Evaluating current assessment techniques of cardiorespiratory fitness

INTRODUCTION

Considerable and convincing global data from cohorts across the health spectrum (i.e. apparently healthy to known disease) indicate that cardiorespiratory fitness (CRF) is a major predictor of overall and cardiovascular disease (CVD)-survival, seemingly with greater prognostic resolution compared to other traditional CVD risk factors. Therefore, the assessment of CRF in research and clinical settings is of major importance.

AREAS COVERED

In this manuscript, we review the technology of measuring CRF assessed by the 'gold standard,' cardiopulmonary exercise testing (CPET), as well as with various other methods (e.g. estimated metabolic equivalents, 6-minute walk tests, shuttle tests, and non-exercise equations that estimate CRF), all of which provide significant prognostic information for CVD- and all-cause survival. The literature through May 2024 has been cited.

EXPERT OPINION

The promotion of physical activity in efforts to improve levels of CRF is needed throughout the world to improve lifespan and, more importantly, healthspan. The routine assessment of CRF should be considered a vital sign that is routinely assessed in clinical practice.

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

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Relative aerobic load of walking in people with multiple sclerosis

OBJECTIVE

To examine the energy demand of walking relative to aerobic capacity in people with multiple sclerosis.

DESIGN

Cross-sectional cohort study.

PATIENTS

A total of 45 people with multiple sclerosis (32 females), median disease duration 15 years (interquartile range (IQR) 9; 20), median Expanded Disability Status Scale 4 (min-max range: 2.0; 6.0).

METHODS

Aerobic capacity, derived from a cardiopulmonary exercise test and gas exchange measurements, assessed during a 6-min overground walk test at comfortable speed, were analysed. The relative aerobic load of walking was determined as the energy demand of walking relative to oxygen uptake at peak and at the first ventilatory threshold. Healthy reference data were used for clinical inference.

RESULTS

People with multiple sclerosis walk at a mean relative aerobic load of 60.0% (standard deviation 12.8%) relative to peak aerobic capacity, and 89.1% (standard deviation 19.9%) relative to the first ventilatory threshold. Fourteen participants walked above the first ventilatory threshold (31%). Peak aerobic capacity was reduced in 45% of participants, and energy demands were increased in 52% of participants.

CONCLUSION

People with multiple sclerosis walk at a relative aerobic load close to their first ventilatory threshold. A high relative aerobic load can guide clinicians to improve aerobic capacity or reduce the energy demands of walking.

Is the Ventilatory Efficiency in Endurance Athletes Different?-Findings from the NOODLE Study

Background: Ventilatory efficiency (VE/VCO2) is a strong predictor of cardiovascular diseases and defines individuals' responses to exercise. Its characteristics among endurance athletes (EA) remain understudied. In a cohort of EA, we aimed to (1) investigate the relationship between different methods of calculation of VE/VCO2 and (2) externally validate prediction equations for VE/VCO2. Methods: In total, 140 EA (55% males; age = 22.7 ± 4.6 yrs; BMI = 22.6 ± 1.7 kg·m-2; peak oxygen uptake = 3.86 ± 0.82 L·min-1) underwent an effort-limited cycling cardiopulmonary exercise test. VE/VCO2 was first calculated to ventilatory threshold (VE/VCO2-slope), as the lowest 30-s average (VE/VCO2-Nadir) and from whole exercises (VE/VCO2-Total). Twelve prediction equations for VE/VCO2-slope were externally validated. Results: VE/VCO2-slope was higher in females than males (27.7 ± 2.6 vs. 26.1 ± 2.0, p < 0.001). Measuring methods for VE/VCO2 differed significantly in males and females. VE/VCO2 increased in EA with age independently from its type or sex (β = 0.066-0.127). Eleven equations underestimated VE/VCO2-slope (from -0.5 to -3.6). One equation overestimated VE/VCO2-slope (+0.2). Predicted and observed measurements differed significantly in nine models. Models explained a low amount of variance in the VE/VCO2-slope (R2 = 0.003-0.031). Conclusions: VE/VCO2-slope, VE/VCO2-Nadir, and VE/VCO2-Total were significantly different in EA. Prediction equations for the VE/VCO2-slope were inaccurate in EA. Physicians should be acknowledged to properly assess cardiorespiratory fitness in EA.

Age, sex, endurance capacity, and chronic heart failure affect central and peripheral factors of oxygen uptake measured by non-invasive and continuous technologies: support of pioneer work using invasive or non-continuous measures

Introduction

It is known that maximum oxygen uptake depends on age, sex, endurance capacity, and chronic heart failure. However, due to the required invasive or often applied non-continuous approaches, less is known on underlying central and peripheral factors. Thus, this study aimed to investigate the effects of age, sex, endurance capacity, and chronic heart failure on non-invasively and continuously measured central and peripheral factors of oxygen uptake.

Methods

15 male children (11 ± 1 years), 15 male (24 ± 3 years) and 14 female recreationally active adults (23 ± 2 years), 12 male highly trained endurance athletes (24 ± 3 years), and 10 male elders (59 ± 6 years) and 10 chronic heart failure patients (62 ± 7 years) were tested during a cardiopulmonary exercise test on a cycling ergometer until exhaustion for: blood pressure, heart rate, stroke volume, cardiac output, cardiac power output, vastus lateralis muscle oxygen saturation, and (calculated) arterio-venous oxygen difference. For the non-invasive and continuous measurement of stroke volume and muscle oxygen saturation, bioreactance analysis and near-infrared spectroscopy were used, respectively. A two-factor repeated measure ANOVA and partial eta-squared effect sizes (η p 2 ) were applied for statistical analyses at rest, 80, and 100% of oxygen uptake.

Results

For the age effect, there were statistically significant group differences for all factors (p ≤ .033; η p 2 ≥ .169 ). Concerning sex, there were group differences for all factors (p ≤ .010; η p 2 ≥ .223 ), except diastolic blood pressure and heart rate (p ≥ .698; η p 2 ≤ .006 ). For the effect of endurance capacity, there were no group differences for any of the factors (p ≥ .065; η p 2 ≤ .129 ). Regarding chronic heart failure, there were group differences for the heart rate and arterio-venous oxygen difference (p ≤ .037; η p 2 ≥ .220 ).

Discussion

Age, sex, endurance capacity, and chronic heart failure affect central and peripheral factors of oxygen uptake measured by non-invasive and continuous technologies. Since most of our findings support pioneer work using invasive or non-continuous measures, the validity of our applied technologies is indirectly confirmed. Our outcomes allow direct comparison between different groups serving as reference data and framework for subsequent studies in sport science and medicine aiming to optimise diagnostics and interventions in athletes and patients.

Translational and Rotational Postural Aberrations Are Related to Pulmonary Functions and Skill-Related Physical Fitness Components in Collegiate Athletes

This study assessed the relationship between body posture displacements, cardiopulmonary exercise testing (CPET), and skill-related physical fitness tests. One hundred male (60%) and female collegiate athletes (22.2 ± 4 yrs) with normal body mass indexes (BMI up to 24.9) were assessed via the PostureScreen Mobile^® app to quantify postural displacements such as head, thorax, and pelvis rotations and translations. CPET and physical performance tests, including the agility t-test, vertical jump test, stork static balance test (SSBT), and dynamic Y-balance test (YBT), were performed. Spearman correlation (r) and p-values are reported. The postural parameters were found to have moderate-to-high associations with the CPET and agility test, moderate correlations with the vertical jump test and SSBT (head and pelvic postures only), and weak correlations with the YBT. As the postural parameters were more asymmetric, both the CPET and performance skills scores were worse. For example: (1) a medium positive correlation was found between cranio-vertebral angle (CVA) and the vertical jump test (r = 0.54; p-value < 0.001) and SSBT (r = 0.57; p-value < 0.001), while a strong negative correlation was found between CVA and the agility test (r = -0.86; p-value < 0.001). (2) A strong positive correlation was found between CVA and oxygen uptake efficiency slope, load watts VO2 at VT, VO2/kg, and load watts at the respiratory compensation point (RCP) (r = 0.65 and r = 0.71; p < 0.001). Conversely, a significant negative correlation was found between CVA and VE/VO2 at VT (r = -0.61; p < 0.001). Postural rotations and translations of the head, thorax, and pelvis were statistically correlated with the physical performance skills and CPET in the young collegiate athletes. There were moderate-to-high associations with cardiopulmonary functions and the agility tests, moderate correlations with the vertical jump test, and weak correlations with the YBT. Postural alignment may be important for optimal physical performance and optimal cardiopulmonary function. Further research is necessary to elucidate the reasons for these correlations found in our sample of young and healthy athletes.

