Fitness Registry Research Articles

Hypertension and Ventilatory Responses During Exercise in the Fitness Registry and the Importance of Exercise National Database (FRIEND).

A high minute ventilation/rate of carbon dioxide production (V̇E/V̇co2) slope during exercise is prognostic for cardiovascular death. Recent data indicate that adults with either controlled or untreated primary hypertension, but not those with uncontrolled hypertension, exhibit a higher V̇E/V̇co2 slope during exercise. However, the sample sizes were modest. Therefore, we used the Fitness Registry and the Importance of Exercise National Database to determine whether adults with hypertension, particularly those with controlled or untreated hypertension, exhibit higher V̇E/V̇co2 slopes compared with adults without hypertension. Using the Fitness Registry and the Importance of Exercise National Database, we isolated primary hypertension by excluding those with any disease other than hypertension or taking any medications other than antihypertension medications. We also excluded current smokers and those with obesity. The V̇E/V̇co2 slope was determined during a peak cycling exercise test. All data are presented as median [interquartile range]. We compared groups using linear regression adjusted for age, male/female, and body mass index. The characteristics of the entire sample (n=4109) were age, 42 [18] years; 48% women; body mass index, 26 [4] kg/m2. The V̇E/V̇co2 slope did not differ between adults with hypertension (n=1940; 24.7 [3.7]) compared with those without hypertension (n=2169; 24.9 [3.8]) (hypertension versus no hypertension, P=0.31; overall model: R2=0.07, F4,4104=73.0; P<0.001). Further, the V̇E/V̇co2 slope did not differ between adults with medication-controlled hypertension (n=107; 24.4 [3.0]), untreated hypertension (n=1626; 24.8 [3.9]), uncontrolled hypertension (n=207; 24.8 [3.0]), or those without hypertension (n=2169; 24.9 [3.8]) (hypertension subgroup versus no hypertension, P≥0.06; overall model: R2=0.07, F6,4102=49.6, P<0.001). Primary hypertension is not associated with V̇E/V̇co2 slope in the Fitness Registry and the Importance of Exercise National Database.

Quantifying assumptions underlying peak oxygen consumption equations across the body mass spectrum.

The goal of this study is toquantify the assumptions associated with the Wasserman-Hansen (WH) and Fitness Registry and the Importance of Exercise: A National Database (FRIEND) predictive peak oxygen consumption (pVO2) equations across body mass index (BMI). Assumptions in pVO2 for both equations were first determined using a simulation and then evaluated using exercise data from the Stanford Exercise Testing registry. We calculated percent-predicted VO2 (ppVO2) values for both equations and compared them using the Bland-Altman method. Assumptions associated with pVO2 across BMI categories were quantified by comparing the slopes of age-adjusted VO2 ratios (pVO2/pre-exercise VO2) and ppVO2 values for different BMI categories. The simulation revealed lower predicted fitness among adults with obesity using the FRIEND equation compared to the WH equations. In the clinical cohort, we evaluated 2471 patients (56.9% male, 22% with BMI >30 kg/m2, pVO2 26.8 mlO2/kg/min). The Bland-Altman plot revealed an average relative difference of -1.7% (95% CI: -2.1 to -1.2%) between WH and FRIEND ppVO2 values with greater differences among those with obesity. Analysis of the VO2 ratio to ppVO2 slopes across the BMI spectrum confirmed the assumption of lower fitness in those with obesity, and this trend was more pronounced using the FRIEND equation. Peak VO2 estimations between the WH and FRIEND equations differed significantly among individuals with obesity. The FRIEND equation resulted in a greater attributable reduction in pVO2 associated with obesity relative to the WH equations. The outlined relationships between BMI and predicted VO2 may better inform the clinical interpretation of ppVO2 values during cardiopulmonary exercise test evaluations.

Chronic Use of Antihypertensive Medications and Peak Exercise Blood Pressure in Adult Men and Women from the BALL ST Cohort.

