The effect of inhaled nitric oxide on maximal oxygen consumption during exercise in acute hypoxia: a randomized double-blind crossover trial

In moderate hypoxia [partial pressure of inspired oxygen ([Formula: see text]) = 85-111 mmHg], the reduction in maximal oxygen consumption (V̇o2max) has been attributed to arterial desaturation, whereas in severe hypoxia ([Formula: see text] < 85 mmHg), elevated pulmonary artery pressure (PAP) is thought to impair peak cardiac output ([Formula: see text]) and therefore V̇o2max. The purpose of this study was to examine whether reducing PAP with inhaled nitric oxide (iNO, a selective pulmonary vasodilator) would increase V̇o2max in moderate and severe acute hypoxia. Twelve young, healthy participants (mean V̇o2max = 45.3 ± 12.2 mL/kg/min), with normal lung function completed the randomized double-blind crossover study over six sessions. Experimental cardiopulmonary exercise tests (CPET) were completed on separate days with participants under the following conditions: 1) acute moderate hypoxia ([Formula: see text] = 89 mmHg), 2) acute severe hypoxia ([Formula: see text] = 79 mmHg), 3) acute moderate hypoxia with 40 ppm iNO, and 4) acute severe hypoxia with 40 ppm iNO (order randomized). On separate days, rest, and exercise (60 W), echocardiography was conducted to determine right ventricular systolic pressure (RVSP/PAP) under conditions 1-4. Resting RVSP was reduced by 2.5 ± 0.8 mmHg with iNO in moderate hypoxia (P = 0.01) and 1.8 ± 0.2 mmHg in severe hypoxia (P = 0.05); however, iNO had no effect on peak [Formula: see text] or V̇o2max in either hypoxic condition. Despite reducing RVSP with iNO in hypoxia, peak [Formula: see text] and V̇o2max were unaffected, suggesting that iNO may not improve exercise tolerance in healthy participants during hypoxic exercise.NEW & NOTEWORTHY The elevation of pulmonary artery pressure (PAP) with hypoxia may impair peak cardiac output ([Formula: see text]) and therefore V̇o2max. Our novel findings show that despite reducing resting RVSP in acute moderate ([Formula: see text] = 89 mmHg) and severe hypoxia ([Formula: see text] = 79 mmHg) with inspired nitric oxide, peak [Formula: see text], and V̇o2max were unaffected.

Cardiac mechanisms for low aerobic power in anthracycline treated, older, long-term breast cancer survivors

Breast cancer survivors have reduced peak aerobic capacity (VO_2peak) which may be related to latent or lingering chemotherapy induced cardiac damage. Nine, older (67 ± 3 years), long-term survivors (9.8 years) of anthracycline based chemotherapy and age- and sex-matched healthy controls were recruited and tested to determine whether: i) VO_2peak remains reduced in long-term survivorship; and ii) reductions in VO_2peak are due to cardiac dysfunction. VO_2peak was significantly reduced in breast cancer survivors relative to healthy controls (15.9 ± 2.0 vs 19.9 ± 3.1 ml/kg/min, p = 0.006), however the heart rate and stroke volume responses to exercise were normal (heart rate reserve; 88 ± 9 vs 85 ± 10 bpm, p = 0.62: stroke volume reserve; 13 ± 6 vs 13 ± 9 ml,p = 0.94). These findings indicate low-normal ventricular size in long-term breast cancer survivors, but normal reserve function.

Prescribing Exercise in Early-Stage Breast Cancer During Chemotherapy: A Simple Periodized Approach to Align With the Cyclic Phases of Chemotherapy

