Since the ancient Olympics, athletes like Hyrox competitor Joanna Wietrzyk have experienced runner’s diarrhoea. What does the science say about extreme exercise’s ‘mechanical jostling of the intestines’? Soiling yourself in

Loop and tube bands are cheaper than a gym membership and take up less space than weights – our exercise buff put 18 to the test • The best treadmills

From sweaty kit to grubby trainers, here’s how to wash, repair and care for activewear more sustainably • The best moisture-wicking underwear, socks and base layers As a running and