Q I’ve just started running, in a bid to get fit after a good few years of neglect. Thing is, I still smoke and am finding it hard to give up. Just how much is my smoking going to effect my running?

A Let’s deal with the damage to your lungs first. Cigarettes contain a cocktail of harmful chemicals that attacks the delicate structures of the lung with devastating consequences. Most people think that the only consequence of this damage is lung cancer, but a more common consequence of smoking is the development of chronic obstructive pulmonary disease (COPD).

lthough this doesn’t normally manifest itself until early middle age, it is developing throughout the smoker’s life, and will actually become apparent earlier in a regular exerciser than in a sedentary smoker, because the sedentary smoker does not push their breathing to its limits. COPD causes the alveoli to collapse, reducing the surface area available for gas exchange, and the airways to become floppy.

The reduction in surface area hampers the lung’s ability to transfer oxygen efficiently. The floppy airways mean that, as you breathe out, the airways collapse. This causes increased breathlessness and also makes breathing more difficult.

The smoke also induces inflammation of the airways, causing them to swell and produce mucus (chronic bronchitis), and paralyses the cilia (small hair-like structures that propel mucus and particles out of the lungs), which increases the likelihood of chest infections.

As far as the immediate effects of smoking are concerned, the main performance-related consequence is carbon monoxide (CO) ‘poisoning’. Smokers have high levels of CO in their blood – the more cigarettes they smoke, the higher the level. CO combines more easily with haemoglobin than oxygen, so it reduces the oxygen carrying capacity of the blood, reducing maximal oxygen uptake.

You may not perceive any problems with your breathing now, probably because the damage progresses very gradually so that you are unaware that you’re more breathless. But every cigarette is inflicting damage to your lungs that will result in impaired performance and disease in the long term.

The good news is that if you quit, many of these damaging changes can be reversed. It has never been easier to get help to quit smoking, and you are twice as likely to succeed if you use the free nicotine replacement therapy (NRT) that is available from all GPs. You can also get help by calling the NHS smokers helpline on 0800-169 0169 or by visiting www.givingupsmoking.co.uk.

—Dr Alison McConnell, exercise physiologist specialising in respiration at Brunel University