed better performance compared to equations from Wier et al. (2006), Jackson et al. (1990), and Schembre & Riebe (2011), although it is acknowledged previous equations were developed for different populations.

Conclusions

Using non-exercise, easily accessible measures can yield acceptable estimates of cardiorespiratory fitness in older adults, which should be further validated in other samples and examined in relation to public health outcomes.

Using cardiorespiratory fitness to operationalize vitality: a path analysis on the hierarchical structure of intrinsic capacity

BACKGROUND

There is a lack of consensus about the operationalization of vitality, which is one of the intrinsic capacity (IC) domains. In particular, no study has investigated whether cardiorespiratory fitness (CRF) can be considered a vitality indicator.

OBJECTIVE

To examine whether vitality is the upstream domain of IC, and establish the validity of CRF as a vitality indicator, using maximal oxygen consumption (VO2 max) as a representative.

METHODS

561 older adults from a longitudinal cohort study were included. Variables under consideration were VO2 max, other IC domains, instrumental activities of daily living (IADL), and handgrip strength, which was considered an already validated indicator of vitality. Using handgrip strength as the reference point, path analyses were performed to examine whether VO2 max followed a similar hierarchical structure in predicting change in IADL difficulty through other IC domains.

RESULTS

The mean age of the participants was 75.5 years. The path model in which vitality was measured by VO2 max demonstrated adequate fit, which was similar to the model in which vitality was measured by handgrip strength. Regarding the path coefficients, the model using VO2 max demonstrated significant total and indirect effects. Notably, the indirect effect was due to the locomotor domain (standardized coefficient = -0.148, p < .001), but not the cognitive or psychological domain.

CONCLUSION

Vitality is the upstream domain of IC. VO2 max can be considered an indicator to operationalize the vitality concept.

Estimated Cardiorespiratory Fitness and Metabolic Risks

This review focuses on the emerging evidence for the association between non-exercise fitness testing, estimated cardiorespiratory fitness (eCRF), and metabolic risk factors. Given the challenges associated with directly measuring cardiorespiratory fitness (CRF) in large populations, eCRF presents a practical alternative for predicting metabolic health risks. A literature search identified seven relevant cohort studies from 2020 to 2024 that investigated the association of eCRF with hypertension, hyperglycemia, dyslipidemia, and obesity. This review consistently demonstrates an inverse relationship between higher eCRF and a lower incidence of metabolic risks, which is in line with CRF cohort studies. It highlights the importance of low eCRF as a primordial indicator for metabolic risks and underscores the potential for broader application. Future research directions should include exploring eCRF's predictive ability across diverse populations and health outcomes and testing its real-world applicability in healthcare and public health settings.

Independent and joint associations of estimated cardiorespiratory fitness and its dynamic changes and obesity with the risk of hypertension: A prospective cohort

Our aim was to examine the independent and joint associations of estimated cardiorespiratory fitness (CRF) and its changes and obesity with risk of hypertension in a rural Chinese population. A prospective cohort including 9848 adults without hypertension at baseline was enrolled. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated by logistic regression models. Restricted cubic splines were used to model the dose-response relationship. During 6 years follow-up, 2,019 individuals developed hypertension. A negative association between estimated CRF and hypertension incidence was observed, with the risk being 0.87 (0.84-0.90) per MET increment. For estimated CRF change, the risks of hypertension were 1.50 (1.27-1.77) and 0.75 (0.59-0.97) for decreasers and increasers, respectively, compared to maintainers. Joint analyses showed individuals in the overweight/obesity-fourth quartile of estimated CRF had a 2.08 times higher risk of hypertension than those in the normal weight-first quartile (Pinteraction < 0.05). Those overweight/obesity-decreasers had the highest risk (OR: 2.19, 95%CI: 1.71-2.81; Pinteraction < 0.05) compared to the normal-maintainers. Similar results for abdominal obesity were also observed. Estimated CRF and its dynamic changes showed a negative association with hypertension incidence in the rural Chinese population.

Cardiorespiratory fitness and metabolic risk in Chinese population: evidence from a prospective cohort study

BACKGROUND

Studies on the association between estimated cardiorespiratory fitness (CRF) and changes in metabolic risk in the Chinese population are limited. This study aims to examine the associations between CRF and changes in metabolic risk.

SUBJECTS AND METHODS

We included 4,862 and 2,700 participants recruited from 28 provinces in the China Health and Retirement Longitudinal Study (CHARLS) in the baseline (Wave 1) and follow-up (Wave 4) analyses, respectively. CRF was calculated using sex-specific longitudinal non-exercise equations. Metabolic indicators included systolic blood pressure (SBP), diastolic blood pressure (DBP), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), and fasting plasma glucose (FPG) levels. The metabolic score was calculated as the number of changes in the above metabolic indicators above the 75th percentile of the distribution of changes (equal to or below the 25th percentile for HDL-C).

RESULTS

In the baseline analysis, CRF was negatively associated with SBP, DBP, TG, and FPG, and positively correlated with HDL-C after adjusting for age, smoking status, and drinking status (all P < 0.0001) in both males and females. In the follow-up analysis, higher baseline CRF was significantly related to a decrease in SBP, DBP, TG, FPG, and metabolic score (all P < 0.0005), and increased HDL-C (P < 0.0001) after further adjustment for corresponding baseline metabolic indicators. The associations remained significant after stratification by sex, except for the changes in HDL-C levels in females. Furthermore, improved CRF was associated with favorable changes in DBP, TG, HDL-C, FPG, and metabolic scores in all populations and males. Significant associations between changes in CRF and DBP, TG, and FPG levels were found in females.

CONCLUSION

Higher baseline CRF and improved CRF were associated with favorable changes in metabolic indicators.

Estimated cardiorespiratory fitness and incident risk of cardiovascular disease in China

BACKGROUND

Limited evidence is available on the association between estimated cardiorespiratory fitness (e-CRF) and incidence of cardiovascular disease (CVD) in Chinese population.

METHODS

A total of 10,507 adults including 5084 men (48.4%) and 5423 (51.6%) women with a median age of 56.0 (25% quantile: 49, 75% quantile 63) years from the China Health and Retirement Longitudinal Study (CHARLS) was recruited in 2011 as baseline. The CVD incident events were followed-up until 2018. e-CRF was calculated from sex-specific longitudinal non-exercise equations and further grouped into quartiles. Cox proportional models were used to calculate hazard ratio (HR) and 95% confidence interval (CI) for incidence risks of CVD, heart disease and stroke.

RESULTS

During a median follow-up of 7 years, a total of 1862 CVD, 1409 heart disease and 612 stroke events occurred. In fully adjusted models, each one MET increment of e-CRF was associated with lower risk of CVD (HR = 0.91, 95%CI = 0.85-0.96 for males, HR = 0.87, 95%CI = 0.81-0.94 for females). Compared with the Quartile (Q)1 group, the HRs (95%CI) of the Q2, Q3 and Q4 groups were 0.84 (0.63-1.03), 0.72 (0.57-0.91) and 0.66 (0.51-0.87) for CVD in males. Females had HRs of 0.79 (0.66-0.96) in Q2, 0.71 (0.57-0.88) in Q3 and 0.58 (0.45-0.75) in Q4 for CVD. The associations between e-CRF and heart disease and stroke were slightly weaker than that for CVD in both males and females.

CONCLUSIONS

Higher e-CRF decreases the incident risk of CVD, heart disease and stroke.

The "Aging Effect" of BMI on Cardiorespiratory Fitness: A New Insight on Functional Evaluation in Obesity

Cardiorespiratory fitness (CRF) is a strong predictor of morbidity and mortality in patients with obesity. This study investigates the CRF range and its clinical determinants in patients with obesity. Moreover, a practical proposal for CRF interpretation is provided. In this study, 542 patients (69% females) with BMI ≥ 30 kg/m2 performed an incremental cardiopulmonary exercise test (CPET). Patients had a median (IQR) age of 47.0 (6.2) years with a mean BMI of 41.7 ± 6.7 kg/m2. Normal values curves of VO2peak/kg showed a median (IQR) of 20.3 (37.6) mL/min/kg. The lower-quartile threshold of VO2peak/kg was at 17.9 mL/min/kg. Analysis of covariance revealed that VO2peak/kg inversely correlates with age and BMI with a significant age × BMI interaction effect (all p < 0.0001); as BMI class increases, CRF decreases, but a smaller age-related decline in VO2peak/kg is observed. A multivariate logistic regression demonstrated that belonging to the lower quartile of VO2peak/kg was independently determined by age (OR 2.549, 95% CI 1.205-5.392, p < 0.0001) and BMI (OR 5.864, 95% CI 2.920-11.778, p < 0.0001) but not by comorbidities. At very high BMI, the effect of age on functional capacity is lower, suggesting that BMI acts as an "aging factor" on CRF. Age and BMI, but not comorbidities, are independent determinants of low VO2peak/kg.

