From Charles Poliquin Live
The front squat is one of your best tools for preventing injury and achieving new levels of athleticism. Research shows you can use it to strengthen the lower back and get chiseled abdominal muscles.
A recent study compared the activity of the trunk muscles of the erector spinae and rectus abdominis in a variety of exercises. Using a load of 40 kg, electromyographic (EMG) readings were recorded for the front and back squat, and the military press. They were compared to muscle activity during an isometric prone bridge (also known as a plank) and isometric superman on a Swiss ball, both held for 30 seconds.
Results showed the following:
• Spinal erector muscle activity was greatest during the front squat, despite the fact that an empty 40 kg bar was used. Heavier loads will train the lower back muscles to an even greater degree.
• The prone bridge produced the greatest muscle activity in the rectus abdominis, followed by the military press and then the front squat.
• Previous studies show much greater rectus abdominis activity during the back squat using heavier loads in the 70 percent of the 1RM range, indicating that the relationship of muscle activity and exercise type is load dependent.
• It is reasonable to use the front squat with heavy loads to train the rectus abdominis muscle as well. A review of how load, stance, and type of squat influences muscle activity found that a loaded front squat works the rectus abdominis, quadriceps, and erector spinae better than the back squat.
The researchers suggest the dynamic front and back squat and military press exercises are preferable for healthy trainees because they require stabilization of the abdominal and trunk muscles during a multi-joint movement, which is representative of daily living.
The plank and other isometric exercises may be useful in injured or the most deconditioned trainees because they teach them to contract the muscles for stabilization. Beyond that, they are largely useless because the plank and superman are performed in a nonfunctional static position that is rarely replicated in daily life or sports.
Another benefit of the squat is that it trains the entire lower body musculature across the functional length tension range, allowing for greater power generation at all levels of movement speed and force.
Basically, the squat has an accelerative component that trains rate of force development, which researchers note will help prevent the general population from falling.
Apply the accelerative component to sports training and we see that the front squat, in particular, trains vertical acceleration to increase jump height.
Take away the understanding that squat training with heavy loads is one of the best methods for training the entire core. Dynamic multi-joint exercises like those tested in this study will help trainees achieve the correct levels and balance of strength in the trunk muscles to enable optimal performance and avoid injury.
Comfort, P., et al. An Electromyographical Comparison of Trunk Muscle activity During Isometric Trunk and Dynamic Strengthening Exercises. Journal of Strength and Conditioning Research. 2011. 2591), 149-154.
Clark, D., Lambert, M., et al. Muscle Activation in the Loaded Free Barbell Squat: A Brief Review. Journal of Strength and Conditioning Research. 2012. 26(4), 1169-1178.