BBC Horizon’s Truth About Exercise

Last month BBC Horizon ran a programme entitled “The Truth About Exercise”. In it Dr Michael Mosley travelled the country speaking to an assortment of Exercise Scientists. One of the first points made was that it takes a lot of exercise to burn calories. In fact, the example provided was that to burn off a cappuccino, a blueberry muffin and a banana, one would have to jog around a track for about 55 mins! Therefore, to stand any chance of losing weight, we must control what we eat.

Fortunately, exercise can have benefits even when no weight is lost. One of the benefits mentioned was the production of an enzyme that helps redistribute fat in the body and sends it to the muscles where it’s burned. This helps reduce the chance of getting atherosclerosis and possibly death from cardiovascular disease. Other health factors that can be improved are insulin sensitivity and the body’s maximum oxygen consumption (VO2 max). Insulin sensitivity is important because it means that blood glucose levels can decrease more rapidly thereby requiring less secretion of insulin by the pancreas. This reduces the likelihood of developing Type 2 diabetes. As for VO2 max, it’s been found to be a good marker of health and longevity.

Next, Dr Mosley met Jamie Timmons, professor of ageing biology at Birmingham University, and was told how training for 7 mins 3 times a week could deliver many of the health and fitness benefits of hours of conventional exercise! The training is called High Intensity Training (HIT) and resembles interval training. Interval training has been around for a long time and has been used by athletes to increase cardiovascular efficiency and increase tolerance to the build-up of lactic acid. The HIT protocol used on the programme was done on a static bike and consisted of: 2 mins warm-up, 20 secs full-out, 2 mins gentle, 20 secs full-out, 2 mins gentle and 20 secs full-out. This added up to a whopping 7 mins and was done 3 times a week for 4 weeks. It’s thought that this type of exercise can appeal to those that are time poor and need to get it done quickly or simply don’t enjoy it and so want to get it over and done with swiftly…hmmmmmm? It’s at this point that I became curious about exactly how many people fell into this category…so I did a little survey among some of my clients.

First I asked them whether they did any exercise or took part in any sports. Amazingly 95% of them did!

I then asked them how many times a week they exercised or took part in sports. Again I was surprised…an average of 3.6 times a week. I started wondering whether they were trying to please or impress me? Apparently 80% of the population doesn’t exercise regularly!

Finally, I asked them why they exercised? This was the last curveball…the most popular answer was because they enjoyed it…it made them feel good! Other popular reasons were for fitness, health (hypertension, diabetes, back pain) and weight loss.

So unfortunately there didn’t seem to be any takers for HIT. The claims are that HIT can give around 24% improvement in insulin sensitivity and 10% increase in VO2 max. After 4 weeks Dr Moseley did in fact improve his insulin sensitivity by exactly 24% but had no change in his VO2 max. His inability to improve his VO2 max was put down to genetics. According to Timmons, research has shown that 20% of the population doesn’t respond to endurance training.

What do I think about the HIT programme? Well, it paints exercising as a chore, but as the survey showed, most people get more from exercise or sports than just an improved insulin sensitivity…they enjoy it, it makes them feel good…possibly because of the endorphin release or a sense of achievement or accomplishment, maybe even because of social interactions? The HIT programme didn’t place much emphasis on fitness but other HIT protocols have. Gibala’s studies have shown benefits but his protocol was longer and a lot more gruelling…definetly not for everyone. There are many components to fitness: endurance, strength, flexibility, speed, agility, etc and I suppose people in the survey were happy to focus on particular aspects of this.

My main issue with the HIT protocol is its intensity. Pedalling “hell for leather” without a warm-up (not one that can be recognised as one anyway!) seems like a recipe for disaster. As a physiotherapist, I was a little uneasy watching Dr Moseley bounce around on his bike whilst pedalling as hard as he could for 20 secs…he should have known better after pulling a hamstring earlier in the programme when trying to sprint without any earlier warm-up…who knows, he may have felt comfortable doing it because he was surrounded by scientists? Surely this is not something that should be recommended to the sedentary masses?

The main drive of the HIT protocol seemed to be on health (primarily insulin sensitivity) and I think there are better, safer and more convenient ways of achieving this. New research published in the journal Diabetes Care has concluded that after meals, regular short bouts of light-intensity or moderate-intensity walking lower glucose and insulin levels. The subjects were asked to walk around for 2 mins every 20 mins. The light intensity walking decreased blood glucose and insulin levels by 24% compared to uninterrupted sitting. That figure is exactly the same as the one achieved by Dr Moseley after the HIT protocol.

If you enjoy exercise or sport and are happy with the fitness you’re achieving, keep it up! If you don’t enjoy exercise or sport and are mainly doing it for health or weight loss, you’re unlikely to keep going very long. My advice would be to focus on increasing your movement through activities of daily living…this was also talked about on Horizon but it seemed to get much less attention than HIT…in my opinion it’s where the real revolution lies…check in next week to find out more…