Effect of COVID-19 on Blood Pressure Profile and Oxygen Pulse during and after the Cardiopulmonary Exercise Test in Healthy Adults

Several reports have shown the impact of COVID-19 history on exercise capacity. This study compared the blood pressure (BP) response and oxygen pulse (O₂ pulse) characteristics in normotensive patients with and without a history of COVID-19 during the cardiopulmonary exercise test (CPET) and post-exercise recovery. This cross-sectional study involved 130 healthy Caucasian adult volunteers (71 participants with a history of COVID-19). All patients underwent the CPET with blood pressure measurements during exercise and post-exercise recovery. The post-COVID group had significantly higher systolic, diastolic, and mean blood pressure after 9 min of recovery and achieved a significantly lower max O₂ pulse (2.02 mL/beat on average) than the controls. It should be noted that the COVID group tended to have higher blood pressure values in all steps, with no differences in heart rate, pulse pressure, and saturation at any step. The COVID-19 outbreak was associated with a higher blood pressure response, significantly, in post-exercise recovery, a lower maximum O₂ pulse, and a lower maximum load achievement. Future studies are needed to determine if these abnormalities during the CPET and the blood pressure variation have prognostic value.

Validity of the Maximal Heart Rate Prediction Models among Runners and Cyclists

Maximal heart rate (HRmax) is a widely used measure of cardiorespiratory fitness. Prediction of HRmax is an alternative to cardiopulmonary exercise testing (CPET), but its accuracy among endurance athletes (EA) requires evaluation. This study aimed to externally validate HRmax prediction models in the EA independently for running and cycling CPET. A total of 4043 runners (age = 33.6 (8.1) years; 83.5% males; BMI = 23.7 (2.5) kg·m^-2) and 1026 cyclists (age = 36.9 (9.0) years; 89.7% males; BMI = 24.0 (2.7) kg·m^-2) underwent maximum CPET. Student t-test, mean absolute percentage error (MAPE), and root mean square error (RMSE) were applied to validate eight running and five cycling HRmax equations externally. HRmax was 184.6 (9.8) beats·min^-1 and 182.7 (10.3) beats·min^-1, respectively, for running and cycling, p = 0.001. Measured and predicted HRmax differed significantly (p = 0.001) for 9 of 13 (69.2%) models. HRmax was overestimated by eight (61.5%) and underestimated by five (38.5%) formulae. Overestimated HRmax amounted to 4.9 beats·min^-1 and underestimated HRmax was in the range up to 4.9 beats·min^-1. RMSE was 9.1-10.5. MAPE ranged to 4.7%. Prediction models allow for limited precision of HRmax estimation and present inaccuracies. HRmax was more often underestimated than overestimated. Predicted HRmax can be implemented for EA as a supplemental method, but CPET is the preferable method.

Age-related decline in peak oxygen uptake: Cross-sectional vs. longitudinal findings. A review

Cardiorespiratory fitness is established as an important prognostic factor for cardiovascular and general health. In clinical settings cardiorespiratory fitness is often measured by cardiopulmonary exercise testing determining the gold-standard peak oxygen uptake (VO_2peak). Due to the considerable impact of age and sex on VO_2peak, results from cardiopulmonary exercise testing are typically assessed in the context of age- and sex-specific reference values, and multiple studies have been conducted establishing reference materials by age and sex using cross-sectional designs. However, crossectional and longitudinal studies have shown somewhat conflicting results regarding age-related declines of VO_2peak, with larger declines reported in longitudinal studies. In this brief review, we compare findings from crossectional and longitudinal studies on age-related trajectories in VO_2peak to highlight differences in these estimates which should be acknowledged when clinicians interpret VO_2peak measurements repeated over time.

External validation of VO2max prediction models based on recreational and elite endurance athletes

In recent years, numerous prognostic models have been developed to predict VO2max. Nevertheless, their accuracy in endurance athletes (EA) stays mostly unvalidated. This study aimed to compare predicted VO2max (pVO2max) with directly measured VO2max by assessing the transferability of the currently available prediction models based on their R2, calibration-in-the-large, and calibration slope. 5,260 healthy adult EA underwent a maximal exertion cardiopulmonary exercise test (CPET) (84.76% male; age 34.6±9.5 yrs.; VO2max 52.97±7.39 mL·min-1·kg-1, BMI 23.59±2.73 kg·m-2). 13 models have been selected to establish pVO2max. Participants were classified into four endurance subgroups (high-, recreational-, low- trained, and "transition") and four age subgroups (18-30, 31-45, 46-60, and ≥61 yrs.). Validation was performed according to TRIPOD guidelines. pVO2max was low-to-moderately associated with direct CPET measurements (p>0.05). Models with the highest accuracy were for males on a cycle ergometer (CE) (Kokkinos R2 = 0.64), females on CE (Kokkinos R2 = 0.65), males on a treadmill (TE) (Wasserman R2 = 0.26), females on TE (Wasserman R2 = 0.30). However, selected models underestimated pVO2max for younger and higher trained EA and overestimated for older and lower trained EA. All equations demonstrated merely moderate accuracy and should only be used as a supplemental method for physicians to estimate CRF in EA. It is necessary to derive new models on EA populations to include routinely in clinical practice and sports diagnostic.

Normal reference values for aerobic fitness in cystic fibrosis: a scoping review

Objective

The importance of aerobic fitness (VO2peak) in cystic fibrosis (CF) is well established, and regular exercise testing is recommended. To standardise VO2peak, a ‘percentage of predicted’ (%pred) derived from normative reference values (NRV), as promoted by the 2015 European Cystic Fibrosis Society Exercise Working Group (ECFS EWG), can be reported. However, the NRVs used in CF and their relative frequency is unknown.

Method

A scoping review was performed via systematic database searches (PubMed, Embase, Web of Science, SciELO, EBSCO) and forward citation searches for studies that include people with CF and report VO2peakas %pred. Studies were screened using Covidence, and data related to patient demographics, testing modality and reference equations were extracted. Additional analyses were performed on studies published in 2016–2021, following the ECFS EWG statement in 2015.

Results

A total of 170 studies were identified, dating from 1984 to 2022, representing 6831 patients with CF, citing 34 NRV. Most studies (154/170) used cycle ergometry, 15/170 used treadmills, and the remainder used alternative, combination or undeclared modalities. In total, 61/170 failed to declare the NRV used. There were 61 studies published since the ECFS EWG statement, whereby 18/61 used the suggested NRV.

Conclusion

There is a wide discrepancy in NRV used in the CF literature base to describe VO2peakas %pred, with few studies using NRV from the ECFS EWG statement. This high variance compromises the interpretation and comparison of studies while leaving them susceptible to misinterpretation and limiting replication. Standardisation and alignment of reporting of VO2peakvalues are urgently needed.