The association of aerobic and muscular fitness with cognitive impairment: Findings from a nationally representative survey

This study aimed to characterize the combined association between cardiorespiratory fitness (CRF), muscular strength, and cognitive outcomes in middle-aged and older adults from low and middle-income countries (LMICs). We analyzed cross-sectional, population-based data from adults aged 50 years or older from six LMICs. Mild cognitive impairment (MCI) was defined according to the National Institute on Aging-Alzheimer's Association criteria. Estimated CRF (eCRF) was calculated using previously validated, sex-specific equations. Handgrip strength (HS) was used as an indicator of muscular strength. We used linear and robust Poisson regression models to examine the associations between eCRF, HS, and MCI. Data from 28,339 adults (63.1 [9.5] years) were analyzed. Participants with low eCRF (PR: 1.45; 95%CI: 1.11, 1.90) and HS (PR: 1.92; 95%CI: 1.79, 2.04) were more prone to have MCI. Participants with low HS showed higher likelihood of MCI than those with preserved HS through the CRF range; however, this difference was not seen among highly fit individuals (10 METs or higher). Each 1-MET (PR: 0.77; 95%CI: 0.67, 0.86) and 5-kgf (PR: 0.63; 95%CI: 0.48, 0.79) increase was associated with a reduction in the likelihood of MCI. eCRF and HS were strongly and independently associated with MCI in middle-aged and older adults.

Establishing Reference Data for Fitness Assessment of Law Enforcement Officers Using a Qualitative Systematic Review

Physical fitness tests are a standard means of evaluating the competence of police officers. This qualitative review aims (i) to document, compare, and examine the reference values available in the current literature regarding fitness tests for Law Enforcement Officers (LEOs), and (ii) to define reference values for the most used fitness tests to assess and predict police officer performance. A total of 1879 records were collected for review from two major literature databases, PubMed and ScienceDirect. After applying our exclusion criteria, a total of 19 studies were considered. All studies demonstrated acceptable methodological quality in fitness assessment, and the most used components were muscle strength, muscular endurance, muscle power, aerobic and anaerobic capacity, flexibility, and agility. This review provides (i) a methodological definition for the physical fitness assessment that helps select the most used fitness tests, (ii) a standardised methodology for establishing reference data for fitness tests appropriate for LEOs; and (iii) aggregate reference values for selected fitness tests. This may improve selection and retention procedures, considering that this group performs its duties in an environment and under conditions that differ from those of other occupational groups. Complementarily, this qualitative review also provides a foundation for developing effective interventions to improve each aspect of fitness testing for police officers.

Nonexercise machine learning models for maximal oxygen uptake prediction in national population surveys

OBJECTIVE

Nonexercise algorithms are cost-effective methods to estimate cardiorespiratory fitness (CRF), but the existing models have limitations in generalizability and predictive power. This study aims to improve the nonexercise algorithms using machine learning (ML) methods and data from US national population surveys.

MATERIALS AND METHODS

We used the 1999-2004 data from the National Health and Nutrition Examination Survey (NHANES). Maximal oxygen uptake (VO2 max), measured through a submaximal exercise test, served as the gold standard measure for CRF in this study. We applied multiple ML algorithms to build 2 models: a parsimonious model using commonly available interview and examination data, and an extended model additionally incorporating variables from Dual-Energy X-ray Absorptiometry (DEXA) and standard laboratory tests in clinical practice. Key predictors were identified using Shapley additive explanation (SHAP).

RESULTS

Among the 5668 NHANES participants in the study population, 49.9% were women and the mean (SD) age was 32.5 years (10.0). The light gradient boosting machine (LightGBM) had the best performance across multiple types of supervised ML algorithms. Compared with the best existing nonexercise algorithms that could be applied to the NHANES, the parsimonious LightGBM model (RMSE: 8.51 ml/kg/min [95% CI: 7.73-9.33]) and the extended LightGBM model (RMSE: 8.26 ml/kg/min [95% CI: 7.44-9.09]) significantly reduced the error by 15% and 12% (P < .001 for both), respectively.

DISCUSSION

The integration of ML and national data source presents a novel approach for estimating cardiovascular fitness. This method provides valuable insights for cardiovascular disease risk classification and clinical decision-making, ultimately leading to improved health outcomes.

CONCLUSION

Our nonexercise models provide improved accuracy in estimating VO2 max within NHANES data as compared to existing nonexercise algorithms.

Epidemiological, mechanistic, and practical bases for assessment of cardiorespiratory fitness and muscle status in adults in healthcare settings

Given their importance in predicting clinical outcomes, cardiorespiratory fitness (CRF) and muscle status can be considered new vital signs. However, they are not routinely evaluated in healthcare settings. Here, we present a comprehensive review of the epidemiological, mechanistic, and practical bases of the evaluation of CRF and muscle status in adults in primary healthcare settings. We highlight the importance of CRF and muscle status as predictors of morbidity and mortality, focusing on their association with cardiovascular and metabolic outcomes. Notably, adults in the best quartile of CRF and muscle status have as low as one-fourth the risk of developing some of the most common chronic metabolic and cardiovascular diseases than those in the poorest quartile. The physiological mechanisms that underlie these epidemiological associations are addressed. These mechanisms include the fact that both CRF and muscle status reflect an integrative response to the body function. Indeed, muscle plays an active role in the development of many diseases by regulating the body's metabolic rate and releasing myokines, which modulate metabolic and cardiovascular functions. We also go over the most relevant techniques for assessing peak oxygen uptake as a surrogate of CRF and muscle strength, mass, and quality as surrogates of muscle status in adults. Finally, a clinical case of a middle-aged adult is discussed to integrate and summarize the practical aspects of the information presented throughout. Their clinical importance, the ease with which we can assess CRF and muscle status using affordable techniques, and the availability of reference values, justify their routine evaluation in adults across primary healthcare settings.

A new set of estimated cardiorespiratory fitness equations are associated with cognitive performance in older adults

This study aimed to develop new equations to estimate cardiorespiratory fitness specifically for older adults and, secondly, to analyze the associations of cardiorespiratory fitness, both objectively measured and estimated using new equations, with cognitive performance. Ninety-two older adults (41 females, 65-75 years) from baseline data of a randomized controlled trial were analyzed ("ClinicalTrials.gov" Identifier: NCT03923712). Participants completed 4 measurement sessions including (i) physiological and health indicators in a laboratory setting, (ii) field-based fitness tests, (iii) sociodemographic and physical activity questionnaires, and (iv) a battery of neuropsychological tests to evaluate cognitive performance. The main findings were as follows: (i) a set of new equations with good predictive value for estimated cardiorespiratory fitness were developed (74-87%), using different scenarios of complexity and/or equipment requirements, and (ii) higher estimated cardiorespiratory fitness, even using its simplest equation (eCRF =  - 1261.99 + 1.97 × 6 min walking test (m) + 1.12 × bioimpedance basal metabolic rate (kcal/day) + 5.25 × basal heart rate (bpm)), was associated with better cognitive performance evaluated by several neuropsychological tests (i.e., language, cognitive flexibility, fluency, attention, and working memory), similar to using objectively measured cardiorespiratory fitness. In summary, a new set of estimated cardiorespiratory fitness equations have been developed with predictive values ranging from 74 to 87% that could be used based on necessity, availability of equipment, resources, or measurement context. Moreover, similar to objectively measured cardiorespiratory fitness, this measure of estimated cardiorespiratory fitness was positively associated with performance on language, fluency, cognitive flexibility, attention, and working memory, independently of sex, age, and education level.

Estimated cardiorespiratory fitness in relation to overall, breast and prostate cancer incidence: the Norwegian HUNT study

PURPOSE

To investigate the relationships between the estimated cardiorespiratory fitness (eCRF) and the incidence of overall, breast, and prostate cancer in a large prospective cohort study.

METHODS

We included 46,968 cancer-free adults who participated in the second survey of the Trøndelag Health Study in Norway. Sex-specific non-exercise algorithms were used to estimate CRF. eCRF was classified into sex and age-specific tertiles, that is, into low, medium and high levels. Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

Over a median of 22.1 years' follow-up, there were 7752 overall, 858 breast and 1376 prostate cancer cases. Medium and high levels of eCRF were associated with a reduced incidence of overall cancer in a dose-response manner in all participants (HR 0.96; 95% CI, 0.90-1.01 and HR 0.85; 95% CI, 0.79-0.91, respectively, and P-value for trend <.001). No association was observed between eCRF and breast cancer incidence in women. Only the high level of eCRF seemed to be associated with a reduced incidence of prostate cancer in men (HR 0.85; 95% CI, 0.72-1.02).

CONCLUSIONS

eCRF may be a practical and cost-effective means of investigating the association between the CRF and cancer incidence.

