Here’s something if you want to impress at the local swimming baths with the “I bet I can hold my breath longer than you” challenge; the POWERbreathe Ironman PLUS (or indeed the Iron Girl).
It’s a device not dissimilar to an inhaler, but by using it a couple of times each day and gradually building up the resistance levels, it builds up your lung strength and capacity.
Being an asthmatic myself, not sure if I would end up a wheezing wreck on the floor after the first go, but it alleges to help those with breathing problems to restore their breathing power. Of course, they do not recommend you come off your meds and just use the Powerbreathe on its own as an alternative (but they do say that after perhaps as little as 3 weeks you may notice you’re not using your preventer inhaler as much). If, like me, your prescriptions cost a small fortune, this may be an idea to get the old lungs fit(ter) and thereby keep a few quid in your wallet.
For those however of a much fitter disposition, it should improve performance and exercise tolerance. It has light, medium and heavy resistance settings so can be suited to all levels of athletic ability.