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Brittany E Smith,1 James E Peterman,2 Matthew P Harber,3 Mary T Imboden,4 Bradley S Fleenor,3 Leonard A Kaminsky,2 Mitchell H Whaley3 1Exercise Science and Exercise Physiology, Kent State University, Kent, OH, 44240, USA; 2Fisher Institute of Health and Wellbeing, Ball State University, Muncie, IN, 47306, USA; 3School of Kinesiology, Ball State University, Muncie, IN, 47306, USA; 4Department of Exercise Science, George Fox University, Portland, OR, 97132, USACorrespondence: Mitchell H Whaley, Email mwhaley@bsu.eduPurpose: To evaluate how the changes in directly measured cardiorespiratory fitness (CRF) relate to the changes in metabolic syndrome (MetS) status following 4– 6 months of exercise training.Methods: Maximal cardiopulmonary exercise (CPX) tests and MetS risk factors were analyzed prospectively from 336 adults (46% women) aged 45.8 ± 10.9 years. MetS was defined according to the National Cholesterol Education Program-Adult Treatment Panel III criteria, as updated by the American Heart Association/National Heart, Lung, and Blood Institute (AHA/NHLBI). Pearson correlations, chi-squares, and dependent 2-tail t-tests were used to assess the relationship between the change in CRF and the change in MetS risk factors, overall number of MetS risk factors, and a MetS severity score following 4– 6 months of participation in a self-referred, community-based exercise program.Results: Overall prevalence of MetS decreased from 23% to 14% following the exercise program (P < 0.05), while CRF improved 15% (4.7 ± 8.4 mL/kg/min, P < 0.05). Following exercise training, the number of positive risk factors declined from 1.4 ± 1.3 to 1.2 ± 1.2 in the overall cohort (P < 0.05). The change in CRF was inversely related to the change in the overall number of MetS risk factors (r = − 0.22; P < 0.05) and the MetS severity score (r = − 0.28; p < 0.05).Conclusion: This observational cohort study indicates an inverse relationship between the change in CRF and the change in MetS severity following exercise training. These results suggest that participation in a community-based exercise program yields significant improvements in CRF, MetS risk factors, the prevalence of the binary MetS, and the MetS severity score. Improvement in CRF through exercise training should be a primary prevention strategy for MetS.Keywords: cardiorespiratory fitness, metabolic syndrome, exercise training, abdominal obesity

Purpose: To determine if individuals chronically (>1 yr) prescribed antihypertensive medications have a normal BP response to peak exercise compared with unmedicated individuals., Methods: 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., Results: 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)., Conclusions: 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., (Copyright © 2024 by the American College of Sports Medicine.)

Exercise capacity (EC) is an important predictor of survival in the general population and in subjects with cardiopulmonary disease. Despite its relevance, considering the percent-predicted workload (%pWL) given by current equations may overestimate EC in older adults. Therefore, to improve the reporting of EC in clinical practice, our main objective was to develop workload reference equations (pWL) that better reflect the relation between workload and age. Using the Fitness Registry and the Importance of Exercise National Database (FRIEND), we analyzed a reference group of 6,966 apparently healthy participants and 1,060 participants with heart failure who underwent graded treadmill cardiopulmonary exercise testing. For the first group, the mean age was 44 years (18 to 79); 56.5% of participants were males and 15.4% had obesity. Peak oxygen consumption was 11.6 ± 3.0 METs in males and 8.5 ± 2.4 METs in females. After partition analysis, we first developed sex-specific pWL equations to allow comparisons to a healthy weight reference. For males, pWL (METs) = 14.1-0.9×10 -3 ×age 2 and 11.5-0.87×10 -3 ×age 2 for females. We used those equations as denominators of %pWL, and based on their distribution, we determined thresholds for EC classification, with average EC defined by the range corresponding to 85% to 115%pWL. Compared with %pWL using current equations, the new equations yielded better-calibrated %pWL across different age ranges. We also derived body mass index-adjusted pWL equations that better assessed EC in subjects with heart failure. In conclusion, the novel pWL equations have the potential to impact the report of EC in practice., Competing Interests: Declaration of competing interest The authors have no competing interests to declare., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Purpose: 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., Methods: 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)., Results: 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., Conclusions: 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., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: Oxygen uptake efficiency slope (OUES), defined as the slope of the linear relationship between oxygen uptake and the semilog transformed ventilation rate measured during an incremental exercise test, may have prognostic utility. The objective of this investigation was to examine the relationship between assessments of OUES and all-cause mortality in a cohort of apparently healthy adults., Methods: The sample included 2220 apparently healthy adults (48% females) with a mean age of 44.7 ± 12.9 yr who performed cardiopulmonary exercise testing. The OUES was calculated from the entire test, using data from the initial 50% (OUES 50 ) and 75% (OUES 75 ) of test time, and normalized to body surface area. Cox proportional hazard models assessed the relationship between measures of OUES and mortality. Prognostic peak oxygen uptake (V˙ o2peak ) and OUES models were compared using the concordance index., Results: There were 310 deaths (29% females) over a follow-up period of 19.8 ± 11.1 yr. For males, OUES, OUES 75 , and normalized OUES had an inverse association with mortality, even after adjusting for traditional risk factors ( P < .05). For females, only the unadjusted OUES, OUES 75 , and normalized OUES models were associated with mortality ( P < .05). The concordance index values indicated that unadjusted OUES 50 and OUES 75 models had lower discrimination than the unadjusted OUES and V˙ o2peak models ( P < .05). Furthermore, OUES did not complement the fully adjusted V˙ o2peak model ( P ≥ .32)., Conclusions: Assessments of OUES are related to all-cause mortality in males but not in females. These findings suggest that OUES can have prognostic utility in apparently healthy males. Moreover, submaximal determinations of OUES could have value when measuring V˙ o2peak is not feasible., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: 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 ., Methods: 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., Results: 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., Conclusions: 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., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Introduction: 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., Purpose: This study aimed to determine reference standards for peak RPE when using the 6-20 Borg scale for both treadmill and cycle tests., Methods: 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., Results: 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., Conclusions: 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., (Copyright © 2022 by the American College of Sports Medicine.)

