We all know that wearing make-up whilst exercising is bad for our skin, so why do we still see gyms full of women wearing full faces of carefully-applied cosmetics? Mascara is one thing - though beware, you may find it running down your cheeks by the end of the session - but with foundation and powder you risk blocking pores and congesting skin that really needs to be able to sweat, sweat, sweat.
"When we get hot, several things happen to our skin. The first is sweating and the second is a slight relaxing and enlarging of the pores. Add a layer of even the best make-up on this and firstly you'll end up with streaky make-up, but you're also increasing the likelihood of a breakout," super-facialist Debbie Thomas tells us. "Your skin needs to breathe - during a good workout even more so. Mix in sweat, heat and open pores and over time the skin will become blocked. Not everyone will get spots, but most will get blackheads coupled with dulling and possible uneven skin texture."
Thomas recommends preparing for a workout by cleansing the skin, then either leaving it bare or applying a light serum suitable for your skin type which will penetrates quickly - a heavier product will just sweat off.
"I love the SkinCeuticals serums - Hydrating B5 hydrates dehydrated and tired skin and Phloretin CF is full of antioxidants. Because we create free radicals when we exercise, it is important to make sure there are enough antioxidants in the skin to counteract them," she explains.
A post-workout cleanse is just as important. With your pores enlarged, sweat and grime have even more opportunity to settle onto the skin and become trapped. "I would recommend a very light cleanse so as not to strip the skin, then you can apply your normal creams depending on time of day," Thomas says.
But what if forgoing make-up simply isn't a step you're prepared to take? The fear of bumping into someone you know whilst out on a jog is a very real one.
"If you must wear make-up during your workout try to use a light, oil-free, tinted moisturiser so that it's not as heavy. Then cleanse your skin as soon as possible - preferably before your skin cools down and your pores tighten again, trapping the make-up and grime in the opening of the pore which can lead to breakouts."
It's enough to deter even the most ardent of make-up lovers.