# The effect of two remote exercise programs on cardiorespiratory fitness, cardiac function, and vascular health in patients with breast cancer PMID: 41704018 Journal: Physiological reports Published: 2026-02-01 Authors: Weeldreyer NR, Ellison CC, Mabalot MB, Helms CE, Nealy ZB, Leicht ZS, Abbate A, Brenin CM, Dillon PM, Millard T, Krukowski RA, Zoellner JM, Angadi SS ## Question Do remotely delivered HIIT and moderate-intensity exercise programs differ in preserving cardiorespiratory fitness, cardiac function, and vascular function when started before and continued through chemotherapy for breast cancer? ## Summary This randomized trial compared two remotely monitored exercise programs in women with breast cancer undergoing chemotherapy: home-based recumbent-bike HIIT and walking-based moderate-intensity exercise. Fifteen of 24 enrolled patients completed all aspects of the study. VO2peak declined significantly in the moderate-intensity group but not the HIIT group, although between-group differences were not statistically significant and the study was underpowered because dropout was higher than expected. Adherence averaged about 61%-64%, chemotherapy side effects were the main reason for noncompliance, and no exercise-related serious adverse events were reported. ## Population - Patients with breast cancer scheduled for chemotherapy and cleared by physicians for exercise. - Sample size: 24 - Age: Completers: MOD 52.6 +/- 11.2 years; HIIT 55.3 +/- 11.9 years. - Sex: Women with breast cancer; exact sex distribution not separately reported. - Fitness level: Baseline VO2peak among completers: MOD 1.50 +/- 0.23 L/min; HIIT 1.58 +/- 0.24 L/min. - Health status: Breast cancer stages I-III or IV with minimal metastatic burden; undergoing chemotherapy. ## Methodology - Randomized trial comparing two remote exercise interventions during chemotherapy. - Exercise began 1-2 weeks before chemotherapy and continued throughout chemotherapy; mean intervention duration was 10.6 weeks for HIIT and 13.0 weeks for MOD. - Remote home-based exercise after two initial in-person familiarization sessions; participants were recruited from the University of Virginia Comprehensive Cancer Center. - Randomized and controlled study design. ## Protocol - Remote cycling HIIT. - Modality: Stationary recumbent bicycle. - Work intervals: Four 4-minute intervals at 85%-90% peak heart rate; alternatives were eight 2-minute intervals or five 3-minute intervals. - Recovery: 3-minute active recovery at about 50% peak heart rate in the standard protocol; alternatives used 2-minute or 3-minute recovery. - Sets or repetitions: 4 intervals standard. - Intensity: 85%-90% peak heart rate for work intervals. - Session duration: About 40 minutes for standard 4x4 with 10-minute warmup, three 3-minute recoveries, and 5-minute cool down. - Frequency: 3 days per week. - Program length: Throughout chemotherapy; mean 10.6 +/- 3.8 weeks in HIIT. - Progression: No formal progression reported; alternative interval structures were allowed for tolerability. - Remote moderate-intensity walking. - Modality: Walking. - Sets or repetitions: Participants accumulated 150 minutes per week in bouts arranged as desired. - Intensity: 70%-75% peak heart rate. - Session duration: Variable bouts totaling 150 minutes per week. - Frequency: Variable; accumulated weekly. - Program length: Throughout chemotherapy; mean 13.0 +/- 6.2 weeks in MOD. ## Outcomes ### VO2peak Status: mixed VO2peak declined significantly within MOD and did not significantly decline within HIIT, but the between-group difference was not statistically significant. MOD 1.50 +/- 0.23 to 1.27 +/- 0.28 L/min, p=0.013, d=1.2; HIIT 1.58 +/- 0.24 to 1.52 +/- 0.28 L/min, p=0.445, d=0.3; between-group p=0.109, d=0.9. ### Oxygen uptake efficiency slope Status: mixed OUES significantly declined in MOD but not HIIT; between-group difference was not significant but had a large effect size. MOD 1.63 +/- 0.27 to 1.29 +/- 0.26 L/min, p=0.002, d=2.5; HIIT 1.57 +/- 0.20 to 1.42 +/- 0.23 L/min, p=0.15, d=0.6; between-group p=0.14, d=0.9. ### Cardiac function Status: mixed No significant between-group differences in cardiac function; HIIT cardiac output increased significantly within group. HIIT cardiac output 4.3 +/- 1.1 to 5.3 +/- 1.0 L/min, p=0.004; between-group cardiac output p=0.097. ### Blood pressure and arterial stiffness Status: mixed MOD showed significant central systolic blood pressure reduction and Aix75 reduction; between-group difference was significant for Aix75 only. MOD central SBP 111 +/- 4.9 to 104 +/- 4 mmHg, p=0.008; Aix75 between-group p=0.040. ### Safety Status: no clear change No exercise-related serious adverse events were reported in either group. ## Practical Insights - Remote HIIT can be structured with heart-rate monitoring, equipment setup, and fallback interval options, but adherence may still be limited during chemotherapy. - For clinical populations, safety messaging should require physician clearance and contraindication screening before HIIT. - Underpowered between-group results should be framed as suggestive preservation of VO2peak, not definitive HIIT superiority. ## Limitations - Greater than anticipated dropout made the study underpowered. - No true non-exercise control group. - Different modalities between groups and cycle-based testing may confound intensity with modality specificity. - All African American participants were in the HIIT group by chance. - Echocardiography limitations may affect cardiac-function measurement. - Broad chemotherapy regimen inclusion may have muted cardiotoxicity-related findings. ## Safety And Adherence - No exercise-related serious adverse events were reported in either group. - Physician clearance was required before exercise training. - The trial used extensive exclusion criteria for cardiac, pulmonary, vascular, metabolic, retinal, and other risk conditions. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/41704018/) (pubmed) - [DOI](https://doi.org/10.14814/phy2.70787) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12914078/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.