Mechanisms of Exercise Intolerance Across the Breast Cancer Continuum: A Pooled Analysis of Individual Patient Data

PURPOSE

The purpose of this study is to evaluate the prevalence of abnormal cardiopulmonary responses to exercise and pathophysiological mechanism(s) underpinning exercise intolerance across the continuum of breast cancer (BC) care from diagnosis to metastatic disease.

METHODS

Individual participant data from four randomized trials spanning the BC continuum ([1] prechemotherapy [n = 146], [2] immediately postchemotherapy [n = 48], [3] survivorship [n = 138], and [4] metastatic [n = 47]) were pooled and compared with women at high-risk of BC (BC risk; n = 64). Identical treadmill-based peak cardiopulmonary exercise testing protocols evaluated exercise intolerance (peak oxygen consumption; V̇O2peak) and other resting, submaximal, and peak cardiopulmonary responses. The prevalence of 12 abnormal exercise responses was evaluated. Graphical plots of exercise responses were used to identify oxygen delivery and/or uptake mechanisms contributing to exercise intolerance. Unsupervised, hierarchical cluster analysis was conducted to explore exercise response phenogroups.

RESULTS

Mean V̇O2peak was 2.78 ml O2.kg-1·min-1 (95% confidence interval [CI], -3.94, -1.62 mL O2.kg-1·min-1; P < 0.001) lower in the pooled BC cohort (52 ± 11 yr) than BC risk (55 ± 10 yr). Compared with BC risk, the pooled BC cohort had a 2.5-fold increased risk of any abnormal cardiopulmonary response (odds ratio, 2.5; 95% confidence interval, 1.2, 5.3; P = 0.014). Distinct exercise responses in BC reflected impaired oxygen delivery and uptake relative to control, although considerable inter-individual heterogeneity within cohorts was observed. In unsupervised, hierarchical cluster analysis, six phenogroups were identified with marked differences in cardiopulmonary response patterns and unique clinical characteristics.

CONCLUSIONS

Abnormal cardiopulmonary response to exercise is common in BC and is related to impairments in oxygen delivery and uptake. The identification of exercise response phenogroups could help improve cardiovascular risk stratification and guide investigation of targeted exercise interventions.

Timing of exercise therapy when initiating adjuvant chemotherapy for breast cancer: a randomized trial

AIMS

The most appropriate timing of exercise therapy to improve cardiorespiratory fitness (CRF) among patients initiating chemotherapy is not known. The effects of exercise therapy administered during, following, or during and following chemotherapy were examined in patients with breast cancer.

METHODS AND RESULTS

Using a parallel-group randomized trial design, 158 inactive women with breast cancer initiating (neo)adjuvant chemotherapy were allocated to receive (1:1 ratio): usual care or one of three exercise regimens-concurrent (during chemotherapy only), sequential (after chemotherapy only), or concurrent and sequential (continuous) (n = 39/40 per group). Exercise consisted of treadmill walking three sessions/week, 20-50 min at 55%-100% of peak oxygen consumption (VO2peak) for ≈16 (concurrent, sequential) or ≈32 (continuous) consecutive weeks. VO2peak was evaluated at baseline (pre-treatment), immediately post-chemotherapy, and ≈16 weeks after chemotherapy. In intention-to-treat analysis, there was no difference in the primary endpoint of VO2peak change between concurrent exercise and usual care during chemotherapy vs. VO2peak change between sequential exercise and usual care after chemotherapy [overall difference, -0.88 mL O2·kg-1·min-1; 95% confidence interval (CI): -3.36, 1.59, P = 0.48]. In secondary analysis, continuous exercise, approximately equal to twice the length of the other regimens, was well-tolerated and the only strategy associated with significant improvements in VO2peak from baseline to post-intervention (1.74 mL O2·kg-1·min-1, P < 0.001).

CONCLUSION

There was no statistical difference in CRF improvement between concurrent vs. sequential exercise therapy relative to usual care in women with primary breast cancer. The promising tolerability and CRF benefit of ≈32 weeks of continuous exercise therapy warrant further evaluation in larger trials.

Mueller maneuver attenuates left atrial phasic volumes and myocardial strain in healthy younger adults

The left atrium (LA) is a key, but incompletely understood, modulator of left ventricular (LV) filling. Inspiratory negative intrathoracic pressure swings alter cardiac loading conditions, which may impact LA function. We studied acute effects of static inspiratory efforts on LA chamber function, LA myocardial strain, and LV diastolic filling. We included healthy adults (10 males/9 females, 24 ± 4 yr) and used Mueller maneuvers to reduce intrathoracic pressure to -30 cmH2O for 15 s. Over six repeated trials, we used echocardiography to acquire LA- and LV-focused two-dimensional (2-D) images, and mitral Doppler inflow and annular tissue velocity spectra. Images were analyzed for LA and LV chamber volumes, tissue relaxation velocities, transmitral filling velocities, and speckle tracking-derived LA longitudinal strain. Repeated measures were made at baseline, early Mueller, late Mueller, then early release, and late release. In the late Mueller compared with baseline, LV stroke volume decreased by -10 ± 4 mL (P < 0.05) and then returned to baseline upon release; this occurred with a -11 ± 9 mL (P < 0.05) end-diastolic volume reduction. Early diastolic LV filling was attenuated, reflected by decreased tissue relaxation velocity (-2 ± 2 cm/s, P < 0.05), E-wave filling velocity (-13 ± 14 cm/s, P < 0.05), and LA passive emptying volume (-5 ± 5 mL, P < 0.05), each returning to baseline with release. LA maximal volume decreased (-5 ± 5 mL, P < 0.05) during the Mueller maneuver, but increased relative to baseline following release (+4 ± 5 mL, P < 0.05), whereas LA peak positive longitudinal strain decreased (-6 ± 6%, P < 0.05) and then returned to baseline. Attenuated LA and in turn, LV filling may contribute to acute stroke volume reductions experienced during forceful inspiratory efforts.NEW & NOTEWORTHY In healthy younger adults, the Mueller maneuver transiently reduces left atrial filling and passive emptying during the reservoir and conduit phases, respectively. Corresponding reductions are seen in left atrial reservoir and conduit phase longitudinal myocardial strain and strain rate. However, left atrial pump phase active function and mechanics are largely preserved compared with baseline. Rapid changes in LA chamber volumes and myocardial strain with recurrent forceful inspiratory efforts and relaxation may reflect acute LA stress.

Lower-Limb Resistance Training Reduces Exertional Dyspnea and Intrinsic Neuromuscular Fatigability in Individuals with COPD

Skeletal muscle atrophy, dysfunction and fatigue are important complications of COPD. Greater reliance on glycolytic metabolism and increased type III/IV muscle afferent activity increase ventilatory drive, promote ventilatory constraint, amplify exertional dyspnea, and limit exercise tolerance. To investigate whether muscular adaptation with resistance training (RT) could improve exertional dyspnea, exercise tolerance, and intrinsic neuromuscular fatigability in individuals with COPD (n=14, FEV₁=62±21% predicted), we performed a proof-of-concept single-arm efficacy study utilizing four-weeks of individualized lower limb RT (3×/week). At baseline, dyspnea (Borg scale), ventilatory parameters, lung volumes (inspiratory capacity maneuvers) and exercise time were measured during a constant-load test (CLT) at 75% maximal workload to symptom limitation. On a separate day, fatigability was assessed using 3 minutes of intermittent stimulation of the quadriceps (initial output of ~25% maximal voluntary force). Following RT, the CLT and fatigue protocols were repeated. Compared to baseline, iso-time dyspnea was reduced (6.0±2.4 vs 4.5±2.4 Borg Units, p=0.02) and exercise time increased (437±405s vs 604±447, p<0.01) following RT. Isotime tidal volume increased (p=0.01) while end-expiratory lung volumes (p=0.02) and heart rate (p=0.03) decreased. Quadriceps force, relative to initial force, was higher at the end of the stimulation protocol post-training (53.2±9.1 vs 46.8±11.9%, p=0.04). This study provides evidence that four-weeks of RT attenuates exertional dyspnea and improves exercise tolerance in individuals with COPD, which in part, is likely due to delayed ventilatory constraint and reduced intrinsic fatigability. A pulmonary rehabilitation program beginning with individualized lower-limb RT may help mitigate dyspnea prior to performing aerobic-training in individuals with COPD.

The Mueller maneuver attenuates left atrial phasic volumes and myocardial strain in healthy younger adults

Background

Negative intrathoracic pressure swings alter cardiac loading conditions, which may impact left atrial hemodynamic function and augment atrial stress. If such changes occur and are repeated chronically, they may contribute to the marked atrial remodeling seen in states associated with forceful inspiratory efforts such as endurance training or obstructive sleep apnea.

Purpose

We studied the acute effects of static inspiratory efforts on left atrial chamber function, myocardial mechanics, and diastolic function.

Methods

We included healthy adults (10M/7F, 24±4 years) and used Mueller maneuvers to reduce intrathoracic pressure to a −30 cmH2O target for 15 seconds. Over 6 repeated trials, we used echocardiography to acquire left atrial and ventricular focused 2D images, and mitral Doppler inflow and annular tissue velocity spectra. Images were analyzed offline to determine left ventricular volumes, tissue relaxation velocities, trans-mitral filling velocities, and phasic left atrial volumes and myocardial strain using speckle-tracking imaging. Repeated measures were made at Baseline, within the last 5 seconds of the Mueller maneuver, and within the first 5 seconds after release, with 3–5 cardiac cycles averaged per measurement.