To determine if individuals chronically (>1 yr) prescribed antihypertensive medications have a normal BP response to peak exercise compared with unmedicated individuals. Participants included 2555 adults from the Ball State Adult Fitness Longitudinal Lifestyle STudy cohort who performed a peak treadmill exercise test. Participants were divided into groups by sex and antihypertensive medication status. Individuals prescribed antihypertensive medications for >1 yr were included. Exaggerated and blunted SBP within each group was categorized using the Fitness Registry and the Importance of Exercise: A National Database (FRIEND) and absolute criteria as noted by the American Heart Association. The unmedicated group had a greater prevalence ( P < 0.05) of blunted SBP responses, whereas the medicated group had a higher prevalence ( P < 0.05) of exaggerated SBP responses using both the FRIEND and absolute criteria. Peak SBP was higher ( P < 0.01) in medicated compared with unmedicated participants in the overall cohort when controlling for age and sex, but not after controlling for resting SBP ( P = 0.613), risk factors ( P = 0.104), or cardiorespiratory fitness ( P = 0.191). When men and women were assessed independently, peak SBP remained higher in the medicated women after controlling for age and resting SBP ( P = 0.039), but not for men ( P = 0.311). Individuals on beta-blockers had a higher peak SBP even after controlling for age, sex, risk factors, and cardiorespiratory fitness ( P = 0.022). Individuals on antihypertensive medications have a higher peak SBP response to exercise. Given the prognostic value of exaggerated peak SBP, control of exercise BP should be considered in routine BP assessment and in the treatment of hypertension.

Hypertension and Ventilatory Ineffciency During Exercise in the Fitness Registry and the Importance of Exercise National Database (FRIEND)

Background: Ventilatory ineffciency (high minute ventilation/rate of carbon dioxide production [V̇E/V̇CO2] slope) during exercise is more common in patients with metabolic syndrome and cardiovascular disease, and is prognostic of cardiovascular mortality. Interestingly, new data suggest that adults with controlled or untreated, but not uncontrolled, primary hypertension (HTN) have ventilatory ineffciency during exercise. However, the sample sizes were modest (n=~20/group). Therefore, we used a large database to test the hypothesis that adults with controlled or untreated, but not uncontrolled, primary HTN have higher V̇E/V̇CO2 slope than adults with no HTN. Methods: We used American Heart Association guidelines for HTN as systolic blood pressure [BP] ≥130mmHg, diastolic BP ≥80, or anti-HTN medication in the Fitness Registry and the Importance of Exercise National Database (FRIEND). To isolate primary HTN, we excluded those with any disease other than HTN, any medication use other than anti-HTN medication(s), current smoking status, and/or obesity (body mass index [BMI]≥30). The V̇E/V̇CO2 slope was determined from a peak cycling exercise test. We excluded adults with a peak respiratory exchange ratio &lt;1.00 during exercise. All data are presented as median[IQR]. We compared groups using linear regression unadjusted and adjusted for sex, fitness, and age. Results: The sample (n=4,659) characteristics were age: 42[18] years old (range 18-91 years); 52% with HTN; 18% female; BMI: 26.0[4.0] kg/m2; cardiorespiratory fitness: 28.5[11.0] mL O2/kg/min; race/ethnicity: &lt;1% American Indian, 3% Asian, 12% Black, 8% Hispanic, 4% Other, &amp; 73% White. The V̇E/V̇CO2 slope during exercise was higher in adults without HTN (n=2,410; 24.9[3.8]) compared to those with uncontrolled HTN (n=252; 24.7[3.0]; standard error of the estimate[SE]: -0.20, 95% confidence interval[CI]: -0.33 to -0.07, p=0.003), but not controlled HTN (n=132; 24.4[3.4]; SE: -0.14, 95%CI: -0.31 to 0.04, p=0.12) or untreated HTN (n=1,865; 24.7[3.7]; SE: -0.05, 95%CI: -0.11 to 0.009, p=0.09) (model: R2=0.002, F3,4655=3.83, p=0.009). However, no pairwise differences were observed after covariate adjustment (model: R2=0.117, F6,4652=103, p&lt;0.001). Conclusion: In contrast to our hypothesis, these data from the FRIEND indicate that primary HTN is not associated with ventilatory ineffciency (i.e., higher V̇E/V̇CO2 slope). National Institutes of Health K01HL160772 (JCW), American Heart Association 23CDA1037938 (JCW). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Impact of cardiorespiratory fitness and diabetes status on cardiovascular disease and all-cause mortality: An NHANES retrospective cohort study

