Peak Exercise Heart Rate Research Articles

Cardiorespiratory Fitness in Childhood Cancer Survivors: A Systematic Review and Meta-Analysis.

Cardiovascular disease (CVD) is a leading cause of mortality in childhood cancer survivors (CCS) that may be related to the cardiotoxic effects of radiation or chemotherapy and concomitant reductions in cardiorespiratory fitness. Therefore, we sought to compare cardiorespiratory fitness (peak oxygen uptake, V̇O2peak) between CCS and age-matched non-cancer controls (CON). Secondary outcomes included hemodynamics and resting cardiac function. Embase, Scopus, MEDLINE, CINAHL and SPORTDiscus databases were searched from inception to June 2023 for eligible studies. Cross-sectional studies with V̇O2peak measured in CCS and CON were included. Differences in outcomes and pooled estimates for each outcome were estimated from a fixed effects meta-analysis and between group differences were reported as a weighted mean difference (WMD). Of 2026 studies identified, 18 reported V̇O2peak (CCS: n=786, 44% female, mean age: 16-years, time post-therapy: 5.8 years; CON: n=1379, 50% female, mean age: 16-years). V̇O2peak was lower in CCS (WMD: -7.08mL/kg/min, 95% CI: -7.75 to -6.42, I2: 79%, n=2,165) with no difference for peak exercise heart rate (WMD: -1.4bpm, 95% CI: -3.0 to 0.2, I2: 63%, n=741). Resting left-ventricular ejection fraction (WMD: -1.61%, 95% CI: -2.60 to -0.62, I2.: 49%, n=222) and systolic blood pressure were lower (WMD: -3.8mmHg, 95% CI: -5.7 to -1.9, I2: 25%, n=184) while resting heart rate was higher in CCS (WMD: 4.9bpm; 95% CI: 1.8 to 7.9, I2: 55%, n=262). CCS have a marked reduction in cardiorespiratory fitness (7.1ml/kg/min lower than CON) that may have important prognostic implications for their future risk of CVD and mortality.

Longitudinal decline in peak V̇o2 with aging in a healthy population is associated with a reduction in peripheral oxygen utilization but not in cardiac output.

Aging is associated with a significant decline in aerobic capacity assessed by maximal exercise oxygen consumption (V̇o2max). The relative contributions of the specific V̇o2 components driving this decline, namely cardiac output (CO) and arteriovenous oxygen difference (A - V)O2, remain unclear. We examined this issue by analyzing data from 99 community-dwelling participants (baseline age: 21-96 yr old; average follow-up: 12.6 yr old) from the Baltimore Longitudinal Study of Aging, free of clinical cardiovascular disease. V̇o2peak, a surrogate of V̇o2max, was used to assess aerobic capacity during upright cycle ergometry. Peak exercise left ventricular volumes, heart rate, and CO were estimated using repeated gated cardiac blood pool scans. The Fick equation was used to calculate (A - V)O2diff,peak from COpeak and V̇o2peak. In unadjusted models, V̇o2peak, (A - V)O2diff,peak, and COpeak declined longitudinally over time at steady rates with advancing age. In multiple linear regression models adjusting for baseline values and peak workload, however, steeper declines in V̇o2peak and (A - V)O2diff,peak were observed with advanced entry age but not in COpeak. The association between the declines in V̇o2peak and (A - V)O2diff,peak was stronger among those ≥50 yr old compared with their younger counterparts, but the difference between the two age groups did not reach statistical significance. These findings suggest that age-associated impairment of peripheral oxygen utilization during maximal exercise poses a stronger limitation on peak V̇o2 than that of CO. Future studies examining interventions targeting the structure and function of peripheral muscles and their vasculature to mitigate age-associated declines in (A - V)O2diff are warranted.NEW & NOTEWORTHY The age-associated decline in aerobic exercise performance over an average of 13 yr in community-dwelling healthy individuals is more closely associated with decreased peripheral oxygen utilization rather than decreased cardiac output. This association was more evident in older than younger individuals. These findings suggest that future studies with larger samples examine whether these associations vary across the age range and whether the decline in cardiac output plays a greater role earlier in life. In addition, studies focused on determinants of peripheral oxygen uptake by exercising muscle may guide the selection of preventive strategies designed to maintain physical fitness with advancing age.

Increased Resting and Peak Exercise Systolic Blood Pressure in Children Throughout the COVID-19 Pandemic.