Results

Compared to Baseline, hemodynamic changes occurred during the late phase of the Mueller maneuver and immediately after release. Left ventricular stroke volume decreased by −10±4 mL (p&lt;0.05) then returned to baseline upon release; this was associated with a −11±9 mL (p&lt;0.05) reduction in end-diastolic volume. Left ventricular early diastolic filling attenuated, reflected by decreases in mitral annular relaxation velocity (−2±2 cm/s, p&lt;0.05), E-wave filling velocity (−13±14 cm/s, p&lt;0.05), and left atrial passive emptying volume (−5±5 mL, p&lt;0.05), each normalizing upon release. Left atrial maximal volume decreased (−5±5 mL, p&lt;0.05) during the Mueller maneuver, but increased relative to baseline (+4±5 mL, p=0.049) following release, while left atrial peak positive longitudinal strain decreased (−6±6%, p&lt;0.05) and normalized upon release.

Conclusions

Attenuated left atrial and in turn ventricular filling may contribute to acute stroke volume reduction during forceful inspiratory efforts. Rapid changes in left atrial chamber volumes and myocardial strain with the release of forceful inspiratory efforts may reflect acute left atrial stress.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Natural Sciences and Engineering Research Council Discovery Grant

Influence of respiratory loading on left-ventricular function in cervical spinal cord injury

KEY POINTS

Cervical spinal cord injury (C-SCI) alters both the cardiac and respiratory systems, however little is known as to how these systems interact following injury. Here, we manipulated inspiratory or expiratory intrathoracic pressure (ITP) to mechanistically test the role of the respiratory pump on circulatory function in highly-trained individuals with C-SCI and an able-bodied reference group. In individuals with C-SCI, greater ITP during expiratory loading caused dynamic hyperinflation that was associated with impaired left-ventricular filling. More negative ITP during inspiratory loading did not significantly alter left-ventricular volumes in either group. Interventions that prevent dynamic hyperinflation and/or enhance the ability to generate expiratory pressures may help preserve left-ventricular filling in individuals with C-SCI.

ABSTRACT

Cervical spinal cord injury (C-SCI) negatively impacts cardiac and respiratory function. As the heart and lungs are linked via the pulmonary circuit these systems are interdependent. Here, we utilized inspiratory and expiratory loading to assess whether augmenting the respiratory pump improves left-ventricular (LV) filling and output in individuals with motor-complete C-SCI. We hypothesized LV end-diastolic volume (LVEDV) would increase and decrease with inspiratory and expiratory loading, respectively. Participants (C-SCI: 7M/1F, 35±7 years; able-bodied: 7M/1F, 32±6 years) were assessed under five conditions during 45° head-up tilt; unloaded, inspiratory loading with -10 and -20cmH₂ O esophageal pressure (Pes) on inspiration, and expiratory loading with +10 and +20cmH₂ O Pes on expiration. An esophageal balloon catheter monitored Pes and LV structure and function were assessed by echocardiography. In C-SCI only, (1) +20cmH₂ O reduced LVEDV vs. unloaded (81±15 vs. 88±11 mL, p = 0.006); (2) heart rate was higher during +20cmH₂ O compared to unloaded (p = 0.001) and +10cmH₂ O (p = 0.002); (3) cardiac output was higher during +20cmH₂ O than unloaded (p = 0.002); and (4) end-expiratory lung volume was higher during +20cmH₂ O vs. unloaded (63±10 vs. 55±13% total lung capacity, p = 0.003) but was unaffected by inspiratory loading. In both groups, -10 and -20cmH₂ O had no significant effect on LVEDV. These findings suggest greater expiratory positive pressure acutely impairs LV filling in C-SCI, potentially via impaired venous return, mediastinal constraint and/or direct ventricular interaction subsequent to dynamic hyperinflation. Inspiratory loading did not significantly improve LV function in C-SCI and neither inspiratory nor expiratory loading affected cardiac function or lung volumes in able-bodied participants. Abstract figure legend Background: Cervical spinal cord injury (C-SCI) alters both the cardiac and respiratory systems. However, expiratory function is compromised to a greater extent than inspiratory function. Experimental set up: To examine how the cardiac and respiratory systems interact following C-SCI we manipulated inspiratory or expiratory intrathoracic pressure (ITP) to mechanistically test how changes in ITP and lung volumes influence cardiac function in highly-trained individuals with C-SCI and an able-bodied reference group. Participants were assessed under five conditions during 45° head-up tilt; unloaded, two inspiratory loading, and two expiratory loading conditions.

KEY FINDINGS

Following C-SCI, greater ITP during expiratory loading increased lung volumes and was associated with impaired left-ventricular filling. Interventions that prevent increases in lung volumes and/or enhance the ability to generate expiratory pressures may help preserve left-ventricular filling in individuals with C-SCI. A portion of this figure was created with biorender.com This article is protected by copyright. All rights reserved.

Validity of Estimated Cardiorespiratory Fitness in Patients With Primary Breast Cancer

Background

Estimated peak oxygen consumption (Vo₂peak) is widely used in oncology; however, estimated Vo₂peak equations were developed in noncancer settings.

Objectives

The aim of this study was to evaluate the validity of estimated Vo₂peak in women with primary breast cancer and to develop oncology-specific estimated Vo₂peak equations.

Methods

Vo₂peak was directly measured (TrueOne 2400, Parvo Medics) during 380 cardiopulmonary exercise tests in women previously treated for breast cancer (mean age: 59 ± 10 years; 3.1 ± 1.2 years post-therapy). The American College of Sports Medicine (ACSM), the Fitness Registry and the Importance of Exercise National Database (FRIEND), and heart failure (HF)-FRIEND equations were used to estimate Vo₂peak. New equations were developed using patient and peak (Onc_peak) or submaximal (Onc_sub) exercise test characteristics.

Results

The median differences between measured and estimated Vo₂peak were 7.0 mL O₂·kg⁻¹·min⁻¹, 3.9 mL O₂·kg⁻¹·min⁻¹, and −0.2 mL O₂·kg⁻¹·min⁻¹ for ACSM, FRIEND, and HF-FRIEND, respectively. The number of estimated Vo₂peak values within ±3.5 mL O₂·kg⁻¹·min⁻¹ of the measured values was 70 (18%), 164 (43%), and 306 (81%) for ACSM, FRIEND, and HF-FRIEND, respectively. The Onc_peak and Onc_Sub models included body mass index, age, a history of chemotherapy or radiation, the peak measured heart rate, and the treadmill grade and/or speed. The median differences between measured and estimated Vo₂peak were 0.02 mL O₂·kg⁻¹·min⁻¹ (Onc_peak) and −0.2 mL O₂·kg⁻¹·min⁻¹ (Onc_sub). Eighty-six percent (n = 325) and 76% (n = 283) estimated Vo₂peak values were within ±3.5 mL O₂·kg⁻¹·min⁻¹ of the measured Vo₂peak values for Onc_peak and Onc_sub, respectively.

Conclusions

HF-FRIEND or oncology-specific equations could be applied to estimate Vo₂peak in patients previously treated for breast cancer in settings where cardiopulmonary exercise tests are not available. (Trial Comparing the Effects of Linear Versus Nonlinear Aerobic Training in Women With Operable Breast Cancer [EXCITE]; NCT01186367

Effects and tolerability of exercise therapy modality on cardiorespiratory fitness in lung cancer: a randomized controlled trial

BACKGROUND

Poor cardiorespiratory fitness (CRF) is a cardinal feature of post-treatment primary lung cancer. The most effective exercise therapy regimen to improve CRF has not been determined.

METHODS

In this parallel-group factorial randomized controlled trial, lung cancer survivors with poor CRF (below age-sex sedentary values) were randomly allocated to receive 48 consecutive supervised sessions thrice weekly of (i) aerobic training (AT)-cycle ergometry at 55% to >95% of peak oxygen consumption (VO₂ peak); (ii) resistance training (RT)-lower and upper extremity exercises at 50-85% of maximal strength; (iii) combination training (CT)-AT plus RT; or (iv) stretching attention control (AC) for 16 weeks. The primary endpoint was change in CRF (VO₂ peak, mL O₂ ·kg^-1 ·min^-1 ). Secondary endpoints were body composition, muscle strength, patient-reported outcomes, tolerability (relative dose intensity of exercise), and safety. Analysis of covariance determined change in primary and secondary endpoints from baseline to post-intervention (Week 17) with adjustment for baseline values of the endpoint and other relevant clinical covariates.

RESULTS

Ninety patients (65 ± 9 years; 66% female) were randomized (AT, n = 24; RT, n = 23; CT, n = 20; and AC, n = 23) of the planned n = 160. No serious adverse events were observed. For the overall cohort, the lost-to-follow-up rate was 10%. Mean attendance was ≥75% in all groups. In intention-to-treat analysis, VO₂ peak increased 1.1 mL O₂ ·kg^-1 ·min^-1 [95% confidence interval (CI): 0.0, 2.2, P = 0.04] and 1.4 mL O₂ ·kg^-1 ·min^-1 (95% CI: 0.2, 2.5, P = 0.02) in AT and CT, respectively, compared with AC. There was no difference in VO₂ peak change between RT and AC (-0.1 mL O₂ ·kg^-1 ·min^-1 , 95% CI: -1.2, 1.0, P = 0.88). Favourable improvements in maximal strength and body composition were observed in RT and CT groups compared with AT and AC groups (Ps < 0.05). No between-group changes were observed for any patient-reported outcomes. Relative dose intensity of exercise was lower in RT and CT compared with AT (Ps < 0.05).

CONCLUSIONS

In the context of a smaller than planned sample size, AT and CT significantly improved VO₂ peak in lung cancer survivors; however, the tolerability-to-benefit ratio was superior for AT and hence may be the preferred modality to target impaired CRF in post-treatment lung cancer survivors.

