It's a common sight in a gym to see someone performing Physioball Crunches or similar trunk flexion exercises. They burn like Hades and are the only way to target your abs.
Right? Wait. Not so fast.
There is an ongoing debate in strength and conditioning circles about the safety and benefit of trunk flexion exercises. Some coaches have completely eliminated them from their programs, while others still use them as a mainstay of their core workouts.
You may not be a strength coach, but there's a good chance you work out on your own at some point. So it's important that you understand the debate so you can make the best core exercise selection.
At Performance U, we believe there's no reason to completely eliminate trunk flexion exercises, because they aren't inherently dangerous if done correctly. You just need to avoid extreme ranges of motion and have no pre-existing back or spinal issues. Bret Contreras and Brad Schoenfeld conducted a study that supported this position.
When considering all of the available evidence, we simply don't see how anyone can take a definitive stand on the issue.
That being said, we certainly don't think that this type of training should be emphasized, especially over integrated, compound core training. (See my article on the Complete Core Workout.)
The Physioball Crunch is an exercise we've used with both athletes and fitness clients. However, if we had to pick one "go-to" abdominal strengthening exercise, it would be the Physioball Pike Rollout.
A 2010 study published in the Journal of Orthopaedic and Sports Physical Therapy compared core muscle activation using a physioball with traditional ab exercises. The study showed that the Physioball Rollout and Physioball Pike most effectively activated the upper and lower abs, obliques and lats, while limiting low back and hip flexor activation.
A Crunch will work your abs, but Rollouts and Pikes more effectively isolate them. And, they limit stress on the hip flexors and low back, which are often overworked.
Physioball Pike Rollout How-To
In light of the results from this study, we combined the Physioball Pike and Rollout to form what we consider the ultimate ab exercise. If you have to choose only one ab exercise, look no further.
The video at the top of this article shows you how to perform the Physioball Pike Roll Out. Start with two sets of six to eight reps and gradually increase the volume or lever arm as you get stronger.