The COVID-19 pandemic created significant disruptions to daily life. Lockdown effects resulted in decreased exercise capacity and increased blood pressure in adults and adolescents in the first year of the pandemic. We examined changes in exercise capacity (peak workload, ventilatory anaerobic threshold-VAT, and VO2 peak), resting BP, and peak exercise BP in children before the COVID-19 pandemic and throughout five 6-month intervals of the pandemic. 951 maximal cardiopulmonary exercise tests completed by healthy children aged ≤ 18years were analyzed retrospectively. BP was auscultated. Tests were divided into pre-pandemic and six-month intervals starting from the declaration of the pandemic (Interval 1: March 11 2020-August 2020, Interval 2: September 2020-February 2021, Interval 3: March-August 2021, Interval 4: September 2021-February 2022, Interval 5: March-August 2022). Peak workload, VAT, and VO2 peak were unchanged from pre-pandemic baseline until Interval 3, when they were significantly decreased. Exercise capacity then returned to values unchanged from baseline. Peak exercise systolic BP was significantly higher than baseline in Intervals 2, 4, and 5. Resting systolic BP was significantly higher than baseline in Interval 5. There was no significant difference in age, sex, BMI, or peak exercise heart rate between intervals. Peak exercise BP was elevated above pre-pandemic baseline when exercise capacity was unchanged. The decrease in exercise capacity subsequently resolved, but the increase in post-exercise BP remained in Intervals 4 and 5. An increase in peak exercise BP preceded a small but significant increase in resting systolic BP.

Rate-Adaptive Atrial Pacing for Heart Failure With Preserved Ejection Fraction

Reduced heart rate during exercise is common and associated with impaired aerobic capacity in heart failure with preserved ejection fraction (HFpEF), but it remains unknown if restoring exertional heart rate through atrial pacing would be beneficial. To determine if implanting and programming a pacemaker for rate-adaptive atrial pacing would improve exercise performance in patients with HFpEF and chronotropic incompetence. Single-center, double-blind, randomized, crossover trial testing the effects of rate-adaptive atrial pacing in patients with symptomatic HFpEF and chronotropic incompetence at a tertiary referral center (Mayo Clinic) in Rochester, Minnesota. Patients were recruited between 2014 and 2022 with 16-week follow-up (last date of follow-up, May 9, 2022). Cardiac output during exercise was measured by the acetylene rebreathe technique. A total of 32 patients were recruited; of these, 29 underwent pacemaker implantation and were randomized to atrial rate responsive pacing or no pacing first for 4 weeks, followed by a 4-week washout period and then crossover for an additional 4 weeks. The primary end point was oxygen consumption (V̇o2) at anaerobic threshold (V̇o2,AT); secondary end points were peak V̇o2, ventilatory efficiency (V̇e/V̇co2 slope), patient-reported health status by the Kansas City Cardiomyopathy Questionnaire Overall Summary Score (KCCQ-OSS), and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels. Of the 29 patients randomized, the mean age was 66 years (SD, 9.7) and 13 (45%) were women. In the absence of pacing, peak V̇o2 and V̇o2 at anaerobic threshold (V̇o2,AT) were both correlated with peak exercise heart rate (r = 0.46-0.51, P < .02 for both). Pacing increased heart rate during low-level and peak exercise (16/min [95% CI, 10 to 23], P < .001; 14/min [95% CI, 7 to 21], P < .001), but there was no significant change in V̇o2,AT (pacing off, 10.4 [SD, 2.9] mL/kg/min; pacing on, 10.7 [SD, 2.6] mL/kg/min; absolute difference, 0.3 [95% CI, -0.5 to 1.0] mL/kg/min; P = .46), peak V̇o2, minute ventilation (V̇e)/carbon dioxide production (V̇co2) slope, KCCQ-OSS, or NT-proBNP level. Despite the increase in heart rate, atrial pacing had no significant effect on cardiac output with exercise, owing to a decrease in stroke volume (-24 mL [95% CI, -43 to -5 mL]; P = .02). Adverse events judged to be related to the pacemaker device were observed in 6 of 29 participants (21%). In patients with HFpEF and chronotropic incompetence, implantation of a pacemaker to enhance exercise heart rate did not result in an improvement in exercise capacity and was associated with increased adverse events. ClinicalTrials.gov Identifier: NCT02145351.

Evidence for Chronotropic Incompetence in Well-healed Burn Survivors.

Due to various pathophysiological responses associated with a severe burn injury, we hypothesized that burn survivors exhibit chronotropic incompetence. To test this hypothesis, a graded peak oxygen consumption (V̇O2peak) test was performed in 94 adults (34 nonburned, 31 burn survivors with 14-35% body surface area grafted, and 29 burn survivors with >35% body surface area grafted). The threshold of 35% body surface area grafted was determined by receiver operating characteristic (ROC) curve analysis. Peak exercise heart rates (HRmax) were compared against age-predicted HRmax within each group. The proportion of individuals not meeting their age-predicted HRmax (within 5 b/min) were compared between groups. Age-predicted HRmax was not different from measured HRmax in the nonburned and moderate burn groups (P = .09 and .22, respectively). However, measured HRmax was 10 ± 6 b/min lower than the age-predicted HRmax in those with a large burn injury (P < .001). While 56 and 65% of individuals in the nonburned and moderate burn group achieved a measured HRmax within 5 b/min or greater of age-predicted HRmax, only 21% of those in the large burn group met this criterion (P < .001). These data provide preliminary evidence of chronotropic incompetence in individuals with severe burn injury covering >35% body surface area.

