Publications by authors named "Mark Haykowsky"

Background: Training load may be an important factor underlying the (patho-)physiologic cardiovascular adaptations from endurance exercise. Yet quantifying training load remains challenging due to the complexity of its components (Frequency, Intensity, Time, and Type; F.I.

View Article and Find Full Text PDF

Background: Paediatric heart failure poses life-long, burdensome symptoms for the health care system and families. Diagnosis and discharge are stressful and anxiety-provoking for caregivers. They face uncertainty about their child's health and become responsible for administering complex care in the home.

View Article and Find Full Text PDF

Aims: Low cardiorespiratory fitness (CRF) is associated with functional disability, heart failure and mortality. Left ventricular (LV) end-diastolic volume (LVEDV) has been linked with CRF, but its utility as a diagnostic marker of low CRF has not been tested.

Methods: This multi-center international cohort examined the relationship between LV size on echocardiography and CRF (peak oxygen uptake [peak VO2] from cardiopulmonary exercise testing) in individuals with LV ejection fraction ≥50%.

View Article and Find Full Text PDF

Aims: Heart failure (HF) has a major impact on exercise tolerance that may (in part) be due to abnormalities in body and skeletal muscle composition. This systematic review and meta-analysis aims to assess how differences in whole-body and skeletal muscle composition between patients with HF and non-HF controls (CON) contribute to reduced peak oxygen uptake (VOpeak).

Methods And Results: The PubMed database was searched from 1975 to May 2024 for eligible studies.

View Article and Find Full Text PDF

Aims: Exercise training (ET) is an effective therapy in heart failure with preserved ejection fraction (HFpEF), but the influence of different ET characteristics is unclear. We aimed to evaluate the associations between ET frequency, duration, intensity [% heart rate reserve (%HRR)] and estimated energy expenditure (EEE) with the change in peak oxygen consumption (V̇O2) over 3 months of moderate continuous training (MCT, 5×/week) or high-intensity interval training (HIIT, 3×/week) in HFpEF.

Methods And Results: ET duration and heart rate (HR) were recorded with a smartphone application.

View Article and Find Full Text PDF

Aims: Cardiovascular disease (CVD) is a leading cause of mortality in childhood cancer survivors (CCS) that may be related to the cardiotoxic effects of radiation or chemotherapy and concomitant reductions in cardiorespiratory fitness. Therefore, we sought to compare cardiorespiratory fitness (peak oxygen uptake, V̇O2peak) between CCS and age-matched non-cancer controls (CON). Secondary outcomes included hemodynamics and resting cardiac function.

View Article and Find Full Text PDF
Article Synopsis
  • The landscape of cancer treatment is advancing, leading to better survival rates, but patients often face increased risks of other health issues, especially cardiovascular disease (CVD).
  • CVD risks are linked to both standard and new cancer therapies, and it's important to look at their effects beyond just heart health.
  • The review introduces a framework using oxygen pathways to assess how cancer treatments affect overall cardiovascular risk and function, aiming to help identify at-risk cancer survivors who may need early intervention to enhance their overall health outcomes.
View Article and Find Full Text PDF

Background: Women are at greater risk for heart failure with preserved ejection fraction (HFpEF).

Objectives: The aim of the study was to compare sex differences in the pathophysiology of exertional breathlessness in patients with high vs low HFpEF likelihood.

Methods: This cohort study evaluated consecutive patients (n = 1,936) with unexplained dyspnea using cardiopulmonary exercise testing and simultaneous echocardiography and quantified peak oxygen uptake (peak VO) and its determinants.

View Article and Find Full Text PDF

Introduction: Short-term clinical outcomes from SARS-CoV-2 infection are generally favorable. However, 15-20% of patients report persistent symptoms of at least 12 weeks duration, often referred to as long COVID. Population studies have also demonstrated an increased risk of incident diabetes and cardiovascular disease at 12 months following infection.

View Article and Find Full Text PDF

Background & Aims: Accurately estimating resting energy requirements is crucial for optimizing energy intake, particularly in the context of patients with varying energy needs, such as individuals with cancer. We sought to evaluate the agreement between resting energy expenditure (REE) predicted by 40 equations and that measured by reference methods in women undergoing active breast cancer treatment stage (I-IV) and post-completion (i.e.

View Article and Find Full Text PDF

Background: We identified peripherally limited patients using cardiopulmonary exercise testing and measured skeletal muscle oxygen transport and utilization during invasive single leg exercise testing to identify the mechanisms of the peripheral limitation.