The severe health consequences of the corona virus disease 2019 (COVID-19) pandemic have been exacerbated by the prevalence of cardiovascular disease (CVD) risk factors, such as physical inactivity, obesity, hypertension, and diabetes. Further, policy decisions during the pandemic augmented unhealthy lifestyle behaviors and health inequalities, likely increasing the global disease burden. Cardiorespiratory fitness (CRF) is a well-established biomarker associated with CVD risk. Emerging data demonstrate that high CRF offers some protection against severe outcomes from COVID-19 infection, highlighting the importance of CRF for population health and the potential for limiting the severity of future pandemics. CRF is best assessed by cardiopulmonary exercise testing (CPET), which will be an important tool for understanding the prolonged pathophysiology of COVID-19, the emergence of long-COVID, and the lasting effects of COVID-19 on CVD risk. Utilization of CRF and CPET within clinical settings should become commonplace because of lessons learned from the COVID-19 pandemic., Competing Interests: Declaration of Competing Interest None., (Copyright © 2022. Published by Elsevier Inc.)

Purpose: 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., Objective: 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)., Methods: 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., Results: 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%., Conclusions: 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., (Copyright © 2022 by the American College of Sports Medicine.)

Purpose: The cardiorespiratory optimal point (COP) is the minimum ventilatory equivalent for oxygen. The COP can be determined during a submaximal incremental exercise test. Reflecting the optimal interaction between the respiratory and cardiovascular systems, COP may have prognostic utility. The aim of this investigation was to determine the relationship between COP and all-cause mortality in a cohort of apparently healthy adults., Methods: The sample included 3160 apparently healthy adults (46% females) with a mean age of 44.0 ± 12.5 yr who performed a cardiopulmonary exercise test. Cox proportional hazards models were performed to assess the relationship between COP and mortality risk. Prognostic peak oxygen uptake (V˙ o2peak ) and COP models were compared using the concordance index., Results: There were 558 deaths (31% females) over a follow-up period of 23.0 ± 11.9 yr. For males, all Cox proportional hazards models, including the model adjusted for traditional risk factors and V˙ o2peak , had a positive association with risk for mortality ( P &lt; .05). For females, only the unadjusted COP model was associated with risk for mortality ( P &lt; .05). The concordance index values indicated that unadjusted COP models had lower discrimination compared with unadjusted V˙ o2peak models ( P &lt; .05) and V˙ o2peak did not complement COP models ( P ≥ .13)., Conclusions: Cardiorespiratory optimal point is related to all-cause mortality in males but not females. These findings suggest that a determination of COP can have prognostic utility in apparently healthy males aged 18-85 yr, which may be relevant when a maximal exercise test is not feasible or desirable., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 The Authors. Published by Wolters Kluwer Health, Inc.)

Background: In 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)., Methods: A 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., Results: There 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., Conclusions: The 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., (© 2022 The Authors.)