High cardiorespiratory fitness (CRF) is associated with decreased mortality in people with pre-diabetes (pre-DM) and diabetes mellitus (DM); however, the degree to which CRF attenuates the risk of cardiovascular disease (CVD)-related and all-cause mortality is unclear. Study objectiveWe examined the impact of CRF status on CVD-related morbidity and all-cause mortality in non-DM, Pre-DM, and DM populations. Design and setting13,968 adults from the Third US National Health and Nutrition Examination Survey (NHANES III) were stratified into non-DM, pre-DM, or DM groups based on HbA1c levels. VO2Max was calculated using the Fitness Registry and Importance of Exercise: A National Database (FRIEND) equation. ParticipantsParticipants were categorized into tertiles of VO2Max; first VO2Max tertile was the lowest VO2Max and third VO2Max tertile was the highest. Main outcome measure(s)Cox regression was used to analyze the relationship between glycemic levels, VO2Max, and CVD-related and all-cause mortality. ResultsThose with DM in the highest fitness tertile had CVD (HR 0.13; 95 % CI 0.06, 0.27; p < 0.0001) and all cause (HR 0.28; 95 % CI 0.21, 0.38; p < 0.0001) mortality rates as low or lower than those with pre-DM (CVD HR 1.02; 95 % CI 0.78, 1.33 p < 0.892; all cause HR 0.96; 95 % CI 0.83, 1.12; p < 0.5496) or non-DM (CVD HR 0.65; 95 % CI 0.52, 0.80; p < 0.0001; all cause HR 0.61; 95 % CI 0.55, 0.68; p < 0.0001) at lower fitness levels. Regardless of DM status, there was lower all-cause mortality with higher CRF levels. ConclusionsHigher fitness levels in DM individuals are associated with total and CVD mortality rates as low or lower than those without DM with lower fitness.

Reference Standards of Cardiorespiratory Fitness Measured With the Cardiopulmonary Exercise Test Using the Treadmill in Chinese Adults Younger Than 60 Years.

Cardiorespiratory fitness (CRF) is a strong predictor of cardiorespiratory diseases and varies by race. The purpose of this study was to provide CRF reference standards and a prediction equation for peak oxygen uptake (V˙O 2peak ) from treadmill-based cardiopulmonary exercise testing (CPX) in Chinese individuals. Healthy participants (n = 4199) who completed a CPX using a treadmill were studied. The percentiles of V˙O 2peak were determined for four age groups (decades). A regression prediction model was developed from the derivation cohort (n = 3361), validated in the independent validation cohort (n = 838), and compared with the widely used Wasserman equation and the Fitness Registry and the Importance of Exercise National Database (FRIEND) equation. The mean V˙O 2peak values of four age groups (20-29, 30-39, 40-49, and 50-59 yr) were 42.6, 41.2, 38.7, and 35.9 mL/kg/min, respectively, for men, and 37.1, 34.7, 32.0, and 30.3 mL/kg/min, respectively, for women. The 50th percentiles of relative V˙O 2peak decreased with age for both sexes. The prediction equation was: Absolute V˙O 2peak (mL/min) = 236.68 - (504.64 × sex [male = 0; female = 1]) + (21.23× weight [kg]) - (14.31 × age [yr]) + (9.46 × height [cm]) (standard error of the estimate = 379.59 mL/min, R2 = 0.66, P < .001).Percentage predicted V˙O 2peak for the validation sample was 100.2%. The novel equation performed better than the other two equations. This study reports the first CRF reference standards and prediction equation generated from treadmill CPX in China. These reference standards provide a framework for interpreting the CRF of the Chinese population and could be useful information for a global CRF database.

A Machine Learning Approach to Developing an Accurate Prediction of Maximal Heart Rate During Exercise Testing in Apparently Healthy Adults.

Maximal heart rate (HR max ) continues to be an important measure of adequate effort during an exercise test. The aim of this study was to improve the accuracy of HR max prediction using a machine learning (ML) approach. We used a sample from the Fitness Registry of the Importance of Exercise National Database, which included 17 325 apparently healthy individuals (81% males) who performed a maximal cardiopulmonary exercise test. Two standard formulas for HR max prediction were tested: Formula1 = 220 - age (yr), root-mean-squared error (RMSE) 21.9, relative root-mean-squared error (RRMSE) 1.1; and Formula2 = 209.3 - 0.72 × age (yr), RMSE 22.7 and RRMSE 1.1. For ML model prediction, we used age, weight, height, resting HR, and systolic and diastolic blood pressure. The following ML algorithms to predict HR max were applied: lasso regression (LR), neural networks (NN), support vector machine (SVM) and random forests (RF). An evaluation was performed using cross-validation and by computing the RMSE and RRMSE, Pearson correlation, and Bland-Altman plots. The best predictive model was explained with Shapley Additive Explanations (SHAP). The HR max for the cohort was 162 ± 20 bpm. All ML models improved HR max prediction and reduced RMSE and RRMSE compared with Formula1 (LR: 20.2%, NN: 20.4%, SVM: 22.2%, and RF: 24.7%). The predictions of all algorithms significantly correlated with HR max ( r = 0.49, 0.51, 0.54, 0.57, respectively; P < .001). Bland-Altman analysis demonstrated lower bias and 95% CI for all ML models in comparison with standard equations. The SHAP explanation showed a high impact of all selected variables. Machine learning, particularly the RF model, improved prediction of HR max using readily available measures. This approach should be considered for clinical application to refine HR max prediction.

