# The Use of Free Weight Squats in Sports: A Narrative Review--Terminology and Biomechanics
## 3 Basic Terminology Related to Squating Movements  
In a discussion dealing with the efficacy and safety of the squat for sport, it is essential that basic terminology can be used to describe the different variants of the squat, squatting depth, and foot placements. Establishment of common terms and descriptors sets a recognizable foundation that allows for a more complete understanding of how various squatting positions and techniques impact both kinetic and kinematic variables and how these variables might relate to various sports performance factors. Defining the Barbell Squat: Squatting movements can be classified into several types or categories that can either be performed bilaterally or unilaterally depending upon which variant of the exercise is being implemented. Typically, the bilateral variants of the squatting movement include the back squat [2, 4, 6, 34], front squat [17, 35], and jump squat [36]. While the unilateral variant (one-legged squat) has been less well defined, it is often used in training [37, 38, 39]. Although these various squat types are commonly discussed in coaching and scientific literature, there is often confusion about the basic concepts related to the performance of these exercises. Therefore, it is essential to establish clear definitions and descriptions of the various squatting motions, which can be applied in either practical or scientific settings. Consequently, this review will use the following terminology as the framework for describing each of the various squatting movements:  
Back squat: The free weight back squat is the most commonly performed squatting movement [40, 41] and is considered to have the greatest potential to increase lower body strength [27, 42]. Because of its ability to impact overall strength, the back squat and its variants have been considered to be one of the cornerstones of sports performance-based strength training interventions used by both professional and amateur athletes [9, 10, 13, 14, 15, 43]. As a whole, there are two basic back squatting techniques, the high bar and low bar squat [4, 16, 33, 44], that are often used in sports performance-based strength and conditioning programs. The high bar squat, sometimes termed the Olympic-style squat, is performed with the bar centered across the shoulders, just below the spinous process of the seventh cervical vertebrae (C7), while the low bar squat, or powerlifting squat, is performed with the bar approximately 5-6 cm further down the back, across the top of the scapula [33, 45]. The low bar squat is most commonly associated with the sport of powerlifting, while the high bar squat is more typically associated with the sport of weightlifting [35, 45]. Generally, the low bar squat is characterized by a larger degree of hip flexion and a hip movement that may be greater than the knee movement [44, 45, 46]. Conversely, the high bar squat is performed in a more upright position resulting in a more equal distribution of joint movement forces between the knee and the hip joints [44, 45]. It should also be noted that squats, particularly high bar full and partial back squats, can be performed explosively, using plantar flexion, and rising on the balls of the feet [47]. An additional derivative of the free weight back squat that is often performed by powerlifters is the box squat [41; 48]. The box squat requires the athlete to perform an eccentric phase (i.e., descent) followed by sitting on a box, typically for a minimum of 1 s, prior to executing the concentric phase (i.e., ascent) of the movement [41; 48]. The box squat can be performed in a full movement, in parallel movements, or in partial movements. By sitting on the box, the athlete removes much of the effect of the stretch shortening cycle [48]. Generally, when athletes perform the box squat, a wider foot stance is selected compared to traditional back squats [41; 48], resulting in different muscle activation patterns [49].