Background: The association between cardiorespiratory fitness (CRF) and metabolic syndrome (MetSyn) is well established. Additional variables derived from cardiopulmonary exercise testing (CPET) have shown prognostic value in some chronic diseases, however, there is limited information on how cardiopulmonary responses to exercise may be altered in individuals with MetSyn. Thus, the purpose of this study was to examine the association between cardiopulmonary variables derived from CPET and MetSyn. Methods: A cohort of 3181 participants (1714 men, 1467 women), aged 20-79 years, completed CPET and metabolic risk factor assessment between January 1, 1971, and November 1, 2020. Cardiopulmonary variables assessed included CRF defined as the maximum volume of oxygen uptake (VO 2max ), ventilatory threshold (VO 2 @VT), oxygen uptake efficiency slope (OUES), the ratio of ventilation to VO 2 at peak exercise (peak V E /VO 2 ) and the V E /VCO 2slope . MetSyn was defined using the National Cholesterol Education Program/Adult Treatment Panel. Results: VO 2max , VO 2 @VT, and OUES were lower ( P  < 0.001) and V E /VCO 2slope was higher ( P  < 0.001) in individuals with MetSyn ( n  = 774), whereas no difference between groups existed for peak V E /VO 2 . Logistic regression analysis revealed that VO 2max [0.91, 0.89-0.93; odds ratio (OR), 95% confidence interval (CI)], VO 2 @VT (0.91, 0.87-0.95; OR, 95% CI), OUES (0.32, 0.20-0.52; OR, 95% CI), and V E /VCO 2slope (1.03, 1.01-1.05 OR, 95% CI) were all associated with the presence of MetSyn ( P  ≤ 0.001). Conclusion: These results indicate that MetSyn is associated with altered cardiopulomary function that may provide insight into the underlying pathophysiology of MetSyn.

Objective: To 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 Methods: Thirty-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., Results: For both men and women, the 50 th 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 mLO 2 ·kg -1 ·min -1 for treadmill CPX and 16.4%, 4.3 mLO 2 ·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 mLO 2 ·kg -1 ·min -1 lower compared with the previous 2015 standards whereas the updated cycling standards were generally comparable to the original 2017 standards., Conclusion: These updated cardiorespiratory fitness reference standards improve the representativeness of the US population compared with the original standards., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Cardiovascular disease (CVD) is the leading cause of death globally. Advancements in the treatment of CVD have reduced mortality rates, yet the global burden of CVD remains high. Considering that CVD is still largely a preventable disease, prioritizing preventative measures through healthy lifestyle (HL) behaviors is necessary to lessen the burden of CVD. HL behaviors, such as regular exercise, healthy eating habits, adequate sleep, and smoking cessation, can influence a number of traditional CVD risk factors as well as a less commonly measured risk factor, cardiorespiratory fitness (CRF). It is important to note that cardiac rehabilitation programs, which traditionally have focused on secondary prevention, also emphasize the importance of making comprehensive HL behavior changes. This review discusses preventative measures to reduce the burden of CVD through an increased uptake and assessment of HL behaviors. An overview of the importance of CRF as a risk factor is discussed along with how to improve CRF and other risk factors through HL behavior interventions. The role of the clinician for promoting HL behaviors to prevent CVD is also reviewed., Competing Interests: Declaration of Competing Interest None., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background The 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 Results The 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 (VO 2peak ) 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 VO 2peak ( P <0.001). The mean VO 2peak was 23% higher for men compared with women and VO 2peak decreased by a mean of 7% per decade for both sexes. Among each decade, the mean VO 2peak from treadmill tests was 21% higher than the VO 2peak from cycle tests. Differences in VO 2peak were observed among the age groups in both sexes according to cardiovascular disease category. Conclusions This 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.

Background: Active commuting is inversely related with cardiovascular disease (CVD) risk factors yet associations with CVD prevalence in the US population are unknown., Methods: Aggregate data from national surveys conducted in 2017 provided state-level percentages of adults who have/had coronary heart disease, myocardial infarction, and stroke, and who actively commuted to work. Associations between active commuting and CVD prevalence rates were assessed using Pearson correlations and generalized additive models controlling for covariates., Results: Significant correlations were observed between active commuting and all CVD rates (r range = -.31 to -.47; P < .05). The generalized additive model analyses for active commuting (walking, cycling, or public transport) in all adults found no relationships with CVD rates; however, a significant curvilinear association was observed for stroke within men. The generalized additive model curves when examining commuting via walking or cycling in all adults demonstrated nuanced, generally negative linear or curvilinear associations between coronary heart disease, myocardial infarction, and stroke., Conclusion: Significant negative correlations were observed between active commuting and prevalence rates of coronary heart disease, myocardial infarction, and stroke. Controlling for covariates influenced these associations and highlights the need for future research to explore the potential of active commuting modes to reduce CVD in the United States.