Re-Visiting Maximal Heart Rate Prediction Using Cross-Validation in Population Aged 7–55 Years

The primary purpose of the present study was to re-visit HR_max prediction by two commonly used equations (i.e., Fox′s and Tanaka′s equation) compared to the direct measured HR_max using the large sample size of Asians. The second aim of the study was to focus on suggesting new equations for the Asian population by separating gender and specific age groups. A total of 672 participants aged from 7 to 55 years were recruited for the study (male: 280 and female: 392), and the maximal graded exercise test with Bruce protocol was used to measure HR_max. All data obtained from the study were analyzed by SPSS 25.0. Additionally, three statistical analysis methods (i.e., Mean Absolute Percent Errors (MAPE), Bland–Altman plots, and equivalence testing) were utilized to confirm the consistency between the measured HR_max and the two prediction equations. The main finding was that two equations showed significant differences in predicting the HR_max of Korean aged from 7 to 55 years. The outcome of children aged from 7 to 14 was a different fit in the agreement compared to other age groups. Fox′s equation had the best fit in the average of the difference closer to zero and completely included within the equivalence zone, but females over 15 years old revealed higher errors than males in the values calculated by the two equations compared to the direct measured HR_max. Consequently, the study demonstrated that both equations tended to overestimate the HR_max for males and females over 15 years old, and the two universal equations were not suitable to predict the HR_max of Koreans except for children aged from 7 to 14 years. The new HR_max prediction equations suggested in this study will more accurately predict the HR_max of Asians, and additional analyses should be examined the cross-validity of the developed HR_max equation by age and gender in the future study.

Comparison of Predicted Exercise Capacity Equations in Adult Korean Subjects

BACKGROUND

Maximal oxygen uptake (VO₂ max) is a useful index to assess exercise capacity. However, there is no reference value for Koreans. This study aimed to compare actual VO₂ max and predicted VO₂ max using exercise capacity equations in Korean subjects.

METHODS

This retrospective study enrolled 383 patients who underwent cardiopulmonary exercise test (CPET) with incremental maximal cycle ergometer test at Asan Medical Center from January 2020 to May 2021. Stage 1 and 2 lung cancer patients with normal lung function and healthy persons of 50 subjects who had maximal CPET were analyzed.

RESULTS

The subjects were aged 65 ± 13 years and predominantly male (74%). CPET results were as follows: absolute VO₂ max, 1.2 ± 0.3 L/min; body weight referenced VO₂ max, 20 ± 3.9 mL/kg/min; peak work rate, 94 ± 24 watts; peak heart rate, 142 ± 21 bpm; peak O₂ pulse, 10 ± 3 mL/beat; minute ventilation, 59 ± 14 L/min; peak respiratory rate, 34 ± 6 breaths per minute; and peak breathing reserve, 41 ± 18%. There was significant discordance between the measured and predicted absolute VO₂ max using the Jones, Hansen, and Wasserman prediction equations developed for Caucasian population (P < 0.001). Agreement using Bland-Altman test between true and predicted absolute VO₂ max was the best in Chinese equation (-0.03, 2SD = 0.55) compared to Jones (0.42, 2SD = 1.07), Hansen (0.44, 2SD = 0.86), and Wasserman (0.42, 2SD = 0.86) equations.

CONCLUSION

The reference value and prediction equation from studies including primarily Caucasians may not be appropriate for Koreans. Since the mean difference is the lowest in Chinese equation, the Chinese equation might be used for the Korean adult population.

Comparison of the FRIEND and Wasserman-Hansen Equations in Predicting Outcomes in Heart Failure

Background

Percentage of age‐predicted peak oxygen uptake (VO₂) achieved (ppVO₂) has been widely used to stratify risk in patients with heart failure. However, there are limitations to traditional normal standards. We compared the recently derived FRIEND (Fitness Registry and the Importance of Exercise: A National Data Base) equation to the widely used Wasserman‐Hansen (WH) ppVO₂ equation to predict outcomes in patients with heart failure.

Methods and Results

A subgroup of 4055 heart failure patients from the FRIEND registry (mean age 53±15 years) was followed for a mean of 28±16 months. The FRIEND and WH equations along with measured peak VO₂ expressed in mL/kg⁻¹ per min⁻¹ were compared for mortality and composite cardiovascular events. ppVO₂ was higher for the FRIEND versus the WH equation (66±30% versus 58±25%; P<0.001). The areas under the receiver operating characteristic curves were slightly but significantly higher for the FRIEND equation for mortality (0.74 versus 0.72; P=0.03) and cardiac events (0.70 versus 0.68; P=0.008). Area under the receiver operating characteristic curve for measured peak VO₂ was 0.70 (P<0.001) for mortality and 0.73 (P<0.001) for cardiovascular events. For each 1‐SD higher ppVO₂ for the FRIEND equation, mortality was reduced by 18% (hazard ratio, 0.82; 95% CI, 0.69–0.97; P<0.02); for each 1‐SD higher ppVO₂ for the WH equation, the mortality was reduced by 17% (hazard ratio, 0.83; 95% CI, 0.71–0.97; P=0.02). The corresponding reductions in risk per 1 SD for cardiovascular events for the FRIEND and WH equations were 23 and 21%, respectively (both P<0.001).

Conclusions

Peak VO₂ expressed as percentage of an age‐predicted standard strongly predicts mortality and major cardiovascular events in patients with heart failure. The FRIEND registry equation exhibited test characteristics slightly superior to the commonly used WH equation.

ARTP statement on cardiopulmonary exercise testing 2021

Cardiopulmonary exercise testing (CPET) has become an invaluable tool in healthcare, improving the diagnosis of disease and the quality, efficacy, assessment and safety of treatment across a range of pathologies. CPET's superior ability to measure the global exercise response of the respiratory, cardiovascular and skeletal muscle systems simultaneously in a time and cost-efficient manner has led to the application of CPET in a range of settings from diagnosis of disease to preoperative assessment. The Association for Respiratory Technology and Physiology Statement on Cardiopulmonary Exercise Testing 2021 provides the practitioner and scientist with an outstanding resource to support and enhance practice, from equipment to testing to leadership, helping them deliver a quality assured service for the benefit of all patient groups.

Normative cardiopulmonary exercise data for endurance athletes: the Cardiopulmonary Health and Endurance Exercise Registry (CHEER)

AIMS

Accurate interpretation of cardiopulmonary exercise testing (CPET) relies on age, gender, and exercise modality-specific reference values. To date, clinically applicable CPET reference values derived from a source population of endurance athletes (EAs) have been lacking. The purpose of this study was to generate CPET reference values for use in the clinical assessment of EA.

METHODS AND RESULTS

Prospective data accrued during the clinical care of healthy EA were used to derive CPET reference values and to develop novel equations for V˙O2peak. The performance of these equations was compared to the contemporary standard of care equations and assessed in a discrete EA validation cohort. A total of 272 EA (age = 42 ± 15 years, female = 31%, V˙O2peak = 3.6 ± 0.83 L/min) met inclusion criteria and comprised the derivation cohort. V˙O2peak prediction equations derived from general population cohorts described a modest amount of V˙O2peak variability [R2 = 0.58-0.70, root mean square error (RMSE) = 0.46-0.54 L/min] but were mis-calibrated (calibration-in-the-large = 0.45-1.18 L/min) among EA leading to significant V˙O2peak underestimation. Newly derived, externally validated V˙O2peak prediction equations for EA that included age, sex, and height for both treadmill (R2 = 0.74, RMSE = 0.42 L/min) and cycle ergometer CPET (Cycle: R2 = 0.69, RMSE = 0.42 L/min) demonstrated improved accuracy.

