In our previous article on lateral shift, we discussed what a lateral shift is and why is it important to identify and correct in athletes. Specifically, we covered the impact a lateral shift has on the loading of soft tissues and joints as well as the impact that it has on the efficiency and power production with the squatting motion. Knowing this, it makes sense that decreasing a lateral shift could potentially reduce the risk for injury, improve efficiency and hence have an impact on power output.
Because the squatting motion is such a fundamental movement in sports and is often used as a performance measure, we will look at a recent study which evaluates two different techniques for measuring vertical height. In the October 2013 issue of The Journal of Strength and Conditioning Research, Mackala et al performed a biomechanical analysis of the Squat Jump and Countermovement Jump.
Since this is not well defined in the authors’ paper, it is helpful to describe the difference between the Squat Jump and the Counter Movement Jump. In this case, the squat jump (SJ) is defined as a jump that is performed from a squatting position. A counter movement jump (CMJ) is defined as a jump where the subject starts in a straddle position (one foot slightly forward), squats down to a pre-determined height and immediately jumps up from that position. The CMJ is more of a short duration preloading of the musculotendinous junction followed by an immediate contraction. In other words the CMJ is more of a proprioceptive neuromuscular facilitation (PNF) or plyometric type of movement versus the SJ.