Inactivity – fuelled by cars and a sedentary work life – has been dubbed the biggest public health problem of the 21st century, a global pandemic with dramatic impact on peoples wellbeing. The latest reports suggest that around the world it was responsible for 5.3 million deaths in 2008 – around one in 10 – more deaths than smoking.
Not only does exercise make you fitter, it can also ward off numerous and often unexpected diseases, from heart attacks, to diabetes, some forms of cancer and dementia. There are tentative signs it might even make you cleverer, by boosting cognitive performance and brain function.
"It's irrefutable that physical activity and exercise are beneficial for health," says sports scientist Chris Easton, at the University of West Scotland.
Latest government guidelines recommend adults under 65 should do 150 minutes of moderate physical activity every week, in bouts of at least 10 minutes. Worryingly, only a fraction of the population manages even that. In the UK just 14% of adults exercise regularly. However, a growing number of sports scientists advocate brief
intensive training sessions to achieve the same health gains. The latest class to hit London's Fitness First gyms is called Tabata, which claims that just 4 minutes of exercise, in 20 second bursts interspersed by 10 seconds of rest, is enough to significantly boost your fitness and get you in shape. The workout is named after the Japanese scientist Izumi Tabata who tested it on the Japanese speed skating team in the 1990s. When Tabata put a group of students through this regime five times a week for six weeks, they ended up significantly fitter than another group of students who ran at a medium intensity for an hour on a treadmill.
But can just four minutes really beat an hour of running? When it comes to fitness, the idea is that during the short bursts your body exceeds its VO2 max and switches into anaerobic respiration, giving you a much bigger impact on fitness. It also seems to help in people with some medical problems, such as metabolic syndromes – which includes diabetes.
Not everyone is convinced though. David Stensel, at the University of Loughborough, cautions that although the benefits for physical fitness are well established, when it comes to preventing disease more research is needed. Besides, he says, "you're not going to persuade large numbers of middle aged people to do that form of exercise on a regular basis. I don't think it's going be the answer from a public health standpoint."
WEIGHT TRAINING
The latest government guidelines prescribe weekly weight training for all. Is is all strength and no cardio?
Not so. "Lifting weights doesn't conjure up images of something that would change your heart structure," says Easton, "but in actual fact it does. And there is quite good evidence now that resistance training, if it's done in the right way, can be beneficial to cardiovascular health." Easton says that these benefits of weightlifting pretty much follow the same principles as high intensity exercise such as spinning. "Essentially weight training is very high intensity exercise."
Any other benefits?
Strength training has also been shown to help ward off diabetes, arthritis and depression. Resistance training is important for the elderly because it helps to maintain muscle mass.
With the ageing population, one of the big concerns is people getting frail, says Timmons, who is studying weight training with elderly people.
"At 60, you don't tend to die of frailty. If you keep going to 80 then you tend to have weak muscles and bones," he says. "If you fall, lose your balance, fracture – that's very much what drives poor quality of life and mortality."
How much should you do?
The government guidelines on exercise recommend two sessions a week, for instance lifting weights at the gym or merely carrying shopping bags. The subjects in his research spend time weight training at the gym like anyone else. "We take them to the gym three times a week and we do progressive weight training – multiple sets, 6-10 reps," Timmons says.
What is he looking at?
Timmons hopes his research will help shed light on why a quarter of people don't seem to improve their muscle strength at all despite the training.
"They are switching on all the processes we expect would lead to muscle growth, but for some reason that's not been integrated into a gain in muscle tissue function." He hopes that by next year, he will have a way of diagnosing these non-responders, so he can get to work on trying to find a solution – for instance they may need more recovery days or a different diet.
Doesn't it also boost your metabolism?
One of the most widely touted benefits is the idea that weight training, including increasingly popular choreographed weights classes such as Body Pump, is that lifting weights keeps your metabolism stocked up for hours after you leave the gym.
"I don't think it is correct to put a figure on how long it is increased for after a weights training session, because it will be dependent on the person and the intensity of the session, but probably something in the region of between three and six hours is not unreasonable for a very vigorous session," Easton says. "If you do a few push ups in your lunch hour then you are not going to get those benefits."
Lifting weights could also help boost your metabolic rate – the calories you burn without doing any exercise – just going about your daily business. According to the American Centers for Disease Control, weight training regularly can boost your metabolic rate by as much as 15%.
Why?
This is partly to do with replacing fat with muscle, because muscle is a more metabolically active tissue that fat, which means it will burn through more energy just at rest. The more you have the more energy it will consume, plus, you will have to use more energy to carry it around (although the same could also be said for fat of course).
So by having more muscle you automatically burn more calories?
Yes, but how much energy muscle mass burns is often overstated. A common myth is that each kilogram of muscle burns about 100 calories per day, so if you gained, say, 1kg of muscle through weight training you would burn an extra 100 calories a day without needing to lift a finger (plus all the calories you have spent getting the muscles in the first place).
Sadly, those figures are inflated, according to the experts, and the real figure is a fraction of that, although it is pretty hard to measure precisely. But in the long term, even a small effect is not to be sniffed at, says Timmons.
CYCLING
Cycling is fun and easy – but is it good exercise?
