Physiologic responses to recumbent versus upright cycle ergometry, and implications for exercise prescription in patients with coronary artery disease

Individualized exercise prescription and cardiac rehabilitation following a spontaneous coronary artery dissection or aortic dissection

Aims

Prescribed aerobic-based exercise training is a low-risk fundamental component of cardiac rehabilitation (CR). Secondary prevention therapeutic strategies following a spontaneous coronary artery dissection (SCAD) or aortic dissection (AD) should include CR. Current exercise guidance for post-dissection patients recommends fundamental training components including target heart rate zones are not warranted. Omitting fundamental elements from exercise prescriptions risks safety and makes it challenging for both clinicians and patients to understand and implement recommendations in real-world practice. We review the principles of exercise prescription for CR, focusing on translating guidelines and evidence from well-studied high-risk CR populations to support the recommendation that exercise testing and individualized exercise prescription are important for patients following a dissection.

Methods and results

When patients self-perceive exercise intensity there is a tendency to underestimate intensities within metabolic domains that should be strictly avoided during routine exercise training following a dissection. However, exercise testing associated with CR enrolment has gained support and has not been linked to adverse events in optimally medicated post-dissection patients. Graded heart rate and blood pressure responses recorded throughout exercise testing provide key information for developing an exercise prescription. An exercise prescription that is reflective of medical history, medications, and cardiorespiratory fitness optimizes patient safety and yields improvements in blood pressure control and cardiorespiratory fitness, among other benefits.

Conclusion

This clinical practice and education article demonstrates how to develop and manage a CR exercise prescription for post-acute dissection patients that can be safe and effective for maintaining blood pressure control and improving cardiorespiratory fitness pre-post CR.

Differences in Peak Oxygen Uptake in Bicycle Exercise Test Caused by Body Positions: A Meta-Analysis

Background: As demand for cardiopulmonary exercise test using a supine position has increased, so have the testing options. However, it remains uncertain whether the existing evaluation criteria for the upright position are suitable for the supine position. The purpose of this meta-analysis is to compare the differences in peak oxygen uptake (VO_2peak) between upright and supine lower extremity bicycle exercise. Methods: We searched PubMed, Web Of Science and Embase from inception to March 27, 2021. Self-control studies comparing VO_2peak between upright and supine were included. The quality of the included studies was assessed using a checklist adapted from published papers in this field. The effect of posture on VO_2peak was pooled using random/fixed effects model. Results: This meta-analysis included 32 self-control studies, involving 546 participants (63% were male). 21 studies included only healthy people, 9 studies included patients with cardiopulmonary disease, and 2 studies included both the healthy and cardiopulmonary patients. In terms of study quality, most of the studies (n = 21, 66%) describe the exercise protocol, and we judged theVO_2peak to be valid in 26 (81%) studies. Meta-analysis showed that the upright VO_2peak exceeded the supine VO_2peak [relative VO_2peak: mean difference (MD) 2.63 ml/kg/min, 95% confidence interval (CI) 1.66-3.59, I ² = 56%, p < 0.05; absolute VO_2peak: MD 0.18 L/min, 95% CI 0.10-0.26, I ² = 63%, p < 0.05). Moreover, subgroup analysis showed there was more pooled difference in healthy people (4.04 ml/kg/min or 0.22 L/min) than in cardiopulmonary patients (1.03 ml/kg/min or 0.12 L/min). Conclusion: VO_2peak in the upright position is higher than that in supine position. However, whether this difference has clinical significance needs further verification. Systematic Review Registration: identifier, CRD42021233468.

Power Output and Efficiency During Supine, Recumbent, and Upright Cycle Ergometry