How does cervical spinal cord injury impact the cardiopulmonary response to exercise?

We compared cardiopulmonary responses to arm-ergometry in individuals with cervical spinal cord injury (C-SCI) and able-bodied controls. We hypothesized that individuals with C-SCI would have higher respiratory frequency (f_b) but lower tidal volume (VT) at a given work rate and dynamically hyperinflate during exercise, whereas able-bodied individuals would not. Participants completed pulmonary function testing, an arm-ergometry test to exhaustion, and a sub-maximal exercise test consisting of four-minute stages at 20, 40, 60, and 80% peak work rate. Able-bodied individuals completed a further sub-maximal test with absolute work rate matched to C-SCI. During work rate matched sub-maximal exercise, C-SCI had smaller VT (main effect p < 0.001) compensated by an increased f_b (main effect p = 0.009). C-SCI had increased end-expiratory lung volume at 80% peak work rate vs. rest (p < 0.003), whereas able-bodied did not. In conclusion, during arm-ergometry, individuals with C-SCI exhibit altered ventilatory patterns characterized by reduced VT, higher f_b, and dynamic hyperinflation that may contribute to the observed reduced aerobic exercise capacity.

Right Ventricular Function and Region-Specific Adaptation in Athletes Engaged in High-Dynamic Sports: A Meta-Analysis

BACKGROUND

Structural remodeling of the right ventricle (RV) is widely documented in athletes. However, functional adaptation, including RV pressure generation and systolic free-wall longitudinal mechanics, remains equivocal. This meta-analysis compared RV pressure and function in athletes and controls.

METHODS

A systematic review of online databases was conducted up to June 4, 2020. Meta-analyses were performed on RV systolic pressures, at rest and during exercise, tricuspid annular plane systolic displacement, myocardial velocity (S'), and global and regional longitudinal strain. Bias was assessed using Egger regression for asymmetry. Data were analyzed using random-effects models with weighted mean difference and 95% CI.

RESULTS

Fifty-three studies were eligible for inclusion. RV systolic pressure was obtained from 21 studies at rest (n=1043:1651; controls:athletes) and 8 studies during exercise (n=240:495) and was significantly greater in athletes at rest (weighted mean difference, 2.9 mmHg [CI, 1.3-4.5 mmHg]; P=0.0005) and during exercise (11.0 [6.5-15.6 mm Hg]; P<0.0001) versus controls. Resting tricuspid annular plane systolic displacement (P<0.0001) and S' (P=0.001) were greater in athletes. In contrast, athletes had similar RV free-wall longitudinal strain (17 studies; n=450:605), compared with controls but showed greater longitudinal apical strain (16 studies; n=455:669; 0.9%, 0.1%-1.8%; P=0.03) and lower basal strain (-2.5% [-1.4 to -3.5%]; P<0.0001).

CONCLUSIONS

Functional RV adaptation, characterized by increased tricuspid annular displacement and velocity and a greater base-to-apex strain gradient, is a normal feature of the athlete's heart, together with a slightly elevated RV systolic pressure. These findings contribute to our understanding of RV in athletes and highlight the importance of considering RV function in combination with structure in the clinical interpretation of the athlete's heart.

Systolic reserve maintains left ventricular-vascular coupling when challenged by adverse breathing mechanics and hypertension in healthy adults

Augmented negative intrathoracic pressures (nITP) and dynamic hyperinflation (DH) are adverse breathing mechanics (ABM) associated with chronic obstructive pulmonary disease (COPD) that attenuate left ventricular (LV) preload and augment afterload. In COPD, hypertension (elevated systemic arterial load) commonly adds additional afterload to the LV. Combined ABM and hypertension may profoundly challenge ventricular-vascular coupling and attenuate stroke volume (SV), particularly if LV systolic reserve is limited. However, even in the healthy heart, the combined impact of ABM and systemic arterial loading on LV function and ventricular-vascular coupling has not been fully elucidated. Healthy volunteers (10 M/9 F, 24 ± 3 yr old) were challenged with mild (-10 cmH₂O nITP and 25% DH) and severe (-20 cmH₂O nITP and 100% DH) ABM, without and with postexercise ischemia (PEI) at each severity. LV SV, chamber geometry, end-systolic elastance (E_es), arterial elastance (E_a), and ventricular-vascular coupling (E_es:E_a) were quantified using echocardiography. Compared with resting control (58 ± 13 mL), SV decreased during mild ABM (51 ± 13 mL), mild ABM + PEI (51 ± 11 mL), severe ABM (50 ± 12 mL), and severe ABM + PEI (47 ± 11 mL) (P < 0.001); similar trends were observed for LV end-diastolic volume. The end-diastolic radius of septal curvature increased, indicating direct ventricular interaction, during severe ABM and severe ABM + PEI (P < 0.001). Compared with control (1.99 ± 0.41 mmHg/mL), E_a increased progressively with mild ABM (2.21 ± 0.47 mmHg/mL) and severe ABM (2.50 ± 0.56 mmHg/mL); at each severity, E_a was greater with superimposed PEI (P < 0.001). However, well-matched E_es increases occurred, and E_es:E_a was unchanged throughout. ABM pose a challenge to ventricular-vascular coupling that is accentuated by superimposed PEI; however, in healthy younger adults, the LV has substantial systolic reserve to maintain coupling.NEW & NOTEWORTHY In healthy younger adults, combined dynamic hyperinflation (DH) and negative intrathoracic pressures (nITP) attenuate left ventricular filling, but through different mechanisms at different severities. DH and nITP contribute to increased left ventricular afterload through mechanical effects in addition to presumed reflexive regulation, which can be further increased by elevated arterial loading. However, within this demographic, the left ventricle has substantial reserve to increase systolic performance, which matches contractility to afterload to preserve stroke volume.

Hemodynamic function of the right ventricular-pulmonary vascular-left atrial unit: normal responses to exercise in healthy adults

With each heartbeat, the right ventricle (RV) inputs blood into the pulmonary vascular (PV) compartment, which conducts blood through the lungs at low pressure and concurrently fills the left atrium (LA) for output to the systemic circulation. This overall hemodynamic function of the integrated RV-PV-LA unit is determined by complex interactions between the components that vary over the cardiac cycle but are often assessed in terms of mean pressure and flow. Exercise challenges these hemodynamic interactions as cardiac filling increases, stroke volume augments, and cycle length decreases, with PV pressures ultimately increasing in association with cardiac output. Recent cardiopulmonary exercise hemodynamic studies have enriched the available data from healthy adults, yielded insight into the underlying mechanisms that modify the PV pressure-flow relationship, and better delineated the normal limits of healthy responses to exercise. This review will examine hemodynamic function of the RV-PV-LA unit using the two-element Windkessel model for the pulmonary circulation. It will focus on acute PV and LA responses that accommodate increased RV output during exercise, including PV recruitment and distension and LA reservoir expansion, and the integrated mean pressure-flow response to exercise in healthy adults. Finally, it will consider how these responses may be impacted by age-related remodeling and modified by sex-related cardiopulmonary differences. Studying the determinants and recognizing the normal limits of PV pressure-flow relations during exercise will improve our understanding of cardiopulmonary mechanisms that facilitate or limit exercise.

Utilizing RE-AIM to examine the translational potential of Project MOVE, a novel intervention for increasing physical activity levels in breast cancer survivors

Translating effective research into community practice is critical for improving breast cancer (BC) survivor health. The purpose of this study is to utilize the RE-AIM framework to evaluate the translational potential of Project MOVE, an innovative intervention focused on increasing physical activity (PA) in BC survivors. A mixed-methods design, including a self-report questionnaire, accelerometry, focus groups, and interviews, was used to inform each RE-AIM dimension. Reach was evaluated by the representativeness of participants. Effectiveness was reflected by change in PA levels and perceptions of satisfaction and acceptability. Adoption was examined using participants' perceived barriers/facilitators to program uptake. Implementation was examined by participants' perceived barriers/facilitators to implementing the program. Maintenance was assessed by participant retention. Assessments occurred at baseline and 6-months. Mixed analysis of variance and content analysis were used to analyze the data. A total of 87 participants participated in Project MOVE and were demographically comparable to similar studies (Reach). Participants indicated high levels of program satisfaction (88%) and previously inactive survivors' significantly increased PA levels from baseline to 6-month follow-up (Effectiveness). Participants reported that a program focused on PA rather than disease helped them overcome barriers to PA (Adoption) and having leaders with BC and exercise expertise was essential to accommodate population specific barriers (Implementation). At 6-months, participant retention was 83% (Maintenance). Project MOVE is an acceptable, practical, and effective program for engaging BC survivors in PA and has the potential to be highly transferable to other populations and regions.

Mechanical cardiopulmonary interactions during exercise in health and disease

The heart and lungs are anatomically coupled through the pulmonary circulation and coexist within the sealed thoracic cavity, making the function of these systems highly interdependent. Understanding of the complex mechanical interactions between cardiac and pulmonary systems has evolved over the last century to appreciate that changes in respiratory mechanics significantly impact pulmonary hemodynamics and ventricular filling and ejection. Furthermore, given that the left and right heart share a common septum and are surrounded by the nondistensible pericardium, direct ventricular interaction is an important mediator of both diastolic and systolic performance. Although it is generally considered that cardiopulmonary interaction in healthy individuals at rest minimally affects hemodynamics, the significance during exercise is less clear. Adverse heart-lung interaction in respiratory disease is of growing interest as it may contribute to the pathogenesis of comorbid cardiovascular dysfunction and exercise intolerance in these patients. Similarly, heart failure represents a pathological uncoupling of the cardiovascular and pulmonary systems, whereby cardiac function may be impaired by the normal ventilatory response to exercise. Despite significant research contributions to this complex area, the mechanisms of cardiopulmonary interaction in the intact human and the clinical consequences of adverse interactions in common respiratory and cardiovascular diseases, particularly during exercise, remain incompletely understood. The purpose of this review is to present the key physiological principles of cardiopulmonary interaction as they pertain to resting and exercising hemodynamics in healthy humans and the clinical implications of adverse cardiopulmonary interaction during exercise in chronic obstructive pulmonary disease (COPD), pulmonary hypertension, and heart failure.