Cardiorespiratory fitness estimations and their ability to predict all-cause mortality in patients with cardiovascular disease

BackgroundIn cardiac rehabilitation programs, cardiorespiratory fitness is commonly estimated (eCRF) from the maximum workload achieved on a graded exercise test. This study compared four well-established eCRF equations in their ability to predict mortality in patients with cardiovascular disease (CVD). MethodsA total of 7269 individuals with CVD were studied (81% male; age 59.4 ± 10.3yr). eCRF was calculated using equations from the American College of Sports Medicine, Bruce et al., the Fitness Registry and the Importance of Exercise International Database, and McConnell and Clark. The eCRF from each equation was compared with a RMANOVA. Cox proportional hazard models assessed the relationship between the eCRF equations and mortality risk. The predictive ability of the models was compared using the concordance index. ResultsThere were 284 deaths (85% male) over a follow-up period of 5.8 ± 2.8yr. Although differences in eCRF were observed between each equation (P < 0.05), the eCRF from each of the four equations was predictive of mortality (P < 0.05). The concordance index values for each of the models were the same (0.77) indicating similar predictive performance. ConclusionsThe four well-established eCRF equations did not differ in their ability to predict mortality in patients with CVD, indicating any could be used for this purpose. However, the differences in eCRF from each of the equations suggest potential differences in their ability to guide clinical care and should be the focus of future research.

A Nonexercise Prediction of Peak Oxygen Uptake for Patients With Cardiovascular Disease: DATA FROM THE FITNESS REGISTRY AND THE IMPORTANCE OF EXERCISE INTERNATIONAL DATABASE (FRIEND).

Nonexercise predictions of peak oxygen uptake (V˙ o2peak ) are used clinically, yet current equations were developed from cohorts of apparently healthy individuals and may not be applicable to individuals with cardiovascular disease (CVD). Our purpose was to develop a CVD-specific nonexercise prediction equation for V˙ o2peak . Participants were from the Fitness Registry and Importance of Exercise International Database (FRIEND) with a diagnosis of coronary artery bypass surgery (CABG), myocardial infarction (MI), percutaneous coronary intervention (PCI), or heart failure (HF) who met maximal effort criteria during a cardiopulmonary exercise test (n = 15 997; 83% male; age 63.1 ± 10.4 yr). The cohort was split into development (n = 12 798) and validation groups (n = 3199). The prediction equation was developed using regression analysis and compared with a previous equation developed on a healthy cohort. Age, sex, height, weight, exercise mode, and CVD diagnosis were all significant predictors of V˙ o2peak . The regression equation was:V˙ o2peak (mL · kg -1 · min -1 ) = 16.18 - (0.22 × age [yr]) + (3.63 × sex [male = 1; female = 0]) + (0.14 × height [cm]) - (0.12 × weight [kg]) + (3.62 × mode [treadmill = 1; cycle = 0]) - (2.70 × CABG [yes = 1, no = 0]) - (0.31 × MI [yes = 1, no = 0]) + (0.37 × PCI [yes = 1, no = 0]) - (4.47 × HF [yes = 1, no = 0]). Adjusted R 2 = 0.43; SEE = 4.75 mL · kg -1 · min -1 .Compared with measured V˙ o2peak in the validation group, percent predicted V˙ o2peak was 141% for the healthy cohort equation and 100% for the CVD-specific equation. The new equation for individuals with CVD had lower error between measured and predicted V˙ o2peak than the healthy cohort equation, suggesting population-specific equations are needed for predicting V˙ o2peak ; however, errors associated with nonexercise prediction equations suggest V˙ o2peak should be directly measured whenever feasible.

Reference Standards for Peak Rating of Perceived Exertion during Cardiopulmonary Exercise Testing: Data from FRIEND.

Peak rating of perceived exertion (RPE) is measured during clinical cardiopulmonary exercise testing (CPX) and is commonly used as a subjective indicator of maximal effort. However, no study to date has reported reference standards or the distribution of peak RPE across a large cohort of apparently healthy individuals. This study aimed to determine reference standards for peak RPE when using the 6-20 Borg scale for both treadmill and cycle tests. The analysis included 9551 tests (8821 treadmill, 730 cycle ergometer) from 13 laboratories within the Fitness Registry and Importance of Exercise National Database (FRIEND). Using data from tests conducted January 1, 1980, to January 1, 2021, percentiles of peak RPE for men and women were determined for each decade from 20 to 89 yr of age for treadmill and cycle exercise modes. Two-way ANOVA was used to compare differences in peak RPE values between sexes and across age groups. There were statistically significant differences in RPE between age groups whether the test was performed on a treadmill or cycle ergometer ( P < 0.05). However, the mean and median RPE for each sex, age group, and test mode were between 18 and 19. In addition, 83% of participants met the traditional RPE criteria of ≥18 for indicating sufficient maximal effort. This report provides the first normative reference standards for peak RPE in both male and female individuals performing CPX on a treadmill or cycle ergometer. Furthermore, these reference standards highlight the general consistency of peak RPE responses during CPX.