Methods: Forty-five patients with heart failure with preserved ejection fraction (70±7 years, 27 females) completed seated upright cardiopulmonary exercise testing and were defined as having a (1) peripheral limitation to exercise if cardiac output/oxygen consumption (VO) was elevated (≥6) or 5 to 6 with a stroke volume reserve >50% (n=31) or (2) a central limitation to exercise if cardiac output/VO slope was ≤5 or 5 to 6 with stroke volume reserve <50% (n=14). Single leg knee extension exercise was used to quantify peak leg blood flow (Doppler ultrasound), arterial-to-venous oxygen content difference (femoral venous catheter), leg VO, and muscle oxygen diffusive conductance.

View Article and Find Full Text PDF

Background: Obesity combined with heart failure with preserved ejection fraction (HFpEF) is the dominant form of HF among older persons. In a randomized trial, we previously showed that a 5-month calorie restriction (CR) program, with or without aerobic exercise training (AT), resulted in significant weight and fat loss and improved exercise capacity. However, little is known regarding the long-term effects of these outcomes after a short-term (5-month) intervention of CR with or without AT in older patients with obesity and HFpEF.

View Article and Find Full Text PDF

Background: Cardiac rehabilitation (CR) modeled care is recommended for patients with breast cancer to mitigate risk of cardiotoxicity. However, the cardiovascular impact of CR-modeled interventions has not been studied.

Objectives: The purpose of this study was to evaluate if a multidisciplinary model of CR reduces cardiotoxicity and improves cardiovascular risk in patients undergoing breast cancer treatment.

View Article and Find Full Text PDF

In a 77-year-old former world-record-holding male marathoner (2:08:33.6), this study sought to investigate the impact of lifelong intensive endurance exercise on cardiac structure, function, and the trajectory of functional capacity (determined by maximal oxygen consumption, V̇o) throughout the adult lifespan. As a competitive runner, our athlete (DC) reported performing up to 150-300 miles/wk of moderate-to-vigorous exercise and sustained 10-15 h/wk of endurance exercise after retirement from competition.

View Article and Find Full Text PDF

Objectives: To determine the impact of running a sub-4 min mile on longevity. It was hypothesised that there would be an increase in longevity for runners who successfully completed a sub-4 min mile compared with the general population.

Methods: As part of this retrospective cohort study, the Sub-4 Alphabetic Register was used to extract the first 200 athletes to run a sub-4 min mile.

View Article and Find Full Text PDF

•Exercise intolerance is common among breast cancer survivors.•Exercise intolerance in breast cancer survivors is related to cardiac, vascular, and skeletal muscle impairments.•Holistic rehabilitation or pharmacological therapies are needed to address these impairments.

View Article and Find Full Text PDF

Postural orthostatic tachycardia syndrome (POTS) is characterized by an excessive heart rate (HR) response upon standing and symptoms indicative of inadequate cerebral perfusion. We tested the hypothesis that during lower body negative pressure (LBNP), individuals with POTS would have larger decreases in cardiac and cerebrovascular function measured using magnetic resonance (MR) imaging. Eleven patients with POTS and 10 healthy controls were studied at rest and during 20 min of -25 mmHg LBNP.

View Article and Find Full Text PDF

This systematic review and meta-analysis examined the physiological mechanisms responsible for lower peak exercise leg oxygen uptake (V̇o) in patients with chronic disease. Studies measuring peak leg V̇o (primary outcome) and its physiological determinants during large (cycle) or small muscle mass exercise (single-leg knee extension, SLKE) in patients with chronic disease were included in this meta-analysis. Pooled estimates for each outcome were reported as a weighted mean difference (WMD) between chronic disease and controls.

View Article and Find Full Text PDF

BACKGROUND: Patients with kidney failure undergoing hemodialysis experience physical deconditioning and multimorbidity. Exercise interventions may mitigate this outcome, but their clinical role is unclear. METHODS: This multicenter, cluster randomized controlled trial evaluated combined endurance and resistance exercise training during hemodialysis versus usual care in chronic kidney failure.

View Article and Find Full Text PDF

Purpose: Improvements in diagnosis and treatment mean that the long-term health of breast cancer survivors (BCS) is increasingly dictated by cardiovascular comorbidities. This is partly a consequence of exposure to cardiotoxic therapies, which result in cardiac dysfunction and decreased cardiorespiratory fitness (CRF). Exercise training (ExT) is a key therapeutic strategy for secondary prevention and increasing CRF in adults with established cardiovascular disease.

View Article and Find Full Text PDF

With significant improvements in the understanding of cancer biology, improved detection, and the use of novel adjuvant therapies, each year more Canadians are surviving a cancer diagnosis. Despite their effectiveness these therapies often result in short- and long-term deleterious effects to major organ systems, particularly cardiovascular. Cardio-oncology is an emerging field of study with the aim to improve cardiovascular health across the oncology disease spectrum.

View Article and Find Full Text PDF