CONCLUSION

Commonly used V˙O2peak prediction equations derived from general population cohorts perform poorly among competitive EA. Newly derived CPET reference values including novel V˙O2peak prediction equations may improve the clinical utility of CPET in this rapidly growing patient population.

Prediction Equations for Maximal Aerobic Capacity on Cycle Ergometer for the Spanish Adult Population

BACKGROUND

Frequently used reference values for clinical exercise testing have been derived from non-random samples and some with poorly defined maximal criteria. Our objective was to obtain population based reference values for peak oxygen uptake (V?O₂) and work rate (WR) for cardiopulmonary exercise testing in a representative sample of Caucasian Spanish men and women.

METHODS

182 men and women, 20-85 years old, were included and exercised on cycle-ergometer to exhaustion. (V?O₂) and WR were measured. The equations obtained from this sample were validated in an independent cohort of 69 individuals, randomly sampled form the same population. Then a final equation merging the two cohorts (=251) was produced.

RESULTS

Height, sex and age resulted predictive of both V?O₂ peak and WR. Weight and physical activity added very little to the accuracy to the equations. The formulas V?O₂peak=0.017·height?(cm)-0.023·age?(years)+0.864·sex?(female=0/male=1)±179?l?min^-1, and peak WR=1.345 · height (cm) - 2.074 · age (years)+76.54 · sex (female=0/male=1)±21.2W were the best compromise between accuracy and parsimony.

CONCLUSIONS

This study provides new and accurate V?O₂ peak and WR rate reference values for individuals of European Spanish descent.

Physical, psychological and nutritional outcomes in a cohort of Irish patients with metastatic peritoneal malignancy scheduled for cytoreductive surgery (CRS) and heated intrapertioneal chemotherapy (HIPEC): An exploratory pilot study

Background

Treatment for peritoneal malignancy (PM) can include cytoreductive surgery (CRS) and heated intrapertioneal chemotherapy (HIPEC) and is associated with morbidity and mortality. Physical, psychological and nutritional outcomes are important pre-operatively. The aim of this pilot study was to investigate these outcomes in patients with PM before and after CRS-HIPEC.

Methods

Between June 2018 and November 2019, participants were recruited to a single-centre study. Primary outcome was cardiopulmonary exercise testing (CPET) variables oxygen uptake (VO₂) at anaerobic threshold (AT) and at peak. Secondary outcome measures were upper and lower body strength, health related quality of life (HRQoL) and the surgical fear questionnaire. Exploratory outcomes included body mass index, nutrient intake and post-operative outcome. All participants were asked to undertake assessments pre CRS-HIPEC and 12 weeks following the procedure.

Results

Thirty-nine patients were screened, 38 were eligible and 16 were recruited. Ten female and 6 male, median (IQR) age 53 (42–63) years. Of the 16 patients recruited, 14 proceeded with CRS-HIPEC and 10 competed the follow up assessment at week 12. Pre-operative VO₂ at AT and peak was 16.8 (13.7–18) ml.kg^-1.min^-1 and 22.2 (19.3–25.3) ml.kg^-1.min^-1, upper body strength was 25.9 (20.3–41.5) kg, lower body strength was 14 (10.4–20.3) sec, HRQoL (overall health status) was 72.5 (46.3–80) % whilst overall surgical fear was 39 (30.5–51). The VO₂ at AT decreased significantly (p = 0.05) and HRQoL improved (p = 0.04) between pre and post- CRS-HIPEC. There were no significant differences for any of the other outcome measures.

Conclusion

This pilot study showed a significant decrease in VO₂ at AT and an improvement in overall HRQoL at the 12 week follow up. The findings will inform a larger study design to investigate a prehabilitation and rehabilitation cancer survivorship programme.

Safety and feasibility of upper limb cardiopulmonary exercise test in Friedreich ataxia

Aims

To explore the feasibility of upper limbs cardiopulmonary exercise test (CPET) in Friedreich ataxia (FRDA) patients and to compare the results with sex, age, and body mass index (BMI) matched cohort of healthy controls (HC).

Methods and results

Cardiopulmonary exercise test was performed using an upper limbs cycle ergometer on fasting subjects. Peak oxygen uptake (peak VO2) was recorded as the mean value of VO2 during a 20 s period at the maximal effort of the test at an appropriate respiratory exchange rate. The ventilatory anaerobic threshold (AT) was detected by the use of the V-slope method. We performed echocardiography with an ultrasound system equipped with a 2.5 MHz multifrequency transducer for complete M-mode, two-dimensional, Doppler, and Tissue Doppler Imaging analyses. We studied 55 FRDA and 54 healthy matched controls (HC). Peak VO2 showed a significant 31% reduction in FRDA patients compared to HC (15.2 ± 5.7 vs. 22.0 ± 6.1 mL/kg/min; P &lt; 0.001). Peak workload was reduced by 41% in FRDA (42.9 ± 12.5 vs. 73.1 ± 21.2 W; P &lt; 0.001). In FRDA patients, peak VO2 is inversely correlated with the Scale for Assessment and Rating of Ataxia score, disease duration, and 9HPT performance, and directly correlated with activities of daily living. The AT occurred at 48% of peak workload time in FRDA patients and at 85% in HC (P &lt; 0.001).

Conclusions

Upper limb CPET is useful in the assessment of exercise tolerance and a possible tool to determine the functional severity of the mitochondrial oxidative defect in patients with FRDA. The cardiopulmonary exercise test is an ideal functional endpoint for Phases II and III trials through a simple, non-invasive, and safe exercise test.

Normative Cardiopulmonary Exercise Test Responses at the Ventilatory Threshold in Canadian Adults 40 to 80 Years of Age

BACKGROUND

Physiologic and symptom responses at the ventilatory threshold (Tvent) during incremental cardiopulmonary exercise testing (CPET) can provide important prognostic information.

RESEARCH QUESTION

This study aimed to develop an updated normative reference set for physiologic and symptom responses at Tvent during cycle CPET (primary aim) and to evaluate previously recommended reference equations from a 1985 study for predicting Tvent responses (secondary aim).

STUDY DESIGN AND METHODS

Participants were adults 40 to 80 years of age who were free of clinically relevant disease from the Canadian Cohort Obstructive Lung Disease. Rate of oxygen consumption (V˙O₂) at Tvent was identified by two independent raters; physiologic and symptom responses corresponding to V˙O₂ at Tvent were identified by linear interpolation. Reference ranges (5th-95th percentiles) for responses at Tvent were calculated according to participant sex and age for 29 and eight variables, respectively. Prediction models were developed for nine variables (oxygen pulse, V˙O₂, rate of CO₂ production, minute ventilation, tidal volume, inspiratory capacity, end-inspiratory lung volume [in liters and as percentage of total lung capacity], and end-expiratory lung volume) using quantile regression, estimating the 5th (lower limit of normal), 50th (normal), and 95th (upper limit of normal) percentiles based on readily available participant characteristics. The two one-sided test of equivalence for paired samples evaluated the measured and 1985-predicted V˙O₂ at Tvent for equivalence.

RESULTS

Reference ranges and equations were developed based on 96 participants (49% men) with a mean ± SD age of 63 ± 9 years. Mean V˙O₂ at Tvent was 50% of measured V˙O₂ peak; the normal range was 33% to 66%. The 1985 reference equations overpredicted V˙O₂ at Tvent: mean difference in men, -0.17 L/min (95% CI, -0.25 to -0.09 L/min); mean difference in women, -0.19 L/min (95% CI, -0.27 to -0.12 L/min).

INTERPRETATION

A contemporary reference set of CPET responses at Tvent from Canadian adults 40 to 80 years of age is presented that differs from the previously recommended and often used reference set from 1985.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00920348; URL: www.clinicaltrials.gov.