Cardiac structure and function in youth with type 2 diabetes in the iCARE cohort study: Cross-sectional associations with prenatal exposure to diabetes and metabolomic profiles

OBJECTIVE

This study aimed to determine the degree of left ventricular (LV) dysfunction and its determinants in adolescents with type 2 diabetes (T2D). We hypothesized that adolescents with T2D would display impaired LV diastolic function and that these cardiovascular complications would be exacerbated in youth exposed to maternal diabetes in utero.

METHODS

Left ventricular structure and function, carotid artery intima media thickness and strain, and serum metabolomic profiles were compared between adolescents with T2D (n = 121) and controls (n = 34). Sub-group analyses examined the role of exposure to maternal diabetes as a determinant of LV or carotid artery structure and function among adolescents with T2D.

RESULTS

Adolescents with T2D were 15.1 ± 2.5 years old, (65% female, 99% Indigenous), had lived with diabetes for 2.7 ± 2.2 years, had suboptimal glycemic control (HbA1c = 9.4 ± 2.6%) and 58% (n = 69) were exposed to diabetes in utero. Compared to controls, adolescents with T2D displayed lower LV diastolic filling (early diastole/atrial filling rate ratio [E/A] = 1.9 ± 0.6 vs 2.2 ± 0.6, P = 0.012), lower LV relaxation and carotid strain (0.12 ± 0.05 vs 0.17 ± 0.05, P = .03) and elevated levels of leucine, isoleucine and valine. Among adolescents with T2D, exposure to diabetes in utero was not associated with differences in LV diastolic filling, LV relaxation, carotid strain or branched chain amino acids.

CONCLUSIONS

Adolescents with T2D display LV diastolic dysfunction, carotid artery stiffness, and elevated levels of select branch chain amino acids; differences were not associated with exposure to maternal diabetes in utero.

Effects of Exercise Therapy Dosing Schedule on Impaired Cardiorespiratory Fitness in Patients With Primary Breast Cancer: A Randomized Controlled Trial

BACKGROUND

Current exercise guidelines for clinical populations recommend an exercise therapy (ET) prescription of fixed intensity (moderate), duration (40-50 minutes per session), and volume (120-160 min/wk). A critical overarching element of exercise programming that has received minimal attention is dose scheduling. We investigated the tolerability and efficacy of 2 exercise training dose regimens on cardiorespiratory fitness and patient-reported outcomes in patients with posttreatment primary breast cancer.

METHODS

Using a parallel-group randomized trial, we randomly allocated 174 postmenopausal patients (2.8 years after adjuvant therapy) with impaired peak oxygen consumption (VO₂peak) to 1 of 2 supervised exercise training interventions delivered with a standard linear (LET) (fixed dose intensity per session for 160 min/wk) or nonlinear (NLET) (variable dose intensity per session for ≈120 min/wk) schedule compared with a stretching attention control group for 16 consecutive weeks. Stretching was matched to exercise dosing arms on the basis of location, frequency, duration, and treatment length. The primary end point was change in VO₂peak (mL O₂·kg^-1·min^-1) from baseline to after intervention. Secondary end points were patient-reported outcomes, tolerability, and safety.

RESULTS

No serious adverse events were observed. Mean attendance was 64%, 75%, and 80% for attention control, LET, and NLET, respectively. In intention-to-treat analysis, VO₂peak increased 0.6±1.7 mL O₂·kg^-1·min^-1 (P=0.05) and 0.8±1.8 mL O₂·kg^-1·min^-1 (P=0.07) in LET and NLET, respectively, compared with attention control. Change in VO₂peak ranged from -2.7 to 4.1 mL O₂·kg^-1·min^-1 and from -3.6 to 5.1 mL O₂·kg^-1·min^-1 in LET and NLET, respectively. Approximately 40% of patients in both exercise dosing regimens were classified as VO₂peak responders (ie, Δ ≥1.32 mL O₂·kg^-1·min^-1). NLET improved all patient-reported outcomes compared with attention control.

CONCLUSIONS

Short-term exercise training, independently of dosing schedule, is associated with modest improvements in cardiorespiratory fitness in patients previously treated for early-stage breast cancer.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01186367.

A preliminary trial examining a 'real world' approach for increasing physical activity among breast cancer survivors: findings from project MOVE

Background

Physical activity (PA) is a safe and effective strategy to help mitigate health challenges associated with breast cancer (BC) survivorship. However, the majority of BC survivors are not meeting the minimum recommended PA (≥150 min of moderate to vigorous intensity). Project MOVE was developed as a model for increasing PA that combined a) Microgrants: funds ($2000) awarded to applicant groups to develop and implement a PA initiative and b) Financial incentives: a reward ($500) for increasing group PA. The purpose of this paper was to provide an exploratory analysis of effectiveness of Project MOVE on PA behavior, PA motivation, and quality of life (QoL) in female BC survivors. The differential outcomes between women meeting and not meeting PA guidelines were also investigated.

Methods

This pre-post test, preliminary trial included groups of adult (18+ years) self-identified female BC survivors, who were post-surgery and primary systemic chemo- and radiation therapy, and living in British Columbia, Canada. PA was assessed by accelerometry. PA motivation and QoL were assessed by self-report. Data were collected at baseline, 6-months, and 12-month time points. Repeated measures mixed ANOVAs were used to test changes in the main outcomes.

Results

A total of 10 groups were awarded microgrants between May 2015 and January 2016. Groups comprised of 8 to 12 women with a total of 87 participants. A statistically significant increase was found between time points on weekly moderate to vigorous PA (p = .012). This was mediated by a significant interaction between those meeting PA guidelines and those not meeting guidelines at baseline by time points (p = .004), with those not meeting guidelines at baseline showing the greatest increase in MVPA. A statistically significant difference across time points was found for intrinsic motivation (p = .02), physical functioning (p < .001), physical health limitations (p = .001), emotional health limitations (p = .023), social functioning (p = .001) and general health (p = .004).

Conclusion

These results provide promising support for a unique approach to increasing PA among BC survivors by empowering women and optimizing PA experiences through the use of microgrants and financial incentives.

Trial registration

ClinicalTrials.gov NCT03548636, Retrospectively registered June 7, 2018.

Novel Methods for Reporting of Exercise Dose and Adherence: An Exploratory Analysis

PURPOSE

The purpose of this study was to explore whether methods adapted from oncology pharmacological trials have utility in reporting adherence (tolerability) of exercise treatment in cancer.

METHODS

Using a retrospective analysis of a randomized trial, 25 prostate cancer patients received an aerobic training regimen of 72 supervised treadmill walking sessions delivered thrice weekly between 55% and 100% of exercise capacity for 24 consecutive weeks. Treatment adherence (tolerability) was assessed using conventional (lost to follow-up and attendance) and exploratory (e.g., permanent discontinuation, dose modification, and relative dose intensity) outcomes.

RESULTS

The mean total cumulative "planned" and "completed" dose was 200.7 ± 47.6 and 153.8 ± 68.8 MET·h, respectively, equating to a mean relative dose intensity of 77% ± 24%. Two patients (8%) were lost to follow-up, and mean attendance was 79%. A total of 6 (24%) of 25 patients permanently discontinued aerobic training before week 24. Aerobic training was interrupted (missing ≥3 consecutive sessions) or dose reduced in a total of 11 (44%) and 24 (96%) patients, respectively; a total 185 (10%) of 1800 training sessions required dose reduction owing to both health-related (all nonserious) and non-health-related adverse events. Eighteen (72%) patients required at least one session to be terminated early; a total of 59 (3%) sessions required early termination.

CONCLUSIONS

Novel methods for the conduct and reporting of exercise treatment adherence and tolerability may provide important information beyond conventional metrics in patients with cancer.

Cerebrovascular function in patients with chronic obstructive pulmonary disease: the impact of exercise training

This study examined cerebral blood flow (CBF) and its regulation before and after a short-term periodized aerobic exercise training intervention in patients with chronic obstructive pulmonary disease (COPD). Twenty-eight patients with COPD (forced expiratory volume in 1 s/forced vital capacity < 0.7 and <lower limit of normal) and 24 healthy control subjects participated in the study. Extracranial CBF (duplex ultrasound), middle cerebral artery velocity (MCAv; transcranial Doppler), cerebrovascular reactivity to hypocapnia and hypercapnia, and dynamic cerebral autoregulation (transfer function analysis) were quantified. These tests were repeated in both patients with COPD ( n = 23) and control subjects ( n = 20) after 8 wk of periodized upper and lower body aerobic exercise training (3 sessions/wk). At baseline, global extracranial CBF was comparable between the COPD and control groups (791 ± 290 vs. 658 ± 143 ml/min, P = 0.25); however, MCAv was lower in patients with COPD compared with control subjects (46 ± 9 vs. 53 ± 10 cm/s, P = 0.05). Although there were no group differences in dynamic cerebral autoregulation or the MCAv response to hypercapnia, patients with COPD had a lower MCAv response to hypocapnia compared with control subjects (−1.1 ± 1.5 vs. −1.6 ± 1.3 cm·s−1·mmHg−1, P = 0.02). After aerobic training, absolute peak O2 consumption increased in both groups, with a greater improvement in control subjects (1.7 ± 0.4 vs. 4.1 ± 0.2 ml·kg−1·min−1, respectively, P = 0.001). Despite these improvements in peak O2 consumption, there were no significant alterations in CBF or any measures of cerebrovascular function after exercise training in either group. In conclusion, patients with COPD have a blunted cerebrovascular response to hypocapnia, and 8 wk of aerobic exercise training did not alter cerebrovascular function despite significant improvements in cardiorespiratory fitness.

