Can electric shocks really make you fitter?
Wearing a padded suit with electrodes to stimulate muscles during workouts is the latest gym fad. But is it really a good idea, asks Michael Mosley.
Most people know about the benefits of doing exercise. These include reducing your risk of cancer, heart disease, stroke and type 2 diabetes. We should also know (it's repeated often enough) that according to government guidelines we need to be doing at least 150 minutes of moderate exercise a week.
The good news is that when people are asked, in surveys, how much exercise they do, most claim to do at least these sorts of levels. What is less reassuring is that when researchers look at what people actually do (by asking them to wear accelerometers which measure movement), they find that we tend to massively overestimate our levels of activity.
Now, one of the main reasons that people give for not doing more exercise is "lack of time". It certainly used to be my excuse. That is why I am a fan of high intensity interval training (HIIT). I first came across this form of exercise when I was making a film, The Truth About Exercise, for the BBC science series Horizon. In the course of making the film I met Jamie Timmons, professor of precision medicine at King's College, London, who assured me that I could get many of the major benefits of exercise from doing a few minutes of HIIT a week
I followed his six week programme of HIIT, on an exercise bike, and, as predicted, saw significant improvements in things like my blood sugar levels.
Since then I have maintained that regime, and thrown in some strength building exercises that we featured on a recent series of Trust Me I'm a Doctor.
Although HIIT and strength-building exercises are now a fairly standard part of any exercise regime, these days they can come with an added twist. Electric shocks.
One of the latest fitness fads is called whole body electrical stimulation, or ES. The idea is that you get into a padded suit that is dotted with electrodes and these will then stimulate muscles all over your body while you are exercising.
The claim is that by doing this you can get the benefits of an hour's workout in about 20 minutes.
Sadly, it is not enough to simply get into the suit. You also have to do a conventional work-out (squats, lunges, running and jogging on the spot, abdominal crunches etc), while the suit is giving you lots of little electric shocks.
The shocks won't make doing these exercises easier - they actually make a workout harder. Much harder. And more painful. The effort, and the pain, it's claimed, will also make doing the exercise more effective.
I haven't personally tried out one of these suits, but I'm told it turns even the simplest squat or lunge into a real, sustained effort.
Using electric shocks to improve physical performance is not quite as unlikely as it sounds. Electrical stimulation has been used as an effective form of rehab for many years. If, for example, you have a muscle which is not being stimulated due to nerve damage, then applying an electrical current can help restore muscle mass, or at least stop it getting any worse.
But is it really a good idea to stimulate lots of muscles all over your body, rather than a few specific ones, if you are otherwise healthy?
Dr Nicola Maffiuletti, from the human performance lab at the Schulthess clinic in Zurich, thinks not.
In a recent letter to the BMJ he and his colleagues expressed concern that "despite limited scientific evidence on the safety and effectiveness of this form of exercise", fitness centres in many countries (including the UK) are now promoting ES to the general public.
In terms of potential risks from this sort of activity, Dr Maffiuletti points to the case of a 20-year-old man who came to his hospital complaining of severe muscle pain shortly after a gym session "based on whole body ES exercise supervised by a fitness professional".
After they had done some tests they discovered that the young man had rhabdomyolysis (muscle breakdown), a serious condition where you see widespread destruction of muscle fibres. This leads to the release of a protein called myoglobin into the blood, which can then lead to kidney failure (if the kidneys are unable to cope). In this case the patient had to stay in hospital on an intravenous drip for five days, while they monitored him.
In response to Dr Maffiuletti's work, the Israeli Ministry of health has recently warned that ES devices "are intended for use by skilled healthcare professionals (primarily physicians and physiotherapists) for the purposes of diagnosis and rehabilitation. The devices must not be used in gyms. Use without medical supervision could cause danger to health".
I think I will stick to the more conventional uses of electricity.
More from the Magazine
Is it better to run outside or on a treadmill? (January 2016)
Can you cheat your way to fitness? (October 2014)
How much better is standing up than sitting? (October 2013)
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