How much core strength most of us need, how to achieve it, how to measure it and how to define core stability and core strength are questions that remain largely unanswered by available science, said Stuart McGill, a professor of spine biomechanics at the University of Waterloo in Ontario and author of the book “Ultimate Back Fitness and Performance,” as well as of numerous, much-cited studies of core performance. “Core performance is quite an involved concept,” he said.
Even the importance or desirability of performing crunches, probably the most iconic and certainly the most common of core exercises, is uncertain....
No one needs to perform hundreds or even dozens of crunches, said Brad Schoenfeld, a professor of exercise science at Lehman College in the Bronx and an author of a newly published review article about core exercises titled “To Crunch or Not to Crunch.” And while everyone needs some basic minimum of core strength — getting up out of a chair requires a certain amount of core strength; serving a tennis ball requires more – “six or eight crunches would be plenty,” he said, “and only a few times a week.”
- "Are Crunches Worth the Effort?," New York Times Well blog
Well examines whether having a strong core helps athletic performance -- in one study of rowers, it didn't; in another study of runners, it did -- and whether crunches are even an effective core exercise.
Do you have a favorite core exercise? Does having a strong core make a difference for you?