Recumbent and supine cycling are common exercise modes in rehabilitation and clinical settings but the influence of postures on work efficiency is unclear. Therefore, the aim of this study was to compare metabolic and ventilatory efficiency during upright, recumbent, and supine postures. Potential differences should be assessed for suitable diagnostics and for prescriptions of training that probably is performed in alternative postures. Eighteen healthy subjects (age: 47.2 ± 18.4 years; 10 female, 8 male) participated in the study and each completed three incremental cycle ergometer tests until exhaustion in upright, recumbent (40°), and supine positions. Gas exchange, heart rate (HR), and lactate concentrations were analyzed and efficiency was calculated subsequently. Testing sessions were performed in random order within a 2-week period. Upright cycling resulted in significantly higher peak values [power output, oxygen uptake (Vo₂), HR] as well as performance at lactate and ventilatory thresholds in comparison to recumbent or supine positions. Vco₂/Vo₂ slope and ventilatory efficiency (VE/Vco₂ slope) were not affected by posture. Aerobic work efficiency (Vo₂/P slope) and gross efficiency (GE) differed significantly between postures. Hereby, GE was lowest in supine cycling, particularly obvious in a mainly aerobic condition at 70 Watt [Median 11.6 (IQR 10.9-13.3) vs. recumbent: 15.9 (IQR 15.6-18.3) and upright: 17.4 (IQR 15.1-18.3)]. Peak power as well as GE and work efficiency values are influenced by cycling position, reinforcing the importance of adjusting test results for training prescriptions. Surprisingly, ventilatory efficiency was not affected in this study and therefore does not seem to falsify test results for pulmonary diagnostics.

The effect of posture on maximal oxygen uptake in active healthy individuals

PURPOSE

Semi-supine and supine cardiopulmonary exercise testing (CPET) with concurrent cardiac imaging has emerged as a valuable tool for evaluating patients with cardiovascular disease. Yet, it is unclear how posture effects CPET measures. We aimed to discern the effect of posture on maximal oxygen uptake (VO₂max) and its determinants using three clinically relevant cycle ergometers.

METHODS

In random order, 10 healthy, active males (Age 27 ± 7 years; BMI 23 ± 2 kg m²) underwent a ramp CPET and subsequent constant workload verification test performed at 105% peak ramp power to quantify VO₂max on upright, semi-supine and supine cycle ergometers. Doppler echocardiography was conducted at peak exercise to measure stroke volume (SV) which was multiplied by heart rate (HR) to calculate cardiac output (CO).

RESULTS

Compared to upright (46.8 ± 11.2 ml/kg/min), VO₂max was progressively reduced in semi-supine (43.8 ± 10.6 ml/kg/min) and supine (38.2 ± 9.3 ml/kg/min; upright vs. semi-supine vs. supine; all p ≤ 0.005). Similarly, peak power was highest in upright (325 ± 80 W), followed by semi-supine (298 ± 72 W) and supine (200 ± 51 W; upright vs. semi-supine vs. supine; all p < 0.01). Peak HR decreased progressively from upright to semi-supine to supine (186 ± 11 vs. 176 ± 13 vs. 169 ± 12 bpm; all p < 0.05). Peak SV and CO were lower in supine relative to semi-supine and upright (82 ± 22 vs. 92 ± 26 vs. 91 ± 24 ml and 14 ± 3 vs. 16 ± 4 vs. 17 ± 4 l/min; all p < 0.01), but not different between semi-supine and upright.

CONCLUSION

VO₂max is progressively reduced in reclined postures. Thus, posture should be considered when comparing VO₂max results between different testing modalities.

A Comparison of Cardiopulmonary Exercise Testing and Field Walking Tests in Community-Dwelling Older Adults With Mild-to-Moderate Alzheimer's Dementia

The purpose of this study was to investigate the relationships among peak exercise parameters on 6-min walk test, shuttle walk test, and laboratory-based cardiopulmonary exercise testing in persons with Alzheimer's dementia. This study is a cross-sectional analysis of the baseline data of 90 participants (age 77.1 [6.6] years, 43% female) from the FIT-AD trial. Cardiopulmonary exercise testing produced significantly higher peak heart rate (118.6 [17.5] vs. 106 [22.8] vs. 106 [18.8] beats/min), rating of perceived exertion (16 [2.1] vs. 12 [2.3] vs. 11 [2.1]), and systolic blood pressure (182 [23.7] vs. 156 [18.9] vs. 150 [16.9] mmHg) compared with the shuttle walk test and 6-min walk test, respectively. Peak walking distance on shuttle walk test (241.3 [127.3] m) and 6-min walk test (365.0 [107.9] m) significantly correlated with peak oxygen consumption (17.1 [4.3] ml·kg-1·min-1) on cardiopulmonary exercise testing (r = .449, p ≤ .001 and r = .435, p ≤ .001), respectively, which is considerably lower than what is seen in older adults and persons with cardiopulmonary diseases.

