Image copyright Getty Images Image caption Asthma symptoms can be brought on by exercise in elite athletes

Professional footballers should be screened for exercise-induced asthma, researchers say, after a study found three in 10 could be affected.

University of Kent scientists used lung tests to identify players with symptoms and improved their fitness after treatment.

Elite athletes are known to be prone to asthma-related problems because of their high-intensity breathing.

Experts said screening made sense and could prevent later problems.

In the study, presented at a meeting of the British Thoracic Society, 97 footballers in England from two Premier League clubs, one Championship club and a League One club had their lung health tested during pre-season.

Coughing and wheezing

Twenty-seven players tested positive for airway or breathing problems, also known as exercise-induced asthma.

Ten of those had no previous history of asthma or airway problems.

When they were treated with appropriate medication, their symptoms - such as tightness of the chest, wheezing and coughing after playing - reduced, and their lung function improved over time.

The researchers also found that their aerobic fitness and performance on the pitch improved.

Image copyright Getty Images Image caption Airway problems can be treated using lung health screening, experts say

Dr John Dickinson, from the school of sport and exercise science at the University of Kent, said although top football clubs were good at screening players for heart problems, they were not carrying out tests which could identify respiratory problems - which were much more common.

"Clubs can't rely on players reporting symptoms because they are not always that obvious and sometimes they are written off as poor fitness," he said.

The researchers used medical tests to assess the footballers' breathing, airway function and how efficiently they could empty their lungs.

They were then able to detect asthma-related symptoms accurately and tailor treatment for those affected.

Improving the health of footballers' airways also has other benefits, Dr Dickinson said.

"They are less likely to pick up coughs and colds."

What is asthma?

It is a common lung condition caused by inflammation or swelling of the breathing tubes that carry air in and out of the lungs

It can cause wheezing, breathlessness, a tight chest and coughing

This can occur after exposure to a trigger, such as allergens (pollens, animal fur and house dust), cigarette smoke, gases, cold air, exercise and chest infections

Asthma can affect people of all ages and the severity of the symptoms varies from person to person

Exercise-induced asthma only happens during or after exercise

Source: NHS - Asthma

High rates of exercise-induced asthma have been found in other sports among elite athletes.

Experts believe it may be connected to athletes exercising regularly at high intensity which means their breathing rates are also high

When the air is cold and dry, and if there is exposure to air pollution or other allergens like pollen, this could worsen symptoms - but more research is needed to confirm this.

Dr Lisa Davies, consultant respiratory physician and chairwoman of the British Thoracic Society's board of trustees, said lungs were pivotal to exercise and life in general.

"In key sports, where the lungs are worked hard and are prone to repeat exposure to different and challenging internal and external conditions - it really makes sense to have lung health screening, so if there are any airway problems they can be treated."