ABSTRACT

Bigaran, A, Howden, EJ, Foulkes, S, Janssens, K, Beaudry, R, Haykowsky, MJ, La Gerche, A, Fraser, SF, and Selig, SE. Prescribing exercise in early-stage breast cancer during chemotherapy: a simple periodized approach to align with the cyclic phases of chemotherapy. J Strength Cond Res 36(10): 2934-2941, 2022-To evaluate whether a periodized aerobic and resistance training plan aligned to the anthracycline chemotherapy (AC) cycles would be well tolerated, feasible, and attenuate the decline in peak oxygen uptake (V̇o2peak) in breast cancer (BC) patients. Twenty-eight women with early-stage BC treated with AC self-selected to undertake exercise training (EX 47 ± 9 years, n = 14) or usual care (53 ± 9 years, n = 14) for 12 weeks as part of a nonrandomized controlled trial. The periodized EX was aligned to the cyclic phases of AC, including AC taper and nontaper weeks. Outcome measures included cardiopulmonary exercise testing. Attendance and adherence variables (relative dose intensity [RDI] and volume load) were calculated to quantify the dose of EX completed relative to the amount of EX prescribed. The mean session attendance was 76% (range 46-88%). The mean ± SD prescribed and completed dose of aerobic training was 332.3 ± 48.7 MET h·wk-1 and 380.6 ± 53.2 MET h·wk-1 (p = 0.02), equating to a mean RDI of 89 ± 17%. For resistance training, the prescribed and completed cumulative dose was 128,264 ± 54,578 and 77,487 ± 26,108 kg (p < 0.001), equating to an RDI of 60 ± 11%. Adherence to the AC taper week RDI (52 ± 14%) for resistance training was significantly lower than the non-AC taper week (72 ± 8%, p = 0.02). The most frequent cause for EX interruption was hospitalization (35%), whereas AC-related illness was the most common cause for missed (57%) or modified EX sessions (64%). This periodized approach was mostly well tolerated for patients with BC. We speculate that a periodized approach may be both more palatable and useful, although this requires further investigation in a randomized controlled trial.

Persistent dyspnea after COVID-19 is not related to cardiopulmonary impairment; a cross-sectional study of persistently dyspneic COVID-19, non-dyspneic COVID-19 and controls

Background: Up to 53% of individuals who had mild COVID-19 experience symptoms for >3-month following infection (Long-CoV). Dyspnea is reported in 60% of Long-CoV cases and may be secondary to impaired exercise capacity (VO_2peak) as a result of pulmonary, pulmonary vascular, or cardiac insult. This study examined whether cardiopulmonary mechanisms could explain exertional dyspnea in Long-CoV.

Methods: A cross-sectional study of participants with Long-CoV (n = 28, age 40 ± 11 years, 214 ± 85 days post-infection) and age- sex- and body mass index-matched COVID-19 naïve controls (Con, n = 24, age 41 ± 12 years) and participants fully recovered from COVID-19 (ns-CoV, n = 14, age 37 ± 9 years, 198 ± 89 days post-infection) was conducted. Participants self-reported symptoms and baseline dyspnea (modified Medical Research Council, mMRC, dyspnea grade), then underwent a comprehensive pulmonary function test, cardiopulmonary exercise test, exercise pulmonary diffusing capacity measurement, and rest and exercise echocardiography.

Results: VO_2peak, pulmonary function and cardiac/pulmonary vascular parameters were not impaired in Long- or ns-CoV compared to normative values (VO_2peak: 106 ± 25 and 107 ± 25%_predicted, respectively) and cardiopulmonary responses to exercise were otherwise normal. When Long-CoV were stratified by clinical dyspnea severity (mMRC = 0 vs mMRC≥1), there were no between-group differences in VO_2peak. During submaximal exercise, dyspnea and ventilation were increased in the mMRC≥1 group, despite normal operating lung volumes, arterial saturation, diffusing capacity and indicators of pulmonary vascular pressures.

Interpretation: Persistent dyspnea after COVID-19 was not associated with overt cardiopulmonary impairment or exercise intolerance. Interventions focusing on dyspnea management may be appropriate for Long-CoV patients who report dyspnea without cardiopulmonary impairment.

Aerobic Fitness Is Related to Myocardial Fibrosis Post-Anthracycline Therapy

PURPOSE

We evaluated the impact of anthracyclines on left ventricular function and myocardial tissue characteristics using cardiovascular magnetic resonance (CMR) imaging to determine their relationship with V˙O2peak.

METHODS

Women with breast cancer who had not yet received treatment (No-AT, n = 16) and had received anthracycline treatment ~1 yr earlier (Post-AT, n = 16) and controls without cancer (CON, n = 16) performed a maximal exercise test and a comprehensive 3T CMR examination, including native myocardial T1 mapping, where elevated T1 times are indicative of myocardial fibrosis. ANOVA and linear regression were used to compare CMR variables between groups and to determine associations with V˙O2peak. Subgroup analysis was performed by categorizing participants as "fit" or "unfit" based on whether their V˙O2peak value was greater or less than 100% of reference value for age, respectively.