Blood-Based Fingerprint of Cardiorespiratory Fitness and Long-Term Health Outcomes in Young Adulthood

Background Cardiorespiratory fitness is a powerful predictor of health outcomes that is currently underused in primary prevention, especially in young adults. We sought to develop a blood-based biomarker of cardiorespiratory fitness that is easily translatable across populations. Methods and Results Maximal effort cardiopulmonary exercise testing for quantification of cardiorespiratory fitness (by peak oxygen uptake) and profiling of >200 metabolites at rest were performed in the FHS (Framingham Heart Study; 2016-2019). A metabolomic fitness score was derived/validated in the FHS and was associated with long-term outcomes in the younger CARDIA (Coronary Artery Risk Development in Young Adults) study. In the FHS (derivation, N=451; validation, N=914; age 54±8 years, 53% women, body mass index 27.7±5.3 kg/m2), we used LASSO (least absolute shrinkage and selection operator) regression to develop a multimetabolite score to predict peak oxygen uptake (correlation with peak oxygen uptake r=0.77 in derivation, 0.61 in validation; both P<0.0001). In a linear model including clinical risk factors, a ≈1-SD higher metabolomic fitness score had equivalent magnitude of association with peak oxygen uptake as a 9.2-year age increment. In the CARDIA study (N=2300, median follow-up 26.9 years, age 32±4 years, 44% women, 44% Black individuals), a 1-SD higher metabolomic fitness score was associated with a 44% lower risk for mortality (hazard ratio [HR], 0.56 [95% CI, 0.47-0.68]; P<0.0001) and 32% lower risk for cardiovascular disease (HR, 0.68 [95% CI, 0.55-0.84]; P=0.0003) in models adjusted for age, sex, and race, which remained robust with adjustment for clinical risk factors. Conclusions A blood-based biomarker of cardiorespiratory fitness largely independent of traditional risk factors is associated with long-term risk of cardiovascular disease and mortality in young adults.

Updating Framingham CVD risk score using waist circumference and estimated cardiopulmonary function: a cohort study based on a southern Xinjiang population

Purpose

To explore the association between waist circumference (WC), estimated cardiopulmonary function (eCRF), and cardiovascular disease (CVD) risk in southern Xinjiang. Update the Framingham model to make it more suitable for the southern Xinjiang population.

Methods

Data were collected from 7705 subjects aged 30–74 years old in Tumushuke City, the 51st Regiment of Xinjiang Production and Construction Corps. CVD was defined as an individual's first diagnosis of non-fatal acute myocardial infarction, death from coronary heart disease, and fatal or non-fatal stroke. The Cox proportional hazards regression analysis was used to analyze the association between WC, eCRF and CVD risk. Restricted cubic spline plots were drawn to describe the association of the two indicators with CVD risk. We update the model by incorporating the new variables into the Framingham model and re-estimating the coefficients. The discrimination of the model is evaluated using AUC, NRI, and IDI metrics. Model calibration is evaluated using pseudo R² values.

Results

WC was an independent risk factor for CVD (multivariate HR: 1.603 (1.323, 1.942)), eCRF was an independent protective factor for CVD (multivariate HR: 0.499 (0.369, 0.674)). There was a nonlinear relationship between WC and CVD risk (nonlinear χ2 = 12.43, P = 0.002). There was a linear association between eCRF and CVD risk (non-linear χ2 = 0.27, P = 0.6027). In the male, the best risk prediction effect was obtained when WC and eCRF were added to the model (AUC = 0.763((0.734,0.792)); pseudo R² = 0.069). In the female, the best risk prediction effect was obtained by adding eCRF to the model (AUC = 0.757 (0.734,0.779); pseudo R² = 0.107).

Conclusion

In southern Xinjiang, WC is an independent risk factor for CVD. eCRF is an independent protective factor for CVD. We recommended adding WC and eCRF in the male model and only eCRF in the female model for better risk prediction.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-14110-y.

Estimating Cardiorespiratory Fitness Without Exercise Testing or Physical Activity Status in Healthy Adults: Regression Model Development and Validation

Background

Low cardiorespiratory fitness (CRF) is an independent predictor of morbidity and mortality. Most health care settings use some type of electronic health record (EHR) system. However, many EHRs do not have CRF or physical activity data collected, thereby limiting the types of investigations and analyses that can be done.

Objective

This study aims to develop a nonexercise equation to estimate and classify CRF (in metabolic equivalent tasks) using variables commonly available in EHRs.

Methods

Participants were 42,676 healthy adults (female participants: n=9146, 21.4%) from the Aerobics Center Longitudinal Study examined from 1974 to 2005. The nonexercise estimated CRF was based on sex, age, measured BMI, measured resting heart rate, measured resting blood pressure, and smoking status. A maximal treadmill test measured CRF.

Results

After conducting nonlinear feature augmentation, separate linear regression models were used for male and female participants to calculate correlation and regression coefficients. Cross-classification of actual and estimated CRF was performed using low CRF categories (lowest quintile, lowest quartile, and lowest tertile). The multiple correlation coefficient (R) was 0.70 (mean deviation 1.33) for male participants and 0.65 (mean deviation 1.23) for female participants. The models explained 48.4% (SE estimate 1.70) and 41.9% (SE estimate 1.56) of the variance in CRF for male and female participants, respectively. Correct category classification for low CRF (lowest tertile) was found in 77.2% (n=25,885) of male participants and 74.9% (n=6,850) of female participants.

Conclusions

The regression models developed in this study provided useful estimation and classification of CRF in a large population of male and female participants. The models may provide a practical method for estimating CRF derived from EHRs for population health research.

Non-Exercise Estimated Cardiorespiratory Fitness and Incident Hypertension

BACKGROUND

The purpose of the current study is to examine the association between non-exercise estimated cardiorespiratory fitness and incident hypertension by sex.

METHODS

A total of 5513 participants (4403 men and 1110 women) free of hypertension from the Aerobics Center Longitudinal Study were followed for incident hypertension, which was determined as resting systolic or diastolic blood pressure at least 130/80 mm Hg or physician diagnosis. Non-exercise estimated cardiorespiratory fitness was estimated in metabolic equivalents (METs) with sex-specific algorithms. Age, body mass index, waist circumference, and resting heart rate were used as continuous variables, whereas being physically active and current smoking were dichotomous variables. Multivariable Cox regression models were used to examine the association between cardiorespiratory fitness and risk of developing hypertension. Hazard ratios and 95% confidence intervals (CIs) were reported as an index of strength of association.

RESULTS

During an average follow-up of 5 years, 61.7% of men and 39.5% of women developed hypertension. In men, the upper and middle tertiles of cardiorespiratory fitness had 22% (95% CI, 0.71-0.86) and 10% (95% CI, 0.82-0.99) lower risk, respectively, of developing hypertension compared with those in the lower tertile. In women, the upper and middle tertiles of cardiorespiratory fitness had 30% (95% CI, 0.55-0.88) and 6% (95% CI, 0.74-1.18) lower risk, respectively, of developing hypertension. Each 1-MET increment was associated with a 10% higher risk of incident hypertension in the overall sample.

CONCLUSION

Cardiorespiratory fitness estimated using a non-exercise algorithm is inversely associated with risk of developing hypertension in men and women.

Association between cardiorespiratory fitness and risk of all-cause and cause-specific mortality

OBJECTIVE

The association of cardiorespiratory fitness (CRF) with all-cause and cause-specific mortality remains unclear in Chinese population. This study aimed to evaluate the risk of all-cause, cardiovascular disease (CVD), cancer and other-cause mortality in Chinese adults using estimated CRF (eCRF).

PATIENTS AND METHODS

We analysed data for 15,566 participants aged ≥20 years recruited in The Rural Chinese Cohort Study during 2007 to 2008 and followed for mortality during 2013 to 2014. eCRF was calculated with sex-specific longitudinal non-exercise algorithms. Cox proportional-hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause and cause-specific mortality risk according to baseline eCRF.

RESULTS

During a median of 6.01 years of follow-up, 859 deaths occurred, including 359 from CVD, 221 from cancer, and 279 from other causes. Each 1 metabolic equivalent increment in eCRF was associated with decreased risk of all-cause mortality (men: HR 0.70, 95% CI [0.66-0.74]; women: 0.59, [0.54-0.64]); CVD mortality (men: 0.70 [0.64-0.77]; women: 0.55, [0.48-0.62]); and other-cause mortality (men: 0.68 [0.62-0.75]; women: 0.57, [0.49-0.66]). The area under receiver operating characteristic curve was significantly higher for eCRF than its modifiable components (waist circumference, body mass index and resting heart rate) in predicting all-cause and cause-specific mortality incidence (all p < .001).

CONCLUSION

eCRF was inversely associated with all-cause, CVD and other-cause mortality.

Association Between Change in Nonexercise Estimated Cardiorespiratory Fitness and Mortality in Men

Objective

To examine the association between change in nonexercise estimated cardiorespiratory fitness (eCRF) and mortality risk in adult men.