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 (VO2peak) across childhood, adolescence and young adulthood in Barth syndrome: Data from cross-sectional and longitudinal studies

Barth syndrome (BTHS) is an ultra-rare, X-linked recessive disorder characterized by cardio-skeletal myopathy, exercise intolerance, and growth delay. Oxygen uptake during peak exercise (VO2peak) has been shown to be severely limited in individuals with BTHS however; the trajectory of VO2peak from childhood to young adulthood is unknown. The objective of this study was to describe VO2peak from childhood through young adulthood in BTHS.

METHODS AND MATERIALS

VO2peak over time was presented through cross-sectional (n = 33 participants) and a longitudinal analyses (n = 12 participants). Retrospective data were obtained through maximal exercise testing on a cycle ergometer from individuals with BTHS who were or are currently enrolled in a research study during July 2006-September 2017. Participants included in the cross-sectional analysis were divided into 3 groups for analysis: 1) children (n = 13), 2) adolescents (n = 8), and 3) young adults (n = 12). Participants in the longitudinal analysis had at least two exercise tests over a span of 2-9 years.

RESULTS

VO2peak relative to body weight (ml/kgBW/min), fat-free mass (FFM) and by percent of predicted VO2peak obtained were not significantly different between children, adolescents and young adults. VO2peak did not longitudinally change over a mean time of ~5 years in late adolescent and young adult participants with repeated tests. A model including both cardiac and skeletal muscle variables best predicted VO2peak.

CONCLUSIONS

In conclusion, VO2peak relative to body weight and fat-free mass demonstrates short- and long-term stability from childhood to young adulthood in BTHS with some variability among individuals.

Is Exercise Training Appropriate for Patients With Advanced Heart Failure Receiving Continuous Inotropic Infusion? A Review

Exercise-based rehabilitation programs have been reported to have beneficial effects for patients with heart failure. However, there is little evidence about whether this is the case in patients with more severe heart failure. In particular, there is a question in the clinical setting whether patients with advanced heart failure and continuous inotropic infusion should be prescribed exercise training. In contrast, many studies conclude that prolonged immobility associated with heart failure profoundly impairs physical function and promotes muscle wasting that could further hasten the course of heart failure. By contrast, exercise training has various effects not only in improving exercise capacity but also on vascular function, skeletal muscle, and autonomic balance. In this review, we summarize the effectiveness and discuss methods of exercise training in patients with advanced heart failure receiving continuous inotropic agents such as dobutamine.

Effects of body position on exercise capacity and pulmonary vascular pressure-flow relationships

There has been revival of interest in exercise testing of the pulmonary circulation for the diagnosis of pulmonary vascular disease, but there still is uncertainty about body position and the most relevant measurements. Doppler echocardiography pulmonary hemodynamic measurements were performed at progressively increased workloads in 26 healthy adult volunteers in supine, semirecumbent, and upright positions that were randomly assigned at 24-h intervals. Mean pulmonary artery pressure (mPAP) was estimated from the maximum tricuspid regurgitation jet velocity. Cardiac output was calculated from the left ventricular outflow velocity-time integral. Pulmonary vascular distensibility α-index, the percent change of vessel diameter per millimeter mercury of mPAP, was calculated from multipoint mPAP-cardiac output plots. Body position did not affect maximum oxygen uptake (Vo2max), maximum respiratory exchange ratio, ventilatory equivalent for carbon dioxide, or slope of mPAP-cardiac output relationships, which was on average of 1.5 ± 0.4 mmHg·l−1·min−1. Maximum mPAP, cardiac output, and total pulmonary vascular resistance were, respectively, 34 ± 4 mmHg, 18 ± 3 l/min, and 1.9 ± 0.3 Wood units. However, the semirecumbent position was associated with a 10% decrease in maximum workload. Furthermore, cardiac output-workload or cardiac output-Vo2 relationships were nonlinear and variable. These results suggest that body position does not affect maximum exercise testing of the pulmonary circulation when results are expressed as mPAP-cardiac output or maximum total pulmonary vascular resistance. Maximum workload is decreased in semirecumbent compared with upright exercise. Workload or Vo2 cannot reliably be used as surrogates for cardiac output.