Prediction Equations for Maximal Aerobic Capacity on Cycle Ergometer for the Spanish Adult Population

BACKGROUND

Frequently used reference values for clinical exercise testing have been derived from non-random samples and some with poorly defined maximal criteria. Our objective was to obtain population based reference values for peak oxygen uptake (V˙O2) and work rate (WR) for cardiopulmonary exercise testing in a representative sample of Caucasian Spanish men and women.

METHODS

182 men and women, 20-85 years old, were included and exercised on cycle-ergometer to exhaustion. (V˙O2) and WR were measured. The equations obtained from this sample were validated in an independent cohort of 69 individuals, randomly sampled form the same population. Then a final equation merging the two cohorts (=251) was produced.

RESULTS

Height, sex and age resulted predictive of both V˙O2 peak and WR. Weight and physical activity added very little to the accuracy to the equations. The formulas V˙O2peak=0.017⋅height(cm)-0.023⋅age(years)+0.864⋅sex(female=0/male=1)±179lmin-1, and peak WR=1.345 · height (cm) - 2.074 · age (years)+76.54 · sex (female=0/male=1)±21.2W were the best compromise between accuracy and parsimony.

CONCLUSIONS

This study provides new and accurate V˙O2 peak and WR rate reference values for individuals of European Spanish descent.

Associations between hemodynamic parameters at rest and exercise capacity in patients with implantable left ventricular assist devices

BACKGROUND

Hemodynamic parameters at rest are known to correlate poorly with peak oxygen uptake (VO₂) in heart failure. However, we hypothesized that hemodynamic parameters at rest could predict exercise capacity in patients with left ventricular assist device (LVAD), because LVAD pump rotational speed does not respond during exercise. Therefore, we investigated the relationships between hemodynamic parameters at rest (measured with right heart catheterization) and exercise capacity (measured with cardiopulmonary exercise testing) in patients with implantable LVAD.

METHODS

We performed a retrospective medical record review of patients who received implantable LVAD at our institution from November 2013 to December 2017.

RESULTS

A total of 20 patients were enrolled in this study (15 males; mean age, 45.8 years; median duration of LVAD support, 356 days). The mean peak VO₂ and cardiac index (CI) were 13.5 mL/kg/min and 2.6 L/min/m², respectively. CI and hemoglobin level were significantly associated with peak VO₂ (CI: r = 0.632, p = 0.003; hemoglobin: r = 0.520, p = 0.019). In addition, pulmonary capillary wedge pressure, right atrial pressure, and right ventricular stroke work index were also significantly associated with peak VO₂. In multiple linear regression analysis, CI and hemoglobin level remained independent predictors of peak VO₂ (CI: β = 0.559, p = 0.006; hemoglobin: β = 0.414, p = 0.049).

CONCLUSIONS

CI at rest and hemoglobin level are associated with poor exercise capacity in patients with LVAD.

Normative Peak Cardiopulmonary Exercise Test Responses in Canadian Adults Aged ≥40 Years

BACKGROUND

Up-to-date normative reference sets for cardiopulmonary exercise testing (CPET) are important to aid in the accurate interpretation of CPET in clinical or research settings.

RESEARCH QUESTION

This study aimed to (1) develop and externally validate a contemporary reference set for peak CPET responses in Canadian adults identified with population-based sampling; and (2) evaluate previously recommended reference equations for predicting peak CPET responses.

STUDY DESIGN AND METHODS

Participants were healthy adults who were ≥40 years old from the Canadian Cohort Obstructive Lung Disease who completed an incremental cycle CPET. Prediction models for peak CPET responses were estimated from readily available participant characteristics (age, sex, height, body mass) with the use of quantile regression. External validation was performed with a second convenience sample of healthy adults. Peak CPET parameters that were measured and predicted in the validation cohort were assessed for equivalence (two one-sided tests of equivalence for paired-samples and level of agreement (Bland-Altman analyses). Two one-sided tests of equivalence for paired samples assessed differences between responses in the derivation cohort using previously recommended reference equations.

RESULTS

Normative reference ranges (5th-95th percentiles) for 28 peak CPET parameters and prediction models for 8 peak CPET parameters were based on 173 participants (47% male) who were 64 ± 10 years old. In the validation cohort (n = 84), peak CPET responses that were predicted with the newly generated models were equivalent to the measured values. Peak cardiac parameters predicted by the previously recommended reference equations by Jones and colleagues and Hansen and colleagues were significantly higher.

INTERPRETATION

This study provides reference ranges and prediction models for peak cardiac, ventilatory, operating lung volume, gas exchange, and symptom responses to incremental CPET and presents the most comprehensive reference set to date in Canadian adults who were ≥40 years old to be identified with population-based sampling.

6-Minute Push Test in Youth Who Have Spina Bifida and Who Self-Propel a Wheelchair: Reliability and Physiologic Response

OBJECTIVE

Despite the common occurrence of lower levels of physical activity and physical fitness in youth with spina bifida (SB) who use a wheelchair, there are very few tests available to measure and assess these levels. The purpose of this study was to determine reliability and the physiologic response of the 6-minute push test (6MPT) in youth with SB who self-propel a wheelchair.

METHODS

In this reliability and observational study, a sample of 53 youth with SB (5-19 years old; mean age = 13 years 7 months; 32 boys and 21 girls) who used a wheelchair performed 2 exercise tests: the 6MPT and shuttle ride test. Heart rate, minute ventilation, respiratory exchange ratio, and oxygen consumption were measured using a calibrated mobile gas analysis system and a heart rate monitor. For reliability, intraclass correlation coefficients (ICCs), SE of measurement, smallest detectable change for total covered distance, minute work, and heart rate were calculated. Physiologic response during the 6MPT was expressed as percentage of maximal values achieved during the shuttle ride test.

RESULTS

The ICCs for total distance and minute work were excellent (0.95 and 0.97, respectively), and the ICC for heart rate was good (0.81). The physiologic response during the 6MPT was 85% to 89% of maximal values, except for minute ventilation (70.6%).

CONCLUSIONS

For most youth with SB who use a wheelchair for mobility or sports participation, the 6MPT is a reliable, functional performance test on a vigorous level of exercise.

IMPACT

This is the first study to investigate physiologic response during the 6MPT in youth (with SB) who are wheelchair using. Clinicians can use the 6MPT to evaluate functional performance and help design effective exercise programs for youth with SB who are wheelchair using.

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

Background

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

Methods and Results

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

Conclusions

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

Reference Values and Predictive Equations for Cardiopulmonary Exercise Testing in Thai Adults

Background: A series of racial specific predictive equations for exercise parameters are needed to determine a lack of cardiopulmonary fitness or having an exercise limitation on cardiopulmonary exercise testing (CPET). Objectives: The study aimed to develop a new set of predictive equations of CPET parameters during maximal cycling exercise for Thai adults. Methods: A sample of 580 Thai adults whom could pass screening tests were asked to fill a health questionnaire and the Global Physical Activity questionnaire. Participants with history of symptomatic heart and pulmonary diseases, current smokers, history of smoking ≥ 10 pack-years, and abnormal spirometry were excluded. The CPET was performed using a cycle ergometer with an incremental symptom-limited protocol. Values of CPET parameters at the peak exercise (oxygen uptake [V̇O2], work rate, heart rate, oxygen pulse, and minute ventilation), lactic acidosis threshold, and ventilatory equivalents for oxygen and carbon dioxide were documented. Analyses were stratified using age and gender criterion. Predictive equations for CPET parameters were established using multivariable linear regression with age (A), weight (W), height (H), and physical activity level (Act) as independent variables. Results: A total of 493 participants (208 men and 285 women) were analysed. The predictive equation of V̇O2peak (L.min-1) for males was: -2.268 + (0.037 × A) - (0.0005 × A2) + (0.016 × W) + (0.014 × H) + (0.104 × Act), (R2 = 0.41, SEE = 0.392), and for females, it was: -0.34 + (0.009 × A) - (0.0002 × A2) + (0.012 × W) + (0.005 × H) + (0.058 × Act), (R2 = 0.44, SEE = 0.220). Conclusions: This is the first study that constructed the predictive equations for cycling CPET parameters in Thai adults. These equations are useful to evaluate the cardiopulmonary health of the Thai population and may be generalized to other populations with geographical or ethnic proximity to the Thai people.