NEW & NOTEWORTHY No study to date has investigated whether exercise training can alter resting cerebral blood flow (CBF) regulation in patients with chronic obstructive pulmonary disease (COPD). This study is the first to assess CBF regulation at rest, before, and after aerobic exercise training in patients with COPD and healthy control subjects. This study demonstrated that while exercise training improved aerobic fitness, it had little effect on CBF regulation in patients with COPD or control subjects.

Effects of mild whole body hypothermia on self-paced exercise performance

This study examined self-paced, high-intensity exercise during mild hypothermia and whether hyperoxia might offset any potential impairment. Twelve trained males each completed 15-km time trials in three environmental conditions: Neutral (23°C, [Formula: see text] 0.21), Cold (0°C, [Formula: see text] 0.21), and Cold+Hyper (0°C, [Formula: see text] 0.40). Cold and Cold+Hyper trials occurred after a 0.5°C drop in rectal temperature. Rectal temperature was higher ( P ≤ 0.016) throughout Neutral compared with Cold and Cold+Hyper; Cold had a higher ( P ≤ 0.035) rectal temperature than Cold+Hyper from 2.5 to 7.5 km, and hyperoxia did not alter thermal sensation or comfort. Oxyhemoglobin saturation decreased from ~98% to ~94% with Neutral and Cold, but was maintained at ~99% in Cold+Hyper ( P < 0.01). Cerebral tissue oxygenation index (TOI) was higher in Neutral than in Cold throughout the time trial (TT) ( P ≤ 0.001), whereas Cold+Hyper were unchanged ( P ≥ 0.567) from Neutral by 2.5 km. Muscle TOI was maintained in Cold+Hyper compared with Neutral and was higher ( P ≤ 0.046) than Cold throughout the entire TT. Power output during Cold (246 ± 41 W) was lower than Neutral (260 ± 38 W) at all 2.5-km intervals ( P ≤ 0.012) except at 12.5 km. Power output during Cold+Hyper (256 ± 42 W) was unchanged ( P ≥ 0.161) from Neutral throughout the TT, and was higher than Cold from 7.5 km onward. Average cadence was higher in Neutral (93 ± 8 rpm) than in either Cold or Cold+Hyper (Cold: 89 ± 7 and Cold+Hyper: 90 ± 8 rpm, P = 0.031). In conclusion, mild hypothermia reduced self-paced exercise performance; hyperoxia during mild hypothermia restored performance to thermoneutral levels, likely due to maintenance of oxygen availability rather than any thermogenic benefit. NEW & NOTEWORTHY We examined self-paced, high-intensity exercise with 0.5°C rectal temperature decreases in a 0°C ambient environment, along with whether hyperoxia could offset any potential impairment. During a 15-km time trial, power output was lower with hypothermia than with thermoneutral. However, with hypothermia, hyperoxia of [Formula: see text] = 0.40 restored power output despite there being no thermophysiological improvement. Hypothermia impairs exercise performance, whereas hyperoxia likely restored performance due to maintenance of oxygen availability rather than any thermogenic benefit.

Influence of vagal control on sex-related differences in left ventricular mechanics and hemodynamics

Left ventricular (LV) twist mechanics differ between men and women during acute physiological stress, which may be partly mediated by sex differences in autonomic control. While men appear to have greater adrenergic control of LV twist, the potential contribution of vagal modulation to sex differences in LV twist remains unknown. Therefore, the present study examined the role of vagal control on sex differences in LV twist during graded lower body negative pressure (LBNP) and supine cycling. On two separate visits, LV mechanics were assessed using two-dimensional speckle-tracking echocardiography in 18 men (22 ± 2 yr) and 17 women (21 ± 4 yr) during -40- and -60-mmHg LBNP and 25% and 50% of peak supine cycling workload with and without glycopyrrolate (vagal blockade). LV twist was not different at baseline but was greater in women during -60 mmHg in both control (women: 16.0 ± 3.4° and men: 12.9 ± 2.3°, P = 0.004) and glycopyrrolate trials (women: 17.7 ± 5.9° and men: 13.9 ± 3.3°, P < 0.001) due to greater apical rotation during control (women: 11.9 ± 3.6° and men: 7.8 ± 1.5°, P < 0.001) and glycopyrrolate (women: 11.6 ± 4.9° and men: 7.1 ± 3.6°, P = 0.009). These sex differences in LV twist consistently coincided with a greater LV sphericity index (i.e., ellipsoid geometry) in women compared with men. In contrast, LV twist did not differ between the sexes during exercise with or without glycopyrrolate. In conclusion, women have augmented LV twist compared with men during large reductions to preload, even during vagal blockade. As such, differences in vagal control do not appear to contribute to sex differences in the LV twist responses to physiological stress, but they may be related to differences in ventricular geometry. NEW & NOTEWORTHY This is the first study to specifically examine the role of vagal autonomic control on sex-related differences in left ventricular (LV) mechanics. Contrary to our hypothesis, vagal control does not appear to primarily determine sex differences in LV mechanical or hemodynamic responses to acute physiological stress. Instead, differences in LV geometry may be a more important contributor to sex differences in LV mechanics.

Hemodynamic effects of incremental lung hyperinflation

Dynamic hyperinflation (DH) is common in chronic obstructive pulmonary disease and is associated with dyspnea and exercise intolerance. DH also has adverse cardiac effects, although the magnitude of DH and the mechanisms responsible for the hemodynamic impairment remain unclear. We hypothesized that incrementally increasing DH would systematically reduce left ventricular (LV) end-diastolic volume (LVEDV) and LV stroke volume (LVSV) because of direct ventricular interaction. Twenty-three healthy subjects (22 ± 2 yr) were exposed to varying degrees of expiratory loading to induce DH such that inspiratory capacity was decreased by 25%, 50%, 75%, and 100% (100% DH =  inspiratory capacity of resting tidal volume plus inspiratory reserve volume ≈ 0.5 l). LV volumes, LV geometry, inferior vena cava collapsibility, and LV end-systolic wall stress were assessed by triplane echocardiography. 25% DH reduced LVEDV (-6 ± 5%) and LVSV (-9 ± 8%). 50% DH elicited a similar response in LVEDV (-6 ± 7%) and LVSV (-11 ± 10%) and was associated with significant septal flattening [31 ± 32% increase in the radius of septal curvature at end diastole (RSC-ED)]. 75% DH caused a larger reduction in LVEDV and LVSV (-9 ± 7% and -16 ± 10%, respectively) and RSC-ED (49 ± 70%). 100% DH caused the largest reduction in LVEDV and LVSV (-13 ± 9% and -18 ± 9%) and an increase in RSC-ED (56 ± 63%). Inferior vena cava collapsibility and LV afterload (LV end-systolic wall stress) were unchanged at all levels of DH. Modest DH (-0.6 ± 0.2 l inspiratory reserve volume) reduced LVSV because of reduced LVEDV, likely because of increased pulmonary vascular resistance. At higher levels of DH, direct ventricular interaction may be the primary cause of attenuated LVSV, as indicated by septal flattening because of a greater relative increase in right ventricular pressure and/or mediastinal constraint. NEW & NOTEWORTHY By systematically reducing inspiratory capacity during spontaneous breathing, we demonstrate that dynamic hyperinflation (DH) progressively reduces left ventricular (LV) end diastolic volume and LV stroke volume. Evidence of significant septal flattening suggests that direct ventricular interaction may be primarily responsible for the reduced LV stroke volume during DH. Hemodynamic impairment appears to occur at relatively lower levels of DH and may have important clinical implications for patients with chronic obstructive pulmonary disease.

Bench-to-Bedside Approaches for Personalized Exercise Therapy in Cancer

The past 2 decades have witnessed a growing body of work investigating the feasibility and efficacy of exercise therapy on a broad array of outcomes in many different oncology scenarios. Despite this heterogeneity, the exercise therapy prescription approach and the dose tested has been largely similar. Thus, current exercise therapy prescriptions in the oncology setting adopt a one-size-fits-all approach. In this article, we provide an overview of personalization of exercise therapy in cancer using the principles of training as an overarching framework. Specifically, we first review the fundamentals of exercise prescription in chronic disease before focusing attention on application of these principles to optimize the safety and efficacy of exercise therapy on (1) cancer treatment-induced cardiovascular toxicity and (2) tumor progression and metastasis.