Patients and Methods

A total of 10,445 men (mean age, 44.6±9.3 years) from the Aerobics Center Longitudinal Study underwent 2 comprehensive medical examinations and peak work rate tests between January 1, 1979, and December 31, 2002, with an average time between measures of 5.7±4.9 years. Participants were observed for 11.6±6.4 years after their second examination until death or December 31, 2003. The eCRF was calculated with the Jackson et al (2012) and Nes et al (2011) published nonexercise estimation equations. Cox proportional hazards models were performed to examine the association between change in eCRF and all-cause and cardiovascular disease (CVD) mortality.

Results

There were 601 deaths (192 CVD deaths) during the follow-up period. For both eCRF equations, a higher eCRF at baseline was associated with significant reductions in mortality risk from all causes and CVD (P<.001). Change in eCRF by the Jackson equation remained significantly associated with all-cause mortality (P<.001) and CVD mortality (P=.02) after multivariable adjustment. Every 1 metabolic equivalent (3.5 mL·kg⁻¹·min⁻¹) increase in eCRF was associated with a 21% and 22% reduction in mortality risk from all causes or CVD, respectively. No significant associations were observed between change in eCRF by the Nes equation and all-cause (P=.69) or CVD (P=.85) mortality risk after multivariable adjustment.

Conclusion

The association between change in nonexercise eCRF and mortality risk may be equation dependent.

Independent and joint associations of non-exercise cardiorespiratory fitness and obesity with risk of type 2 diabetes mellitus in the Rural Chinese Cohort Study

BACKGROUND AND AIMS

An association between cardiorespiratory fitness (CRF) and type 2 diabetes mellitus (T2DM) has not been established in the Chinese population. This study aimed to estimate the independent and joint associations of CRF and obesity with T2DM incidence in the rural Chinese population.

METHODS AND RESULTS

We conducted a prospective study of 11,825 non-T2DM subjects among rural Chinese adults. Cox regression models were used to estimate the independent and joint associations between CRF and obesity exposure on T2DM. Restricted cubic splines were used to model the dose-response association. During a median follow-up of 6.01 years, 835 participants developed T2DM. In comparison to quartile 1 of CRF, the multivariate hazard ratios (HRs) and 95% confidence intervals (CIs) of quartiles 2, 3, 4 were 0.75 (0.61-0.91), 0.54 (0.43-0.68), and 0.42 (0.32-0.55), respectively. When stratified by sex, the results were similar. Joint analyses showed that overweight/obesity-unfit individuals had a 2.28 times higher risk of developing T2DM than the normal weight-fit referent (HR 2.28, 95% CI 1.84-2.83; P_interaction <0.001). The risk for the overweight/obesity-fit category (HR 1.61, 95% CI 1.21-2.15) was larger than for the normal weight-unfit category (HR 1.38, 95% CI 0.97-1.95) versus the normal weight-fit referent. Similar joint associations for waist circumference and CRF with T2DM were also observed.

CONCLUSION

A negative association was observed between CRF and risk of T2DM. Overweight/obese or abdominal obesity and unfit participants showed the highest risks of T2DM. It is therefore strongly recommended that fitness-enhancing be encouraged for the prevention of T2DM, especially among obesity participants.

Accuracy of Non-Exercise Estimated Cardiorespiratory Fitness in Japanese Adults

Cardiorespiratory fitness (CRF) is an independent predictor of morbidity and mortality. In Japan, annual physical exams are mandatory in workplace settings, and most healthcare settings have electronic medical records (EMRs). However, in both settings, CRF is not usually determined, thereby limiting the potential for epidemiological investigations using EMR data. PURPOSE: To estimate CRF (mL/kg/min) using variables commonly recorded in EMRs. METHODS: Participants were 5293 Japanese adults (11.7% women) who completed an annual physical exam at a large gas company in Tokyo, Japan, in 2004. The mean age was 48.3 ± 8.0 years. Estimated CRF (eCRF) was based on age, measured body mass index, resting heart rate, systolic and diastolic blood pressure, and smoking. Measured CRF was determined by a submaximal cycle ergometer graded exercise test. RESULTS: Regression models were used for males and females to calculate Pearson’s correlation and regression coefficients. Cross-classification of measured CRF and eCRF was conducted using the lowest quintile, quartile, and tertile as the unfit categories. R’s for eCRF were 0.61 (MD 4.41) for men and 0.64 (MD 4.22) for women. The overall accuracy level was reasonable and consistent across models, yet the unfit lower tertile model provided the best overall model when considering the positive predictive value and sensitivity. CONCLUSION: eCRF may provide a useful method for conducting investigations using data derived from EMRs or datasets devoid of CRF or physical activity measures.

Association of Estimated Cardiorespiratory Fitness in Midlife With Cardiometabolic Outcomes and Mortality

IMPORTANCE

The associations of estimated cardiorespiratory fitness (eCRF) during midlife with subclinical atherosclerosis, arterial stiffness, incident cardiometabolic disease, and mortality are not well understood.

OBJECTIVE

To examine associations of midlife eCRF with subclinical atherosclerosis, arterial stiffness, incident cardiometabolic disease, and mortality.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included 2962 participants in the Framingham Study Second Generation (conducted between 1979 and 2001). Data were analyzed from January 2020 to June 2020.

EXPOSURES

eCRF was calculated using sex-specific algorithms (including age, body mass index, waist circumference, physical activity, resting heart rate, and smoking) and was categorized as: (1) tertiles of standardized eCRF at examination cycle 7 (1998 to 2001); (2) tertiles of standardized average eCRF between examination cycles 2 and 7 (1979 to 2001); and (3) eCRF trajectories between examination cycles 2 and 7, with the lowest tertile or trajectory (ie, low eCRF) as referent group.

MAIN OUTCOMES AND MEASURES

Subclinical atherosclerosis (carotid intima-media thickness [CIMT], coronary artery calcium [CAC] score); arterial stiffness (carotid-femoral pulse wave velocity [-1000/CFPWV]); incident hypertension, diabetes, chronic kidney disease (CKD), cardiovascular disease (CVD), and mortality after examination cycle 7.

RESULTS

A total of 2962 participants were included in this cohort study (mean [SD] age, 61.5 [9.2] years; 1562 [52.7%] women). The number of events or participants at risk after examination cycle 7 (at a mean follow-up of 15 years) was 728 of 1506 for hypertension, 214 of 2268 for diabetes, 439 of 2343 for CKD, 500 of 2608 for CVD, and 770 of 2962 for mortality. Compared with the low eCRF reference value, high single examination eCRF was associated with lower CFPWV (β [SE], -11.13 [1.33] ms/m) and CIMT (β [SE], -0.12 [0.05] mm), and lower risk of hypertension (hazard ratio [HR], 0.63; 95% CI, 0.46-0.85), diabetes (HR, 0.38; 95% CI, 0.23-0.62), and CVD (HR, 0.71; 95% CI, 0.53-0.95), although it was not associated with CKD or mortality. Similarly, compared with the low eCRF reference, high eCRF trajectories and mean eCRF were associated with lower CFPWV (β [SE], -11.85 [1.89] ms/m and -10.36 [1.54] ms/m), CIMT (β [SE], -0.19 [0.06] mm and -0.15 [0.05] mm), CAC scores (β [SE], -0.67 [0.25] AU and -0.63 [0.20] AU), and lower risk of hypertension (HR, 0.54; 95% CI, 0.34-0.87 and HR, 0.48; 95% CI, 0.34-0.68), diabetes (HR, 0.27; 95% CI, 0.15-0.48 and HR, 0.31; 95% CI, 0.18-0.54), CKD (HR, 0.63; 95% CI, 0.40-0.97 and HR, 0.64; 95% CI, 0.44-0.94), and CVD (HR, 0.46; 95% CI, 0.31-0.68 and HR, 0.43; 95% CI, 0.30-0.60). Compared with the reference value, a high eCRF trajectory was associated with lower risk of mortality (HR, 0.69; 95% CI, 0.50-0.95).

CONCLUSIONS AND RELEVANCE

In this cohort study, higher midlife eCRF was associated with lower burdens of subclinical atherosclerosis and vascular stiffness, and with a lower risk of hypertension, diabetes, chronic kidney disease, cardiovascular disease, and mortality. These findings suggest that midlife eCRF may serve as a prognostic marker for subclinical atherosclerosis, arterial stiffness, cardiometabolic health, and mortality in later life.

Prediction of Cardiorespiratory Fitness in Czech Adults: Normative Values and Association with Cardiometabolic Health

Cardiorespiratory fitness (CRF) is a strong independent predictor of morbidity and mortality. However, there is no recent information about the impact of CRF on cardiometabolic risk specifically in Central and Eastern Europe, which are characterized by different biological and social determinants of health. In this cross-sectional study normative CRF values were proposed and the association between CRF and cardiometabolic outcomes was evaluated in an adult Czechian population. In 2054 participants (54.6% females), median age 48 (IQR 19 years), the CRF was predicted from a non-exercise equation. Multivariable-adjusted logistic regressions were carried out to determine the associations. Higher CRF quartiles were associated with lower prevalence of hypertension, type 2 diabetes (T2D) and dyslipidemia. Comparing subjects within the lowest CRF, we see that those within the highest CRF had decreased chances of hypertension (odds ratio (OR) = 0.36; 95% CI: 0.22-0.60); T2D (OR = 0.16; 0.05-0.47), low HDL-c (OR = 0.32; 0.17-0.60), high low-density lipoprotein (OR = 0.33; 0.21-0.53), high triglycerides (OR = 0.13; 0.07-0.81), and high cholesterol (OR = 0.44; 0.29-0.69). There was an inverse association between CRF and cardiometabolic outcomes, supporting the adoption of a non-exercise method to estimate CRF of the Czech population. Therefore, more accurate cardiometabolic studies can be performed incorporating the valuable CRF metric.

