Mike Reinold posted some interesting findings with the difference between back squats and front squats with some EMG research. While comparison between exercises is a great start, most programs are holistic and include an array of exercises. The fear with back squats is that the spine will get injured, and even bilateral lifts are being dropped in favor to single leg options in order to decrease the risk of compression, shear forces, and mechanical strain from technique errors. Eliminating or reducing forces may decrease injuries to the spine, but eventually you have to play and performance is the end of the road. Injury reduction is number one, but not playing because of a decrease in performance or not performing at a high level is not a solution. Also athletes are able to perform at high levels without much training, making a large discrepancy between preparation and performance. When you train well, you increase the buffer zone, or the risk and performance threshold, but not stressing the body safely is dead end or a path to failure. All exercises have specific risks, and load (weight) is an increase. With increases of rhabdomyolysis in the media we know fatigue is also a risk, and high rep work is also a risk as technique will be often compromised.
So what are some solutions? Well use the minimum load to achieve what is necessary. Sufficient loads don’t mean doing single leg exercises with a weight vest. Many times the weights are multipliers of bodyweight and that is fine, since sport often demands 4-6 + times one’s bodyweight. Without eccentric strength, the most efficient movement is not effective.
Maximally load bilateral lifts with great technique and progressive loading. While Bosch may be promoting single leg olympic lifts, where is the bilateral deficit working as no documented performances with the exercise have shown to increase power. I always ask people talking about movement quality what they do after they get people cleaned up and what power is necessary to be better or competitive. Movement quality is a starting point and progressive loading is a law of sports science, not an option.
Bilateral lifts are symmetrical, so we are able to distribute strain on the knees and hips, two areas that are important and help decrease the stress to the spine. Forces go up through the legs starting with the feet, and we are seeing a huge influx of joint mobility work on the feet to help the hamstring and low back injuries we are seeing in Athletics. A bad knee or hip usually goes up the chain, meaning the back is going to take up the slack if the knees and hips are compromised. Robbing Peter to pay Paul with single leg exercises means paying the piper down the road.
Some lifts are not symmetrical, such as the jerk and many single leg exercises. Nothing wrong with having purposeful exercises that challenge the base of support. Researchers are looking at the spine to see the effects of loading exercises such as the split jerk, Modified Single Leg Squats, and Lateral Squat as we speak. Asymmetry in single leg exercises have more risks to rotary forces to the lumbar spine. One exercise such as the bulgarian squat/lunge can anteriorly rotate the pelvis, increasing the shear forces to the spine, especially if the bar is loaded on the back. Many athletes have tight hip flexors and pulling on the anterior inferior iliac spine from the rectus attachment. Looking at any freestyle wrestling meet you will see a foot being grabbed from behind and the athlete quickly falls forward unless he escapes. The same applies to the Bulgarian when rear foot is too far back or contributing more as the loads increase. Efforts to decrease spinal compression with the absence of squatting are not without risks. A bar on the back with a less stable base from a split stance with the rear foot on a toe is not proven to be safer through any research. Keeping the rear leg closer at more of a 90/90 position rectifies the problem but decreases the balance leg and the overall load, thus decreasing the exploitation of the bilateral deficit. EMG studies on the balance leg to see it’s contribution in progressive loading have been proposed already.
The Jerk is now looked at with new eyes. It’s not considered a single leg exercise but because of bulgarian trends people are looking at it and seeing why people are able to create rapid balance in a position of asymmetry. The body is able to adapt, but without reference from balanced symmetrical exercises the body has less reference points. I am not worried about the jerk as the forefoot has amazing abilities to create balance, but tips of the toes or top of the foot is not as effective.
Various single leg exercises are very effective for injury reduction with muscle balance and recruitment, but prime movers are still prime for many things besides propulsion. The major muscles of the legs have been researched to dampen and redirect forces, and not preparing major muscle groups is foolish. Load the single leg exercises but don’t depend on them.
All exercises have risks, and no exercise is free of sin. It’s important to have a complete program and remember that stress is not just from weight, but a myriad of possible variables.