HIIT Versus Moderate Continuous Training in ACHD (PhiT)

April 23, 2026 updated by: University of Alberta

Physical Activity in Tetralogy: A Randomized Trial of Interval Training Versus Moderate Continuous Training

This study is a single center randomized controlled trial evaluating the effect of an exercise training intervention (interval training or moderate continuous training) compared to usual care (no training) on exercise capacity in patients with congenital heart disease (CHD).

Our primary aim is to determine the impact of interval training (IT) compared to moderate continuous exercise training (MCT) versus controls (no exercise) on exercise capacity as measured by peak VO2. Secondary aims are to: 1) assess the safety of exercise training in CHD, 2) evaluate the effect of exercise training on cardiac structure and function and 3) assess the effects of exercise training on quality of life and long-term physical activity.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Adults with congenital heart disease (ACHD) have reduced exercise capacity which is an independent predictor of adverse outcome including hospitalization and mortality in this patient population. When aerobic exercise capacity is measured by cardiopulmonary exercise testing (CPET), peak oxygen consumption (peak VO2) averages 22ml/kg/min in ACHD, less than half of age matched controls, and similar to patients with heart failure. Factors contributing to low exercise capacity include central factors related to abnormal cardiac anatomy, ventricular systolic and diastolic dysfunction, valvular abnormalities, pulmonary hypertension, chronotropic incompetence and impaired pulmonary function as well as peripheral factors such as skeletal muscle conditioning. Clinicians may further contribute to reluctance around exercise by failing to encourage physical activity or giving inappropriate exercise restrictions to ACHD.

The aim of our study was to explore the efficacy of HIIT compared to MCT on aerobic exercise capacity as measured by peak VO2 in ACHD patients. Secondary aims were to determine the effect of exercise on various physiologic variables, to assess the safety of HIIT in ACHD, to evaluate the effect of exercise training on cardiac structure and function as assessed by cardiac MRI and to measure the impact of exercise training on quality of life (QoL).

This was a single center randomized controlled trial designed in accordance with CONSORT guidelines. Participants were randomized with a 1:1:1 ratio into three groups: HIIT, MCT or control group. Randomization occurred by clusters defined by week of attendance in the clinic. Permuted blocks of 3, 6, and 9 were used to ensure a similar number of weeks randomized to the three groups, with randomization sequence generated by one author (AM). Participants were enrolled by a study coordinator who assigned participants to one of the three groups. Participants underwent testing at baseline and after 12 weeks of the intervention.

Study Type

Interventional

Enrollment (Actual)

47

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Canada
    • Alberta
      • Edmonton, Alberta, Canada, T6G 2B7
        • Jim Pattison Center for Cardiac Rehabilitation

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Medically stable patients aged 16 or great with congenital heart disease.

Exclusion Criteria:

  • Uncorrected cyanotic congential heart disease (SpO2 </= 85%)
  • Severe outflow tract obstruction (peak Doppler gradient >50 mmHg)
  • Sustained arrhythmia

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: HIIT
High intensity interval training: 3 session per week of long-interval protocol involving 5 minutes of warmup, 5 intervals of 4 minutes of internse aerobic activity with 4 periods of 3 minutes of low to moderate intensity activity and a 5 minute cool down period.
Other: Exercise Intervention
Participants will take part in 3 exercise sessions per week of either HIIT or MCT training.
Experimental: MCT
Moderate continuous training: 3 sessions per week involving a 5 minut warmup, 40 minutes of aerobic activity and 5 minutes of cool down.
Other: Exercise Intervention
Participants will take part in 3 exercise sessions per week of either HIIT or MCT training.
No Intervention: Control
Control group participants will continue their usual level of physical activity.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in peak VO2 from baseline to 12 weeks post enrollment
Time Frame: From enrollment to the end of the 12 week treatment
Participants will complete a cardiopulmonary exercise test at baseline and after 12 weeks to determine peak VO2 values.
From enrollment to the end of the 12 week treatment

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Determination of adverse events
Time Frame: Participants will be monitored throughout the exercise training and one hour afterward.
High intensity exercise has the potential to transiently increase the risk of arrhythmias and myocardial infarction in susceptible persons. Participants will be monitored throughout exercise for any adverse events defined as cardiac arrest, myocardial infarction, sustained ventricular or suprraventricular arrhythmias or heart failure.
Participants will be monitored throughout the exercise training and one hour afterward.
Cardiac adaptation
Time Frame: Cardiac MRI's will be performed at baseline with follow-up scans at 4 weeks of starting and at completion of the 12 week intervention.
Cardiac MRI will be used to assess right ventricular volumes and ejection fraction. Pulmonary regurgitation fraction, left ventricular volumes and ejection fraction will also be assess.
Cardiac MRI's will be performed at baseline with follow-up scans at 4 weeks of starting and at completion of the 12 week intervention.
Impact of exercise program on physical activity levels.
Time Frame: Participants will wear the accelerometers at baseline and 6 months after randomization to collect data for 4 days.
Participants will wear SenseWear arm bands (accelerometers) to describe baseline physical activity levels and to assess long-term changes in physical activity 6 months after randomization. Data will be acquired for 4 days at each time-point and change from baseline compared between exercise training groups and usual care.
Participants will wear the accelerometers at baseline and 6 months after randomization to collect data for 4 days.
The effect of exercise training on quality of life.
Time Frame: Participants will complete questionnaires during study visits or be sent a link by email to complete the questionnaires on-line at baseline, 3 months (after exercise training intervention) and 6 months after randomization.
Participants will complete a quality of life questionnaire, satisfaction with life scale and New York Heart Association (NYHA) Functional Classification.
Participants will complete questionnaires during study visits or be sent a link by email to complete the questionnaires on-line at baseline, 3 months (after exercise training intervention) and 6 months after randomization.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Alberta

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

October 20, 2015

Primary Completion (Actual)

May 31, 2023

Study Completion (Actual)

April 30, 2024

Study Registration Dates

First Submitted

April 15, 2026

First Submitted That Met QC Criteria

April 15, 2026

First Posted (Actual)

April 22, 2026

Study Record Updates

Last Update Posted (Actual)

April 29, 2026

Last Update Submitted That Met QC Criteria

April 23, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • Pro00059680

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data will not be shared. Data will be analyzed and presented per treatment group.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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