RESULTS

Left ventricular end-diastolic volume, ejection fraction, and mass were similar between groups. Post-AT, T1 times were elevated (1534 ± 32 vs 1503 ± 28 ms, P < 0.01), and V˙O2peak was reduced (23.1 ± 7.5 vs 29.5 ± 7.7 mL·kg-1⋅min-1, P = 0.02) compared with CON. In No-AT, T1 times and V˙O2peak were similar to CON. In the Post-AT group, T1 time was associated with V˙O2peak (R2 = 64%), whereas in the absence of anthracyclines (i.e., No-AT and CON groups), T1 time was not associated with V˙O2peak. Regardless of group, all fit women had similar T1 times, whereas unfit women Post-AT had higher T1 than unfit CON (1546 ± 22 vs 1500 ± 33 ms, P < 0.01).

CONCLUSIONS

After anthracycline chemotherapy, an elevated T1 time suggesting greater extent of myocardial fibrosis, was associated with lower V˙O2peak. However, those who were fit did not have evidence of myocardial fibrosis after anthracycline treatment.

Exercise Intolerance in Anthracycline-Treated Breast Cancer Survivors: The Role of Skeletal Muscle Bioenergetics, Oxygenation, and Composition

BACKGROUND

Peak oxygen consumption (VO₂ ) is reduced in women with a history of breast cancer (BC). We measured leg blood flow, oxygenation, bioenergetics, and muscle composition in women with BC treated with anthracycline chemotherapy (n = 16, mean age: 56 years) and age- and body mass index-matched controls (n = 16).

MATERIALS AND METHODS

Whole-body peak VO₂ was measured during cycle exercise. ³¹ Phosphorus magnetic resonance (MR) spectroscopy was used to measure muscle bioenergetics during and after incremental to maximal plantar flexion exercise (PFE). MR imaging was used to measure lower leg blood flow, venous oxygen saturation (S_v O₂ ), and VO₂ during submaximal PFE, and abdominal, thigh, and lower leg intermuscular fat (IMF) and skeletal muscle (SM).

RESULTS

Whole-body peak VO₂ was significantly lower in BC survivors versus controls (23.1 ± 7.5 vs. 29.5 ± 7.7 mL/kg/minute). Muscle bioenergetics and mitochondrial oxidative capacity were not different between groups. No group differences were found during submaximal PFE for lower leg blood flow, S_v O₂ , or VO₂ . The IMF-to-SM ratio was higher in the thigh and lower leg in BC survivors (0.36 ± 0.19 vs. 0.22 ± 0.07, p = .01; 0.10 ± 0.06 vs. 0.06 ± 0.02, p = .03, respectively) and were inversely related to whole-body peak VO₂ (r = -0.71, p = .002; r = -0.68, p = .003, respectively)_. In the lower leg, IMF-to-SM ratio was inversely related to VO₂ and O₂ extraction during PFE.

CONCLUSION

SM bioenergetics and oxidative capacity in response to PFE are not impaired following anthracycline treatment. Abnormal SM composition (increased thigh and lower leg IMF-to-SM ratio) may be an important contributor to reduced peak VO₂ during whole-body exercise among anthracycline-treated BC survivors.

IMPLICATIONS FOR PRACTICE

Peak oxygen consumption (peak VO₂ ) is reduced in breast cancer (BC) survivors and is prognostic of increased risk of cardiovascular disease-related and all-cause mortality. Results of this study demonstrated that in the presence of deficits in peak VO₂ 1 year after anthracycline therapy, skeletal muscle bioenergetics and oxygenation are not impaired. Rather, body composition deterioration (e.g., increased ratio of intermuscular fat to skeletal muscle) may contribute to reduced exercise tolerance in anthracycline BC survivors. This finding points to the importance of lifestyle interventions including caloric restriction and exercise training to restore body composition and cardiovascular health in the BC survivorship setting.

