An interventional study of Threshold-Based Aerobic Exercise Intensity Prescription and Range-Based Aerobic Exercise Intensity Prescription in Cardiovascular Diseases and Cardiac Rehabilitation, sponsored by Hasselt University. Not yet recruiting at 9 sites in Belgium. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-02.
Sponsored by Hasselt University · Not applicable, Interventional, and Treatment
Cardiac rehabilitation is an important part of the treatment of patients with cardiovascular disease. Supervised aerobic exercise improves physical fitness, functional capacity, and quality of life. However, the most effective method for prescribing exercise intensity during cardiac rehabilitation remains uncertain.
The T-REXI-CR trial aims to determine whether prescribing aerobic exercise intensity based on individual ventilatory thresholds leads to greater improvements in functional capacity than the guideline-recommended approach based on heart rate reserve.
This pragmatic, multicentre, randomised controlled trial will compare two exercise intensity prescription strategies in patients participating in cardiac rehabilitation programmes in Belgium.
Participants will be randomly assigned to one of two groups:
Both groups will participate in a 15-week supervised aerobic exercise programme, targeting 40 exercise sessions. The programmes will follow the same training structure and progression principles, differing primarily in the method used to determine exercise intensity.
The study will assess whether threshold-based exercise prescription provides additional benefits compared with conventional range-based prescription, with the aim of informing clinical practice and improving the delivery of cardiac rehabilitation.
BACKGROUND AND RATIONALE
Exercise-based cardiac rehabilitation is a cornerstone of secondary cardiovascular prevention. Although the benefits of aerobic exercise training are well established, uncertainty remains regarding the optimal method for individualising exercise intensity.
Current guidelines commonly recommend prescribing aerobic exercise intensity using predefined percentages of heart rate reserve (HRR). However, these percentage-based ranges may not accurately reflect individual physiological responses to exercise, particularly in patients with cardiovascular disease.
An alternative approach is to prescribe exercise intensity according to ventilatory thresholds identified during cardiopulmonary exercise testing (CPET). The first ventilatory threshold (VT1) and second ventilatory threshold (VT2) provide individual physiological reference points for defining exercise intensity domains. This approach may improve the precision of exercise prescription and potentially optimise training adaptations.
Despite the physiological rationale supporting threshold-based exercise prescription, evidence from large, pragmatic randomised controlled trials comparing this strategy with guideline-recommended range-based prescription in routine cardiac rehabilitation remains limited.
STUDY OBJECTIVE
The T-REXI-CR trial is designed to evaluate whether threshold-based aerobic exercise intensity prescription is superior to guideline-recommended HRR-based prescription for improving functional capacity in patients undergoing cardiac rehabilitation.
STUDY APPROACH
The study is designed as a pragmatic, multicentre, parallel-group, superiority randomised controlled trial conducted within routine cardiac rehabilitation services in Belgium.
Both study groups will receive supervised aerobic exercise training within a common 15-week programme, with a target of 40 sessions. Exercise prescriptions will be centrally generated and will follow standardised progression principles. The main difference between groups will be the method used to define individual exercise intensity boundaries.
The study will evaluate changes in functional capacity, alongside patient-reported health outcomes and other clinically relevant measures. Assessments will be performed at baseline, approximately four months, and eight months.
CLINICAL RELEVANCE
Both exercise prescription strategies are already used in clinical practice and are compatible with the Belgian cardiac rehabilitation system. By directly comparing these approaches under routine clinical conditions, the trial aims to provide evidence to support exercise prescription decisions and inform future cardiac rehabilitation recommendations.
5,368 studies on the registry are indexed under Cardiovascular Diseases; 939 are open to participants now.
This study's planned enrollment of 230 is above the median of 100 across 3,084 interventional studies indexed under Cardiovascular Diseases.
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VT1 and VT2 will be identified locally by the clinical team performing the CPET, according to routine practice at each participating centre. Participants in whom either threshold cannot be identified will not proceed to randomisation.
EXCLUSION CRITERIA
The HRR criterion is a study-specific operational criterion intended to ensure a sufficient overall heart-rate range for practical implementation of heart rate-based exercise prescription. In the range-based comparator arm, an HRR of ≥35 bpm corresponds to a prescribed heart-rate interval of approximately 10 bpm or more between 40% and 69% HRR.
These criteria are designed to reflect routine clinical practice while ensuring safe and appropriate application of the exercise prescription strategies under investigation.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants allocated to this group will receive an individualised aerobic exercise prescription based on the first and second ventilatory thresholds (VT1 and VT2) determined during cardiopulmonary exercise testing (CPET). Exercise intensity will be prescribed using heart rate boundaries corresponding to these physiological thresholds. Participants will follow a 15-week supervised cardiac rehabilitation programme, targeting 40 exercise sessions, with centrally generated prescriptions and standardised progression principles.
Other: Threshold-Based Aerobic Exercise Intensity Prescription
Participants allocated to this group will receive an individualised aerobic exercise prescription based on the guideline-recommended range of 40-69% of heart rate reserve (HRR), calculated using resting and peak heart rates obtained during CPET. Participants will follow the same 15-week supervised cardiac rehabilitation programme, targeting 40 exercise sessions, with centrally generated prescriptions and standardised progression principles.