Mechanisms of Exercise Capacity Improvement after Cardiac Rehabilitation Following Myocardial Infarction Assessed with Combined Stress Echocardiography and Cardiopulmonary Exercise Testing.

Cardiac rehabilitation (CR) is indicated in all patients after acute myocardial infarction (AMI) to improve prognosis and exercise capacity (EC). Previous studies reported that up to a third of patients did not improve their EC after CR (non-responders). Our aim was to assess the cardiac and peripheral mechanisms of EC improvement after CR using combined exercise echocardiography and cardiopulmonary exercise testing (CPET-SE). The responders included patients with an improved EC assessed as a rise in peak oxygen uptake (VO2) ≥ 1 mL/kg/min. Peripheral oxygen extraction was calculated as arteriovenous oxygen difference (A-VO2Diff). Out of 41 patients (67% male, mean age 57.5 ± 10 years) after AMI with left ventricular ejection fraction (LVEF) ≥ 40%, 73% improved their EC. In responders, peak VO2 improved by 27% from 17.9 ± 5.2 mL/kg/min to 22.7 ± 5.1 mL/kg/min, p < 0.001, while non-responders had a non-significant 5% decrease in peak VO2. In the responder group, the peak exercise heart rate, early diastolic myocardial velocity at peak exercise, LVEF at rest and at peak exercise, and A-VO2Diff at peak exercise increased, the minute ventilation to carbon dioxide production slope decreased, but the stroke volume and cardiac index were unchanged after CR. Non-responders had no changes in assessed parameters. EC improvement after CR of patients with preserved LVEF after AMI is associated with an increased heart rate response and better peripheral oxygen extraction during exercise.

Prolonged heart rate recovery time after 6-minute walk test is an independent risk factor for cardiac events in heart failure: A prospective cohort study

ObjectivesTo determine whether the time for peak exercise heart rate to return to resting heart rate after the 6-minute walk test (6MWT) can predict cardiac events in patients with heart failure (HF) within 2 years. DesignProspective cohort study. SettingHF outpatient facility at a tertiary teaching hospital. ParticipantsSeventy-six patients with HF, New York Heart Association functional classification II and III, and left ventricular ejection fraction <50%. Main outcome measuresPatients used a heart rate monitor to measure the time for peak exercise heart rate to return to resting heart rate after the 6MWT. Data were analysed using Polar Pro-Trainer 5 software (Kempele, Finland). Patients were followed for >2 years for cardiac events (hospitalisations and death). ResultsThirty-four patients had cardiac events during the 2-year follow-up period. However, there was a significant difference in the time to return to resting heart rate between the groups with and without cardiac events {with 3.6 (SD 1.1) vs without 2.8 (SD 1.1) minutes; mean difference of 0.79 (95% confidence interval (CI) of the difference 0.28 to 1.28; P=0.003}. No significant differences between patients with and without cardiac events were found for mean walking distance, mean heart rate recovery at 1minute and mean heart rate recovery at 2minutes. The receiver operating curve discriminated between patients with and without cardiac events (área under the curve 0.71, 95% CI 0.61 to 0.81; P<0.001). Using logistic regression analysis, prolonged time to return to resting heart rate (≥3minutes) independently increased the risk for cardiac events 6.9-fold (95% CI 2.34 to 20.12; P<0.001). The Kaplan–Meier curve showed more cardiac events in patients with prolonged time to return to resting heart rate (P=0.028). ConclusionsProlonged time to return to resting heart rate (≥3minutes) after the 6MWT was an independent predictor of cardiac events in patients with HF.

Prefrontal Cortex Hemodynamics During Exercise in Older Adults With Motoric Cognitive Risk Syndrome