Peak Circulatory Power during Maximal Cardiopulmonary Exercise Testing: Reference Standards from the FRIEND Registry.

Normative standards for key cardiopulmonary exercise (CPX) test variables, including peak circulatory power (CircP), are needed to guide the interpretation of clinical exercise responses in individuals with and without disease. This study aimed to establish age- and sex-specific reference standards for peak CircP derived from a healthy cohort from the Fitness Registry and the Importance of Exercise: A National Database (FRIEND). CPX test data from apparently healthy males and females from eight FRIEND United States exercise laboratories were considered. Inclusion criteria included ages 20-79 yr and a maximal, symptom-limited exercise test performed on a treadmill or cycle ergometer. CircP was calculated as the product of peak oxygen consumption and peak systolic blood pressure. Reference values were determined on both treadmill and cycle ergometer for males and females per age decade. A stepwise linear regression to predict CircP was derived from two-thirds of the sample while the remaining one-third was used as a validation cohort. A total of 6736 CPX tests (47% treadmill, 53% female) were included in the analysis. Overall, CircP was higher in males, higher on tests conducted on a treadmill, and decreased with age. Sex, exercise mode, age, and body mass index were the most significant contributors to CircP (multiple R = 0.75, R2 = 0.57, root-mean-square error = 1200 mm Hg·mL O 2 ·kg -1 ·min -1 , P < 0.001). Using the generated prediction equation, the average percent-predicted CircP for the validation cohort was 101.3% ± 28.1%. These results establish reference standards for CircP, a potentially important prognostic indicator of cardiovascular health. Future research exploring the role of percentiles and percent-predicted values for CircP is necessary as they may provide additional prognostic insight.

Validity of Estimated Cardiorespiratory Fitness in Patients With Primary Breast Cancer

BackgroundEstimated peak oxygen consumption (Vo2peak) is widely used in oncology; however, estimated Vo2peak equations were developed in noncancer settings. ObjectivesThe aim of this study was to evaluate the validity of estimated Vo2peak in women with primary breast cancer and to develop oncology-specific estimated Vo2peak equations. MethodsVo2peak was directly measured (TrueOne 2400, Parvo Medics) during 380 cardiopulmonary exercise tests in women previously treated for breast cancer (mean age: 59 ± 10 years; 3.1 ± 1.2 years post-therapy). The American College of Sports Medicine (ACSM), the Fitness Registry and the Importance of Exercise National Database (FRIEND), and heart failure (HF)-FRIEND equations were used to estimate Vo2peak. New equations were developed using patient and peak (Oncpeak) or submaximal (Oncsub) exercise test characteristics. ResultsThe median differences between measured and estimated Vo2peak were 7.0 mL O2·kg−1·min−1, 3.9 mL O2·kg−1·min−1, and −0.2 mL O2·kg−1·min−1 for ACSM, FRIEND, and HF-FRIEND, respectively. The number of estimated Vo2peak values within ±3.5 mL O2·kg−1·min−1 of the measured values was 70 (18%), 164 (43%), and 306 (81%) for ACSM, FRIEND, and HF-FRIEND, respectively. The Oncpeak and OncSub models included body mass index, age, a history of chemotherapy or radiation, the peak measured heart rate, and the treadmill grade and/or speed. The median differences between measured and estimated Vo2peak were 0.02 mL O2·kg−1·min−1 (Oncpeak) and −0.2 mL O2·kg−1·min−1 (Oncsub). Eighty-six percent (n = 325) and 76% (n = 283) estimated Vo2peak values were within ±3.5 mL O2·kg−1·min−1 of the measured Vo2peak values for Oncpeak and Oncsub, respectively. ConclusionsHF-FRIEND or oncology-specific equations could be applied to estimate Vo2peak in patients previously treated for breast cancer in settings where cardiopulmonary exercise tests are not available. (Trial Comparing the Effects of Linear Versus Nonlinear Aerobic Training in Women With Operable Breast Cancer [EXCITE]; NCT01186367

Abstract EP57: A Non-exercise Prediction Of Cardiorespiratory Fitness For Patients With Cardiovascular Disease: Data From The Fitness Registry And The Importance Of Exercise International Database (FRIEND)