Aerobic exercise training does not alter vascular structure and function in chronic obstructive pulmonary disease

NEW FINDINGS

What is the central question of this study? Chronic obstructive pulmonary disease (COPD) is associated with endothelial dysfunction, arterial stiffness and systemic inflammation, which are linked to increased cardiovascular disease risk. We asked whether periodized aerobic exercise training could improve vascular structure and function in patients with COPD. What is the main finding and its importance? Eight weeks of periodized aerobic training did not improve endothelial function, arterial stiffness or systemic inflammation in COPD, despite improvements in aerobic capacity, blood pressure and dyspnoea. Short-term training programmes may not be long enough to improve vascular-related cardiovascular risk in COPD. Chronic obstructive pulmonary disease (COPD) has been associated with endothelial dysfunction and arterial stiffening, which are predictive of future cardiovascular events. Although aerobic exercise improves vascular function in healthy individuals and those with chronic disease, it is unknown whether aerobic exercise can positively modify the vasculature in COPD. We examined the effects of 8 weeks of periodized aerobic training on vascular structure and function and inflammation in 24 patients with COPD (age, 69 ± 7 years; forced expiratory volume in 1 second as a percentage of predicted (FEV₁ %pred), 68 ± 19%) and 20 matched control subjects (age, 64 ± 5 years; FEV₁ %pred, 113 ± 16%) for comparison. Endothelial function was measured using brachial artery flow-mediated dilatation, whereas central and peripheral pulse wave velocity, carotid artery intima-media thickness, carotid compliance, distensibility and β-stiffness index were measured using applanation tonometry and ultrasound. Peak aerobic power (V̇O2 peak ) was measured using an incremental cycling test. Upper and lower body cycling training was performed three times per week for 8 weeks, and designed to optimize vascular adaptation by increasing and sustaining vascular shear stress. Flow-mediated dilatation was not increased in COPD patients (+0.15 ± 2.27%, P = 0.82) or control subjects (+0.34 ± 3.20%, P = 0.64) and was not different between groups (P = 0.68). No significant improvements in central pulse wave velocity (COPD, +0.30 ± 1.79 m s^-1 versus control subjects, -0.34 ± 1.47 m s^-1 ) or other markers of vascular structure or function were found within or between groups. The V̇O2 peak increased significantly in COPD and control subjects, and was greater in control subjects (1.6 ± 1.4 versus 4.1 ± 3.7 ml kg min^-1 , P = 0.003), while blood pressure and dyspnoea were reduced in COPD patients (P < 0.05). These findings demonstrate that 8 weeks of aerobic training improved cardiorespiratory fitness and blood pressure in COPD but had little effect on other established markers of cardiovascular disease risk.

Acute volume loading exacerbates direct ventricular interaction in a model of COPD

Volume loading increases left ventricular (LV) stroke volume (LVSV) through series interaction, but may paradoxically reduce LVSV in the presence of large increases in right ventricular (RV) afterload because of direct ventricular interaction (DVI). RV afterload is often increased in chronic obstructive pulmonary disease (COPD) as a result of pathological changes to respiratory mechanics, namely increased negative intrathoracic pressure (nITP), dynamic lung hyperinflation (DH), and increased pulmonary vascular resistance (PVR). These hallmarks of COPD negatively impact LV hemodynamics in normovolemia. However, it is unknown how these heart-lung interactions are impacted by acute volume loading. Twenty healthy subjects (23 ± 2 yr) completed the study protocol, involving acute volume loading via 20° head-down tilt (HDT) in isolation and with 1) inspiratory resistance of -20 cmH₂O (HDT+nITP) and 2) nITP, expiratory resistance to induce DH and hypoxic-mediated increases in PVR (HDT+COPD model). LV volumes and geometry were assessed using triplane echocardiography. HDT significantly increased LVSV by 10 ± 10% through an 8 ± 6% increase in LV end-diastolic volume (LVEDV). HDT+nITP paradoxically decreased LVSV by 11 ± 12% and LVEDV by 6 ± 9% from supine baseline, or -14 ± 10% LVSV and -15 ± 13% LVEDV from HDT (P < 0.001). HDT+COPD model decreased LVSV (21 ± 10% and 28 ± 11%) and LVEDV (16 ± 10% and 22 ± 10%) from both supine and HDT, respectively (P < 0.001). Under all conditions, significant septal flattening (increased radius of septal curvature) occurred, indicating DVI. Thus, when RV afterload is increased and/or an external constraint to ventricular filling exists, acute volume loading appears to paradoxically reduce LVSV. These findings have important implications for understanding how volume status impacts cardiopulmonary interactions in COPD.NEW & NOTEWORTHY Volume loading may exacerbate adverse cardiopulmonary interaction in COPD; however, the mechanisms remain unclear. We found that when negative intrathoracic pressure is increased, acute volume loading paradoxically reduces stroke volume. This reduction in stroke volume is considerably greater in a model of COPD, owing to the effects of lung hyperinflation.

Bench-to-Bedside Approaches for Personalized Exercise Therapy in Cancer

The past 2 decades have witnessed a growing body of work investigating the feasibility and efficacy of exercise therapy on a broad array of outcomes in many different oncology scenarios. Despite this heterogeneity, the exercise therapy prescription approach and the dose tested has been largely similar. Thus, current exercise therapy prescriptions in the oncology setting adopt a one-size-fits-all approach. In this article, we provide an overview of personalization of exercise therapy in cancer using the principles of training as an overarching framework. Specifically, we first review the fundamentals of exercise prescription in chronic disease before focusing attention on application of these principles to optimize the safety and efficacy of exercise therapy on (1) cancer treatment-induced cardiovascular toxicity and (2) tumor progression and metastasis.

Increased left ventricular extracellular volume and enhanced twist function in type 1 diabetic individuals

Individuals with type 1 diabetes (T1D) characteristically have high glycemic levels that over time can result in reactive fibrosis and abnormalities in myocardial function. T₁ mapping with magnetic resonance imaging (MRI) can estimate the extent of reactive fibrosis by measurement of the extracellular volume fraction (ECV). The extent of alterations in the ECV and associated changes in left ventricular (LV) function and morphology in individuals with T1D is unknown. Fourteen individuals with long-term T1D and 14 sex-, age-, and body mass index-matched controls without diabetes underwent MRI measurement of myocardial T₁ and ECV values as well as LV function and morphology. Ventricular mass, volumes, and global function (LVEF and circumferential/longitudinal/radial strain) were similar in those with T1D and controls. However, those with T1D had larger myocardial ECV (22.1 ± 1.8 vs. 20.1 ± 2.1, P = 0.008) and increased native (noncontrast) myocardial T₁ values (1,211 ± 44 vs. 1,172 ± 43 ms, P < 0.001) as compared with controls. Both the ECV and native T₁ values significantly correlated with several components of torsion and circumferential-longitudinal shear strain (E_cl, the shear strain component associated with twist). Individuals with T1D had increased systolic torsion (P = 0.035), systolic torsion rate (P = 0.032), peak E_cl (P = 0.001), and rates of change of systolic (P = 0.007) and diastolic (P = 0.007) E_cl Individuals with T1D, with normal structure, LVEF, and strain, have increased extracellular volume and increased native T₁ values with associated augmented torsion and E_cl These measures may be useful in detecting the early stages of diabetic cardiomyopathy and warrant larger prospective studies.NEW & NOTEWORTHY Individuals with type 1 diabetes, with normal left ventricular structure and function (ejection fraction and strain), have signs of interstitial fibrosis, measured with MRI as increased extracellular volume fraction and increased native myocardial T₁, which significantly correlated with a number of measures of augmented left ventricular twist function. These measures may be useful in detecting the early stages of diabetic cardiomyopathy.

The influence of adrenergic stimulation on sex differences in left ventricular twist mechanics

KEY POINTS

Sex differences in left ventricular (LV) mechanics occur during acute physiological challenges; however, it is unknown whether sex differences in LV mechanics are fundamentally regulated by differences in adrenergic control. Using two-dimensional echocardiography and speckle tracking analysis, this study compared LV mechanics in males and females matched for LV length during post-exercise ischaemia (PEI) and β₁ -adrenergic receptor blockade. Our data demonstrate that while basal rotation was increased in males, LV twist was not significantly different between the sexes during PEI. In contrast, during β₁ -adrenergic receptor blockade, LV apical rotation, twist and untwisting velocity were reduced in males compared to females. Significant relationships were observed between LV twist and LV internal diameter and sphericity index in females, but not males. These findings suggest that LV twist mechanics may be more sensitive to alterations in adrenergic stimulation in males, but more highly influenced by ventricular structure and geometry in females.

ABSTRACT

Sex differences in left ventricular (LV) mechanics exist at rest and during acute physiological stress. Differences in cardiac autonomic and adrenergic control may contribute to sex differences in LV mechanics and LV haemodynamics. Accordingly, this study aimed to investigate sex differences in LV mechanics with altered adrenergic stimulation achieved through post-handgrip-exercise ischaemia (PEI) and β₁ -adrenergic receptor (AR) blockade. Twenty males (23 ± 5 years) and 20 females (22 ± 3 years) were specifically matched for LV length (males: 8.5 ± 0.5 cm, females: 8.2 ± 0.6 cm, P = 0.163), and two-dimensional speckle-tracking echocardiography was used to assess LV structure and function at baseline, during PEI and following administration of 5 mg bisoprolol (β₁ -AR antagonist). During PEI, LV end-diastolic volume and stroke volume were increased in both groups (P < 0.001), as was end-systolic wall stress (P < 0.001). LV twist and apical rotation were not altered from baseline or different between the sexes; however, basal rotation increased in males (P = 0.035). During β₁ -AR blockade, LV volumes were unchanged but blood pressure and heart rate were reduced in both groups (P < 0.001). LV apical rotation (P = 0.036) and twist (P = 0.029) were reduced in males with β₁ -AR blockade but not females, resulting in lower apical rotation (males: 6.8 ± 2.1 deg, females: 8.8 ± 2.3 deg, P = 0.007) and twist (males: 8.6 ± 1.9 deg, females: 10.7 ± 2.8 deg, P = 0.008), and slower untwisting velocity (males: 68.2 ± 22.1 deg s^-1 , females: 82.0 ± 18.7 deg s^-1 , P = 0.046) compared to females. LV twist mechanics are reduced in males compared to females during reductions to adrenergic stimulation, providing preliminary evidence that LV twist mechanics may be more sensitive to adrenergic control in males than in females.