Peak oxygen pulse (O 2 pulse peak ) may have predictive utility for health outcomes yet, presently, has only been examined in men and only using a single baseline measure., Purpose: The primary aim of this investigation was to evaluate the relationship between O 2 pulse peak and all-cause mortality in apparently healthy women and men. A secondary aim was to explore the relationship between longitudinal changes to O 2 pulse peak and mortality., Methods: The sample included 3877 participants (43% women) for the primary aim and 759 participants (32% women) who performed two cardiopulmonary exercise tests ≥1 year apart for the secondary aim. Cox proportional hazard models were performed to determine the relationship between O 2 pulse peak and mortality. Prognostic peak oxygen consumption (VO 2peak ) and O 2 pulse peak models were compared using the concordance index and Akaike information criterion (AIC)., Results: In the assessment from baseline, there were 730 deaths over a 24.7 ± 11.8 year follow-up period. For men, a single measure of O 2 pulse peak was inversely associated with risk for mortality (P < 0.05). However, the concordance index and AIC indicated lower discrimination compared to VO 2peak models and O 2 pulse peak did not provide complementary benefit to VO 2peak models. For women, O 2 pulse peak was not associated with mortality risk. In the longitudinal analysis, there were 168 deaths over a follow-up of 20.1 ± 11.4 years. Changes to O 2 pulse peak were not significantly related to mortality in either sex., Conclusions: Within an apparently healthy cohort, a single assessment of O 2 pulse peak is related to all-cause mortality in men but not women. Further, longitudinal changes to O 2 pulse peak are not predictive of mortality in either sex. These findings suggest O 2 pulse peak may have limited prognostic utility in healthy individuals, particularly within healthy women., Competing Interests: Declaration of Competing Interest The authors have no conflicts of interest to declare., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Purpose: Cardiopulmonary exercise testing (CPX) is the gold standard approach for the assessment of cardiorespiratory fitness (CRF). The primary aim of the current study was to determine reference standards for the minute ventilation/carbon dioxide production (V˙E/V˙co2) slope in a cohort from the "Fitness Registry and the Importance of Exercise: A National Database" (FRIEND) Registry., Methods: The current analysis included 2512 tests from 10 CPX laboratories in the United States. Inclusion criteria included CPX data on apparently healthy men and women: (1) age ≥20 yr; and (2) with a symptom-limited exercise test performed on a treadmill. Ventilation and V˙co2 data, from the initiation of exercise to peak, were used to calculate the V˙E/V˙co2 slope via least-squares linear regression. Reference values were determined for men and women by decade of life., Results: On average, V˙E/V˙co2 slope values were lower in men and increased with age independent of sex. Fiftieth percentile values increased from 27.1 in the second decade to 33.9 in the eighth decade in men and from 28.5 in the second decade to 33.7 in the eighth decade in women. In the overall group, correlations with baseline characteristics and the V˙E/V˙co2 slope were statistically significant (P < .05) although generally weak, particularly for age and body mass index., Conclusion: The results of the current study establish reference values for the V˙E/V˙co2 slope when treadmill testing is performed, and all exercise data are used for the slope calculation. These results may prove useful in enhancing the interpretation of CPX results when assessing CRF., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

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., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: journals.permissions@oup.com.)

Background: Healthy vascular aging (HVA) and cardiorespiratory fitness (CRF) are each independently associated with lower cardiovascular disease-related mortality. It is unknown, however, whether the CRF-related reductions in cardiovascular disease risk are related to HVA. We hypothesized that HVA would be associated with higher CRF in men and women from the Ball State Adult Fitness Longitudinal Lifestyle STudy (BALL ST)., Methods: Apparently healthy men and women ≥50 yr of age from the BALL ST cohort (n = 101) who underwent a maximal cardiopulmonary exercise test to assess CRF (V˙O2peak) were included in the study. Participants were divided into either HVA, defined as brachial systolic blood pressure <140/90 mm Hg without taking medications and carotid-femoral pulse wave velocity <7.6 m/sec, or no HVA for subjects with SBP >140/90 mm Hg and/or PWV >7.6 m/sec., Results: Participants with HVA had a higher age- and sex-adjusted CRF percentile (62 ± 5 vs 47 ± 3, P < .05), with women having a greater prevalence of HVA than men (36% vs 15%, P < .05). Both carotid-femoral pulse wave velocity (r =-0.27, P < .05) and brachial systolic blood pressure (r =-0.23, P < .05) were independently and inversely associated with CRF for the entire cohort. Men and women with HVA were younger having a lower body fat percentage and higher low-density lipoprotein cholesterol (P < .05, all)., Conclusions: These data demonstrate that HVA is associated with higher CRF, which may partially explain the preventative cardioprotective effects of CRF., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Physical activity (PA) is beneficial for both mental and physical health, yet many individuals do not meet PA recommendations. There are a multitude of approaches to increase levels of PA and the role of the community is one area of growing interest. This review discusses the community environment as well as programs within the community and their influence on PA levels. Despite some research limitations, there are clear factors associated with community-based PA. Strategies that improve the built environment along with community-based programs have shown success, although differences between the characteristics of communities can mean strategies to promote PA are not universally effective. Additional research is needed on effective strategies that can be tailored to the characteristics of the community to increase PA. Further, public health interventions and policies should consider the role of the community when aiming to increase PA levels., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Equations are often used to predict cardiorespiratory fitness (CRF) from submaximal or maximal exercise tests. However, no study has comprehensively compared these exercise-based equations with directly measured CRF using data from a single, large cohort., Purpose: This study aimed to compare the accuracy of exercise-based prediction equations with directly measured CRF and evaluate their ability to classify an individual's CRF., Methods: The sample included 4871 tests from apparently healthy adults (38% female, age 44.4 ± 12.3 yr (mean ± SD)). Estimated CRF (eCRF) was determined from 2 nonexercise equations, 3 submaximal exercise equations, and 10 maximal exercise equations; all eCRF calculations were then compared with directly measured CRF, determined from a cardiopulmonary exercise test. Analysis included Pearson product-moment correlations, standard error of estimate values, intraclass correlation coefficients, Cohen κ coefficients, and the Benjamini-Hochberg procedure to compare eCRF with directly measured CRF., Results: All eCRF values from the prediction equations were associated with directly measured CRF (P < 0.01), with intraclass correlation coefficient estimates ranging from 0.07 to 0.89. Although significant agreement was found when using eCRF to categorize participants into fitness tertiles, submaximal exercise equations correctly classified an average of only 51% (range, 37%-58%) and maximal exercise equations correctly classified an average of only 59% (range, 43%-76%)., Conclusions: Despite significant associations between exercise-based prediction equations and directly measured CRF, the equations had a low degree of accuracy in categorizing participants into fitness tertiles, a key requirement when stratifying risk within a clinical setting. The present analysis highlights the limited accuracy of exercise-based determinations of eCRF and suggests the need to include cardiopulmonary measures with maximal exercise to accurately assess CRF within a clinical setting.