Cardiopulmonary responses at various angles of cycle backrest inclination

The purpose of this study was to evaluate cardiopulmonary responses during submaximal cycle exercise at various angles of backrest inclination. Ten healthy Japanese men of mean age 25.9 yrs, height 170.6 cm, and body mass 66.1 kg, performed cycle exercises at a constant workload which reached the anaerobic threshold, at 20 degrees, 40 degrees, and 60 degrees of backrest inclination from the vertical plane, but the angle between the seat and back rest was kept at 110 degrees. The results were as follows: 1) Both cardiac output and stroke volume showed a higher value at the resting control state and during exercise as the backrest angle increased. 2) Oxygen consumption, carbon dioxide output, heart rate, gas exchange ratio, and oxygen pulse were not affected by the angle of backrest inclination. 3) Tidal volume at 20 degrees of backrest inclination was higher than at 60 degrees. 4) No significant differences were found in minute ventilation between each backrest angle. These findings suggest that changes in the backrest angle significantly alter cardiopulmonary parameters at rest and during exercise; in particular, an angle difference of 40 degrees may be enough to alter tidal volume, cardiac output and stroke volume, but not the minute ventilation.

Supine cycling in pediatric exercise testing: disparity in performance measures

Supine cycling may be an important alternative modality for exercise testing. Subtle differences in supine and upright exercise physiology have been suggested but not fully explored in the pediatric population. The aim of this study was to compare peak and submaximal metabolic data in the upright and supine exercise positions. Healthy children (N = 100) performed cardiopulmonary exercise tests using supine and upright cycle ergometry. Recruitment was governed by grant funding and not based on sample size calculations. Subjects exercised to exhaustion. Paired Student's t-tests were used to compare upright and supine data; simple linear regression analyses examined correlations between the two modalities. Peak heart rate was similar in both testing positions. Although peak oxygen uptake (peak VO2), oxygen uptake at anaerobic threshold (VO2@AT), VO2 when the respiratory exchange ratio is consistently at or above 1.0 (VO2@RER1.0), and the oxygen uptake efficiency slope were significantly higher in the upright position, no difference was considered of practical significance when applying Cohen's effect size criteria. Therefore, it may be reasonable for pediatric exercise laboratories to use established normative data and predictions for upright cycling position and apply them to metabolic measures obtained in supine exercise testing. Supine cycling with submaximal parameters may allow objective assessment of exercise capacity in children who undergo exercise echocardiography or cannot perform upright exercise testing.

A pilot study comparing physiological responses of phase III cardiac patients to recumbent and upright exercise using the RPE scale

Ratings of perceived exertion (RPE) are used for exercise programming of cardiac rehabilitation patients, whenever it is difficult to use heart rate to set intensity due to medication or other factors. This investigation examined the physiological responses to two stepping exercise modes (upright and recumbent) at the same RPE. Analysis indicated significant physiological differences between the modes of exercise which may be mediated by postural differences. Specifically, the physiological responses to the recumbent exercise, but not the upright exercise, had the expected relationship with RPE, with recumbent stepping requiring less physiological effort than the upright stepping at the same RPE. As such, we cannot recommend with confidence that the prescription for upright exercise be made based on data from recumbent exercise or vice-versa.

Comparison of cardiovascular responses between upright and recumbent cycle ergometers in healthy young volunteers performing low-intensity exercise: assessment of reliability of the oxygen uptake calculated by using the ACSM metabolic equation

OBJECTIVES

To clarify (1) differences in cardiovascular response during low-intensity exercise in the upright versus the recumbent position, and (2) whether the oxygen uptake (V o 2 ) calculated by the American College of Sports Medicine (ACSM) metabolic equation reflects the actual V o 2 at low-intensity testing.

DESIGN

Repeated-measures comparison study.

SETTING

University research laboratory.

PARTICIPANTS

Thirty-one healthy, young volunteers (age, 23+/-2y).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Blood pressure, rate pressure product (RPP), V o 2 , oxygen pulse, carbon dioxide output (V co 2 ), and ventilatory equivalent (V e ) were measured during graded exercise testing using upright and recumbent cycle ergometers. The estimated V o 2 was calculated by using the ACSM metabolic equation.

RESULTS

Systolic blood pressure, RPP, V o 2 , oxygen pulse, V co 2 , and V e at 15 or 30W were significantly higher in the recumbent position than in the upright one ( P <.05), however, no significant differences were observed at 50 and 70W. The estimated V o 2 during exercise was significantly higher than the actual one, at every level of intensity, from 15 to 70W ( P <.05).

