High-intensity workouts are safe... even with heart problems

I HAVE been a big fan of high-intensity interval training (HIIT) since 2012, when I met Professor Jamie Timmons, who pioneered the research in this area.

He said I’d see significant improvements in my aerobic fitness and blood sugar levels if I committed to just a few minutes’ exercise a week. And, sure enough, after a few weeks of doing very short bursts of high- intensity training on an exercise bike, I noticed big improvements in my overall fitness.

But soon after I started extolling the virtues of HIIT, the broadcaster Andrew Marr had a stroke, which initially appeared to be caused by overdoing it on a rowing machine.

As a result, many people came to believe that HIIT is potentially dangerous, and best avoided unless you’re young, fit and healthy.

But the truth is that HIIT, done properly, appears to be safe, even for people with heart problems. And a recent study by University Hos- pitals Coventry and Warwickshire NHS Trust adds support to that claim. They put 382 heart patients — average age 59 — through a twice-weekly exercise programme: either 40 minutes of moderately intense cycling, or ten minutes of intense cycling, broken up into one-minute bursts, followed by a minute of gentle peddling.

After eight weeks, all the participants had improved their fitness, but the HIIT group saw the biggest improvements. The researchers concluded that this approach is safe and effective, even for those with pre-existing heart disease.

So what happened in the case of Andrew Marr? When we later met, he told me that before his stroke, he’d had a couple of mini-strokes, or TIAs (transient ischaemic attacks), which he’d ignored, not realising their significance. On one occasion, for example, he’d briefly lost the power of speech, which he put down to overwork.

Doing vigorous exercise may have dislodged a pre-existing blood clot, but it’s unlikely to have been the real cause. The tragedy is that if he’d been aware of some of the common warning signs of a TIA (e.g. slurred speech or facial drooping), he could have been seen by medics and a fullblown stroke likely averted.

With any form of exercise, it’s best to start gradually. But you shouldn’t be afraid of injecting a little bit of intensity, even if it’s just pushing yourself a little bit harder when out on a walk.