Introduction: Cardiorespiratory fitness (CRF) is a strong independent predictor of cardiovascular disease (CVD) and CVD mortality. However, little is known in regards to how CRF has trended in apparently healthy adults over the past several decades., Purpose: To analyze trends in CRF and CVD risk factors over the last 50 years in a population of apparently healthy adult men and women., Methods: Participants were 4,214 apparently healthy adults (2,390 men and 1,824 women) from the Ball State Adult Fitness Longitudinal Lifestyle STudy (BALL ST) that performed maximal cardiopulmonary exercise testing between 1970-2019 for the assessment of CRF defined as VO2max (ml/kg/min). Participants were self-referred either to a community-based exercise program, fitness testing, or were research subjects in exercise related studies and were placed into groups by decade based on testing date., Results: CRF showed a general trend to decline (P<0.05) from the 1970s to the 2000s with an increase (P<0.05) from the 2000s to the 2010s for both men and women. This pattern persisted for age and sex-adjusted CRF level, determined by Fitness Registry and the Importance of Exercise: A National Data Base (FRIEND). For both women and men, CRF across the decades was associated (P<0.05) with the prevalence of physical inactivity, smoking, obesity, dyslipidemia and hypertension, and with diabetes in men only., Conclusion: CRF declined from 1970 through the 2000s in a cohort of apparently healthy men and women which was associated with worsening CVD risk profiles. However, the decline in CRF was attenuated over the past decade which may have a positive impact on future CVD in the population. Promoting physical activity to increase CRF should be a primary aspect of CVD prevention programs., Competing Interests: The authors have declared that no competing interests exist.

Purpose: Cardiorespiratory fitness (CRF) is known to be directly related to fat-free mass (FFM), therefore, it has been suggested that normalizing CRF to FFM (V˙O2peakFFM) may be the most accurate expression of CRF as related to exercise performance and cardiorespiratory function. However, the influence of V˙O2peakFFM (mL·kg FFM·min) on predicting mortality has been largely unexplored. This study aimed to primarily assess the relationship between V˙O2peakFFM and all-cause and disease-specific mortality risk in apparently healthy adults. Further, this study sought to compare the predictive ability of V˙O2peakFFM to V˙O2peak normalized to total body weight (V˙O2peakTBW) for mortality outcomes., Methods: Participants included 2905 adults (1555 men, 1350 women) who completed a cardiopulmonary exercise test between 1970 and 2016 to determine CRF. Body composition was assessed using the skinfold method to estimate FFM. Cardiorespiratory fitness was expressed as V˙O2peakTBW and V˙O2peakFFM. Participants were followed for 19.0 ± 11.7 yr after their cardiopulmonary exercise test for mortality outcomes. Cox-proportional hazard models were performed to determine the relationship of V˙O2peakFFM with mortality outcomes. Parameter estimates were assessed to compare the predictive ability of CRF expressed as V˙O2peakTBW and V˙O2peakFFM., Results: Overall, V˙O2peakFFM was inversely related to all-cause, cardiovascular disease, and cancer mortality, with a 16.2%, 8.4%, and 8.0% lower risk per 1 mL·kg FFM·min improvement, respectively (P < 0.01). Further, assessment of the parameter estimates showed V˙O2peakFFM to be a significantly stronger predictor of all-cause mortality than V˙O2peakTBW (parameter estimates, -0.49 vs -0.16)., Conclusions: Body composition is an important factor when considering the relationship between CRF and mortality risk. Clinicians should consider normalizing CRF to FFM when feasible, because it will strengthen the predictive power of the measure.

