University of Hull research has established that high-intensity interval training (HIIT) is safe for people with stable coronary artery disease (CAD) and increases cardiorespiratory fitness by a clinically meaningful level compared to standard rehabilitation programmes.
Evidence shows that people with higher levels of cardiorespiratory fitness generally have better health outcomes and live longer lives.
A clinical trial, which is the culmination of seven years’ work for a team of exercise scientists based at universities in Hull, Coventry and Cardiff, showed that HIIT is a viable option to improve cardiorespiratory fitness and quality of life in people with coronary artery disease.
HIIT is characterised by short, intense bursts of exercise interspersed by short recovery periods.
HIIT sessions were completed twice per week for 8 weeks and each session took up to 20 minutes to complete, making HIIT a very time-efficient form of exercise.
Whilst HIIT has been recommended for people with coronary artery disease in North America and Europe, it has yet to be recommended as a frontline treatment option for people with CAD in the UK.
The trial which was originally conceived in 2016 is the largest multi-centre HIIT study ever conducted in people with CAD and has significant implications for clinical practice in the UK.
Professor Lee Ingle based in the School of Sport, Health and Rehabilitation Science within the University of Hull’s Faculty of Health Sciences, said: “Improving heart health through exercise and lifestyle education is an accepted part of rehabilitation for people with established heart disease in the UK. But historically, there has been a lack of consensus regarding what form of exercise is most effective and safe. To date there have been no large-scale randomised controlled trials which have compared HIIT with traditional training interventions in the UK which have meant that governing bodies have been reluctant to advocate its use.
“What is interesting is that international trials show that HIIT is extremely safe and well-tolerated in stable patients with CAD, and our trial confirms this assertion in people from the UK. But not only was HIIT safe, it also produced clinically meaningful improvements in cardiorespiratory fitness compared to a matched dose of moderate intensity training.
“Additionally, another key marker, the ventilatory anaerobic threshold, which reflects an individual’s ability to carry out activities of daily living or prolonged physical activity without undue fatigue was also improved by a clinically meaningful level in people who did HIIT. “
The study, which has been published in the European Journal of Preventive Cardiology, showed that:
- High-intensity interval training was more effective than moderate-intensity exercise training for improving cardiorespiratory fitness and the ventilatory anaerobic threshold in people with CAD attending eight weeks of cardiac rehabilitation.
- High-intensity interval training was safe and well tolerated.
The researchers conducted a multi-centre clinical trial with 382 patients from 6 outpatient CR centres based in Hull, Coventry and Cardiff. Participants were randomised to twice-weekly HIIT (n = 187) or MISS (n = 195) for 8 weeks. HIIT consisted of 10 × 1 min intervals of vigorous exercise (>85% maximum capacity) interspersed with 10 x 1 min periods of lower intensity recovery. MISS was 20 min of moderate-intensity continuous exercise (60–80% maximum capacity). The primary outcome was the change in cardiorespiratory fitness [peak oxygen uptake (VO2 peak)] at 8 week follow-up. Secondary outcomes included cardiovascular disease risk markers, cardiac structure and function, adverse events, and health-related quality of life.
Professor Ingle said: “The next stage is to lobby our governing bodies responsible for cardiac rehabilitation in the UK to advocate HIIT as a frontline treatment option in people with stable coronary artery disease.”