CONCLUSIONS

Cardiovascular responses should be carefully monitored even during low-intensity exercise using a recumbent cycle ergometer. The V o 2 estimated using the ACSM metabolic equation did not reflect the actual V o 2 during low-intensity exercise at 70W or less.

Aerobic exercise function of patients with persistent coronary artery aneurysms secondary to Kawasaki disease

Nine patients with persistent coronary artery aneurysms 1.7-14.0 years after an episode of Kawasaki disease underwent progressive bicycle ergometry with expiratory gas analysis. Two of the patients had aneurysms complicated by angiographically documented coronary artery stenosis. Results of the exercise tests were compared to those obtained from a group of age- and gender-matched normal control subjects. The Kawasaki disease patients did not differ significantly from the control subjects with regard to peak oxygen consumption (81 +/- 7% versus 79 +/- 12% predicted), peak workload (75 +/- 13% versus 77 +/- 9% predicted), anaerobic threshold (21.9 +/- 6.5 versus 18.9 +/- 4.0 ml/kg per minute) or oxygen pulse (96 +/- 7% versus 90 +/- 14% predicted). None of the patients developed significant ST segment changes or rhythm disturbances during exercise. The exercise function of the patients with coronary artery stenosis did not differ from that of patients without stenosis. It was concluded that the aerobic exercise function of patients with persistent coronary artery aneurysms after an episode of Kawasaki disease appears to be well preserved. Kawasaki disease patients with significant coronary artery pathology are not accurately identified by a single assessment of aerobic exercise function.

Physiologic responses of cardiac patients to supine, recumbent, and upright cycle ergometry

Physiological responses were compared in nine stable male cardiac patients (mean +/- standard error (SE): age, 68.3 +/- 8.1 years; height, 172.7 +/- 3.9cm; weight, 72.8 +/- 14.5kg) during stationary cycling in the supine, recumbent, and upright positions. A discontinuous exercise protocol was performed in which each stage included 3 minutes of exercise and 1 minute of recovery. Each subject's workload started at 150kgm.min-1 and increased by 150kgm.min-1 per stage until volitional fatigue. Testing sessions were randomized and performed 1 week apart. Subjects continued their normal medication regimen. All subjects were participants in a community-based cardiac rehabilitation program. Dependent variables were assessed at two different intensities; submaximal (300kgm.min +/- 1) and maximal. A two-way repeated measures ANOVA found no significant differences in systolic blood pressure (SBP), diastolic blood pressure (DBP), minute ventilation (VE), respiratory exchange ratio (R), rate pressure product (RPP), and rating of perceived exertion (RPE) at submaximal (300kgm.min +/- 1) and maximal exercise efforts. Heart rate (HR) was significantly lower (p < or = .05) in the supine position compared with either the upright or recumbent positions during the submaximal workload. In addition, oxygen uptake (VO2) was significantly lower in the supine position at the submaximal workload (p < or = .05) compared with both upright and recumbent. No difference in HR or VO2 was observed at maximal exercise. Regressions of HR on VO2 showed similar slopes and intercepts for supine, recumbent, and upright ergometry.(ABSTRACT TRUNCATED AT 250 WORDS)

Usefulness of transesophageal pacing during exercise for evaluating palpitations in top-level athletes

The aim of this study was to verify the use of transesophageal atrial pacing in reproducing tachyarrhythmias in 22 top-level athletes symptomatic for palpitations, with no evidence of arrhythmias or cardiac anomalies by the standard noninvasive diagnostic techniques. The transesophageal stimulation protocol was divided in 2 sections: at rest and during exercise on the bicycle ergometer in the upright position. Although transesophageal pacing at rest did not induce any arrhythmias in 18 of 22 athletes, during exercise it induced tachyarrhythmias. This occurred in all 16 athletes who had palpitations during physical activity. Electrophysiologic characteristics of induced atrial tachyarrhythmia suggested reentry within the atrioventricular node in 9 of 18 athletes: atrial fibrillation in 5, atrial flutter in 2, orthodromic reciprocating tachycardia due to concealed anomalous pathway in 1, and automatic atrial tachycardia in 1. This study stresses the clinical importance of palpitations during physical exercise and shows that transesophageal pacing performed during exercise is an important diagnostic tool in reproducing the previously described symptoms and in detecting the underlying tachyarrhythmias.