If you are holding it in when you really need to go you put your kidneys under intense strain and if you do it regularly it's even worse. (fitnessandpower.com)
Keep in mind that having two consecutive pregnancies close together puts a more intense strain on your body. (bellefit.com)
Until now the covenant has not been put on a statutory footing, but intense strain on the armed forces in recent years - especially during the period when British soldiers were serving overseas in both Iraq and Afghanistan - has helped increase pressure on politicians to change that. (politics.co.uk)