Association of Exercise Behavior with Overall Survival in Stage I-IIIA Lung Cancer

Rationale: Exercise assessments may help predict outcomes for patients with diagnosed lung cancer. Objectives: We examined the relationship between prediagnosis exercise behavior and clinical outcomes among patients with stage I-IIIA lung cancer. Methods: In a retrospective cohort study of patients with stage I-IIIA lung cancer at Kaiser Permanente Colorado who had at least one Exercise Vital Sign assessment-a questionnaire tool to help promote exercise in chronic disease management-within the year before diagnosis, we defined exercise behavior as active (any min/wk of moderate-to-vigorous-intensity physical activity) or inactive (no moderate-to-vigorous physical activity). The outcomes were 1) overall survival (OS) and 2) acute healthcare use (AHCU). We used the Kaplan-Meier method, Cox proportional hazard model, and negative binomial regression model to analyze the effects of exercise on outcomes, adjusting for demographic, socioeconomic, clinical, and lung-cancer characteristics. Results: Among 552 patients with lung cancer, 230 (42%) were identified as physically active before their diagnosis of cancer. There was no significant difference in the stage distribution between active and inactive patients. The median survival times were 2.4 years for the active group and 1.8 years for inactive patients (P < 0.001). The mean rates (standard deviations) of AHCU were 1.09 (1.55) and 2.31 (5.61) per person-year for active and inactive groups, respectively (P < 0.01). Active exercise, compared with inactivity, was associated with better OS (hazard ratio, 0.52 [0.39-0.69]) and lower AHCU (rate ratio, 0.63 [0.49-0.80]) in unadjusted analyses; in adjusted analyses, active exercise was associated with better OS (hazard ratio, 0.62 [0.45-0.86]), but AHCU was not lower by a statistically significant amount (rate ratio, 0.82 [0.65-1.04]). Conclusions: Prediagnosis active exercise was associated with better OS after diagnosis of stage I-IIIA lung cancer. Exercise assessments may help predict outcomes, risk-stratify patients for curative-intent therapy, and identify those who would benefit from increased physical activity and exercise.

Is estimated cardiorespiratory fitness an effective predictor for cardiovascular and all-cause mortality? A meta-analysis

BACKGROUND AND AIMS

Estimated cardiorespiratory fitness (eCRF) derived from algorithm correlates well with exercise testing-measured CRF, yet its clinical use for mortality risk stratification has not been systematically evaluated. This meta-analysis with dose-response analysis was conducted to quantify its association with risk of cardiovascular and all-cause mortality.

METHODS

Electronic databases were searched for prospective cohort studies that investigated the association of eCRF with risk of cardiovascular and all-cause mortality. Study-specific multivariate-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) per 1-metabolic equivalent (MET) higher of eCRF were pooled using a random-effects model.

RESULTS

Twenty-five datasets from 8 cohort studies that enrolled more than 170,000 participants were included. The summary HR per 1-MET higher of eCRF was 0.83 (95% CI 0.80 to 0.86) for cardiovascular mortality (11 datasets) and 0.83 (95% CI 0.78 to 0.88) for all-cause mortality (14 datasets) in the general population. These associations showed no sex-difference and were all linearly shaped (all p_nonlinearity ≥ 0.27). The performance of eCRF (assessed by the area under the curve) in discriminating future risk of cardiovascular and all-cause mortality was higher than all its components (such as physical activity, resting heart rate, and body mass index, all p < 0.05), but slightly lower than exercise testing-measured CRF.

CONCLUSIONS

Higher eCRF was independently associated with lower risk of cardiovascular and all-cause mortality in the general population, indicating that eCRF might hold the potential as an effective and practical risk prediction tool in epidemiological or population research.

Predicting maximal oxygen uptake from a 3-minute progressive knee-ups and step test

Background

Cardiorespiratory fitness assessment is crucial for diagnosing health risks and assessing interventions. Direct measurement of maximum oxygen uptake (V̇O₂ max) yields more objective and accurate results, but it is practical only in a laboratory setting. We therefore investigated whether a 3-min progressive knee-up and step (3MPKS) test can be used to estimate peak oxygen uptake in these settings.

Method

The data of 166 healthy adult participants were analyzed. We conducted a V̇O₂ max test and a subsequent 3MPKS exercise test, in a balanced order, a week later. In a multivariate regression model, sex; age; relative V̇O₂ max; body mass index (BMI); body fat percentage (BF); resting heart rate (HR0); and heart rates at the beginning as well as at the first, second, third, and fourth minutes (denoted by HR0, HR1, HR2, HR3, and HR4, respectively) during a step test were used as predictors. Moreover, R² and standard error of estimate (SEE) were used to evaluate the accuracy of various body composition models in predicting V̇O₂max.

Results

The predicted and actual V̇O₂ max values were significantly correlated (BF% model: R² = 0.624, SEE = 4.982; BMI model: R² = 0.567, SEE = 5.153). The BF% model yielded more accurate predictions, and the model predictors were sex, age, BF%, HR0, ΔHR3−HR0, and ΔHR3−HR4.

Conclusion

In our study, involving Taiwanese adults, we constructed and verified a model to predict V̇O₂ max, which indicates cardiorespiratory fitness. This model had the predictors sex, age, body composition, and heart rate changes during a step test. Our 3MPKS test has the potential to be widely used in epidemiological research to measure V̇O₂ max and other health-related parameters.

A history of smoking does not reduce long-term benefits of cardiac rehabilitation on cardiorespiratory fitness in men and women with cardiovascular disease

Smoking is an important risk factor for cardiovascular disease and all-cause mortality. Cardiac rehabilitation (CR) is effective for reducing the risk of recurrent cardiac events through improving cardiorespiratory fitness (CRF). Little is known about the influence of smoking on CRF throughout long-term CR. The purpose of this analysis was to compare CRF trajectories among individuals with positive and negative smoking history enrolled in long-term CR. Participants had a positive smoking history if they currently or formerly smoked (Smoke+, n = 55, mean age = 64.9 ± 9.0 years) and had a negative history if they never smoked (Smoke–, n = 34, mean age = 61.4 ± 9.0 years). CRF (peak oxygen uptake) was measured at baseline and annually thereafter for 6 years. The Smoke+ group had lower CRF compared with the Smoke– group over enrollment (β = −3.29 (SE = 1.40), 95% confidence interval (CI) −6.04 to −0.54, p = 0.02), but there was no interaction of smoking history and enrollment (β = 0.35 (SE = 0.21), 95% CI: −0.06 to 0.77, p = 0.10). Moreover, trajectories were not influenced by pack-years (β = 0.01 (SE = 0.01), 95% CI: −0.01 to 0.04, p = 0.23) or time smoke-free (β = −0.002 (SE = 0.01), 95% CI: −0.02 to 0.02, p = 0.80). Although the trajectories of CRF do not appear to be affected by smoking behaviour, individuals without a history of smoking maintained higher CRF throughout enrollment.

Novelty:

The benefits of long-term exercise-based cardiac rehabilitation on cardiorespiratory fitness are similar between those who have smoked and those who have never smoked. Neither the number of pack-years nor the length of time spent smoke-free influence cardiorespiratory fitness trajectories following long-term cardiac rehabilitation.

Nonexercise Equations for Determining Change in Cardiorespiratory Fitness

PURPOSE

This study aimed to determine whether change in estimated cardiorespiratory fitness (eCRF) is associated with change in measured cardiorespiratory fitness (mCRF) independent of exercise amount and intensity over 24 wk.

METHODS

Participants were 163 sedentary adults with abdominal obesity (mean ± SD waist circumference, 109.9 ± 11.5 cm) randomly assigned to (i) no-exercise control (n = 42); (ii) low-amount, low-intensity exercise (LALI; n = 39); (iii) high-amount, low-intensity exercise (HALI; n = 51); and (iv) high-amount, high-intensity exercise (HAHI; n = 31). mCRF was measured using a maximal treadmill test at baseline, 8, 16, and 24 wk. eCRF was calculated using a published nonexercise equation with the following variables: sex, age, waist circumference, resting heart rate, and self-selected physical activity.

RESULTS

Participants attended 115 of 120 exercise sessions prescribed (96.0% ± 4.0% adherence). eCRF change from baseline to 8, 16, and 24 wk was not different from mCRF change for control, LALI, or HALI (P = 0.03). In HAHI, eCRF change was significantly greater than mCRF change at all time points (P < 0.001). Further analysis revealed that change in eCRF systematically overestimated and underestimated small and large changes in mCRF, respectively, in all groups (P < 0.001).