Clinical recommendations for cardiopulmonary exercise testing in children with respiratory diseases

INTRODUCTION

Cardiopulmonary exercise testing (CPET) quantitates and qualitates the integrated physiological response of a person to incremental exercise and provides additional information compared to static lung function tests alone.

AREAS COVERED

This review covers rationale for the use of CPET parameters beyond the usual parameters like peak oxygen uptake and peak minute ventilation in children with respiratory disease.

EXPERT OPINION

CPET provides a wealth of data from rest, submaximal and maximal exercise and data during recovery from exercise. In this review, an interpretative approach is described for analyzing CPET data in children with respiratory disease.

Left Atrial Volume, Cardiorespiratory Fitness, and Diastolic Function in Healthy Individuals: The HUNT Study, Norway

Background Left atrial (LA) size and cardiorespiratory fitness (CRF) are predictors of future cardiovascular events in high-risk populations. LA dilatation is a diagnostic criterion for left ventricular diastolic dysfunction. However, LA is dilated in endurance athletes with high CRF, but little is known about the association between CRF and LA size in healthy, free-living individuals. We hypothesized that in a healthy population, LA size was associated with CRF and leisure-time physical activity, but not with echocardiographic indexes of left ventricular diastolic dysfunction. Methods and Results In this cross-sectional study from HUNT (Nord-Trøndelag Health Study), 107 men and 138 women, aged 20 to 82 years, without hypertension, cardiovascular, pulmonary, or malignant disease participated. LA volume was assessed by echocardiography and indexed to body surface area LAVI (left atrial volume index). CRF was measured as peak oxygen uptake (VO_2peak) using ergospirometry, and percent of age- and-sex-predicted VO_2peak was calculated. Indexes of left ventricular diastolic dysfunction were assessed in accordance with latest recommendations. LAVI was >34 mL/m² in 39% of participants, and LAVI was positively associated with VO_2peak and percentage of age- and-sex-predicted VO_2peak (β [95% CI], 0.11 [0.06-0.16] and 0.18 [0.09-0.28], respectively) and weighted minutes of physical activity per week (β [95% CI], 0.01 [0.003-0.015]). LAVI was not associated with other indexes of left ventricular diastolic dysfunction. There was an effect modification between age and VO_2peak/percentage of age- and-sex-predicted VO_2peak showing higher LAVI with advanced age and higher VO_2peak/percentage of age- and-sex-predicted VO_2peak as presented in prediction diagrams. Conclusions Interpretation of LAVI as a marker of diastolic dysfunction should be done in relation to age-relative CRF. Studies on the prognostic value of LAVI in fit subpopulations are needed.

Reference Values for Cardiorespiratory Fitness in Healthy Koreans

We investigated reference values for cardiorespiratory fitness (CRF) for healthy Koreans and Koreans with coronary heart disease (CHD) and used them to identify inter-ethnic differences in CRF, differences over time in CRF, and differences in CRF between the healthy population and patients with CHD. The study population for healthy Koreans was derived from the database of KISS FitS (Korea Institute of Sports Science Fitness Standards) between 2014 and 2015. The study population for Koreans with CHD was derived from the database of the Korea University Guro Hospital Cardiac Rehabilitation Registry between June 2015 and December 2018. In healthy Koreans, there was a significant difference between sex and age groups for VO₂ max. The VO₂ max of healthy Koreans differed from that of Westerners in age-related reference values. Our results were not significantly different from those of the Korean population in the past, except for a small decline in the young population. There seemed to be a clear inter-ethnic difference in CRF. We could also identify signs of small change in CRF in younger age groups. Therefore, CRF should be assessed according to ethnic or national standards, and it will be necessary to establish a reference for each nation or ethnicity with periodic updates.

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSION

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

Correlates and Determinants of Cardiorespiratory Fitness in Adults: a Systematic Review

Background

Enhanced cardiorespiratory fitness (CRF) is now a well-established predictor of numerous adverse health outcomes. Knowledge about the pathways leading to enhanced CRF is essential for developing appropriate interventions. Hence, the aim of this review was to provide a detailed overview of the current state of research regarding individual factors associated with or influencing CRF among the general adult population.

Methods

We searched the PubMed, EMBASE, and Cochrane Library databases and also conducted a search for grey literature (Google Scholar). Eligible indicators of CRF were objectively assessed measures of CRF by submaximal or maximal exercise testing measured using treadmill or cycle ergometer tests. We included quantitative observational studies of the general adult population. Using a semi-quantitative approach, we compiled summary tables aggregating the study results for each potential correlate or determinant of CRF.

Results

We identified 3005 studies, 78 of which met the inclusion criteria. Almost all of these studies were conducted in high-income countries. Study quality scores assessing the risk of bias in the individual studies ranged from 40 to 100%. Male sex, age (inverse), education, socioeconomic status, ethnicity, body mass index (inverse), body weight (inverse), waist circumference, body fat (inverse), resting heart rate (inverse), C-reactive protein (inverse), smoking (inverse), alcohol consumption, and multiple measures of leisure-time physical activity were independently and consistently associated with CRF.

Conclusions

In synthesizing the current research on the correlates and determinants of CRF among adults, this systematic review identified gaps in the current understanding of factors influencing CRF. Beyond the scope of this review, environmental and interpersonal determinants should be further investigated.

Systematic Review Registration

PROSPERO, CRD42017055456.

Electronic supplementary material

The online version of this article (10.1186/s40798-019-0211-2) contains supplementary material, which is available to authorized users.

Reference values for maximum work rate in apparently healthy Dutch/Flemish adults: data from the LowLands fitness registry

Background: The peak oxygen uptake (VO₂peak) test is the gold standard for cardiorespiratory fitness. However, the test is demanding, requiring sophisticated apparatus for measuring the oxygen uptake. Peak work rate (WRpeak) testing is a promising substitute for peak VO₂peak testing. However, there is a paucity of research conducted to determine reference values (RVs) for WRpeak. Methods: The database from the LowLands fitness registry was used, containing data from health checks from apparently healthy subjects among various professions. Exercise tests were performed using a cycle ergometer and a calibrated metabolic cart. Analysis was executed on 3463 subjects, 2868 male and 595 female. Reference values with corresponding centiles were developed using the LMS method. Results: VO₂peak and WRpeak where highly associated with Pearson's correlation of 0.9 (p = .001). Weight, height, maximum heart rate, and the respiratory exchange ratio had a positive significant effect (p < .001) on WRpeak, and age a negative significant effect, in both males and females. The following formulas were computed for RVs: WRpeak=-102+(1.5 * weight[kg])+(1.9 * height[cm])-(2.0 * age)-(sex * 60[M:0;V:1]) WRpeak/kg=2.45-(0.026 * weight[kg])+(0.024 * height[cm])-(0.024 * age)-(sex * 0.84 [M:0;V:1]) Conclusions: WRpeak can be used as a substitute for VO₂peak when a respiratory gas-analysis system is not available. This study provides RVs for WRpeak and WRpeak/kg in a healthy Dutch/Flemish adult population using cycle ergometry. Further research is needed to obtain RVs for elderly subjects, specific diseases, ethnicities and ergometers.