The motoric cognitive risk syndrome (MCR) is a recently described pre-dementia syndrome in older adults characterized by slow gait coupled with subjective cognitive complaints. While previous studies have demonstrated the benefits of exercise on cerebral hemodynamics in healthy older adults, to date, no study has characterized the effects of exercise on these parameters among more vulnerable older persons with MCR. To address this knowledge gap, we investigated how the brain area responsible for high-order cognitive function (i.e., prefrontal cortex) is affected during acute cycling exercise in 19 older adults with MCR (Age (mean ± SD): 73.7 ± 7.1 years; BMI: 32.1 ± 5.5 kg/m2; gait speed: 0.55 ± 0.1 m/s; Modified Mini-Mental score: 91.8 ± 6.8; 74% female). Participants performed an incremental submaximal cycling test and we used functional near-infrared spectroscopy to assess changes in concentrations of Oxyhemoglobin (O2Hb), Deoxyhemoglobin (dHb) and total hemoglobin (Hbt) during exercise. Results showed that participants cycled for 4.9 ± 0.5 minutes, achieved a submaximal load of 54.7 ± 17.3 watts, a peak exercise heart rate of 95.7 ± 14.7 beats/min and a rate of perceived exertion (13.8 ± 2.0). Compared to baseline, there was an increase of 97.3 % in the O2Hb, 86 % on the Hbt and an 87.9 decrease of dHb while exercising. Our findings suggest that acute exercise at light through moderate intensity increases prefrontal cortex oxygenation in older adults with MCR. Additional studies are also warranted to characterize the effects of chronic exercise on cerebral hemodynamics in at-risk older adults.

Exercise cardiac MRI unmasks cardiac dysfunction in childhood and adolescent cancer survivors with reduced cardiopulmonary fitness

Abstract Background Young cancer survivors are at increased risk of impaired cardiopulmonary fitness (VO2peak) and heart failure. Assessment of exercise cardiac reserve may reveal sub-clinical abnormalities that better explain impairments in fitness and long term heart failure risk. Purpose To investigate the presence of impaired VO2peak in pediatric cancer survivors with increased risk of heart failure, and to assess its relationship with resting cardiac function and cardiac reserve Methods Twenty pediatric cancer survivors (aged 8–24 years) treated with anthracycline chemotherapy underwent cardiopulmonary exercise testing to quantify VO2peak, with a value &amp;lt;85% of predicted defined as impaired VO2peak. Resting cardiac function was assessed using 3-dimensional echocardiography, with cardiac reserve quantified from resting and peak exercise heart rate (HR), stroke volume index (SVi) and cardiac index (CI) using exercise cardiac magnetic resonance imaging. Results 12 of 20 survivors (60%) had impaired VO2peak (97±14% vs. 70±16% of age and gender predicted). There were no differences in echocardiographic or CMR measurements of resting cardiac function between survivors with normal or impaired VO2peak. However, those with reduced VO2peak had diminished cardiac reserve, with a lesser increase in CI (Fig. 1A) and SVi (Fig. 1B) during exercise (Interaction P=0.001 for both), whilst the HR response was similar (Fig. 1C; P=0.71). Conclusions Resting measures of cardiac function are insensitive to significant cardiac dysfunction amongst pediatric cancer survivors with reduced VO2peak. Measures of cardiopulmonary fitness and cardiac reserve may aid in early identification of survivors with heightened risk of long-term heart failure. Figure 1 Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): National Heart Foundation

Effectiveness and safety of exercise training and rehabilitation in pulmonary hypertension: a systematic review and meta-analysis.

BackgroundPulmonary hypertension (PH) is a chronic progressive disease characterized by increasing pulmonary vascular resistance, poor prognosis and high disability rate. Although many targeted drugs for PH have been put to clinical use, most patients still have poor exercise tolerance and quality of life. Exercise training is considered to further improve exercise capacity and quality of life in patients with PH, but it has not been fully studied and utilized. The aim of this systematic review and meta-analysis is to evaluate the effectiveness and safety of exercise training in patients with PH.MethodsA search was conducted for the meta-analysis using the databases PubMed, Embase, Cochrane Library, including literature published before December 2018. The primary outcome of this meta-analysis was a change in the 6-minute walk distance (6MWD). In addition, peak oxygen uptake (PeakVO2), resting pulmonary arterial systolic pressure (PASPrest), resting heart rate (HRrest), peak exercise heart rate (HRpeak), oxygen uptake anaerobic threshold (VO2 at AT), maximum workload and quality of life (QoL) were also assessed.ResultsA total of 651 patients in 17 studies were included. A meta-analysis showed that exercise training was associated with significant improvement in the 6MWD [weighted mean difference (WMD): 64.75 m (95% CI: 53.19–76.31 m, P<0.001)], peakVO2 [WMD: 1.78 mL/min/kg (95% CI: 1.27–2.29 mL/min/kg, P<0.001)], HRpeak [WMD: 11.07 beats/min (95% CI: 8.04–14.11 beats/min, P<0.001)] and QoL measured by SF-36 questionnaire subscale scores. Furthermore, exercise training is well tolerated, and no major adverse event occurred related to exercise training.ConclusionsExercise training is associated with a significant improvement in exercise capacity, cardiorespiratory fitness and quality of life among patients with PH and proved to be safe for stable PH patients with optimization of medical therapy. However, more large-scale multicenter studies are needed to confirm the effectiveness and safety of exercise training in patients with PH.