Other: Range-Based Aerobic Exercise Intensity Prescription
Aerobic exercise intensity is individually prescribed according to the first and second ventilatory thresholds (VT1 and VT2) identified during baseline CPET. These thresholds are used to establish individualised heart rate training boundaries. Exercise prescriptions are centrally generated and follow a common FITT-VP framework, including predefined progression principles. Training is delivered within routine supervised cardiac rehabilitation, up to three sessions per week over 15 weeks, with a target of 40 sessions. The main aerobic training phase lasts 25-35 minutes per session, excluding warm-up and cool-down.
Aerobic exercise intensity is individually prescribed using the guideline-recommended range of 40-69% of heart rate reserve (HRR), calculated from resting and peak heart rates obtained during baseline CPET. Exercise prescriptions are centrally generated and follow the same FITT-VP framework and predefined progression principles as the threshold-based group. Training is delivered within routine supervised cardiac rehabilitation, up to three sessions per week over 15 weeks, with a target of 40 sessions. The main aerobic training phase lasts 25-35 minutes per session, excluding warm-up and cool-down.
Change in Peak Oxygen Uptake (VO2peak) From Baseline to 4 Months
The primary outcome is the change in peak oxygen uptake (VO2peak), expressed in mL/kg/min, from baseline to 4 months. VO2peak will be measured using symptom-limited cardiopulmonary exercise testing (CPET) according to standardised procedures. Change will be calculated as the 4-month value minus the baseline value. The primary comparison will assess the between-group difference in mean change in VO2peak.
Time frame: Baseline and 4 months (±1 week)
Change in Peak Oxygen Uptake (VO2peak) From Baseline to 8 Months
Change in peak oxygen uptake (VO2peak), expressed in mL/kg/min, measured by cardiopulmonary exercise testing (CPET). Change will be calculated as the 8-month value minus the baseline value. The between-group difference in mean change will be evaluated to assess the sustainability of the intervention effect.
Time frame: Baseline and 8 months (±1 week)
Proportion of Participants Achieving a Clinically Meaningful Improvement in VO2peak
Proportion of participants achieving an increase in VO2peak of at least 1 mL/kg/min compared with baseline, as measured by CPET. Participants will be classified as responders or non-responders at each follow-up assessment. The proportion of responders will be compared between treatment groups.
Time frame: Baseline, 4 months (±1 week), and 8 months (±1 week)
Change in Disease-Specific Quality of Life Assessed by HeartQoL
Change in disease-specific health-related quality of life measured using the HeartQoL questionnaire. HeartQoL is a validated patient-reported outcome instrument for patients with cardiovascular disease. Scores range from 0 to 3, with higher scores indicating better quality of life. Changes from baseline will be compared between treatment groups at 4 and 8 months.
Time frame: Baseline, 4 months (±1 week), and 8 months (±1 week)
Change in Health-Related Quality of Life Assessed by EQ-5D-5L
Change in health-related quality of life measured using the EQ-5D-5L questionnaire. The instrument assesses five dimensions of health: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Responses will be used to derive an EQ-5D-5L health utility index score using the applicable value set. Changes from baseline will be compared between treatment groups at 4 and 8 months.
Time frame: Baseline, 4 months (±1 week), and 8 months (±1 week)
Adherence to Supervised Exercise Training (key secondary outcome)
Adherence to supervised exercise training will be calculated as the percentage of supervised exercise sessions attended relative to the total number of sessions individually prescribed or scheduled during the 15-week intervention period. Data will be obtained from routine cardiac rehabilitation attendance records and the electronic case report form (eCRF). The target of 40 sessions will not be used as a fixed denominator, as the number of prescribed or scheduled sessions may vary between participants.
Time frame: Throughout the 15-week supervised intervention period (assessed at 4 months)
Number of Supervised Exercise Sessions Attended
Total number of supervised aerobic exercise training sessions attended during the 15-week cardiac rehabilitation programme, obtained from routine attendance records and the electronic case report form (eCRF). This measure represents treatment exposure and will be summarised and compared between treatment groups.
Time frame: Throughout the 15-week supervised intervention period (assessed at 4 months)
Plan to share: Yes — Individual participant data (IPD) may be shared in pseudonymised form after database lock and completion of the study, in accordance with the Research Agreement between the Sponsor (Hasselt University) and the Belgian Health Care Knowledge Centre (KCE). Upon request, KCE may receive the pseudonymised study dataset for non-commercial research and public health-related purposes. Further access by eligible institutions or researchers will be subject to applicable contractual arrangements, data protection requirements, and relevant approvals under the General Data Protection Regulation (GDPR). Directly identifiable participant information will not be included in the shared study dataset.
Supporting information: Study protocol, Statistical analysis plan
Time frame: Pseudonymised individual participant data may be made available upon request after database lock and completion of the study, subject to the applicable Research Agreement and data protection requirements. The duration of data availability will be determined by the relevant contractual arrangements and applicable data retention policies.
Access criteria: The Belgian Health Care Knowledge Centre (KCE) may request access to the pseudonymised study dataset in accordance with the Research Agreement. Requests from other eligible institutions or researchers for non-commercial research or public health-related purposes will be considered by the Sponsor, Hasselt University, subject to applicable contractual provisions, scientific justification, data protection requirements, and necessary approvals. Access may require a data use agreement specifying the permitted purposes and conditions of use. Direct personal identifiers will not be provided.
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