Curing breast cancer and killing the heart: A novel model to explain elevated cardiovascular disease and mortality risk among women with early stage breast cancer

Due to advances in prevention, early detection and treatment, early breast cancer mortality has decreased by nearly 40% during the last four decades. Yet, the risk of cardiovascular disease (CVD) mortality is significantly elevated following a breast cancer diagnosis, and it is a leading cause of death in this population. This review will discuss the most recent evidence for risks, pathology, mechanisms, and prevention of CVD morbidity and mortality in women with breast cancer. This evidence will be synthesized into a new model 'the compounding risk and protection model.' This model proposes that the balance between risk factors (i.e., older age, pre-existing traditional CVD risk factors and shared biologic pathways for CVD and cancer such as inflammation, as well as treatment-related and lifestyle toxicity) and potential protection factors (i.e., lifelong non-smoking, regular physical activity, a healthy diet rich in fruits and vegetables, and management of body weight and stress, heart failure therapy) determine the individual risk of CVD morbidity and mortality after diagnosis of early breast cancer.

Determinants of exercise intolerance in breast cancer patients prior to anthracycline chemotherapy

Women with early-stage breast cancer have reduced peak exercise oxygen uptake (peak VO2 ). The purpose of this study was to evaluate peak VO2 and right (RV) and left (LV) ventricular function prior to adjuvant chemotherapy. Twenty-nine early-stage breast cancer patients (mean age: 48 years) and 10 age-matched healthy women were studied. Participants performed an upright cycle exercise test with expired gas analysis to measure peak VO2 . RV and LV volumes and function were measured at rest, submaximal and peak supine cycle exercise using cardiac magnetic resonance imaging. Peak VO2 was significantly lower in breast cancer patients versus controls (1.7 ± 0.4 vs. 2.3 ± 0.5 L/min, P = 0.0013; 25 ± 6 vs. 35 ± 6 mL/kg/min, P = 0.00009). No significant difference was found between groups for peak upright exercise heart rate (174 ± 13 vs. 169 ± 16 bpm, P = 0.39). Rest, submaximal and peak exercise RV and LV end-diastolic and end-systolic volume index, stroke index, and cardiac index were significantly lower in breast cancer patients versus controls (P < 0.05 for all). No significant difference was found between groups for rest and exercise RV and LV ejection fraction. Despite preserved RV and LV ejection fraction, the decreased peak VO2 in early-stage breast cancer patients prior to adjuvant chemotherapy is due in part to decreased peak cardiac index secondary to reductions in RV and LV end-diastolic volumes.

Meta-analysis of Exercise Training on Left Ventricular Ejection Fraction in Heart Failure with Reduced Ejection Fraction: A 10-year Update

BACKGROUND

The role of exercise training modality to attenuate left ventricular (LV) remodeling in heart failure patients with reduced ejection fraction (HFrEF) remains uncertain. The authors performed a systematic review and meta-analysis of published reports on exercise training (moderate-intensity continuous aerobic, high-intensity interval aerobic, and resistance exercise) and LV remodeling in clinically stable HFrEF patients.

METHODS

We searched MEDLINE, Cochrane Central Registry of Controlled Trials, CINAHL, and PubMed (2007 to 2017) for randomized controlled trials of exercise training on resting LV ejection fraction (EF) and end-diastolic and end-systolic volumes in HFrEF patients.

RESULTS

18 trials reported LV ejection fraction (LVEF) data, while 8 and 7 trials reported LV end-diastolic and LV end-systolic volumes, respectively. Overall, moderate-intensity continuous training (MICT) significantly increased LVEF (weighted mean difference, WMD = 3.79%; 95% confidence interval, CI, 2.08 to 5.50%) with no change in LV volumes versus control. In trials ≥6 months duration, MICT significantly improved LVEF (WMD = 6.26%; 95% CI 4.39 to 8.13%) while shorter duration (<6 months) trials modestly increased LVEF (WMD = 2.33%; 95% CI 0.84 to 3.82%). High-intensity interval training (HIIT) significantly increased LVEF compared to control (WMD = 3.70%; 95% CI 1.63 to 5.77%) but was not different than MICT (WMD = 3.17%; 95% CI -0.87 to 7.22%). Resistance training performed alone or combined with aerobic training (MICT or HIIT) did not significantly change LVEF.