Heart-lung interaction in a model of COPD: importance of lung volume and direct ventricular interaction

Chronic obstructive pulmonary disease (COPD) is associated with dynamic lung hyperinflation (DH), increased pulmonary vascular resistance (PVR), and large increases in negative intrathoracic pressure (nITP). The individual and interactive effect of these stressors on left ventricular (LV) filling, emptying, and geometry and the role of direct ventricular interaction (DVI) in mediating these interactions have not been fully elucidated. Twenty healthy subjects were exposed to the following stressors alone and in combination: 1) inspiratory resistive loading of -20 cmH₂O (nITP), 2) expiratory resistive loading to cause dynamic hyperinflation (DH), and 3) normobaric-hypoxia to increase PVR (hPVR). LV volumes and geometry were assessed using triplane echocardiography. LV stroke volume (LVSV) was reduced during nITP by 7 ± 7% (mean ± SD; P < 0.001) through a 4 ± 5% reduction in LV end-diastolic volume (LVEDV) (P = 0.002), while DH reduced LVSV by 12 ± 13% (P = 0.001) due to a 9 ± 10% reduction in LVEDV (P < 0.001). The combination of nITP and DH (nITP+DH) caused larger reductions in LVSV (16 ± 16%, P < 0.001) and LVEDV (12 ± 10%, P < 0.001) than nITP alone (P < 0.05). The addition of hPVR to nITP+DH did not further reduce LV volumes. Significant septal flattening (indicating DVI) occurred in all conditions, with a significantly greater leftward septal shift occurring with nITP+DH than either condition alone (P < 0.05). In summary, the interaction of nITP and DH reduces LV filling through DVI. However, DH may be more detrimental to LV hemodynamics than nITP, likely due to mediastinal constraint of the heart amplifying DVI.

Innovative approach for increasing physical activity among breast cancer survivors: protocol for Project MOVE, a quasi-experimental study

INTRODUCTION

Physical activity is a cost-effective and non-pharmaceutical strategy that can help mitigate the physical and psychological health challenges associated with breast cancer survivorship. However, up to 70% of women breast cancer survivors are not meeting minimum recommended physical activity guidelines. Project MOVE is an innovative approach to increase physical activity among breast cancer survivors through the use of Action Grants, a combination of microgrants (small amounts of money awarded to groups of individuals to support a physical activity initiative) and financial incentives. The purpose of this paper is to describe the rationale and protocol of Project MOVE.

METHOD AND ANALYSIS

A quasi-experimental pre-post design will be used. Twelve groups of 8-12 adult women who are breast cancer survivors (N=132) were recruited for the study via face-to-face meetings with breast cancer-related stakeholders, local print and radio media, social media, and pamphlets and posters at community organisations and medical clinics. Each group submitted a microgrant application outlining their proposed physical activity initiative. Successful applicants were determined by a grant review panel and informed of a financial incentive on meeting their physical activity goals. An evaluation of feasibility will be guided by the reach, effectiveness, adoption, implementation, maintenance (RE-AIM) framework and assessed through focus groups, interviews and project-related reports. Physical activity will be assessed through accelerometry and by self-report. Quality of life, motivation to exercise and social connection will also be assessed through self-report. Assessments will occur at baseline, 6 months and 1 year.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the University of British Columbia's Behavioural Research Ethics Board (#H14-02502) and has been funded by the Canadian Cancer Society Research Institute (project number #702913). Study findings will be disseminated widely through peer-reviewed publications, academic conferences, local community-based presentations, as well as partner organisations, including the Canadian Cancer Society.

Females have greater left ventricular twist mechanics than males during acute reductions to preload

Compared to males, females have smaller left ventricular (LV) dimensions and volumes, higher ejection fractions (EF), and higher LV longitudinal and circumferential strain. LV twist mechanics determine ventricular function and are preload-dependent. Therefore, the sex differences in LV structure and myocardial function may result in different mechanics when preload is altered. This study investigated sex differences in LV mechanics during acute challenges to preload. With the use of conventional and speckle-tracking echocardiography, LV structure and function were assessed in 20 males (24 ± 6.2 yr) and 20 females (23 ± 3.1 yr) at baseline and during progressive levels of lower body negative pressure (LBNP). Fourteen participants (8 males, 6 females) were also assessed following a rapid infusion of saline. LV end-diastolic volume, end-systolic volume, stroke volume (SV), and EF were reduced in both groups during LBNP (P < 0.001). While males had greater absolute volumes (P < 0.001), there were no sex differences in allometrically scaled volumes at any stage. Sex differences were not detected at baseline in basal rotation, apical rotation, or twist. Apical rotation and twist increased in both groups (P < 0.001) with LBNP. At -60 mmHg, females had greater apical rotation (P = 0.009), twist (P = 0.008), and torsion (P = 0.002) and faster untwisting velocity (P = 0.02) than males. There were no differences in mechanics following saline infusion. Females have larger LV twist and a faster untwisting velocity than males during large reductions to preload, supporting that females have a greater reliance on LV twist mechanics to maintain SV during severe reductions to preload.

Reliability of maximal cardiopulmonary exercise testing in men with prostate cancer

PURPOSE

To accurately assess exercise interventions and to evaluate acute and chronic cardiovascular effects in patients with early-stage cancer, consistently reliable functional outcome measures must be obtained. An incremental cardiopulmonary exercise test (CPET) with gas exchange measurement to assess peak oxygen consumption (V˙O2peak) provides the gold standard outcome of cardiorespiratory fitness.

METHODS

In the context of a randomized controlled trial, 40 patients with prostate cancer (mean age, 59 ± 7 yr) after radical prostatectomy performed two maximal CPET within 5.6 ± 5.5 d of each other. Incremental treadmill tests were performed in the morning under identical laboratory conditions. Reliability and within-subject variability from test 1 to test 2 for peak and submaximal variables were assessed by correlation coefficients, intraclass correlations (ICC), Bland-Altman plots, coefficient of variation, and paired t-tests.

RESULTS

There was high reliability between CPET for V˙O2peak (r = 0.92; P < 0.001; ICC, 0.900), ventilatory threshold (r = 0.88; P < 0.001; ICC, 0.927), minute ventilation-carbon dioxide production relation (V˙E/V˙CO2) (r = 0.86; P < 0.001; ICC, 0.850), and peak heart rate (r = 0.95; P < 0.001; ICC, 0.944). However, high within-subject variability was observed for all CPET parameters (mean coefficient of variation, 4.7%). Compared with those for test 1, significantly higher mean values were observed for V˙O2peak (27.0 ± 5.6 vs 28.1 ± 5.3 mL·kg·min, P < 0.05), ventilatory threshold (1.91 ± 0.5 vs 1.97 ± 0.4 L·min, P < 0.05), and V˙E/V˙CO2 (31.3 ± 5.8 vs 32.8 ± 3.4, P < 0.05) in test 2.

CONCLUSIONS

These findings indicate the presence of significant, and potentially clinically important, variability in CPET procedures in men with clinically localized prostate cancer and have important implications for the application and use of CPET to evaluate the efficacy of interventions to improve aerobic capacity in the oncology setting.

Ventricular-Arterial Coupling in Breast Cancer Patients After Treatment With Anthracycline-Containing Adjuvant Chemotherapy

BACKGROUND

Anthracycline-containing chemotherapy (Anth-C) is associated with long-term cardiovascular mortality. Although cardiovascular risk assessment has traditionally focused on the heart, evidence has demonstrated that vascular dysfunction also occurs during and up to 1 year following Anth-C. Whether vascular dysfunction persists long-term or negatively influences cardiac function remains unknown. Hence, the present study evaluated ventricular-arterial coupling, in concert with measures of vascular structure and function, in the years following Anth-C.

METHODS

Arterial elastance (Ea), end-systolic elastance (Ees), and ventricular-arterial coupling (Ea/Ees) were measured during rest and exercise using echocardiography. Resting vascular function (flow-mediated dilation) and structure (carotid intima-media thickness, arterial stiffness) were also measured.

RESULTS

Thirty breast cancer survivors (6.5 ± 3.6 years after Anth-C) with normal left ventricular ejection fraction (LVEF) (60% ± 6%) and 30 matched controls were studied. At rest, no differences were found in Ea, Ees, Ea/Ees, or LVEF between groups. The normal exercise-induced increase in Ees was attenuated in survivors at 50% and 75% of maximal workload (p < .01). Ea/Ees was also higher at all workloads in the survivors compared with the controls (p < .01). No differences in vascular structure and function were observed between the two groups (p > .05).

CONCLUSION

In the years after Anth-C, ventricular-arterial coupling was significantly attenuated during exercise, primarily owing to decreased LV contractility (indicated by a reduced Ees). This subclinical dysfunction appears to be isolated to the heart, as no differences in Ea were observed. The previously reported adverse effects of Anth-C on the vasculature appear to not persist in the years after treatment, as vascular structure and function were comparable to controls.

IMPLICATIONS FOR PRACTICE

Anthracycline-induced cardiotoxicity results in significantly impaired ventricular-arterial coupling in the years following chemotherapy, owing specifically to decreased left ventricular contractility. This subclinical dysfunction was identified only under exercise stress. A comprehensive evaluation of vascular structure and function yielded no differences between those treated with anthracyclines and controls. Combined with a stress stimulus, ventricular-arterial coupling might hold significant value beyond characterization of integrative cardiovascular function, in particular as a part of a risk-stratification strategy after anthracycline-containing chemotherapy. Although vascular function and structure were not different in this cohort, this does not undermine the importance of identifying vascular (dys)function in this population, because increases in net arterial load during exercise might amplify the effect of reductions in contractility on cardiovascular function after anthracycline-containing chemotherapy.