Determinants of Cardiorespiratory Fitness After Bariatric Surgery: Insights From a Randomised Controlled Trial of a Supervised Training Program

BackgroundSeverely obese patients have decreased cardiorespiratory fitness (CRF) and poor functional capacity. Bariatric surgery–induced weight loss improves CRF, but the determinants of this improvement are not well known. We aimed to assess the determinants of CRF before and after bariatric surgery and the impact of an exercise training program on CRF after bariatric surgery. MethodsFifty-eight severely obese patients (46.1 ± 6.1 kg/m2, 78% women) were randomly assigned to either an exercise group (n = 39) or usual care (n = 19). Exercise training was conducted from the 3rd to the 6th months after surgery. Anthropometric measurements, abdominal and mid-thigh computed tomographic scans, resting echocardiography, and maximal cardiopulmonary exercise testing was performed before bariatric surgery and 3 and 6 months after surgery. ResultsWeight, fat mass, and fat-free mass were reduced significantly at 3 and 6 months, without any additive impact of exercise training in the exercise group. From 3 to 6 months, peak aerobic power (V̇O2peak) increased significantly (P < 0.0001) in both groups but more importantly in the exercise group (exercise group: from 18.6 ± 4.2 to 23.2 ± 5.7 mL/kg/min; control group: from 17.4 ± 2.3 to 19.7 ± 2.4 mL/kg/min; P value, group × time = 0.01). In the exercise group, determinants of absolute V̇O2peak (L/min) were peak exercise ventilation, oxygen pulse, and heart rate reserve (r2 = 0.92; P < 0.0001), whereas determinants of V̇O2peak indexed to body mass (mL/kg/min) were peak exercise ventilation and early-to-late filling velocity ratio (r2 = 0.70; P < 0.0001). ConclusionsA 12-week supervised training program has an additive benefit on cardiorespiratory fitness for patients who undergo bariatric surgery.

Pharmacological vs Exercise Stress Echocardiography for Detection of Cardiac Allograft Vasculopathy.

ObjectiveTo test the hypothesis that exercise and dobutamine would provide levels of cardiac stress that are comparable to those achieved in a general stress test population, and to one another, in heart transplant recipients.Patients and MethodsFrom February 10, 2015, to December 31, 2017, 81 patients underwent exercise stress (N=45) or dobutamine stress (N=36) echocardiography at a mean ± SD of 11±14 years (range, 1-29 years) after heart transplant. Hemodynamic and inotropic responses were compared between groups, and to a prior test, longitudinally. The primary outcome was peak heart rate (HR) × systolic blood pressure (SBP).ResultsPeak exercise HR × SBP × 10−3 was a mean ± SD of 24.9±4.9 mm Hg/min for exercise stress vs 21.2±3.4 mm Hg/min during dobutamine stress (P<.001). In 35 patients who underwent a dobutamine stress test followed later by another dobutamine stress test, peak HR × SBP changed by 4.2%±16% (P=.05). In 25 patients who underwent a dobutamine stress test followed later by an exercise stress test, peak HR × SBP increased by 12%±23% (P=.002 vs serial dobutamine stress tests). Peak exercise HR did not correlate with time since heart transplant, patient age, or graft age. Peak dobutamine HR correlated modestly with patient age (r2=0.28). Inotropic responses were similar in both groups. Overall, patients preferred exercise stress testing to dobutamine stress tests. Dobutamine stress testing was more expensive than exercise stress tests.ConclusionExercise induces a level of cardiac stress that is equal to or greater than dobutamine-induced stress, at lower cost, in heart transplant recipients who express preference for exercise stress testing.

The placebo effect on aerobic fitness test results is preserved following a multidisciplinary intervention program for treating childhood obesity.

The aim of the study was to examine the placebo effect on fitness test results in trained and untrained overweight and obese children. Twenty pre-pubertal overweight children performed two pairs of progressive treadmill exercise tests before and 12weeks into a multidisciplinary program for the treatment of childhood obesity. In each test pair, at random order, participants received different types of information regarding a water drink consumed prior to testing-standard information (water) vs deliberate positive information (presumed energy drink, placebo). The intervention led to a significant change (P<.05) in BMI%ile (95.6±4.4 vs 93.6±6.9), % fat (35.4±6.0 vs 31.6±5.8), baseline heart rate (104.2±11.6 vs 94.0±7.0bpm), total leisure activity score-Godin (9.3±8.8 vs 41.5±15.2), total screen time (6.9±5.8 vs 3.1±1.4h/d), and a significant improvement in fitness. Following the placebo drink, both groups achieved a significantly higher peak heart rate (untrained: 176.1±13.7 vs 167.5±16.8; trained: 170.7±11.6 vs 166.2±11.4bpm) and longer running time (untrained: 559.9±151.0 vs 434.4±140.3seconds; trained: 728.3±177.3 vs 667.1±176.1seconds). Despite longer exercise duration and higher peak exercise heart rate, average, and peak RPE were lower after the placebo drink (untrained: 12.1±2.3 vs 13.6±2.1; trained:10.0±1.8 vs 11.6±2.1), recovery time was shorter (untrained: 119.2±25.3 vs 133.2±23.7seconds; trained: 92.6±18.9 vs 102.7±18.3seconds). The placebo-induced change in running time and peak RPE were significantly greater prior to training. The significant information placebo effect is preserved in trained overweight children. Information, as well as other motivating aidsand fatigue distractors may be useful in enhancing physical performancein obese children.

