The dream of toned abs and a tight butt might have prompted you to embark on an exercise programme, but as the new year and its good intentions slip further into the past it becomes difficult to stick to any training plan, however gentle.
What's more, exercising does seem somewhat vain. Is working up a sweat simply to squeeze back into your skinny jeans the best use of your time?
There are far better reasons to keep fit than weight loss. The real benefits of exercise are the spectacular ways in which it can improve our health. Regular exercise can help to prevent a number of common and chronic ailments, including flu, cancers, depression, high blood pressure, diabetes and strokes. It can even make you cleverer.
We're all hung up on quitting vices such as smoking, but couch potatoes are at as much risk of developing serious illness as smokers. This is not a get-out-of-jail-free card for smokers, rather a cautionary tale for people who take no exercise whatsoever. The NHS spent £74m trying to persuade us to quit smoking last year. Finding out that inactivity is just as lethal – contributing to heart disease, diabetes, hypertension, cancer, depression, arthritis and osteoporosis – should be enough to shock us into our sportsgear.
"We need to refocus the message on physical activity, which can have a bigger impact on health than losing weight," says Robert Sallis, the co-director of sports medicine at the Fontana Medical Center in California.
"Exercise can be used like a vaccine to prevent disease, and a medication to treat disease. If there were a drug with the same benefits as exercise, it would instantly be the standard of care."
Previous studies have found that exercise can reduce the risk of developing Alzheimer's disease by up to 40 per cent. The latest research shows that running is the best exercise for mental agility, and that jogging just a few times a week can stimulate the memory and even make your brain grow bigger.
The study investigated the recall abilities of mice after running and was carried out by researchers at Cambridge University and at the US National Institute on Aging. Researchers already knew that exercise boosts brain power. This new evidence reveals why it does so, and should help scientists to uncover methods of slowing down the mental deterioration common in older people.
Presidents Barack Obama and Nicolas Sarkozy have often been snapped pounding pavements while preparing for important global meetings, and even tubby Gordon Brown took to jogging through Hyde Park in the mornings.
Colds and flu
Depending on your age, fears about developing heart disease and cancers might not be your first priority, but taking positive action to fend off common colds and a week of feverish, influenza-induced bed-rest is an attractive prospect for everyone.
Research shows that regular exercise, which can simply mean a brisk 30- to 45-minute walk five times a week, can boost the body's immune system. This means our bodies are primed to kill off viruses and bacterial infections before they take hold. Exercise even improves the body's response to the flu vaccine.
According to Dr David Nieman, a professor of health and exercise science at America's Appalachian State University in North Carolina, regular exercise can be compared to "a cleaner who comes in for an hour a day, so by the end of the month, your house looks much better". Two types of immune cells circulate more freely in the blood during exercise, zapping any bugs. Although our immune systems return to normal after three hours, the benefits of the exercise accumulate, reducing the incidence of illness over time.
Dr Nieman's research shows that people who walk briskly for 45 minutes, five times a week for 12 to 15 weeks, suffer from fewer and milder colds and flu than lazier counterparts. This is good news for employers, as it means they take between a quarter and a half fewer sick days. "No pill or nutritional supplement has the power of near-daily moderate activity in lowering the number of sick days people take," Dr Nieman says.
The ways in which exercise can fight cancer – our great modern malaise along with depression – are incredible. Harvard Medical School has collated more than 60 studies from recent years to show that women who exercise regularly reduce their chances of developing breast cancer by 20 to 30 per cent. The reasons for this are not yet fully clear, but scientists expect it is because of the way exercise lowers oestrogen levels.
As well as reducing the chance of developing breast cancer in the first place, exercise slashes mortality rates and aids rehabilitation among cancer sufferers. A study of 3,000 women published in The Journal of the American Medical Association showed that breast cancer patients who walked for three to five hours a week at an average pace were twice as likely to survive as women who didn't exercise.
Exercise has been proved to cause a staggering reduction in the incidence of colon cancer, which affects 36,500 people in Britain each year and kills 16,000. Estimates of its success rate as a preventive treatment vary from 25 per cent to up to 60 per cent. The British Journal of Cancer reported the conservative 25 per cent recently, and said that all exercise, including manual labour, would count.
Why is exercise so effective? Our large intestines work like a sewage plant. What our body can use is recycled while the waste is stored for disposal. The longer it sits there, the more opportunity toxic matter has to seep out of the waste and into the surrounding tissues, causing, in the long term, illnesses such as cancer. Exercise gets the body and digestive system moving, thus reducing the time old waste sits in the colon.
Dr Kathleen Wolin, who conducted the research at the Washington University School of Medicine, said she hoped that in the future, it would be possible to give people specific details on how they could adapt their lifestyles to avoid cancers.
It is said that obsessive long- distance runners look old because of the repeated shocks the skin on their faces and necks (and elsewhere) has to absorb as they hit the ground with force. There is no new research to dispute this, but ongoing research is investigating how regular exercise can combat the ageing of our cells. Exercise has already been shown to reduce typical wear and tear – the ongoing damage sustained by cells that underlies conditions such as high blood pressure and cholesterol and Type 2 diabetes (the most common form and linked to obesity). Current research is investigating whether exercise lengthens strands of DNA known as telomeres. Telomeres prevent cells from dividing and remaining active if they get too short, which contributes to the ageing process and chronic illnesses.
In November 2009, a study published in Circulation, the journal of the American Heart Association, found that exercise did affect ageing at a cellular level. The study compared two groups of athletes with two groups of otherwise healthy but inactive people. It found the athletes' telomeres were in significantly better shape than the non-athletes'.
It is thought that if exercise affects the way cells age, it should affect the way our cardiovascular system ages, too.
How much exercise do you need to do?
As previously mentioned, other studies show that exercise can help to ward off heart disease, diabetes, hypertension, cancer, depression, arthritis and osteoporosis. Even if you don't need to exercise to lose weight, you should still get moving to keep your health in check. "Even lean men and women who are inactive are at higher risk of death and disease," Robert Sallis says.
So how much is enough? The NHS recommends fitting at least 30 minutes of moderate exercise into every day. Its definition of moderate includes brisk walking, walking uphill and carrying heavy bags back from a shop, all of which can be slotted into a daily routine. Lighter exercise might be housework, gardening or DIY, going for a short walk or playing with your children in the garden.
The benefits of vigorous exercise such as running, cycling, swimming, playing sports, lifting weights and doing exercise classes also come highly recommended. But this is where the advice gets tricky: although a fair amount of vigorous exercise is important, too much can be bad for us. Last year, a Norwegian study found that women who exercise daily or to the point of exhaustion are three times more likely to experience fertility problems.
Too much high-intensity exercise, such as training for a marathon or other endurance events, can encourage the release of stress hormones into the body, which then temporarily reduce its immunity, making infection and illness more likely. In a five-year study of 350 ultra-marathon runners, 25 per cent fell ill after a race.
If a 100-mile dash through the Sierra Nevada mountains is not on your horizon just yet, you have nothing to fear and everything to gain from sticking to a sensible exercise routine.
What exercise can do
* Treat depression as effectively as Prozac or behavioural therapy
* Lower the risk of developing colon cancer by 60 per cent
* Reduce the risk of breast cancer remission and mortality by around 50 per cent
* Lead to a 40 per cent reduction in cases of high blood pressure
* Cut the incidence of diabetes by 50 per cent
* Reduce the risk of stroke by 27 per cent
* Lower the risk of developing Alzheimer's by around 40 per cent
Source: American College of Sports Medicine