Finally, you’re probably not doing tens of thousands of crunches. The pig spines studied were subjected to many thousands of flexion and extension cycles, Schoenfeld points out. The review notes that the total times a spine was bent in each study ranged from 4,400 to 86,400. “That’s not the way we generally crunch,” he says. “I don’t know people who do 4,000 crunches.”
To this date, though, there still aren’t any human studies on how crunches impact the spine, Schoenfeld says. Even though the only research we have is on dead animals, Schoenfeld says that the research that exists doesn’t necessarily have zero meaning—”there could be some extrapolation, and it does point to the fact that we need to balance volume and other factors, and if you overdo it, there might be issues,” he says. “But the literature should not be taken at face value and conclude that people should never do crunches.”
One other thing: Schoenfeld’s review mentions that there could potentially be some benefits to spinal flexion exercises like crunches, in terms of increasing spinal fluid exchange and promoting better nutrient delivery to the discs. Smith says that yes, spinal literature does suggest that loading the discs a certain amount could have benefits. Specifically, repetitively placing a certain amount of stress on the area may increase the flow of fluid and consequently, help nutrients travel throughout the spine more effectively. “Too much [stress] is bad, but too little is also bad,” Smith says. But he adds that what we should actually take away from that research is that it’s important to be active in general and use our core muscles regularly—not that we need to be doing crunches in particular. “Any good functional activity where you’re up and doing things, getting your core moving, is beneficial,” he says.
So should we be doing crunches or not?
Schoenfeld says that deciding which exercises to do and not do really just comes down to goals. If your goal is to get a faster race time, you’d do speed work, not heavy dead lifts. If your goal is to get stronger all over, you’d do heavy dead lifts, not speed work. If a certain move isn’t going to bring you any closer to your goals, then there’s probably no reason you should do it or feel like you have to. (Of course, not everyone has super-specific fitness goals. If you work out for general health and fitness, you probably don’t have to obsess too much about whether you should do one exercise versus another.)
That said, the best reason to do crunches is for hypertrophy (growth in muscle size) of the rectus abdominis. Crunches are an effective exercise for that, according to all experts I talked to. So if you’re a bodybuilder or physique competitor, crunches may be an important part of your training regimen.
But if you’re not, and your goal is to strengthen and stabilize your core (including the rectus abdominis!) overall, you probably would be fine never doing crunches again and just focusing on other exercises that keep your core strong and healthy (more on that in a bit).
Also, if you have certain back problems or injuries, you may want to avoid crunches. “It’s better to err on the side of caution and not use them if you have spinal discomfort without being able to [pinpoint what’s causing it],” says Schoenfeld. If you’re ever unsure about whether crunches (or any other exercise) are safe for you, always talk to your doctor.****
Here are some more efficient core exercises if you’d like to skip crunches forever.
Working your core is great for your health and stability, but for the majority of us, that means doing exercises that work multiple muscles that make up the core at once and help us both strengthen and stabilize this important area as a whole. Having a strong core is critical for supporting your body through daily activities, workouts, and sports. Plus, maintaining strength and stability can be helpful for avoiding lower-back pain and discomfort.