CONCLUSIONS

In clinically stable HFrEF patients, MICT is an effective therapy to attenuate LV remodeling with the greatest benefits occurring with long-term (≥6 months) training. HIIT performed for 2 to 3 months is superior to control, but not MICT, for improvement of LVEF.

Exercise cardiac magnetic resonance imaging: a feasibility study and meta-analysis

Cardiac stress testing improves detection and risk assessment of heart disease. Magnetic resonance imaging (MRI) is the clinical gold-standard for assessing cardiac morphology and function at rest; however, exercise MRI has not been widely adapted for cardiac assessment because of imaging and device limitations. Commercially available magnetic resonance ergometers, together with improved imaging sequences, have overcome many previous limitations, making cardiac stress MRI more feasible. Here, we aimed to demonstrate clinical feasibility and establish the normative, healthy response to supine exercise MRI. Eight young, healthy subjects underwent rest and exercise cinematic imaging to measure left ventricular volumes and ejection fraction. To establish the normative, healthy response to exercise MRI we performed a comprehensive literature review and meta-analysis of existing exercise cardiac MRI studies. Results were pooled using a random effects model to define the left ventricular ejection fraction, end-diastolic, end-systolic, and stroke volume responses. Our proof-of-concept data showed a marked increase in cardiac index with exercise, secondary to an increase in both heart rate and stroke volume. The change in stroke volume was driven by a reduction in end-systolic volume, with no change in end-diastolic volume. These findings were entirely consistent with 17 previous exercise MRI studies (226 individual records), despite differences in imaging approach, ergometer, or exercise type. Taken together, the data herein demonstrate that exercise cardiac MRI is clinically feasible, using commercially available exercise equipment and vendor-provided product sequences and establish the normative, healthy response to exercise MRI.

Erratum to: Impact of Exercise Training on Peak Oxygen Uptake and its Determinants in Heart Failure with Preserved Ejection Fraction

[This corrects the article DOI: 10.15420/cfr.2016:16:2.].

Meta-analysis of Exercise Training on Vascular Endothelial Function in Cancer Survivors

Cancer and cardiovascular disease (CVD) are leading causes of morbidity and mortality in the United States. Vascular endothelial dysfunction, an important contributor in the development of CVD, improves with exercise training in patients with CVD. However, the role of regular exercise to improve vascular function in cancer survivors remains equivocal. We performed a meta-analysis to determine the effect of exercise training on vascular endothelial function in cancer survivors. We searched PubMed (1975 to 2016), EMBASE CINAHL (1937 to 2016), OVID MEDLINE (1948 to 2016), and Cochrane Central Registry of Controlled Trials (1991 to 2016) using search terms: vascular function, endothelial function, flow-mediated dilation [FMD], reactive hyperemia, exercise, and cancer. Studies selected were randomized controlled trials of exercise training on vascular endothelial function in cancer survivors. We calculated pooled effect sizes and performed a meta-analysis. We identified 4 randomized controlled trials (breast cancer, n=2; prostate cancer, n=2) measuring vascular endothelial function by FMD (n=3) or reactive hyperemia index (n=1), including 163 cancer survivors (exercise training, n=82; control, n=81). Aerobic exercise training improved vascular function (n=4 studies; standardized mean difference [95% CI]=0.65 [0.33, 0.96], I²=0%; FMD, weighted mean difference [WMD]=1.28 [0.22, 2.34], I²=23.2%) and peak exercise oxygen uptake (3 trials; WMD [95% CI]=2.22 [0.83, 3.61] mL/kg/min; I²=0%). Our findings indicate that exercise training improves vascular endothelial function and exercise capacity in breast and prostate cancer survivors.

Impact of Exercise Training on Peak Oxygen Uptake and its Determinants in Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection (HFpEF) accounts for over 50 % of all HF cases, and the proportion is higher among women and older individuals. A hallmark feature of HFpEF is dyspnoea on exertion and reduced peak aerobic power (VO_2peak) secondary to central and peripheral abnormalities that result in reduced oxygen delivery to and/or utilisation by exercising skeletal muscle. The purpose of this brief review is to discuss the role of exercise training to improve VO_2peak and the central and peripheral adaptations that reduce symptoms following physical conditioning in patients with HFpEF.