It’s a commonly accepted tenet that resistance training adaptations follow a “strength-endurance continuum” whereby lifting heavy loads maximizes strength increases while light load training leads to optimal improvements in local muscle endurance. Conventional wisdom also postulate...
November 19, 2011
First off, I want to apologize for my lack of recent posts to the blog. I’ve been swamped with projects as well as a seemingly endless sea of papers associated with my Ph.D. studies. Hopefully my workload will ease a bit in the coming weeks and I’ll have more time to provide ongoing content.
In the meantime, I wanted to take this opportunity to comment on the reaction by a select few fitness professionals to the review paper that Bret Contreras and I wrote titled, To Crunch or Not to Crunch. A small but vocal portion of the strength and conditioning community seems to feel that it’s heresy to challenge their dogged position that crunches are inherently evil. One strength coach has gone so far as to claim that we were “deliberately trying to be controversial” by stating that spinal flexion exercise is not necessarily a one way ticket to back surgery. Amazing! I’m of the belief that it’s controversial to claim the crunch — an exercise that has seemingly been around since the dawn of man — has no place in a person’s training routine. Go figure…
Here are the facts: Bret and I are not only practitioners, but scientists as well. When we wrote the article, our sole intention was to seek the truth. We reviewed hundreds of peer-reviewed articles on the subject — pretty much every study that was in any way related to spinal flexion — and took an unbiased view in our reporting of what we found. Based on the body of literature, there simply is not sufficient evidence to support the contention that healthy individuals should abstain from performing crunches. Moreover, there is even some research to suggest that it may have a positive effect on spinal health. Should evidence come out in the future that refutes these findings, we’ll be the first to acknowledge it and rethink our position. But as evidence-based practitioners, the recommendations we made in our paper are solidly in line with current research, personal experience, and the needs of the individual. This is the essence of evidence-based practice.
Are crunches for everyone? Certainly not. We clearly state in the article that they should be avoided by those with existing spinal issues such as disc herniation, disc prolapse, and/or flexion intolerance. But understand that the same is true for any exercise. Squats, presses and rows are all terrific exercises, but they may be contraindicated for a given individual depending on his/her goals, abilities, and injury status. As Stuart McGill has been aptly quoted as saying subsequent to publication of our article, “Crunches are neither bad nor good. The most important thing is the assessment to determine what’s right thing for the person in front of you. The next most important thing is to respect the load/posture/repetition variables in your algebra, i.e. don’t overwork the tissue beyond the ability to adapt or beyond its tolerance to failure.” I couldn’t agree more.
Unfortunately, there are those who choose to take a cult-like stance with respect to fitness. Rather than embracing new information, they instead cling to their rigidly-held beliefs and flame against anyone who poses a threat to their stance. This kind of attitude is not only unscientific, it’s unprofessional and can only set back exercise science and have a negative effect on the fitness industry as a whole. Ultimately everyone loses, including the general public who are caught in the crossfire.
Here’s an interesting anecdote. Back in the early 1960′s, a professor from the University of Texas named Karl Klein railed against the performance of deep squats. Klein conducted studies showing that weight lifters who frequently performed deep squats displayed an increased incidence of laxity in the collateral and anterior cruciate ligaments compared to a control group that did not, leading him to conclude that squatting below parallel had a detrimental effect on ligamentous stability. “Anything below a half knee bend,” he was quoted as saying in a 1962 Sports Illustrated article, “is useless and ruinous.” (Side note: The SI article was ironically titled “The Knee is Not for Bending.” Sound familiar? The similarities are eerie).
Now Klein was a distinguished researcher at the time and, as you may imagine, his claims had far reaching implications: The US Army subsequently removed squat jumps from their training protocols; the New York State school system banned deep knee bends from gym class; and the American Medical Association came out with a position statement cautioning against the performance of deep knee exercises because of their potential for severe injury to the internal and supporting structures of the knee joint. The upshot: For years, deep squats were widely considered passe. In fact, due to one man’s crusade, the negative view of deep squats is still being felt 50 years later as some continue to admonish the exercise as inherently dangerous.
Fast forward to today. Research has ultimately refuted Klein’s findings. No correlation has been found between deep squatting and ligamentous stability, including results from studies that attempted to replicate Klein’s methods. In fact, the prevailing body of evidence shows that ACL and PCL forces actually diminish at higher knee flexion angles. I covered this subject extensively in my NSCA Hot Topic article, The Biomechanics of Squat Depth. If you haven’t already given it a read, you may well find it enlightening, especially in the context of the current controversy over spinal flexion exercise. Could there be any parallels between the two topics? As they say, time will tell.
Bottom line is that it’s fine to have an opinion on a subject provided you’re open to other viewpoints. With respect to spinal flexion, I encourage you to read the research and draw your own conclusions rather than being swayed by some opinionated “fitness guru.” With a firm understanding of the available evidence, we can then debate the topic logically, rationally, and civilly to facilitate a better understanding of the issues. We shouldn’t care who is right or wrong, just that we ultimately get it right. Only through an open exchange of ideas can science move forward. This way, everyone wins.