Hemodynamic Changes During Physiological and Pharmacological Stress Testing in Healthy Subjects, Aortic Stenosis and Aortic Coarctation Patients-A Systematic Review and Meta-Analysis

Introduction: Exercise testing has become a diagnostic standard in the evaluation and management of heart disease. While different methods of exercise and pharmacological stress testing exist, only little is known about their comparability. We aimed to assess hemodynamic changes during dynamic exercise, isometric exercise, and dobutamine stress testing at different stress intensities in healthy subjects and patients with aortic stenosis (AS) and aortic coarctation (CoA).

Methods: A systematic literature search (PROSPERO 2017:CRD42017078608) in MEDLINE of interventional trials was conducted to identify eligible studies providing evidence of changes in hemodynamic parameters under different stress conditions acquired by MRI or echocardiography. A random effects model was used to estimate pooled mean changes in hemodynamics.

Results: One hundred and twenty-eight study arms with a total of 3,139 stress-examinations were included. In healthy subjects/(where available) in AS, pooled mean changes (95% CIs) during light dynamic stress were 31.78 (27.82–35.74) bpm in heart rate (HR) and 6.59 (2.58–10.61) ml in stroke volume (SV). Changes during light pharmacological stress were 13.71 (7.87–19.56)/14.0 (9.82–18.18) bpm in HR, and 5.47 (0.3–10.63)/8.0 (3.82–12.18) ml in SV. Changes during light isometric stress were 18.44 (10.74–26.14)/5.0 (−1.17–11.17) bpm in HR and −4.17 (−14.37–6.03)/−4.0 (−16.43–8.43) ml in SV. Changes during moderate dynamic stress were 49.57 (40.03–59.1)/46.45 (42.63–50.27) bpm in HR and 11.64 (5.87–17.42) ml in SV. During moderate pharmacological stress, changes in HR were 42.83 (36.94–48.72)/18.66 (2.38–34.93) bpm and in SV 6.29 (−2.0–14.58)/13.11 (7.99–18.23) ml. During high intensity dynamic stress changes in HR were 89.31 (81.46–97.17)/55.32 (47.31–63.33) bpm and in SV 21.31 (13.42–29.21)/−0.96 (−5.27–3.35) ml. During high pharmacological stress, changes in HR were 53.58 (36.53–70.64)/42.52 (32.77–52.28) bpm, and in SV 0.98 (−9.32–11.27)/14.06 (−1.62–29.74) ml. HR increase and age were inversely correlated at high stress intensities. In CoA, evidence was limited to single studies.

Conclusion: This systematic review and meta-analysis presents pooled hemodynamic changes under light, moderate and high intensity exercise and pharmacological stress, while considering the potential influence of age. Despite limited availability of comparative studies, the reference values presented in this review allow estimation of the expected individual range of a circulatory response in healthy individuals and patients with AS and may contribute to future study planning and patient-specific models even when stress testing is contraindicated.

Peak oxygen uptake reference values for cycle ergometry for the healthy Dutch population: data from the LowLands Fitness Registry

Peak oxygen uptake (V′_O2peak) is recognised as the best expression of aerobic fitness. Therefore, it is essential that V′_O2peak reference values are accurate for interpreting a cardiopulmonary exercise test (CPET). These values are country specific and influenced by underlying biological ageing processes. They are normally stratified per paediatric and adult population, resulting in a discontinuity at the transition point between prediction equations. There are currently no age-related reference values available for the lifespan of individuals in the Dutch population. The aim of this study is to determine the best-fitting regression model for V′_O2peak in the healthy Dutch paediatric and adult populations in relation to age.

In this retrospective study, CPET cycle ergometry results of 4477 subjects without reported somatic diseases were included (907 females, age 7.9–65.0 years). Generalised additive models were employed to determine the best-fitting regression model. Cross-validation was performed against an independent dataset consisting of 3518 subjects (170 females, age 6.8–59.0 years).

An additive model was the best fitting with the largest predictive accuracy in both the primary (adjusted R²=0.57, standard error of the estimate (see)=556.50 mL·min⁻¹) and cross-validation (adjusted R²=0.57, see=473.15 mL·min⁻¹) dataset.

This study provides a robust additive regression model for V′_O2peak in the Dutch population.

Peak oxygen uptake has a nonlinear dependence on years of age in the paediatric and adult Dutch populationshttp://ow.ly/H3fH30nIjRy

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

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

Ventilatory efficiency response is unaffected by fitness level, ergometer type, age or body mass index in male athletes

The aim of this study was to evaluate the ventilatory efficiency (V_E/VCO₂ slope) and the respiratory control (Vt/Ti slope) in a wide range of athletes and describe the influence of fitness level, age, ergometer type or BMI on these parameters. Ninety-one males (30.4±10.53 years; 175.52±7.45 cm; 71.99±9.35 kg) were analysed retrospectively for the study. Ventilatory efficiency reacted similarly in athletes independently of the fitness level, age, BMI or the ergometer used for testing. No significant differences were found in V_E/VCO₂ slope and the Vt/Ti slope between variables analyzed (P>0.05). The slope of the predictive equations was similar in all cases studied in V_E/VCO₂ slope and the Vt/Ti slope. Moreover, the central control impulse of respiration was not affected by the variables studied. These observations suggest that ventilatory efficiency (V_E/VCO₂ slope) could be a variable fixed by the respiratory system which tends to respond similarly in athletes.

Feasibility of Exercise Testing in Patients Who Are Critically Ill: A Prospective, Observational Multicenter Study

OBJECTIVE

To evaluate the feasibility and safety of exercise testing and to describe the physiological response to exercise of patients in the Intensive Care Unit (ICU).

DESIGN

A prospective observational multicenter study.

SETTING

Two mixed medical-surgical ICUs.

PARTICIPANTS

Patients (N=37; with no primary neurological disorders, 59% men; median age 50y; ICU length of stay 14.5d; Acute Physiology and Chronic Health Evaluation IV 73.0) who had been mechanically ventilated for more than 48 hours and were hemodynamically stable enough to perform physical exercise.

INTERVENTIONS

A passive or active incremental exercise test, depending on muscle strength, on a bed-based cycle ergometer.

MAIN OUTCOME MEASURES

Feasibility and safety were evaluated based on protocol adherence and adverse events. Physiological responses to exercise quantified as changes in respiratory frequency (RF), oxygen uptake (Vo₂), carbon dioxide output (Vco₂), respiratory exchange ratio (RER), and blood lactate.

RESULTS

Thirty-seven patients of whom 18 were mechanically ventilated underwent the exercise test. The active incremental test was performed by 28, and the passive test by 9 participants. Thirty-three (89%) accomplished the test according to the protocol and 1 moderate severe adverse event (bradycardia; heart rate 44) occurred shortly after the test. RF, Vo₂, Vco₂, and lactate increased significantly, whereas RER did not change during the active incremental exercise test. No changes were observed during the passive exercise test.

CONCLUSIONS

It is safe and feasible to perform exercise testing on a bed-based cycle ergometer in patients who are critically ill and a physiological response could be measured. Future research should investigate the clinical value of exercise testing in daily ICU practice and whether exercise capacity and its limiting factors could be determined by incremental exercise testing.

The Role of Gas Exchange Variables in Cardiopulmonary Exercise Testing for Risk Stratification and Management of Heart Failure with Reduced Ejection Fraction

Heart failure with reduced ejection fraction (HFrEF) is common in the developed world and results in significant morbidity and mortality. Accurate risk assessment methods and prognostic variables are therefore needed to guide clinical decision making for medical therapy and surgical interventions with the ultimate goal of decreasing risk and improving health outcomes. The purpose of this review is to examine the role of cardiopulmonary exercise testing (CPET) and its most commonly used ventilatory gas exchange variables for the purpose of risk stratification and management of HFrEF. We evaluated five widely studied gas exchange variables from CPET in HFrEF patients based on nine previously used systematic criteria for biomarkers. This paper provides clinicians with a comprehensive and critical overview, class recommendations and evidence levels. Although some CPET variables met more criteria than others, evidence supporting the clinical assessment of variables beyond peak V̇O₂ is well-established. A multi-variable approach also including the V̇_E-V̇CO₂ slope and EOV is therefore recommended.

