Squats are a fundamental human movement as well as a resting position.
To build great strength, mobility and muscle you need to squat. For strength and muscle mass, squat with resistance; for mobility, squat deeply for time.
The Elastic Strength program includes split squats and either deep front squats or high bar back squats or both. Here's why.
In daily life and most athletic activities, we exert force against the ground with only one leg at a time. When walking, running or sprinting, we propel ourselves forward with only one leg at time. When jumping we most often jump off one leg.
When you use only one leg at a time, that leg receives greater neural drive than if you use both legs at once. You produce more force per leg when using one leg at a time.
Split squats are therefore more like daily and athletic activities than bilateral squats.
In addition you can safely squat very deeply with single leg squats. Deeper squats load the quadriceps and buttocks in their most stretched position, which results in greater muscle activation and loading.1 Deeper squats also take the knees through a full range of motion, which is important for maintaining healthy knee cartilage.2
When researchers compared 2 types of split squats (one with rear leg elevated, the other not) to back squats, they found that split squats are as effective as back squats for activating the hip and thigh musculature, while using half the load.3 In fact, the rear leg elevated split squat produced slightly greater activation of the hamstrings than the back squat.
This means that by doing split squats you can increase the strength and size of your hips and thighs as effectively as with back squats, but with far less axial loading of and wear-and-tear on the spine. Doing back squats with a barbell load equal to your bodyweight puts loads of 6-10 times your bodyweight on your lumbar spine.4
Therefore, the standard Elastic Strength Program includes either tuck split squats or full split squats. I recommend tuck split squats to most people; the tuck split allows a greater range of motion and balance; the full split squat involves more balancing and is more hazardous, but may be helpful for developing split strength for the front split. For best results load these with elastic resistance bands for variable resistance.
Front squats require a more upright posture than the back squat. As a consequence, deep front squats are safer for the lower back and knees than back squats.5
In addition, it appears that the front squat is superior to the back squat for training the lower back and abdominal muscles.6
Therefore I recommend front squats over back squats. In other words, if you can do front squats, you should do front squats. High bar back squats should be done infrequently if at all to reduce wear and tear on the lumbar spine.
You should do deep front squats because they develop more mobility than shallow squats, put less shear stress on the knees while training the cartilage through a full range of motion, put more load on the lumbar erector muscles, and require less external load resulting in less wear and tear particularly on the lumbar spine.
Front squats are even safer if you use the X3 Bar and resistance bands rather than a barbell, because resistance bands reduce the load in the deep position where the torso is most inclined and stress on the lumbar spine is greatest.
If you do back squats instead of front squats, you should do deep high bar back squats.
Deep high bar back squats train the hips and thighs with less external loading than low bar back squats. A more upright posture and deeper squat translates to less external loading which puts less stress on the lumbar disks and knees while maintaining a high work load on the hips and quadriceps.2
I review the research in favor of high bar squats here.
By deep, I mean as deep as you can manage with a neutral spine. If you can't squat deeply I recommend working on squat mobility.
You must squat hard and progressively to develop your hips and quadriceps.
The Elastic Strength Program is designed so that it can include both the split squat and the front squat.
1. McMahon GE, Onambele-Pearson GL, Morse CI, et al.: How deep should you squat to maximize a holistic training response? Electromyographic, energetic, cardiovascular, hypertrophic and mechanical evidence. Chapter 8 in Electrodiagnosis in New Frontiers of Clinical Research. http://dx.doi.org/10.5772/56386.
2. Hartmann H, Wirth K, Mickel C, et al. Stress for Vertebral Bodies and Intervertebral Discs with Respect to Squatting Depth. J Funct Morphol Kinesiol 2016;1:254-268. doi:10.3390/jfmk1020254.
3. DeFOREST BA, Cantrell GS, Schilling BK. Muscle Activity in Single- vs. Double-Leg Squats. Int J Exerc Sci. 2014;7(4):302–310. Published 2014 Oct 1.
4. Cappozzo A, Felici F, Figura F, Gazzani F. Lumbar spine loading during half-squat exercises. Med Sci Sports Exerc 1985 Oct;17(5):613-20.
5. Chow, J. (2009). A Biomechanical Comparison of Back and Front Squats in Healthy Trained Individuals. Journal of Strength and Conditioning Research, 23(1), 284-292.
6. 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.