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.

Objective: To begin the process of developing global reference standards for adults from directly measured cardiorespiratory fitness (CRF)., Methods: Percentiles of maximal oxygen consumption (VO 2 max) for men and women were determined for each decade from 20 through 79 years of age using International data from the Fitness Registry and Importance of Exercise: A National Database (FRIEND-I) along with previously published data from seven studies. FRIEND-I data from January 1, 2014, through January 1, 2019, included 11,678 maximal treadmill tests from three countries, whereas the previously published reports included 32,329 maximal treadmill tests from six countries., Results: FRIEND-I data revealed significant differences between sex and age groups for VO 2 max (P<0.01). For the 20- to 29-years of age group, the 50 th percentile VO 2 max in men and women were 49.5 mLO 2 ⋅kg -1 ⋅min -1 and 40.6 mLO 2 ⋅kg -1 ⋅min -1 , respectively. VO 2 max declined an average of 9% per decade with the 50 th percentile for the 70- to 79-years of age group having a VO 2 max of 30.8 mLO 2 ⋅kg -1 ⋅min -1 in men and 25.0 mLO 2 ⋅kg -1 ⋅min -1 in women. These results were similar in magnitude and direction to the previously published literature. Within both the FRIEND-I and previously published data there were CRF differences between countries., Conclusion: This report begins to establish global reference standards for CRF. Continued development of FRIEND-I will increase global representation providing an improved ability to identify and stratify CRF risk categories., (Copyright © 2019. Published by Elsevier Inc.)

Objective This study aimed to evaluate the impact of the Stand Up Victoria intervention - a multicomponent workplace intervention that successfully reduced workplace sitting - on productivity in the short- and longer-term. Methods Desk-based workers [5-39 per worksite; 68% women; mean age 45.6 (standard deviation 9.4) years] were cluster randomized by office worksite to receive intervention (7 worksites, 136 workers) or control (7 worksites, 95 workers). The intervention used organizational-, environmental-, and individual-level approaches to address workplace sitting. Productivity outcomes were measured via the Health and Work Questionnaire (HWQ; 10 outcomes) and Work Limitations Questionnaire (WLQ; 5 outcomes), administered at 0 (baseline), 3 (initial), and 12 (long-term) months. Intervention effects were assessed by linear mixed models, accounting for repeated measures and clustering, baseline values, and potential confounders. Evaluable case and multiple imputation analyses were used. Results At 12 months, trends for improvement were observed in the HWQ non-work satisfaction subscale (P=0.053) and stress item (P=0.086). Intervention effects on remaining outcomes for the HWQ were small and non-significant at both timepoints. At 3 months, intervention effects showed significant improvements in the WLQ mental demands subscale (P=0.043). At 12 months, intervention effects showed significant (P<0.05) small-to-moderate improvements in four WLQ outcomes (weighted total score, time-, mental-, and output demands), with physical demands showing a small significant worsening. Conclusions were robust to missing data assumptions. Conclusions The intervention improved some measures of productivity at 12 months, providing important evidence to the business case supporting workplace sitting-reduction interventions.

Background: In laboratory settings, cycling workstations improve cardiometabolic risk factors. Our purpose was to quantify risk factors following a cycling intervention in the workplace., Methods: Twenty-one office workers who sat at work ≥6 hours per day underwent baseline physiological measurements (resting blood pressure, blood lipid profile, maximum oxygen consumption [V˙O2max], body composition, and 2-h oral glucose tolerance test). Participants were randomly assigned to a 4-week intervention only group (n = 12) or a delayed intervention group (n = 9) that involved a 4-week control condition before beginning the intervention. During the intervention, participants were instructed to use the cycling device a minimum of 15 minutes per hour, which would result in a total use of ≥2 hours per day during the workday. Following the intervention, physiological measurements were repeated., Results: Participants averaged 1.77 (0.48) hours per day of cycling during the intervention with no changes in actigraphy-monitored noncycling physical activity. Four weeks of the workplace intervention increased V˙O2max (2.07 [0.44] to 2.17 [0.44] L·min-1, P < .01); end of V˙O2max test power output (166.3 [42.2] to 176.6 [46.1] W, P < .01); and high-density lipoprotein cholesterol (1.09 [0.17] to 1.17 [0.24] mmol·L-1, P = .04)., Conclusions: A stationary cycling device incorporated into a sedentary workplace for 4 weeks improves some cardiometabolic risk factors with no compensatory decrease in noncycling physical activity.