CONCLUSIONS

eCRF change was associated with mCRF change at 24 wk independent of exercise amount but not intensity. Systematic variation between eCRF and mCRF highlights a possible limitation when using eCRF to follow change in mCRF, specifically that eCRF does not capture the individual variability of the mCRF response.

Cardiorespiratory Fitness and the Risk of First Acute Myocardial Infarction: The HUNT Study

Background

The majority of studies evaluating cardiorespiratory fitness (CRF) as a cardiovascular risk factor use cardiovascular mortality and not cardiovascular disease events as the primary end point, and generally do not include women. The aim of this study was to investigate the association of estimated CRF (eCRF) with the risk of first acute myocardial infarction (AMI).

Methods and Results

We included 26 163 participants (51.5% women) from the HUNT study (Nord‐Trøndelag Health Study), with a mean age of 55.7 years, without cardiovascular disease at baseline. Baseline eCRF was grouped into tertiles. AMI was derived from hospital records and deaths from the Norwegian Cause of Death Registry. We used Fine and Gray regression modeling to estimate subdistribution hazards ratio (SHR) of AMI, accounting for competing risk of death. During a mean (range) follow‐up of 13 (0.02–15.40) years (347 462 person‐years), 1566 AMI events were recorded. In fully adjusted models men in the 2 highest eCRF had 4% (SHR: 0.96, 95% CI: 0.83–1.11) and 10% (SHR: 0.90, 95% CI: 0.77–1.05) lower SHR of AMI, respectively, when compared with men in the lowest tertile. The corresponding numbers in women were 12% (SHR: 0.88, 95% CI: 0.72–1.08) and 25% (SHR: 0.75, 95% CI: 0.60–0.95).

Conclusions

eCRF was inversely associated with risk of AMI event among women but not in men. Our data suggest that high eCRF may have substantial benefit in reducing the risk of AMI. Therefore, our data suggest that an increased focus on eCRF as a cardiovascular disease risk marker in middle‐aged and older adults is warranted.

Prediction of cardiovascular health by non-exercise estimated cardiorespiratory fitness

Objective

To estimate the incidence of major biological cardiovascular disease (CVD) risk factors in adults using non-exercise estimated cardiorespiratory fitness (eCRF).

Methods

200 039 healthy people (99 957 women), aged ≥18 years (38.5±12.1 years) from the Taiwan MJ Cohort. eCRF was estimated with validated algorithms. Biological CVD risk factors, including hypertension (HTN), hypercholesterolemia, atherogenic dyslipidaemia, type 2 diabetes mellitus (T2DM) and systemic inflammation, were assessed by standardised physical examinations and laboratory tests.

Results

In a basic model, baseline eCRF was inversely associated with the incidence of each CVD risk factor in both men and women (HR per 1 metabolic equivalent (MET) increase in eCRF ranged from 0.53 for T2DM in women to 0.96 for hypercholesterolemia in women). In full adjusted models, the associations were attenuated but remained statistically significant, with the exception of hypercholesterolemia in women. In a subcohort of 116 313 individuals with two repeated exposure measurements, an increase in eCRF was associated in both sexes with a subsequent lower incidence of CVD risk factors (HR per 1-MET increase ranged from 0.58 to 0.91 in models adjusted for age, year of examination and baseline eCRF). Comparisons of predictive performance showed that the addition of eCRF to values of traditional CVD risk factors had relevant improvements in risk discrimination (C-index increased from 0.1% to 3.2%), mainly for HTN and T2DM risk prediction.

Conclusions

eCRF and its changes predict the incidence of biological CVD risk factors, especially HTN and T2DM. Routine assessment of eCRF in clinical settings is technically feasible and might be useful for CVD prevention.

Accuracy of Nonexercise Prediction Equations for Assessing Longitudinal Changes to Cardiorespiratory Fitness in Apparently Healthy Adults: BALL ST Cohort

Background

Repeated assessment of cardiorespiratory fitness (CRF) improves mortality risk predictions in apparently healthy adults. Accordingly, the American Heart Association suggests routine clinical assessment of CRF using, at a minimum, nonexercise prediction equations. However, the accuracy of nonexercise prediction equations over time is unknown. Therefore, we compared the ability of nonexercise prediction equations to detect changes in directly measured CRF.

Methods and Results

The sample included 987 apparently healthy adults from the BALL ST (Ball State Adult Fitness Longitudinal Lifestyle Study) cohort (33% women; average age, 43.1±10.4 years) who completed 2 cardiopulmonary exercise tests ≥3 months apart (3.2±5.4 years of follow‐up). The change in estimated CRF (eCRF) from 27 distinct nonexercise prediction equations was compared with the change in directly measured CRF. Analysis included Pearson product moment correlations, SEE values, intraclass correlation coefficient values, Cohen's κ coefficients, γ coefficients, and the Benjamini‐Hochberg procedure to compare eCRF with directly measured CRF. The change in eCRF from 26 of 27 equations was significantly associated to the change in directly measured CRF (P<0.001), with intraclass correlation coefficient values ranging from 0.06 to 0.63. For 16 of the 27 equations, the change in eCRF was significantly different from the change in directly measured CRF. The median percentage of participants correctly classified as having increased, decreased, or no change in CRF was 56% (range, 39%–61%).

Conclusions

Variability was observed in the accuracy between nonexercise prediction equations and the ability of equations to detect changes in CRF. Considering the appreciable error that prediction equations had with detecting even directional changes in CRF, these results suggest eCRF may have limited clinical utility.

Is there an association between cardiorespiratory fitness and stage of illness in psychotic disorders? A systematic review and meta-analysis

BACKGROUND

Clinical staging models describe where an individual exists on a continuum from asymptomatic at-risk states (Stage 0) through to established late-stage disease (Stage 4). We applied this framework to systematically assess evidence for any associations between objectively assessed cardiorespiratory fitness (CRF) and stage of psychosis.

METHOD

Nine electronic databases were searched for relevant publications from inception until October 31, 2019. Pooled effect sizes (Hedges' g and 95% confidence intervals (95% CI)) were estimated for differences in CRF for studies that reported mean oxygen uptake (max, peak, or predicted VO₂ in ml/kg/min).

RESULTS

Thirty-eight studies were eligible. Findings indicated that suboptimal CRF can be present at Stages 0 and 1. Meta-analyses of 22 studies demonstrated that CRF was significantly reduced in individuals classified between Stages 1 and 4 compared with matched or general population controls (g = -0.93; 95% CI -1.14, -0.71). Mean VO₂ was decreased by 28% in Stage 4 compared with Stage 1 (34.1 vs. 24.66 ml/kg/min); the largest effect size for CRF reduction was reported between Stages 2 and 3 (g = -1.16; 95% CI -1.31, -1.03).

CONCLUSIONS

Although not identifying direct causal links between clinical stage and CRF, using this framework may enhance understanding of co-associations between mental and physical health markers across the entire spectrum of psychosis. Limitations include lack of research on CRF in Stages 0 and 1 alongside problems determining stage in some studies. However, impaired CRF is reported in emerging psychosis, supporting calls that early intervention programmes should address both mental and physical wellbeing.

Survival of the Fittest: Impact of Cardiorespiratory Fitness on Outcomes in Men and Women with Cardiovascular Disease

Cardiovascular disease (CVD) in general and myocardial infarction in particular are the leading causes of mortality in men and women globally. Sex differences in CVD recovery exist, with higher rates of mortality, recurrent myocardial infarction, and poor functional outcomes seen in women compared to men with CVD. Physical inactivity has been identified as a crucial modifiable risk factor linked with poor survival and recovery in patients with CVD. Cardiac rehabilitation programs that aim to improve physical inactivity and cardiorespiratory fitness (CRF), a measure of physical fitness in patients with CVD, have gained popularity. The goals of this commentary were to summarize the existing literature on the impact of CRF on survival in patients with CVD, to document the impact of sex on CVD outcomes, and to highlight any gaps in current knowledge. Even minor improvements in CRF have been linked with improved survival, although contemporary data from randomized controlled trials have shown mixed results. Gender differences in cardiac rehabilitation have been well documented, with lower referral, enrollment, and completion rates noted in women compared to men with CVD. However, data on sex differences in CRF with cardiac rehabilitation are scant, mostly indicating lower peak CRF observed in female compared to male patients on completion. It is unclear whether similar thresholds of peak CRF are needed in male and female patients to improve survival after onset of CVD, and whether exercise prescriptions need to be adapted to include additional forms of exercise. CRF is also influenced by age, with a decline in peak exercise capacity with advancing age observed in both sexes, but steeper declines noted in men than women. From this perspective, we review the data intersecting age, sex, and exercise on survival in patients with CVD, as well as the biological mechanisms at play, and we identify areas for future research (Clin Ther. 2020; 42:XXX-XXX) © 2020 Elsevier Inc.