Exercise cardiovascular magnetic resonance reveals reduced cardiac reserve in pediatric cancer survivors with impaired cardiopulmonary fitness

BackgroundPediatric cancer survivors are at increased risk of cardiac dysfunction and heart failure. Reduced peak oxygen consumption (peak VO2) is associated with impaired cardiac reserve (defined as the increase in cardiac function from rest to peak exercise) and heart failure risk, but it is unclear whether this relationship exists in pediatric cancer survivors. This study sought to investigate the presence of reduced peak VO2 in pediatric cancer survivors with increased risk of heart failure, and to assess its relationship with resting cardiac function and cardiac haemodynamics and systolic function during exercise.MethodsTwenty pediatric cancer survivors (8–24 years; 10 male) treated with anthracycline chemotherapy ± radiation underwent cardiopulmonary exercise testing to quantify peak VO2, with a value < 85% of predicted defined as impaired peak VO2. Resting cardiac function was assessed using 2- and 3-dimensional echocardiography, with cardiac reserve quantified from resting and peak exercise heart rate, stroke volume index (SVI) and cardiac index (CI) using exercise cardiovascular magnetic resonance (CMR).ResultsTwelve of 20 survivors (60%) had reduced peak VO2 (70 ± 16% vs. 97 ± 14% of age and gender predicted). There were no differences in echocardiographic or CMR measurements of resting cardiac function between survivors with normal or impaired peak VO2. However, those with reduced peak VO2 had diminished cardiac reserve, with a lesser increase in CI and SVI during exercise (Interaction P < 0.01 for both), whilst the heart rate response was similar (P = 0.71).ConclusionsWhilst exercise intolerance is common among pediatric cancer survivors, it is poorly explained by resting measures of cardiac function. In contrast, impaired exercise capacity is associated with impaired haemodynamics and systolic functional reserve measured during exercise. Consequently, measures of cardiopulmonary fitness and cardiac reserve may aid in early identification of survivors with heightened risk of long-term heart failure.

Healthy Aging and Cardiovascular Function: Invasive Hemodynamics During Rest and Exercise in 104 Healthy Volunteers

ObjectivesThe aim of this study was to evaluate the association between age and invasive cardiovascular hemodynamics during upright exercise among healthy adults. BackgroundThe marked age-related decline in maximal exercise oxygen uptake (peak VO2) may contribute to the high burden of heart failure among older individuals and their greater severity of exertional symptoms. However, the mechanisms underlying this decline are not well understood. MethodsA total of 104 healthy community-dwelling volunteers age 20 to 76 years well screened for cardiovascular disease underwent exhaustive upright exercise with brachial and pulmonary artery catheters; radionuclide ventriculography; and expired gas analysis for the measurement of peak VO2, cardiac output, left ventricular stroke volume, end-diastolic volume, end-systolic volume, ejection fraction, pulmonary capillary wedge pressure, and arteriovenous oxygen difference. ResultsOver a 5.5-decade age range, there was a 40% decline in peak VO2 due primarily to reduced peak exercise cardiac output; peak arteriovenous oxygen difference was unaffected by age. The lower age-related exercise cardiac output was related to lower peak exercise heart rate and stroke volume. Aging was also associated with lower peak exercise ejection fraction, indicating reduced inotropic reserve. Peak exercise end-diastolic volume was lower with aging despite similar left ventricular filling pressure, suggesting age-related reduced diastolic compliance limiting the use of the Frank-Starling mechanism to compensate for reduced chronotropic and inotropic reserves. These age relationships were unaffected by sex. ConclusionsThe age-related decline in exercise capacity among healthy persons is due predominantly to cardiac mechanisms, including reduced chronotropic and inotropic reserve and possibly reduced Frank-Starling reserve. Peak exercise left ventricular filling pressure and arteriovenous oxygen difference are unchanged with healthy aging.