Our purpose was to determine if using an individual's power-specific gross efficiency improves the accuracy of estimating energy expenditure from cycling power. 30 subjects performed a graded cycling test to develop 4 gross efficiencies: individual power-specific gross efficiencies, a group mean power-specific gross efficiency, individual fixed gross efficiencies, and a group mean fixed gross efficiency. Energy expenditure was estimated from power using these different gross efficiencies and compared to measured energy expenditure during moderate- and hard-intensity constant-power and 2 variable-power cycling bouts. Estimated energy expenditures using individual or group mean power-specific gross efficiencies were not different from measured energy expenditure across all cycling bouts (p>0.05). To examine the intra-individual variability of the estimates, absolute difference scores (absolute value of estimated minus measured energy expenditure) were compared, where values closer to zero represent more accurate individual estimates. The absolute difference score using individual power-specific gross efficiencies was significantly lower compared to the other gross efficiencies across all cycling bouts (p<0.01). Significant and strong correlations (r≥0.97, p<0.001) were found across all cycling bouts between estimated and measured energy expenditures using individual power-specific gross efficiencies. In conclusion, using an individual's power-specific gross efficiency significantly improves their energy expenditure estimate across different power outputs., (© Georg Thieme Verlag KG Stuttgart · New York.)

Unlabelled: We have previously shown that motor-driven (passive) stationary cycling elevates energy expenditure (EE)., Purpose: This study aimed to quantify how acute passive cycling affects glucose and insulin responses to an oral glucose tolerance test (OGTT) and basic cognition compared with sitting and moderate-intensity active cycling., Methods: Twenty-four physically inactive healthy males completed three trials in randomized order involving 30-min conditions of sitting, passive cycling, and moderate-intensity cycling. During each condition, EE was measured, and participants performed cognitive tests. After each condition, a 2-h OGTT was performed., Results: EE was significantly higher during the cycling conditions compared with sitting (1.36 ± 0.58 and 6.50 ± 1.73 kcal·min greater than sitting for passive and moderate-intensity, respectively). A significant correlation was found between body fat percentage and postsitting OGTT 2-h postplasma glucose (r = 0.30, P < 0.05); thus, participants were divided into lean (n = 11) and nonlean (n = 13) groups. In the nonlean group, compared with sitting, passive cycling lowered 2-h postplasma glucose (7.7 ± 1.3 vs 6.9 ± 1.6 mmol·L, respectively, P < 0.05), and the Matsuda whole-body insulin sensitivity index (WBISI) was higher (2.74 ± 0.86 vs 3.36 ± 1.08, P < 0.05). In addition, passive and moderate-intensity cycling had similar beneficial effects on 2-h postplasma glucose and WBISI. Cognitive performance did not significantly differ between the sitting and passive cycling conditions., Conclusions: Two-hour postplasma glucose was lower and WBISI after acute passive cycling was higher in nonlean participants. Given that and the increase in EE without changes in cognitive performance, we propose passive cycling as a promising intervention to counteract some of the deleterious effects of prolonged sitting in the workplace.

Introduction: Pedelecs are bicycles that provide electric assistance only when a rider is pedaling and have become increasingly popular., Purpose: Our purpose was to quantify usage patterns over 4 weeks of real-world commuting with a pedelec and to determine if pedelec use would improve cardiometabolic risk factors., Methods: Twenty sedentary commuters visited the laboratory for baseline physiological measurements [body composition, maximum oxygen consumption ([Formula: see text]), mean arterial blood pressure (MAP), blood lipid profile, and 2-h oral glucose tolerance test (OGTT)]. The following 4 weeks, participants were instructed to commute using a pedelec at least 3 days week(-1) for 40 min day(-1) while wearing a heart rate monitor and a GPS device. Metabolic equivalents (METS) were estimated from heart rate data. Following the intervention, we repeated the physiological measurements., Results: Average total distance and time were 317.9 ± 113.8 km and 15.9 ± 3.4 h, respectively. Participants averaged 4.9 ± 1.2 METS when riding. Four weeks of pedelec commuting significantly improved 2-h post-OGTT glucose (5.53 ± 1.18-5.03 ± 0.91 mmol L(-1), p < 0.05), [Formula: see text] (2.21 ± 0.48-2.39 ± 0.52 L min(-1), p < 0.05), and end of [Formula: see text] test power output (165.1 ± 37.1-189.3 ± 38.2 W, p < 0.05). There were trends for improvements in MAP (84.6 ± 10.5-83.2 ± 9.4 mmHg, p = 0.15) and fat mass (28.6 ± 11.3-28.2 ± 11.4 kg, p = 0.07)., Conclusion: Participants rode a pedelec in the real world at a self-selected moderate intensity, which helped them meet physical activity recommendations. Pedelec commuting also resulted in significant improvements in 2-h post-OGTT glucose, [Formula: see text], and power output. Pedelecs are an effective form of active transportation that can improve some cardiometabolic risk factors within only 4 weeks.