Comparison of non-exercise cardiorespiratory fitness prediction equations in apparently healthy adults

AIMS

A recent scientific statement suggests clinicians should routinely assess cardiorespiratory fitness using at least non-exercise prediction equations. However, no study has comprehensively compared the many non-exercise cardiorespiratory fitness prediction equations to directly-measured cardiorespiratory fitness using data from a single cohort. Our purpose was to compare the accuracy of non-exercise prediction equations to directly-measured cardiorespiratory fitness and evaluate their ability to classify an individual's cardiorespiratory fitness.

METHODS

The sample included 2529 tests from apparently healthy adults (42% female, aged 45.4 ± 13.1 years (mean±standard deviation). Estimated cardiorespiratory fitness from 28 distinct non-exercise prediction equations was compared with directly-measured cardiorespiratory fitness, determined from a cardiopulmonary exercise test. Analysis included the Benjamini-Hochberg procedure to compare estimated cardiorespiratory fitness with directly-measured cardiorespiratory fitness, Pearson product moment correlations, standard error of estimate values, and the percentage of participants correctly placed into three fitness categories.

RESULTS

All of the estimated cardiorespiratory fitness values from the equations were correlated to directly measured cardiorespiratory fitness (p < 0.001) although the R2 values ranged from 0.25-0.70 and the estimated cardiorespiratory fitness values from 27 out of 28 equations were statistically different compared with directly-measured cardiorespiratory fitness. The range of standard error of estimate values was 4.1-6.2 ml·kg-1·min-1. On average, only 52% of participants were correctly classified into the three fitness categories when using estimated cardiorespiratory fitness.

CONCLUSION

Differences exist between non-exercise prediction equations, which influences the accuracy of estimated cardiorespiratory fitness. The present analysis can assist researchers and clinicians with choosing a non-exercise prediction equation appropriate for epidemiological or population research. However, the error and misclassification associated with estimated cardiorespiratory fitness suggests future research is needed on the clinical utility of estimated cardiorespiratory fitness.

The association between cardiorespiratory fitness and the incidence of common mental health disorders: A systematic review and meta-analysis

BACKGROUND

Physical activity is associated with a lower incidence of common mental health disorder, but less is known about the impact of cardiorespiratory fitness (CRF).

METHODS

In this review, we systematically evaluated the relationship between CRF and the incidence of common mental health disorders in prospective cohort studies. We systematically searched six major electronic databases from inception to 23rd of May 2019. We assessed study quality using the Newcastle-Ottawa scale.

RESULTS

We were able to pool the hazard ratios (HRs) and 95% confidence intervals (CIs) of four studies including at least 27,733,154 person-years of data. We found that low CRF (HR = 1.47, [95% CI 1.23 - 1.76] p < 0.001 I2 = 85.1) and medium CRF (HR = 1.23, [95% CI 1.09 - 1.38] p < 0.001 I2 = 87.20) CRF are associated with a 47% and 23% greater risk of a common mental health disorders respectively, compared with high CRF. We found evidence to suggest a dose-response relationship between CRF and the risk of common mental health disorders.

LIMITATIONS

We were only able to identify a small number of eligible studies from our search and heterogeneity was substantial in the subsequent meta-analysis.

CONCLUSIONS

Our findings indicate that there is a longitudinal association between CRF levels and the risk of a common mental health disorder. CRF levels could be useful for identifying and preventing common mental health disorders at a population-level.

Validation of Cardiorespiratory Fitness Measurements in Adolescents

Cardiorespiratory fitness (CRF) is an important indicator of adolescent cardiovascular well-being and future cardiometabolic health but not always feasible to measure. The purpose of this study was to estimate the concurrent validity of the non-exercise test (NET) for adolescents against the Progressive Aerobic Capacity Endurance Run (PACER^®) and direct measures of VO_2max as well as to examine the concurrent validity of the PACER^® with a portable metabolic system (K4b^2™). Forty-six adolescents (12-17 years) completed the NET prior to performing the PACER^® while wearing the K4b^2™. The obtained VO_2max values were compared using linear regression, intra-class correlation (ICC), and Bland-Altman plots, and α was set at 0.05. The VO_2max acquired directly from the K4b^2™ was significantly correlated to the VO_2max indirectly estimated from the NET (r = 0.73, p < 0.001, r² = 0.53, ICC = 0.67). PACER^® results were significantly related to the VO_2max estimates from the NET (r = 0.81, p < 0.001, r² = 0.65, ICC = 0.72). Direct measures from the K4b^2™ were significantly correlated to the VO_2max estimates from the PACER^® (r = 0.87, p < 0.001, r² = 0.75, ICC = 0.93). The NET is a valid measure of CRF in adolescents and can be used when an exercise test is not feasible.

Cardiorespiratory Fitness without Exercise Testing Can Predict All-Cause Mortality Risk in a Representative Sample of Korean Older Adults

This study examined the association between cardiorespiratory fitness (CRF) without exercise testing and all-cause mortality in Korean older adults. The present study was carried out using data from the 2008 and 2011 Living Profiles of Older People Survey. A total of 14,122 participants aged 60 years and older (57% women) completed the 2008 baseline and 2011 follow-up assessments (i.e., socioeconomic status, health behaviors and conditions, and prevalence of chronic diseases), and they were included for the final analyses. CRF was estimated (eCRF) with sex-specific algorithms and classified as lower (lowest 25%), middle (middle 50%), and upper (highest 25%). Cox proportional hazards regression was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) across eCRF categories. In total, multivariable-adjusted HRs and 95% CIs were 1 for the upper eCRF group (referent), 1.059 (0.814~1.378) for the middle eCRF group, and 1.714 (1.304~2.253) for the lower eCRF group. In men, multivariable-adjusted HRs and 95% CIs were 1 for the upper eCRF group (referent), 1.011 (0.716~1.427) for the middle eCRF group, and 1.566 (1.098~2.234) for the lower eCRF group. In women, multivariable-adjusted HRs and 95% CIs were 1 for the upper eCRF group (referent), 1.064 (0.707~1.602) for the middle eCRF group, and 1.599 (1.032~2.478) for the lower eCRF group. The current findings suggest that eCRF may have an independent predictor of all-cause mortality, underscoring the importance of promoting physical activity to maintain a healthful level of CRF in Korean geriatric population.

Associations of Changes in Cardiorespiratory Fitness and Symptoms of Anxiety and Depression With Brain Volumes: The HUNT Study

Objective: We investigated the independent and joint associations of changes in estimated cardiorespiratory fitness (eCRF) and symptoms of anxiety and depression with brain volumes in individuals from the general population. Method: 751 participants (52% women, aged 50-67 years) from the Nord-Trøndelag Health Study (HUNT) MRI cohort were included. eCRF obtained from a non-exercise algorithm and symptoms of anxiety and depression were assessed twice; at HUNT2 (1995-97) and HUNT3 (2006-08). Brain MRI was performed shortly after HUNT3. Brain parenchymal fraction (BPF), bilateral hippocampal and total cortical volume were extracted from brain MRI obtained at 1.5T, using FreeSurfer and Statistical Parametric Mapping. Results: Multiple regression revealed that participants whose eCRF increased had larger BPF (β = 0.09, 95% CI 0.02, 0.16) and larger hippocampal volume (β = 0.09, 95% CI 0.03, 0.16) compared to participants whose eCRF remained low. Participants whose eCRF remained high had larger BPF (β = 0.15, 95% CI 0.07, 0.22) and larger cortical volume (β = 0.05, 95% CI 0.01, 0.09). Participants whose anxiety symptoms worsened had smaller BPF (β = -0.09, 95% CI -0.15, -0.02) and cortical volume (β = -0.05, -0.08, -0.01) than participants whose anxiety symptoms remained low. Each ml/kg/min increase in eCRF was associated with larger cortical volume among individuals with worsening of anxiety symptoms (β = 0.13, 95% CI 0.001, 0.27), and larger BPF among individuals whose depressive symptoms improved (β = 0.28, 95% CI 0.02, 0.53). Conclusion: Promoting exercise intended to improve eCRF may be an important public health initiative aimed at maintaining brain health among middle-aged individuals with and without changing psychological symptoms.

A cross-sectional study on the relationship between cardiorespiratory fitness, disease severity and walking speed in persons with Multiple Sclerosis

BACKGROUND

In persons with Multiple Sclerosis (PwMS) cardiorespiratory fitness has been associated with disease severity, walking capacity and comorbidities. However, current evidence is of moderate quality and a large-scale single-center study is needed to further elucidate these relationships OBJECTIVE: The purpose of the study was 1) to examine the relationship between cardiorespiratory fitness and disease severity in PwMS; 2) to investigate the relationship between cardiorespiratory fitness and walking speed and comorbidities; and 3) to examine the potential impact of Multiple Sclerosis (MS) disease type on these relationships METHODS: Data was collected from a database consisting of data from 700 inpatients at Valens Rehabilitation Center, Switzerland. VO₂peak (cardiorespiratory fitness), information on disease course and MS type, walking performance, comorbidities and anthropometric was eligible from 242 PwMS.

