Can vigorous exercise fight off flu?
Exercise is known to bring many health benefits, which is why people work with personal trainers, attend classes run by fitness instructors and play sport to improve their fitness levels.
But a recent study has gone a step further in suggesting that vigorous exercise might be able to fight off the flu.
What is flu?
Many people confuse flu with a heavy cold as some of the symptoms are similar. However, while someone with a cold can continue with their daily activities including going to work, a bout of the flu is much more debilitating.
The fever and aching muscles that accompany symptoms such as a sore throat, cough and headache usually require bed rest of up to a week and can leave the sufferer feeling tired for some time afterwards. Because flu is infectious, it’s a good idea to avoid contact with others.
Exercise and the immune system
A strong immune system not only helps us to recover when we suffer from an illness but it can help prevent us becoming ill in the first place. A personal trainer will usually recommend that a client should follow a healthy diet (see our blogs on The benefits of reducing sugar intake, How to avoid weight gain during winter, Do you know your macronutrients? and Exercise v diet), get plenty of rest (see our blog on The importance of sleep for exercise recovery and performance and avoid smoking, as well as exercising regularly, in order to ensure that their immune system is working at its optimum level.
Preventing flu with vigorous exercise
New data from the London School of Hygiene and Tropical Medicine’s online Flu Survey has suggested that we can reduce the chance of developing flu by carrying out two-and-a-half hours of vigorous exercise – or more – every week.
An annual event launched in 2009, the Flu Survey invites members of the public to register and log in each week with information about whether or not they have any of the symptoms associated with the flu. Those who register are also asked questions such as their age, whether they have had a flu jab and how much time they spend a week carrying out vigorous exercise. Because many people who have flu don’t visit their doctor, the survey is able to gather data that isn’t available through GP surgeries.
Based on the answers from the 4,800 or so people who took part this year, the report suggested that for every 1,000 people, 100 cases of flu could be prevented by taking part in regular vigorous exercise.
The type of exercise classed as vigorous could be anything from running (see our blog on The pros and cons of barefoot running) or cycling at speed to competitive sport – a personal trainer would be able to advise on the options for their clients (see our blogs on Personal Training: The FITT principle and Energy expenditure during exercise). It appeared that there was no similar link to a reduction in flu for those taking part in moderate exercise, such as fast walking.
One of the authors of the report, Dr Alma Adler, a Research Fellow at the London School of Hygiene and Tropical Medicine, said: "We need to treat this result cautiously as these are preliminary findings. However, they are consistent with findings for other conditions and really show the health benefits of exercise.”
Encouraging clients to work hard in a personal training session
While the survey found that reports of flu-like symptoms were down from last year – 4.7% compared with 6% last year – anyone who has suffered from the flu will know how unpleasant it can be.
For personal trainers and fitness instructors, the survey’s findings could be a good incentive for their clients to work hard during training sessions and to carry out at least two-and-a-half hours of vigorous exercise each week.
However, it should be noted that while aerobic exercise can help open up the airways for those who have a cold, if clients are experiencing flu symptoms, they should rest and refrain from vigorous exercise until they recover. This is particularly important if they have a fever, as exercise is likely to raise their temperature further.