A reference equation for maximal aerobic power for treadmill and cycle ergometer exercise testing: Analysis from the FRIEND registry

Background

Maximal oxygen uptake (VO2max) is a powerful predictor of health outcomes. Valid and portable reference values are integral to interpreting measured VO2max; however, available reference standards lack validation and are specific to exercise mode. This study was undertaken to develop and validate a single equation for normal standards for VO2max for the treadmill or cycle ergometer in men and women.

Methods

Healthy individuals ( N = 10,881; 67.8% men, 20–85 years) who performed a maximal cardiopulmonary exercise test on either a treadmill or a cycle ergometer were studied. Of these, 7617 and 3264 individuals were randomly selected for development and validation of the equation, respectively. A Brazilian sample (1619 individuals) constituted a second validation cohort. The prediction equation was determined using multiple regression analysis, and comparisons were made with the widely-used Wasserman and European equations.

Results

Age, sex, weight, height and exercise mode were significant predictors of VO2max. The regression equation was: VO2max (ml kg–1 min–1) = 45.2 – 0.35*Age – 10.9*Sex (male = 1; female = 2) – 0.15*Weight (pounds) + 0.68*Height (inches) – 0.46*Exercise Mode (treadmill = 1; bike = 2) ( R = 0.79, R2 = 0.62, standard error of the estimate = 6.6 ml kg–1 min–1). Percentage predicted VO2max for the US and Brazilian validation cohorts were 102.8% and 95.8%, respectively. The new equation performed better than traditional equations, particularly among women and individuals ≥60 years old.

Conclusion

A combined equation was developed for normal standards for VO2max for different exercise modes derived from a US national registry. The equation provided a lower average error between measured and predicted VO2max than traditional equations even when applied to an independent cohort. Additional studies are needed to determine its portability.

Reference values for peak oxygen uptake: cross-sectional analysis of cycle ergometry-based cardiopulmonary exercise tests of 10 090 adult German volunteers from the Prevention First Registry

OBJECTIVE

This study aims to construct quantile reference values for peak oxygen uptake (V̇O_2peak) measured by cycle ergometry-based incremental cardiopulmonary exercise tests.

DESIGN

Cross-sectional study using quantile regressions to fit sex-specific and age-specific quantile curves. Exercise tests were conducted using cycle ergometry. Maximal effort in the exercise tests wass assumed when respiratory exchange ratio  ≥1.1 or lactate ≥8 mmol/L or maximal heart rate ≥90% of the age-predicted maximal heart rate. This was assessed retrospectively for a random subsample with an a priori calculated sample size of n=252 participants.

SETTING

A network of private outpatient clinics in three German cities recorded the results of cycle ergometry-based cardiopulmonary exercise tests to a central database (Prevention First Registry) from 2001 to 2015.

PARTICIPANTS

10 090 participants (6462 men, 3628 women) from more than 100 local companies volunteered in workplace health promotion programmes. Participants were aged 21 to 83 years, were free of acute complaints and had primarily sedentary working environments.

MAIN OUTCOME MEASURE

Peak oxygen uptake was measured as absolute V̇O_2peak in litres of oxygen per minute and relative V̇O_2peak in millilitres of oxygen per kilogram of body mass per minute.

RESULTS

The mean age for both men and women was 46 years. Median relative V̇O_2peak was 36 and 30 mL/kg/min at 40 to 49 years, as well as 32 and 26 mL/kg/min at 50 to 59 years for men and women, respectively. An estimated proportion of 97% of the participants performed the exercise test until exertion.

CONCLUSIONS

Reference values and nomograms for V̇O_2peak were derived from a large sample of preventive healthcare examinations of healthy white-collar workers. The presented results can be applied to participants of exercise tests using cycle ergometry who are part of a population that is comparable to this study.

The Obesity Factor: How Cardiorespiratory Fitness is Estimated More Accurately in People with Obesity

OBJECTIVE

Cardiopulmonary exercise testing is clinically used to estimate cardiorespiratory fitness (CRF). The relation to total body mass (TBM) leads to an underestimation of CRF in people with obesity and to inappropriate prognostic and therapeutic decisions. This study aimed to determine body composition-derived bias in the estimation of CRF in people with obesity.

METHODS

Two hundred eleven participants (58.8% women; mean BMI 35.7 kg/m² [± 6.94; 20.7-58.6]) were clinically examined, and body composition (InBody720; InBody Co., Ltd., Seoul, South Korea) and spiroergometrical peak oxygen consumption (VO₂ peak) were assessed. The impacts of TBM, lean body mass (LBM), and skeletal muscle mass (SMM) on CRF estimates were analyzed by the application of respective weight models. Linear regression and plotting of residuals against BMI were performed on the whole study population and two subgroups (BMI < 30 kg/m² and BMI ≥ 30 kg/m² ).

RESULTS

For every weight model, Δmean VO₂ peak (expected - measured) was positive. LBM and SMM had a considerable impact on VO₂ peak demand (P = 0.001; ΔR²  = 2.3%; adjusted R²  = 56% and P = 0.001; ΔR² = 2.7%; adjusted R²  = 56%), whereas TBM did not. Confounding of body composition on VO₂ peak did not differ in LBM and SMM.

CONCLUSIONS

TBM-adjusted overestimation of relative VO₂ demand is much higher in people with obesity than in those without. LBM or SMM adjustment may be superior alternatives, although small residual body composition-derived bias remains.

Wheelchair Shuttle Test for Assessing Aerobic Fitness in Youth With Spina Bifida: Validity and Reliability

BACKGROUND

Testing aerobic fitness in youth is important because of expected relationships with health.

OBJECTIVE

The purpose of the study was to estimate the validity and reliability of the Shuttle Ride Test in youth who have spina bifida and use a wheelchair for mobility and sport.

DESIGN

Ths study is a validity and reliability study.

METHODS

The Shuttle Ride Test, Graded Wheelchair Propulsion Test, and skill-related fitness tests were administered to 33 participants for the validity study (age = 14.5 ± 3.1 y) and to 28 participants for the reliability study (age = 14.7 ± 3.3 y).

RESULTS

No significant differences were found between the Graded Wheelchair Propulsion Test and the Shuttle Ride Test for most cardiorespiratory responses. Correlations between the Graded Wheelchair Propulsion Test and the Shuttle Ride Test were moderate to high (r = .55-.97). The variance in peak oxygen uptake (VO2peak) could be predicted for 77% of the participants by height, number of shuttles completed, and weight, with large prediction intervals. High correlations were found between number of shuttles completed and skill-related fitness tests (CI = .73 to -.92). Intraclass correlation coefficients were high (.77-.98), with a smallest detectable change of 1.5 for number of shuttles completed and with coefficients of variation of 6.2% and 6.4% for absolute VO2peak and relative VO2peak, respectively.

CONCLUSIONS

When measuring VO2peak directly by using a mobile gas analysis system, the Shuttle Ride Test is highly valid for testing VO2peak in youth who have spina bifida and use a wheelchair for mobility and sport. The outcome measure of number of shuttles represents aerobic fitness and is also highly correlated with both anaerobic performance and agility. It is not possible to predict VO2peak accurately by using the number of shuttles completed. Moreover, the Shuttle Ride Test is highly reliable in youth with spina bifida, with a good smallest detectable change for the number of shuttles completed.