RESULTS

Cardiorespiratory fitness and Expanded Disability Status Scale (EDSS) was inversely related (r = -0.465, p < .01). A multiple linear regression analysis showed that an increase of 1 point on the EDSS score was associated with a decrease of 1.88 mL kg^-1 min^-1 and explained 36% of the variance, when adjusted for time since diagnosis, gender, age, and MS type. Walking speed and cardiorespiratory fitness was significantly correlated (r = 0.584, p < .01) and the relapse remitting MS (RRMS) group (1.12 ± 0.42 m/s) walked significantly faster than the secondary progressive MS (SPMS) group (0.91 ± 0.37 m/s) p < .05, but the difference was non-significant when adjusted for age, p = .429.

CONCLUSION

The present study shows that 1) an increase of 1 EDSS point is associated with a decrease of 1.88 mL kg^-1 min^-1 when adjusted for time since diagnosis, gender, age and MS type, 2) cardiorespiratory fitness and walking speed was significantly related but only minimally affected by MS type, and 3) hypertension is associated with a lower cardiorespiratory fitness level.

Predictive Modeling of VO2max Based on 20 m Shuttle Run Test for Young Healthy People

This study presents mathematical models for predicting VO2max based on a 20 m shuttle run and anthropometric parameters. The research was conducted with data provided by 308 young healthy people (aged 20.6 ± 1.6). The research group includes 154 females (aged 20.3 ± 1.2) and 154 males (aged 20.8 ± 1.8). Twenty-four variables were used to build the models, including one dependent variable and 23 independent variables. The predictive methods of analysis include: the classical model of ordinary least squares (OLS) regression, regularized methods such as ridge regression and Lasso regression, artificial neural networks such as the multilayer perceptron (MLP) and radial basis function (RBF) network. All models were calculated in R software (version 3.5.0, R Foundation for Statistical Computing, Vienna, Austria). The study also involved variable selection methods (Lasso and stepwise regressions) to identify optimum predictors for the analysed study group. In order to compare and choose the best model, leave-one-out cross-validation (LOOCV) was used. The paper presents three types of models: for females, males and the whole group. An analysis has revealed that the models for females ( RMSE C V = 4.07 mL·kg−1·min−1) are characterised by a smaller degree of error as compared to male models ( RMSE C V = 5.30 mL·kg−1·min−1). The model accounting for sex generated an error level of RMSE C V = 4.78 mL·kg−1·min−1.

Long-term Changes in Depressive Symptoms and Estimated Cardiorespiratory Fitness and Risk of All-Cause Mortality: The Nord-Trøndelag Health Study

OBJECTIVE

To assess the independent and combined associations of long-term changes in depressive symptoms (DSs) and estimated cardiorespiratory fitness (eCRF) with all-cause mortality.

PARTICIPANTS AND METHODS

This is a longitudinal cohort study of 15,217 middle-aged and older individuals attending both the second (from August 15, 1995, through June 18, 1997) and third (from October 3, 2006, through June 25, 2008) health surveys of the Nord-Trøndelag Health Study, Norway, and followed until December 31, 2014. Depressive symptoms were estimated using the validated Hospital Anxiety and Depression Scale, and a validated nonexercise model estimated eCRF. Hazard ratios (HRs) were computed using Cox regression. All-cause mortality was ascertained using the Norwegian Cause of Death Registry.

RESULTS

The mean age was 63.3±8.9 years, and 7932 (52.1%) were women. During the follow-up period of 7.1±1.1 years, 1157 participants (7.6%) died. Multivariable-adjusted analyses revealed that persistently low DSs were independently associated with a 28% risk reduction of all-cause mortality (HR, 0.72; 95% CI, 0.56-0.92; P=.008) as compared with persistently high DSs. Persistently high eCRF independently predicted a 26% lower risk of death (HR, 0.76; 95% CI, 0.66-0.88; P<.001) relative to low eCRF. Analyses of changes in DSs and eCRF revealed that persistently high eCRF combined with decreased or persistently low DSs decreased mortality risk by 49% (HR, 0.51; 95% CI, 0.28-0.91; P=.02) and 47% (HR, 0.53; 95% CI, 0.37-0.76, P=.001), respectively.

CONCLUSION

Maintaining low DSs and high eCRF was independently associated with a lower risk of all-cause mortality. The lowest mortality risk was observed for persistently high eCRF combined with decreased or persistently low DSs. These results emphasize the effect of preventing DSs and maintaining high CRF on long-term mortality risk, which is potentially important for long-term population health.

Nonexercise Estimated Cardiorespiratory Fitness and All-Cancer Mortality: the NHANES III Study

OBJECTIVE

To examine the relationship between estimated cardiorespiratory fitness (eCRF) using nonexercise equations and all-cancer mortality in a representative sample of the US population.

PARTICIPANTS AND METHODS

A total of 8506 study participants were derived from the Third National Health and Nutrition Examination Survey, conducted from October 18, 1988, to October 15, 1994. They were followed for all-cancer mortality. Participants' CRF was estimated from nonexercise models that were determined by age, body mass index, waist circumference, resting heart rate, physical activity status, and smoking status, and further grouped into quintiles. Hazard ratios (HRs) and 95% CIs were calculated from Cox proportional hazards models for the relationship between eCRF and all-cancer mortality.

RESULTS

During a mean of 19.5 years of follow-up, 455 cancer deaths (263 men and 192 women) were registered. After adjustment for race/ethnicity, age, educational level, current smoking, hypertension, diabetes mellitus, and hypercholesterolemia, each 1-metabolic equivalent increase in eCRF was associated with 30% (95% CI, 24%-35%) and 27% (95% CI, 18%-36%) risk reduction for all-cancer mortality in men and women, respectively. When eCRF was categorized into quintiles, HRs (95% CIs) were 0.47 (0.24-0.95), 0.81 (0.46-1.44), 0.49 (0.26-0.93), and 0.57 (0.31-1.06) across incremental quintiles in women (quintile 1 was the reference group). However, none of the HRs reached statistical significance in men.

CONCLUSION

The eCRF was inversely associated with all-cancer mortality in quintiles 2 and 4 in women. More research is needed to further understand the association between eCRF and all-cancer mortality in men.

Racial Differences in the Association Between Nonexercise Estimated Cardiorespiratory Fitness and Incident Stroke

OBJECTIVE

To examine the association between estimated cardiorespiratory fitness (eCRF) and incident stroke by black and white race.

PARTICIPANTS AND METHODS

A total of 24,162 participants from the REasons for Geographic And Racial Differences in Stroke study (13,232 [54.8%] women; 9543 [39.5%] blacks; mean age, 64.6±9.3 years) without stroke at enrollment between January 15, 2003, and October 30, 2007, were followed for incident stroke through March 31, 2016. Baseline eCRF in maximal metabolic equivalents was determined using nonexercise sex-specific algorithms and further grouped into age- and sex-specific tertiles.

RESULTS

Over a mean of 8.3±3.2 years of follow-up, 945 (3.9%) incident strokes occurred (377 in blacks and 568 in whites). The association between eCRF and stroke risk differed significantly by race (PInteraction<.001). In whites, after adjustment for stroke risk factors and physical functioning score, the hazard ratio of stroke was 0.82 (95% CI, 0.67-1.00) times lower in the middle tertile of eCRF than in the lowest tertile and was 0.54 (95% CI, 0.43-0.69) times lower in the highest tertile of eCRF. The protective effect of higher levels of eCRF on stroke incidence was more pronounced in those 60 years or older among whites. No association between eCRF and stroke risk was observed in blacks.

CONCLUSION

Estimated cardiorespiratory fitness measured using nonexercise equations is a useful predictor of stroke in whites. The lack of an overall association between eCRF and stroke risk in blacks suggests that the assessment of eCRF in blacks may not be helpful in primary stroke prevention.

Transcultural adaptation and new proposal for the nursing outcome, Physical condition (2004)

Objectives:

cross-culturally adapt to the Spanish context and make a new proposal for the nursing outcome, Physical Condition (2004), of the Nursing Outcomes Classification (NOC) for its precise use in clinical practice.

Method:

a cross-cultural adaptation study and a proposal for the nursing outcome, Physical Condition, was conducted and supported by the opinion of 26 experts. The data was obtained through an electronic form, and a quantitative analysis was conducted, using the SPSS software.

Results:

the version adapted to the Spanish context was obtained and the proposal of the outcome, Physical Condition, received agreement from 26 experts, with a mean score greater than 7.6 for adequacy of the outcome definition and its indicators, and 8.5 for the relevance of the indicators.

Conclusions:

the version adapted to the Spanish context and a new proposal for Physical Condition were obtained. The results obtained indicate a high level of adequacy and relevance, an instrument of great utility in the clinic, and research was obtained to evaluate the interventions directed to the improvement of the physical condition.