I first discovered the GHD sit-up exercise when my business partner forwarded me some images of it being performed; he knew that I might not be able to believe my eyes and thought it would be funny to send it to me. Initially, I thought it was some kind of crafted humor that you might see in a mass email.
Clicking on the link in the email brought me to a web article of the GHD exercise where the tone was serious and the exercise was being promoted. Oh my. Immediately I wanted to know a little bit about how this exercise was founded, who was doing it, and how long it has been around.
After doing a little research, I learned that GHD sit-ups are re-emerging into the fitness industry from an organization called CrossFit. GHD situps (formerly known as the roman chair situp) are now gaining popularity in gyms even outside of the CrossFit organization. When such an exercise like this starts to go viral in the strength and conditioning world, I take the time and energy to dissect it and explain the benefits and or drawbacks to my clients. In the particular case of the GHD sit-up exercise, I hardly have any benefits to add from my dissection.
Below are the hard facts as to why glute ham developer (GHD) sit-ups are not safe for the majority of people.
1. If you blow out a disc in this position, it would be particularly nasty. You would need to have someone move you out of that position, which could cause more damage.
2. Dangerous shear forces are exerted on all five the lumbar discs when rising up from the bottom of the exercise. The hip flexors (medically known as the illiacus, psoas, rectus femoris and sartorious) are the prime movers in the exercise. Within the hip flexor group, the psoas is a muscle that connects directly into transverse process T-12 and through all lumbar segments. Additionally, the psoas inserts into the lateral aspects of all lumbar discs. Too much force going through this muscle can cause some serious back problems.
3. Since most people are weak in the abdominal muscles in comparison to the hip flexors, this exercise is likely to further promote a strength imbalance. The abdominals do have to work extremely hard to stabilize the movement so they will get worked, but not in the degree that the psoas muscles need to work.
4. There is a high risk of tearing an abdominal muscle. Due to the extreme difficulty of the exercise, it is hard to “build up to it”. As stated in point #3, the abdominal muscles are heavily taxed as they must counter forces going through muscles crossing the hip joint. The problem is, most people cannot properly stabilize a movement like this with their abdominal muscles. If you do not have a finely tuned, properly functioning abdominal wall- the risk for abdominal strain skyrockets. Most abdominal type exercises are not even close to being as risky as the GHD exercise regarding risk of abdominal muscle tearing or strain.
5. There is a high risk of cramping the quadratus lumborum (QL), a muscle that arises from the pelvis and inserts into 12th rib. When under enough load in spinal flexion, the QL is activated, but it has a poor mechanical advantage, often resulting in a muscle strain. As seen in most health clubs, the seated abdominal crunch machine can be quite the culprit for QL strains. However, abdominal crunch machines (which I despise as well) are much safer than GHD sit-ups due to the legs being fixed in a flexed position. …Which brings me to point #6.
6. Due to the higher rate of speed in full spine flexion at the top of the range of motion, a posterior lumbar disc bulge is much more likely to happen due to the legs being locked. When you lock the knees, the hamstring and leg muscles pull down on the pelvis so that it cannot rotate forward like it normally would. One of the most common ways to injure your back is to have your legs locked in extension when reaching over a piece of furniture to open a window. This exercise is somewhat analogous to lifting a window while locking the legs.
7. There is a risk of severe hip flexor muscle strain, especially in those people who may have weak hip flexors. The hip flexor in this exercise is the prime mover, moving over 70% of the total body weight. This brings me to point #8.
8. About 70% of the total body weight is being lifted, due to the apex point being located directly under the middle to upper femur, creating an aggressive lever on the hip, low back and sacral area. Creating a heavy and long lever in the hip/back area and add in a little speed and you have yourself a nice little chiropractic basket.
9. When rising up to the top of the position, the knee has a tremendous amount of extension forces going through it, subjecting it to both hyper-extension and shear.
10. There is a high risk of tearing the hamstring muscle due to the legs being locked and the speed of the movement at the top range of motion.
There are many different exercises out there which strengthen the trunk and hip flexors. The risk versus reward just doesn’t add up well with the GHD sit-up exercise. Come to think of it, the only reward will be a financial one for an orthopedic surgeon when he has to operate on the GHD sit-up victim.
In the strength and conditioning arena, GHD sit-ups is not the first, and will not be the last exercise that blatantly needs to be policed.