Split Lunges / Split Squats are examples of a closed chain asymmetrical strength exercises. There is great debate in the strength world of which technique is correct for the performance of the Split Lunge, which is also called the Split Squat in some circles.
The first technique requires that the rear knee bend only slightly – 10˚-15˚ degrees, so that the iliopsoas fascia is lengthened through tension. This was the technique favored by my mentor – the late Charles Poliquin. He called this the Split Squat.
The second technique involves bending the rear knee during the descent so that the knee drops straight downward. The final position is reached with the rear thigh perpendicular to the floor, as well as the front tibia / fibula complex (these are the lower leg bones). This method of split squatting was popularized by Jay Schroeder.
Primal Rotational Patterns uses both versions and adds to the confusion by changing the names of the exercises. The long rear leg version is referred to in Primal Rotational Patterns as Split Lunge, while the fully flexed rear knee version is referred to as Split Squat. A simple pneumonic helps us to remember the difference: we lunge forward; we squat downward.
Split Lunges place a hallmark on iliopsoas function. Split Squats require more recruitment from rectus femoris. Both exercises have healthy implications for the fascial relationships of the groin and are critical to preventing and healing hernias.
Both exercises place a great amount of importance on the length – tension relationship of the flexor hallucis longus. This muscle originates on the fibula – the non-weight bearing bone of the lower leg – and inserts at the base of the base of the phalanx of the fist toe, or base of the big toe.