Drag area (Ad ) is a primary factor determining aerodynamic resistance during level cycling and is therefore a key determinant of level time trial performance. However, Ad has traditionally been difficult to measure. Our purpose was to determine the value of adding field-measured Ad as a correlate of level cycling time trial performance. In the field, 19 male cyclists performed a level (22.1 km) time trial. Separately, field-determined Ad and rolling resistance were calculated for subjects along with projected frontal area assessed directly (AP ) and indirectly (Est AP ). Also, a graded exercise test was performed to determine [Formula: see text] peak, lactate threshold (LT), and economy. [Formula: see text] peak ([Formula: see text]) and power at LT were significantly correlated to power measured during the time trial (r = 0.83 and 0.69, respectively) but were not significantly correlated to performance time (r = - 0.42 and -0.45). The correlation with performance time improved significantly (p < 0.05) when these variables were normalized to Ad . Of note, Ad alone was better correlated to performance time (r = 0.85, p < 0.001) than any combination of non-normalized physiological measure. The best correlate with performance time was field-measured power output during the time trial normalized to Ad (r = - 0.92). AP only accounted for 54% of the variability in Ad . Accordingly, the correlation to performance time was significantly lower using power normalized to AP (r = - 0.75) or Est AP (r = - 0.71). In conclusion, unless normalized to Ad , level time trial performance in the field was not highly correlated to common laboratory measures. Furthermore, our field-measured Ad is easy to determine and was the single best predictor of level time trial performance.

Exercise efficiency at low power outputs, energetically comparable to daily living activities, can be influenced by homeostatic perturbations (e.g., weight gain/loss). However, an appropriate efficiency calculation for low power outputs used in these studies has not been determined. Fifteen active subjects (seven females, eight males) performed 14, 5-min cycling trials: two types of seated rest (cranks vertical and horizontal), passive (motor-driven) cycling, no-chain cycling, no-load cycling, cycling at low (10, 20, 30, 40 W), and moderate (50, 60, 80, 100, 120 W) power outputs. Mean delta efficiency was 57% for low power outputs compared to 41.3% for moderate power outputs. Means for gross (3.6%) and net (5.7%) efficiencies were low at the lowest power output. At low power outputs, delta and work efficiency values exceeded theoretical values. In conclusion, at low power outputs, none of the common exercise efficiency calculations gave values comparable to theoretical muscle efficiency. However, gross efficiency and the slope and intercept of the metabolic power vs mechanical power output regression provide insights that are still valuable when studying homeostatic perturbations., (© 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Short-duration passive cycling, during which a motor drives the pedals, elevates metabolic energy expenditure. Our purpose was to investigate the feasibility of passive cycling as a physical inactivity countermeasure by quantifying how the number of legs involved, cycling cadence, and habituation influence energy expenditure. Eleven non-cyclists participated. We compared one- and two-leg passive cycling at cadences of 60 and 90 RPM. To investigate if there are habituation effects, we conducted multiple 5-min trials and a prolonged 30-min passive cycling trial. The increase in energy expenditure above rest during passive cycling was significantly greater for two legs compared to one leg (39 vs. 16% at 60 RPM and 96 vs. 45% at 90 RPM). The increase in energy expenditure above rest was greater for 90 versus 60 RPM two-leg passive cycling (96 vs. 39%; p < 0.001). Repeated trials showed no evidence of habituation and the increase in energy expenditure was maintained for the duration of the 30-min trial. In conclusion, energy expenditure during passive cycling is directly related to the number of legs involved and cycling cadence. Two-leg passive cycling at 90 RPM resulted in energy expenditures similar to the walking workstation, suggesting its potential as a physical inactivity countermeasure.

Purpose: To compare the demands of a 6-d stage race using field measures of power output and HR in male (n=8) and female (n=10) competitive cyclists., Methods: HR and power output were monitored in males and females competing in separate races on identical courses including a prolog (4 km), four circuit/road races (mean ± SD: 118 ± 23 km), and a criterium (47 km). All subjects participated in laboratory-based exercise testing within 2 wk of the race., Results: Compared with females, males took 10%, 22%, and 10% less time to complete the prolog, circuit/road races, and criterium, respectively. For males, power output in the prolog, circuit/road races, and criterium averaged 405, 247, and 278 W, respectively. For females, power output averaged 295, 160, and 205 W, respectively. During the prolog, the percent time spent below, at, and above the lactate threshold was 29%, 9%, and 62%, respectively, for males and 24%, 7%, and 69%, respectively, for females. For the circuit/road races, these values were 57%, 10%, and 33%, respectively, for males and 62%, 10%, and 28%, respectively, for females. During the criterium, these values were 51%, 6%, and 43%, respectively, for males, and 50%, 8%, and 42%, respectively, for females., Conclusions: Although men had faster finishing times and higher absolute power outputs, no significant difference was found between men and women in their relative power response. These findings suggest that pacing strategy is based on relative exercise responses and not on absolute exercise responses., (© 2011 by the American College of Sports Medicine)