Introduction: The importance of cardiorespiratory fitness (CRF) for stratifying mortality risk and guiding clinical care in patients with cardiovascular disease (CVD) is well-established. An American Heart Association Scientific Statement suggests routine clinical assessment of CRF using non-exercise prediction equations when direct assessment from a cardiopulmonary exercise test is not feasible. However, current prediction equations have been created from cohorts of apparently healthy individuals. Hypothesis: A CVD-specific non-exercise equation would have higher accuracy for predicting CRF compared to an equation developed from a cohort without known CVD. Methods: Participants from the Fitness Registry and Importance of Exercise International Database (FRIEND) with a diagnosis of coronary artery bypass surgery (CABG), myocardial infarction (MI), percutaneous coronary intervention (PCI), or heart failure (HF) who performed a cardiopulmonary exercise test were studied (83% [10,417 of 12,578] male; age 62.7 ± 10.3 years). The cohort (12,578 tests; 49% [6,190] treadmill tests) was split into development (10,062) and validation (2,516) groups. The prediction equation was developed using multiple regression analysis and comparisons were made with a CRF prediction equation developed on an apparently healthy cohort using FRIEND. Results: Age, sex, height, body mass, exercise mode, and CVD diagnosis were all significant predictors of CRF. The regression equation was: CRF (mL/kg/min) = 17.03 – (0.21 * age [years]) + (3.60 * sex [male = 1; female = 0]) + (0.12 * height [cm]) – (0.11 * body mass [kg]) + (3.75 * mode [treadmill = 1; cycle = 0]) – (2.40 * CABG [yes = 1, no = 0]) – (0.29 * MI [yes = 1, no = 0]) + (0.75 * PCI [yes = 1, no = 0]) – (3.90 * HF [yes = 1, no = 0]) (adjusted R 2 = 0.42, SEE = 4.74 mL/kg/min). When compared to measured CRF in the validation group (19.6 ± 6.2 mL/kg/min), predicted CRF was similar for the CVD equation (19.8 ± 4.1 mL/kg/min [101%]) and higher for the healthy cohort equation (28.2 ± 7.0 mL/kg/min [144%]; P &lt;0.05). Significant Pearson correlations were found when using either prediction equation although the correlation when using the CVD equation was higher (r = 0.65) than that for the healthy cohort equation (r = 0.48, P &lt;0.05). Differences between equations were also observed for root mean square error (4.7 and 10.9 mL/kg/min for the CVD and healthy cohort equations, respectively). Conclusions: As hypothesized, the CVD-specific non-exercise equation was a better predictor of CRF in a cohort of individuals with CVD. The new equation for individuals with CVD provided a lower mean error between measured and predicted CRF than an equation developed from an apparently healthy cohort. Thus, population specific equations are needed for predicting CRF; however, the error associated with non-exercise prediction equations suggests CRF should be directly measured whenever feasible.

Is BMI Associated with Cardiorespiratory Fitness? A Cross-Sectional Analysis Among 8470 Apparently Healthy Subjects Aged 18–94 Years from the Low-Lands Fitness Registry

ObjectiveThe purpose of the present study was to investigate the association between cardiorespiratory fitness (CRF) measured as peak oxygen uptake (VO2peak, expressed in mL/min) and body mass index (BMI) in a large cohort of apparently healthy subjects.MethodsBMI and VO2peak were measured in a cross-sectional study of 8470 apparently healthy adults. VO2peak (mL/min) was determined by an incremental cycle ergometer test to exhaustion. Linear regression analyses were performed to identify predictors of CRF.ResultsThere was no difference in CRF between adults with a normal weight (BMI between 18.5–24.9 kg/m2) and those who were overweight (BMI 25.0–29.9 kg/m2). Subjects who were underweight (BMI < 18.5 kg/m2) as well as females who were obese (BMI ≥ 30.0 kg/m2) showed a reduced CRF compared to the normal and overweight groups. Age, height, and gender were significant predictors of CRF (R2 = 0.467, P < 0.0001); BMI did not add significantly to this relationship.ConclusionOur findings indicate that BMI was not associated with CRF in addition to age, height, and gender. In subjects with a BMI < 18.5 kg/m2, CRF was lower compared to subjects with a BMI between 18.5 and 29.9 kg/m2. In obese subjects, CRF was only lower in females compared to females with a BMI between 18.5 and 29.9 kg/m2. Correcting CRF for BMI may be beneficial for subjects with a low BMI, and females with a BMI ≥ 30.0 kg/m2. The outcome of this study might help to improve the interpretation of exercise testing results in individuals with a low or high BMI.