Airway inflammation, cough and athlete quality of life in elite female cross-country skiers: A longitudinal study

The aim of this study was to investigate the effect of a season of cross-country training and racing on airway inflammation, cough symptoms, and athlete quality of life in female skiers. Eighteen elite female skiers performed sputum induction and completed the Leicester Cough Questionnaire (LCQ) and the Recovery-Stress Questionnaire (REST-Q) at three time points (T1 - May/Jun, T2 - Oct/Nov, T3 - Jan-Mar) during the year. No changes were observed between T1 and T2. However, an increase in sputum eosinophils and lymphocytes (P < 0.05) and a significant change in all three domains of the LCQ were observed between T1 and T3 (P < 0.05). A significant association was found between the total yearly hours of training and the change in the total cell count (r(2)  = 0.74; P = 0.006), and a number of other sputum cell counts between T1 and T3. No changes were observed for any domain of the REST-Q. The results of this study demonstrate that airway inflammation and cough symptoms are significantly increased in elite female cross-country skiers across a year of training and racing. The increase in airway inflammation is related to the total amount of training and is worse during the winter months when athletes are training and racing in cold, dry air.

A framework for prescription in exercise-oncology research

The field of exercise-oncology has increased dramatically over the past two decades, with close to 100 published studies investigating the efficacy of structured exercise training interventions in patients with cancer. Of interest, despite considerable differences in study population and primary study end point, the vast majority of studies have tested the efficacy of an exercise prescription that adhered to traditional guidelines consisting of either supervised or home-based endurance (aerobic) training or endurance training combined with resistance training, prescribed at a moderate intensity (50-75% of a predetermined physiological parameter, typically age-predicted heart rate maximum or reserve), for two to three sessions per week, for 10 to 60 min per exercise session, for 12 to 15 weeks. The use of generic exercise prescriptions may, however, be masking the full therapeutic potential of exercise treatment in the oncology setting. Against this background, this opinion paper provides an overview of the fundamental tenets of human exercise physiology known as the principles of training, with specific application of these principles in the design and conduct of clinical trials in exercise-oncology research. We contend that the application of these guidelines will ensure continued progress in the field while optimizing the safety and efficacy of exercise treatment following a cancer diagnosis.

Obesity negatively impacts lung function in children and adolescents

OBJECTIVES

To investigate the relationship between weight status (body mass index [BMI] percentile and BMI z-score) and lung volumes in healthy children and adolescents.

HYPOTHESES

We hypothesized that: (a) there would be a significant inverse relationship between age- and sex-specific BMI distribution and functional residual capacity (FRC), and expiratory reserve volume (ERV), respectively; and (b) obese children would have significantly reduced FRC and ERV compared to their non-obese peers.

METHODS

The medical records of all individuals who successfully performed pulmonary function testing between 2000 and 2007 at two university children's hospitals were reviewed. Participants were excluded if they had cardiopulmonary, neuromuscular, or chest wall disease.

RESULTS

Of 1,469 record reviewed, 327 subjects met study criteria. Percent predicted ERV was lowest in the obese group (P < 0.001) while residual volume (RV) was lowest in the overweight and obese groups (P < 0.001). Underweight participants had a lower percent predicted forced vital capacity (FVC) (P = 0.027) and vital capacity (VC; P = 0.039). Obese participants had the lowest FEV1 /FVC (P < 0.001). A positive linear relationship existed between BMI z-score and percent predicted FVC, VC, and diffusing capacity of carbon monoxide (DLCO ). A negative linear relationship was found between BMI z-score and percent predicted FRC, ERV, RV, and absolute FEV1 /FVC.

CONCLUSIONS

Our results show that increasing weight status in children and adolescents is associated with a general reduction in lung volume measurements, which may reflect impaired lung function, increased respiratory symptoms, and decreased functional status.

Comparison of performance status with peak oxygen consumption in operable patients with non-small-cell lung cancer

BACKGROUND AND OBJECTIVE

In this era of increasing options for treatment of 'surgical' lung cancer patients, preoperative physiologic assessment of accurate patient selection is becoming more important. The variability in an objective measure of cardiorespiratory fitness (peak oxygen consumption (VO2peak )) across performance in operable non-small-cell lung cancer (NSCLC) patients enrolled in the Cancer and Leukemia Group B trial was compared.

METHODS

Using a cross-sectional design, 392 NSCLC patients underwent an incremental cardiopulmonary cycling exercise test to symptom limitation with expired gas analysis to determine VO2peak . Performance status (PS) was assessed using the Eastern Cooperative Oncology Group (ECOG) tool.

RESULTS

There was a significant decrease in VO2peak across increasing ECOG categories (P < 0.0001). However, there was a large range in VO2peak for any given ECOG category with overlap between categories (ECOG 0: 5.0-31.5 mL/kg/min; ECOG 1: 4.3-24.8 mL/kg/min; ECOG 2: 8.9-21.9 mL/kg/min; ECOG 3; 3.3-11.7 mL/kg/min).

CONCLUSIONS

PS scoring systems do not provide a sensitive measure of functional status. Objective measures such as VO2peak may be a useful in the clinical management of oncology patients.

Pre-exercise participation cardiovascular screening in a heterogeneous cohort of adult cancer patients

BACKGROUND

The purpose of this study was to investigate the extent of pre-exercise participation ("preparticipation") health screening in a heterogeneous cohort of adult cancer patients.

METHODS

Patients (n = 413) with histologically confirmed solid or hematologic malignancy were categorized into preparticipation health screening risk stratification based on American College Sports Medicine (ACSM) recommendations. Risk of an exercise-related event was evaluated during a symptom-limited cardiopulmonary exercise test (CPET) with 12-lead electrocardiography (ECG).

RESULTS

Participant risk was categorized as low risk (n = 59, 14%), moderate risk (n = 217, 53%), and high risk (n = 137, 33%). Mean peak oxygen consumption was 21.7 ± 6.7 mL/kg(-1) per minute(-1) or 19.5 ± 21.7% below age- and sex-predicted sedentary values. No major serious adverse events or fatal events were observed during CPET procedures. A total of 31 positive ECG tests were observed, for an event rate of 8%. ACSM risk stratification did not predict the risk of a positive test. Age, statin use, antiplatelet therapy use, cardiovascular disease, prior treatment with anthracycline or radiation therapy, and being sedentary were predictors of a positive test (all p < .10).

CONCLUSION

The patient risk-stratification profile strongly suggests that the use of formalized preparticipation health screening is required in all oncology scenarios; however, risk of an exercise-induced event is low, suggesting that the use of exercise testing is not required for pre-exercise clearance in the majority of patients.

Effects of nonlinear aerobic training on erectile dysfunction and cardiovascular function following radical prostatectomy for clinically localized prostate cancer

Erectile dysfunction (ED) is a major adverse effect of radical prostatectomy (RP). We conducted a randomized controlled trial to examine the efficacy of aerobic training (AT) compared with usual care (UC) on ED prevalence in 50 men (n=25 per group) after RP. AT consisted of five walking sessions per week at 55-100% of peak oxygen uptake (VO2peak) for 30-60 min per session following a nonlinear prescription. The primary outcome was change in the prevalence of ED, as measured by the International Index of Erectile Function (IIEF), from baseline to 6 mo. Secondary outcomes were brachial artery flow-mediated dilation (FMD), VO2peak, cardiovascular (CV) risk profile (eg, lipid profile, body composition), and patient-reported outcomes (PROs). The prevalence of ED (IIEF score ≤ 21) decreased by 20% in the AT group and by 24% in the UC group (difference: p=0.406). There were no significant between-group differences in any erectile function subscale (p>0.05). Significant between-group differences were observed for changes in FMD and VO2peak, favoring AT. There were no group differences in other markers of CV risk profile or PROs. In summary, nonlinear AT does not improve ED in men with localized prostate cancer in the acute period following RP.

TRIAL REGISTRATION

Clinicaltrials.gov identifier NCT00620932.

Evidence-based risk assessment and recommendations for physical activity clearance: respiratory disease

The 2 most common respiratory diseases are chronic obstructive pulmonary disease (COPD) and asthma. Growing evidence supports the benefits of exercise for all patients with these diseases. Due to the etiology of COPD and the pathophysiology of asthma, there may be some additional risks of exercise for these patients, and hence accurate risk assessment and clearance is needed before patients start exercising. The purpose of this review was to evaluate the available literature regarding the risks of exercise for patients with respiratory disease and provide evidence-based recommendations to guide the screening process. A systematic review of 4 databases was performed. The literature was searched to identify adverse events specific to exercise. For COPD, 102 randomized controlled trials that involved an exercise intervention were included (n = 6938). No study directly assessed the risk of exercise, and only 15 commented on exercise-related adverse events. For asthma, 30 studies of mixed methodologies were included (n = 1278). One study directly assessed the risk of exercise, and 15 commented on exercise-related adverse events. No exercise-related fatalities were reported. The majority of adverse events in COPD patients were musculoskeletal or cardiovascular in nature. In asthma patients, exercise-induced bronchoconstriction and (or) asthma symptoms were the primary adverse events. There is no direct evidence regarding the risk of exercise for patients with COPD or asthma. However, based on the available literature, it would appear that with adequate screening and optimal medical therapy, the risk of exercise for these respiratory patients is low.