P888Left ventricular diastolic function and left atrial longitudinal function during exercise correlate with exercise capacity in patients with hypertrophic cardiomyopathy

Abstract Background The clinical course of hypertrophic cardiomyopathy (HCM) is heterogeneous and the development of heart failure (HF) is difficult to predict. Exercise echocardiography can provide information about mechanisms involved in the occurrence of HF symptoms: development of intraventricular obstruction, increase in mitral regurgitation (MR) severity, impaired left ventricular (LV) and left atrial (LA) function. Purpose To analyse the changes in LV and LA function during exercise and to identify the main correlates of exercise capacity in patients (pts) with HCM, in sinus rhythm and with normal LV ejection fraction. Methods We have prospectively enrolled 32 pts (48±17 years, 15 men) with HCM and no obstruction at rest. A symptom limited exercise echocardiogram was performed in all pts using a table ergometer. Maximum LV wall thickness (LVWT), indexed left atrial volume (LAVi), septal E', E/septal E' ratio, were measured at rest (r) and during exercise (e). Global longitudinal LV strain (GLS) and LA strain (LAɛ) were assessed by speckle tracking echocardiography at rest and during exercise. The peak LV outflow tract gradient, systolic pulmonary artery pressure (PAP), and MR degree were recorded at rest and during exercise. Exercise-related symptoms, peak exercise heart rate (HR) and exercise capacity calculated in metabolic equivalents (METs) were also recorded. Results The mean value of achieved METs was 5.9±1.4, the peak HR was 124±25 bpm, representing 72±12% of maximal HR, during a mean of 8.5±2.5 minutes of exercise. Thirteen pts developed LV gradients &gt;30 mmHg. Fifteen pts were asymptomatic, while 17 pts reported dyspnea during exercise. There were no significant differences between pts with and without symptoms regarding: age, rE', rE/E', rGLS, rLAɛ, rMR, rPAP, LAVi, eE/e', eGLS, eMR, ePAP (p&gt;0.05 for all). Symptomatic pts had lower values for eE' (p=0.01), eLAɛ (p=0.03) and tended to have higher values for LVWT (p=0.06) and a higher prevalence of eLV outflow tract obstruction (p=0.13) compared to asymptomatic pts. In symptomatic group of pts, E' (p=0.004), PAP (p&lt;0.001) and GLS (p=0.04) significantly increased and LAɛ tended to decrease (p=0.18) during exercise. Age (r=−0.44, p=0.01), rE' (r=0.40, p=0.02), eE' (r=0.46, p=0.01), ePAP (r=−0.35, p=0.04) and LVWT (r=−0.32, p=0.07) significantly correlated with achieved METs in HCM pts overall. In multivariate analysis, eE' (β=0.60, 95% CI 0.122 to 0.009, p=0.003) was the only parameter independently correlated with exercise capacity (expressed in METs). Conclusions Symptomatic pts had a worse LV diastolic function (as expressed by E') and a severe LA longitudinal dysfunction (as expressed by LAɛ) during exercise. E' during exercise was the only parameter independently correlated with exercise capacity in pts with HCM. These suggest that a detailed analysis of LV and LA function during exercise could provide additional information to predict the occurrence of HF in HCM pts.

Heart Rate Response During Treadmill Exercise Test in Children and Adolescents With Congenital Heart Disease.

Background: Impaired exercise capacity is a common feature of congenital heart disease (CHD). In adults with CHD, it has been shown that impaired heart rate response during exercise may contribute to exercise limitation. Systematic data in children and adolescents on this topic is limited. We therefore purposed to assess heart rate response during treadmill exercise testing in children and adolescents with CHD compared to healthy controls.Methods: One hundred and sixty three children and adolescents (103 with CHD, median age 15 years and 60 age-matched controls) performed cardiopulmonary exercise testing and were included in this study. Beyond peak oxygen consumption, increase in heart rate from resting level to peak exercise (heart rate reserve) and decrease of heart rate after peak exercise (heart rate recovery) were measured. Chronotropic index was defined as percentage of age predicted maximal heart rate reserve. According to data from adults on bicycle exercise, chronotropic incompetence was assumed for chronotropic index below 0.8.Results: While resting heart rate was similar between both groups, peak heart rate, heart rate reserve as well as chronotropic index were lower in the CHD group than in controls. Chronotropic index was lowest in patients with single ventricle hemodynamics and correlated with peak oxygen consumption. Heart rate recovery was impaired in the CHD group 1 and 2 min after peak exercise compared to controls and correlated with peak oxygen consumption. Chronotropic index below 0.8 was a relatively frequent finding even in the control group suggesting that the threshold of 0.8 appears inadequate for the identification of chronotropic incompetence using treadmill exercise testing in children. After normalizing to the 2.5th chronotropic index percentile of the control group we obtained a chronotropic incompetence threshold of 0.69.Conclusion: As an adjunct to measurement of peak oxygen consumption, heart rate response to exercise appears to be a physiologically important diagnostic parameter in children and adolescents with CHD. However, interpretation of heart rate response needs to consider specific age characteristics and the mode of exercise test. Our data may help future studies on chronotropic incompetence using treadmill ergometer protocols in children and adolescents.