Updated Reference Standards for Cardiorespiratory Fitness Measured with Cardiopulmonary Exercise Testing: Data from the Fitness Registry and the Importance of Exercise National Database (FRIEND)

ObjectiveTo provide updated reference standards for cardiorespiratory fitness (CRF) for the United States derived from cardiopulmonary exercise (CPX) testing when using a treadmill or cycle ergometer. Patients and MethodsThirty-four laboratories in the United States contributed data to the Fitness Registry and the Importance of Exercise National Database. Analysis included 22,379 tests (16,278 treadmill and 6101 cycle ergometer) conducted between January 1, 1968, through March 31, 2021, from apparently healthy adults (aged 20 to 89 years). Percentiles of peak oxygen consumption for men and women were determined for each decade from 20 through 89 years of age for treadmill and cycle exercise modes, as well as when defining maximal effort as respiratory exchange ratio (RER) greater than or equal to 1.0 or RER greater than or equal to 1.1. ResultsFor both men and women, the 50th percentile scores for each exercise mode decreased with age and were higher in men across all age groups and higher for treadmill compared with cycle CPX. The average rate of decline per decade over a 6-decade period was 13.5%, 4.0 mLO2·kg-1·min-1 for treadmill CPX and 16.4%, 4.3 mLO2·kg-1·min-1 for cycle CPX. Observationally, the mean peak oxygen consumption was similar whether using an RER criterion of greater than or equal to 1.0 or greater than or equal to 1.1 across the different test modes, ages, and for both sexes. The updated reference standards for treadmill CPX were 1.5 – 4.6 mLO2·kg-1·min-1 lower compared with the previous 2015 standards whereas the updated cycling standards were generally comparable to the original 2017 standards. ConclusionThese updated cardiorespiratory fitness reference standards improve the representativeness of the US population compared with the original standards.

Reference Standards for Cardiorespiratory Fitness by Cardiovascular Disease Category and Testing Modality: Data From FRIEND.

BackgroundThe importance of cardiorespiratory fitness for stratifying risk and guiding clinical decisions in patients with cardiovascular disease is well‐established. To optimize the clinical value of cardiorespiratory fitness, normative reference standards are essential. The purpose of this report is to extend previous cardiorespiratory fitness normative standards by providing updated cardiorespiratory fitness reference standards according to cardiovascular disease category and testing modality.Methods and ResultsThe analysis included 15 045 tests (8079 treadmill, 6966 cycle) from FRIEND (Fitness Registry and the Importance of Exercise National Database). Using data from tests conducted January 1, 1974, through March 1, 2021, percentiles of directly measured peak oxygen consumption (VO2peak) were determined for each decade from 30 through 89 years of age for men and women with a diagnosis of coronary artery bypass surgery, myocardial infarction, percutaneous coronary intervention, or heart failure. There were significant differences between sex and age groups for VO2peak (P<0.001). The mean VO2peak was 23% higher for men compared with women and VO2peak decreased by a mean of 7% per decade for both sexes. Among each decade, the mean VO2peak from treadmill tests was 21% higher than the VO2peak from cycle tests. Differences in VO2peak were observed among the age groups in both sexes according to cardiovascular disease category.ConclusionsThis report provides normative reference standards by cardiovascular disease category for both men and women performing cardiopulmonary exercise testing on a treadmill or cycle ergometer. These updated and enhanced reference standards can assist with patient risk stratification and guide clinical care.

Cardiorespiratory Fitness’ Indirect Assessment With Running Metabolic Equations Among Healthy Active Men

