Fitness experts are now advising against doing too many sit-ups for risk of back injury.
According to the Wall Street Journal, Stuart McGill, a professor of spine biomechanics at the University of Waterloo, says sit-ups put hundreds of pounds of compressive force on the spine. This pressure combined with the repeated flexing motion of a sit-up can squeeze spinal discs and possibly lead to herniation.
Others are catching on. The Journal reports that an editorial in a paper covering the U.S. Navy has called for taking sit-ups out of annual fitness tests, and the Canadian Armed Forces has already done away with them. The creator of the P90X workout also says he no longer does sit-ups.
What to do instead of sit-ups? Experts recommend the plank pose, which works out core muscles but puts less harmful pressure on the lower back.