Left Ventricular Function Before and After Aerobic Exercise Training in Women With Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) is a chronic debilitating illness. The effects of vigorous aerobic exercise training (AET) on heart function in PAH are poorly understood. Eighteen women with PAH (aged 56.2 ± 8.8 yr, body mass index: 28.8 ± 7.3 kg/m) underwent 10 wk of vigorous AET. Cardiac function was observed at rest and peak exercise using bioelectrical impedance cardiography before and after the AET. Cardiac function was observed in a small PAH subset (n = 7) for 10 wk before beginning the AET. A cohort of sedentary women (n = 19) served as healthy controls. Left ventricular ejection fraction (48 ± 9.2 vs 61.5 ± 13.3%, P = .034) and the systemic vascular resistance index (2258 ± 419.1 vs 2939 ± 962.4 dyn·sec/cm·m, P = .008) were lower at supine rest in the baseline PAH group versus the healthy group, as were peak exercise heart rate (140 ± 13.3 vs 170 ± 13.8 beats/min, P < .001) and systemic vascular resistance index (828 ± 141.1 vs 824 ± 300.9 dyn·sec/cm·m, P = .050) after controlling for age and heart rate. Systemic vascular resistance index measured at peak exercise decreased in the PAH group after AET (828 ± 141.1 vs 766 ± 139.6 dyn·sec/cm·m, P = .020). Left ventricular early diastolic filling ratio worsened in the PAH subset prior to AET (95.9 ± 19.4 vs 76.2 ± 18.9%, P = .043) and remained unchanged after AET. Vigorous AET was not associated with significant declines in left ventricular systolic or diastolic function in women with PAH. Aerobic exercise training may be beneficial for reducing afterload and may preserve left ventricular diastolic function.

Ultra-short-term heart rate recovery after maximal exercise in elite European table tennis players

The purpose of this study was to examine heart rate (HR) responses during 10-s intervals over the first minute of recovery (i.e., ultra-short-term recovery) after table tennis-specific maximal exercise in elite and sub-elite players. Twenty-five elite (22.8 ± 6.1 years) and 18 sub-elite (20.1 ± 2.2 years) table tennis players completed a specific table tennis test performing forehand offensive strokes against balls launched from a table tennis robot by an experienced coach at a rate of approximately 60 balls/min until exhaustion. Immediately upon exercise cessation, the participants were placed in a lying position for 60 s of HR recording. In general, both absolute heart rate and heart rate expressed as a percentage of the peak exercise heart rate were possibly to likely lower (50–92% likelihood of being different; magnitude-based inference), suggesting faster heart rate recovery, in elite players than in sub-elite players. Therefore, we conclude that elite players have faster HR recovery than sub-elite players and that ultra-short-term recovery can be used to monitor training routines.

High intensity interval training protects the heart during increased metabolic demand in patients with type 2 diabetes: a randomised controlled trial

AimThe present study assessed the effect of high intensity interval training on cardiac function during prolonged submaximal exercise in patients with type 2 diabetes.MethodsTwenty-six patients with type 2 diabetes were randomized to a 12 week of high intensity interval training (3 sessions/week) or standard care control group. All patients underwent prolonged (i.e. 60 min) submaximal cardiopulmonary exercise testing (at 50% of previously assess maximal functional capacity) with non-invasive gas-exchange and haemodynamic measurements including cardiac output and stroke volume before and after the intervention.ResultsAt baseline (prior to intervention) there was no significant difference between the intervention and control group in peak exercise oxygen consumption (20.3 ± 6.1 vs. 21.7 ± 5.5 ml/kg/min, p = 0.21), and peak exercise heart rate (156.3 ± 15.0 vs. 153.8 ± 12.5 beats/min, p = 0.28). During follow-up assessment both groups utilized similar amount of oxygen during prolonged submaximal exercise (15.0 ± 2.4 vs. 15.2 ± 2.2 ml/min/kg, p = 0.71). However, cardiac function i.e. cardiac output during submaximal exercise decreased significantly by 21% in exercise group (16.2 ± 2.7–12.8 ± 3.6 L/min, p = 0.03), but not in the control group (15.7 ± 4.9–16.3 ± 4.1 L/min, p = 0.12). Reduction in exercise cardiac output observed in the exercise group was due to a significant decrease in stroke volume by 13% (p = 0.03) and heart rate by 9% (p = 0.04).ConclusionFollowing high intensity interval training patients with type 2 diabetes demonstrate reduced cardiac output during prolonged submaximal cardiopulmonary exercise testing. Ability of patients to maintain prolonged increased metabolic demand but with reduced cardiac output suggests cardiac protective role of high intensity interval training in type 2 diabetes.Trial registrationISRCTN78698481. Registered 23 January 2013, retrospectively registered.