VO2max is defined as the highest amount of oxygen the cardiovascular and pulmonary systems can supply and the highest amount of oxygen the muscular system can use during intense physical exertion. It is widely accepted as the criterion measure of cardiorespiratory fitness. Unfortunately, accessibility to VO2max’s direct measurement is restricted. Therefore, several metabolic equations have been developed to estimate VO2max using indirect calculation. The most commonly used equations are those developed by the American College of Sports Medicine (ACSM) and recently, the research group of Fitness Registry and the Importance of Exercise National Database developed a new metabolic equation (FRIEND). PURPOSE: The aim of this study is to evaluate the accuracy of the ACSM and FRIEND equations to estimate VO2max comparatively to direct O2 consumption measurement in healthy active men. METHODS: 54 healthy active men aged between 19-60y.o. (36,6±5,4)(BMI: 24,1±2,6kg/m2) performed a maximal treadmill test using a metabolic cart (Vyntus CPX) to measure direct VO2max (mL O2/kg*min-1). VO2max estimation was then calculated using ACSM and FRIEND running metabolic equations. For analysis, they were separated in two age groups (18-34 vs 35-60y.o.) to evaluate if it has an impact on the metabolic equations used. Results were compared using a two-way ANOVA. RESULTS: When compared to the direct measurement (53,9±7,2 (18-34y.o.) and 49,8±4,4 (35-60y.o.)), both ACSM and FRIEND equations showed significantly higher results in both age group (mean overestimation: 12,7; p<0,001 and 3,7; p=0,005, respectively). However, the FRIEND equation was significantly lower than the ACSM equation (mean difference: 9,0; p<0,001). Moreover, ACSM showed a very large effect size (Hedge’s g=1,84) while FRIEND showed a medium effect size (Hedge’s g=0,58). As for the two age groups, results varied similarly using the two equations (p=0,781). CONCLUSIONS: The VO2max calculated with the metabolic equations for running showed overestimated values in our male sample. The average difference between direct and indirect measurement when using the FRIEND equation suggests a better accuracy. More research is needed to evaluate the accuracy in different populations and different fitness levels to optimize the VO2 estimation formula.

Low but not high exercise systolic blood pressure is associated with long-term all-cause mortality

ObjectivesThe risks associated with achieving a high peak systolic blood pressure (SBP) during clinical exercise testing remain controversial, although this issue has not been evaluated in relation to predicted SBP...

Comparing individual and population differences in minute ventilation/carbon dioxide production slopes using centile growth curves and log-linear allometry.

Identifying vulnerable groups and/or individuals’ cardiorespiratory fitness (CRF) is an important challenge for clinicians/researchers alike. To quantify CRF accurately, the assessment of several variables is now standard practice including maximal oxygen uptake (VʹCO2) and ventilatory efficiency, the latter assessed using the minute ventilation/carbon dioxide production (VʹE/VʹCO2) slope. Recently, reference values (centiles) for VʹE/VʹCO2 slopes for males and females aged 20 to 80 have been published, using cardiopulmonary exercise testing (CPX) data (treadmill protocol) from the Fitness Registry and the Importance of Exercise National Database (FRIEND Registry).In the current observational study we provide centile curves for the FRIEND Registry VʹE/VʹCO2 slopes, fitted using the generalised additive model for location, scale and shape (GAMLSS), to provide individuals with a more precise estimate of where their VʹE/VʹCO2 slopes fall within the population. We also confirm that by adopting allometric models (incorporating a log transformation), the resulting ANCOVAs provided more normal and homoscedastic residuals, with superior goodness-of-fit using the Akaike information criterion (AIC)=14 671 (compared with traditional ANCOVA's AIC=15 008) that confirms allometric models are vastly superior to traditional ANCOVA models.In conclusion, providing sex-by-age centile curves rather than referring to reference tables for ventilatory efficiency (VʹE/VʹCO2 slopes) will provide more accurate estimates of where an individual's particular VʹE/VʹCO2 slope falls within the population. Also, by adopting allometric models researchers are more likely to identify real and valid inferences when analysing population/group differences in VʹE/VʹCO2 slopes.

Reference values for maximum oxygen uptake relative to body mass in Dutch/Flemish subjects aged 6\u201365\xa0years: the LowLands Fitness Registry

BackgroundThe maximum oxygen uptake (VO2max) during cardiopulmonary exercise testing (CPET) is considered the best measure of cardiorespiratory fitness.AimTo provide up-to-date reference values for the VO2max per kilogram of body mass (VO2max/kg) obtained by CPET in the Netherlands and Flanders.MethodsThe Lowlands Fitness Registry contains data from health checks among different professions and was used for this study. Data from 4612 apparently healthy subjects, 3671 males and 941 females, who performed maximum effort during cycle ergometry were analysed. Reference values for the VO2max/kg and corresponding centile curves were created according to the LMS method.ResultsAge had a negative significant effect (p < .001) and males had higher values of VO2max/kg with an overall difference of 18.0% compared to females.Formulas for reference values were developed:Males: VO2max/kg = − 0.0049 × age2 + 0.0884 × age + 48.263 (R2 = 0.9859; SEE = 1.4364)Females: VO2max/kg = − 0.0021 × age2 − 0.1407 × age + 43.066 (R2 = 0.9989; SEE = 0.5775).Cross-validation showed no relevant statistical mean difference between measured and predicted values for males and a small but significant mean difference for females. We found remarkable higher VO2max/kg values compared to previously published studies.ConclusionsThis is the first study to provide reference values for the VO2max/kg based on a Dutch/Flemish cohort. Our reference values can be used for a more accurate interpretation of the VO2max in the West-European population.