With high intensity interval training gaining in popularity, does the evidence suggest there are safe and effective cardiovascular health benefits for this type of exercise? Rod Tucker investigates.
The NHS has described exercise as a miracle cure that is able to reduce the risk of major illnesses such as heart disease, stroke, Type 2 diabetes and even cancer.
In order to achieve these benefits, the UK Government’s guidelines recommend that adults aged between 19 and 64 should undertake at least 150 minutes of moderate aerobic activities, such as cycling or brisk walking, every week, combined with strength training on two or more days per week. Sadly, this message is not filtering through to he general public.
A report by the British Heart Foundation suggested that physical inactivity and sedentary lifestyles cost the NHS as much as £1.2 billion a year and around 39% of adults (about 20 million people) fail to meet the Government’s physical activity targets. There are a range of possible reasons for this but one that is consistently reported among those who are not sufficiently active is lack of time.
The value of HIIT
One potential solution to achieving the same benefits of exercise in a much shorter space of time that is gaining in popularity is high intensity interval training (HIIT), which involves intermittent periods of intense exercise, i.e. going flat out, separated by periods of recovery.
In recent years, the value of HIIT as an exercise intervention has been extensively researched and compared to moderate intensity continuous training (MICT) such as jogging or cycling. The consensus appears to be that HIIT offers comparable health benefits to MICT. Furthermore, according to a new systematic review and meta-analysis of 786 studies, HIIT produced a 28.5% greater reduction in fat loss compared to MICT.
Many of the HIIT studies have been short-term and undertaken in laboratories using expensive exercise equipment. So, how transferable are these results to the real-world?
One recent ‘real-world’ 12-month study of adherence to HIIT in overweight adults sought to answer to this question. Participants could select HIIT or MICT as an exercise intervention and the results showed that adherence to HIIT reduced from 60% to 19% by 12 months. Nevertheless, for those who continued with HIIT, health outcomes were equivalent to those assigned to MICT.
Safe and effective?
But how safe or effective is HIIT for the majority of people who are likely to have a range of long-term health problems including cardiovascular disease, type 2 diabetes and are generally older. And should pharmacists be recommending this form of exercise?
This has been the subject of much scientific scrutiny with one review suggesting that HIIT may improve fitness and should be a component of the care for those with coronary artery disease. Similarly, HIIT improved glycaemic control, body composition, hypertension and dyslipidaemia in patients with type 2 diabetes and was beneficial in patients with heart failure and even older people.
While this research indicates the value of HIIT for patients with a range of health conditions, pharmacists should ensure that customers seek advice from their GP before embarking on HIIT.
Finally, HIIT is not without problems and exertional rhabdomyolysis (dissolution of muscle) has been reported in people who participate in vigorous and intense spinning classes. Nevertheless, the growth of HIIT gym classes is testament to the popularity of this form of exercise for achieving improvements in health and fitness but in the least amount of time.
