INTRODUCTION
The back squat is a cornerstone of an athlete's physical training program and is fundamental to lower-body strength development. The nature of bilateral loading allows for absolute loads to be considerably higher than unilateral alternatives such as the rear-foot elevated-split squat (RFESS) (39). If full range of motion can be achieved, there is a high mobility requirement for the lower-body joints (34), especially at the hips and ankles. Numerous studies have highlighted a strong association between lower-body strength (through the back squat) and acceleration (30,35), speed (1,35), and power (36). Thus, developing maximal squat strength is a good prerequisite for many high-velocity movement patterns in sport. Consequently, when 1 exercise has the potential to successfully compliment an athlete's overall athleticism and set a solid foundation for sporting performance, many coaches aim to optimize back squat technique.
A common method of determining competency in a given task is through movement screening, which has gained a high level of interest in the past 10–15 years. Multiple methods exist such as the Functional Movement Screen (2,13,24), Movement Competency Screen (26,27), as well as the overhead and single-leg squat assessments (3–5). Although numerous variations of screening exist, a common theme among them all is the use of a squat pattern to get a generic impression of movement competency in this task. Furthermore, Myer et al. (34) has suggested using an unloaded squat as a screening tool because it is in the coach's interest to have a strong understanding of perfect technique, given it is so commonly prescribed. At this point, note that squat mechanics will differ considerably depending on whether the focus is on the high-bar or low-bar technique (16).
The high-bar squat is characterized by a more upright torso, deeper squat, and increased quadriceps recruitment. The low-bar position requires greater hip flexion range of motion and increased forward lean during the lift (16). Although both versions may have their respective advantages, the high-bar version may be more favorable and will be used as a reference point for optimal technique. Thus, any corrections to technique have been suggested in line with this squat variation. Although numerous flaws in technique are possible, a common flaw is when athletes perform an “excessive forward lean” during their squat pattern. To the author's knowledge, little of the literature published to date has aimed to outline guidance on how best to correct an athlete's excessive forward lean, specifically in respect to the high-bar back squat.
The aim of this article is to provide coaches with an integrated system that may help to reinforce optimal movement competency in the high-bar back squat exercise for those athletes who demonstrate an excessive forward lean. Variations of the back squat are suggested to give coaches a reference point for how to correct this common flaw in technique.
HIGH-BAR VERSUS LOW-BAR SQUAT
One important aspect of interpreting subjective movement quality is to understand what optimal looks like. Figure 1A represents the optimal high-bar back squat technique, and Figure 1B shows excessive forward lean compensation. This compensation can only be viewed clearly from a lateral view; thus, only figures from this perspective have been included. Powerlifters typically back squat with a low-bar position with the barbell resting further down the spine (8). In this instance, the natural response to this altered bar position is a purposeful increase in hip flexion and torso lean (16); thus, accommodating the lower-bar position and change in center of mass. In addition, the low-bar squat has been shown to recruit the erector spinae and gluteal complex to a greater extent than the high-bar version (16). Therefore, if increased posterior chain development is the goal from this exercise, then the low-bar squat may be the preferred choice. However, some literature has suggested that this variation may increase shear forces at the lumbar spine (8,14). Considering the low-bar squat is characterized by a naturally increasing forward lean (40), there may be a propensity to lose form under maximal loads, especially for those athletes unfamiliar with this variation or already exhibiting a forward lean during the squat pattern. It is not being suggested that the low-bar squat automatically increases the risk of injury; however, if an excessive forward lean is present during screening or under light loads, the low-bar squat may further reinforce this movement compensation. The low-bar squat may not be the preferred choice in this instance. Thus, the remainder of this article will focus on correcting squat mechanics in relation to the technique and positioning seen in Figure 1A.
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Figure 1.: A) Optimal back squat technique. B) Excessive forward lean in the back squat. The subject in A and B is wearing weightlifting shoes which may alter body position compared with regular running trainers. Fortenbaugh et al. (
12) compared weightlifting shoes with running shoes and reported significantly lower horizontal trunk displacement (
p = 0.04) for the weightlifting shoe condition when back squatting at 60% 1 repetition maximum (1RM). This type of shoe allows for a more erect trunk posture, which the authors suggested may be a safer strategy for athletes to adopt under loaded squat conditions. Similar methods were used by Sato et al. (
38) who reported notably reduced forward trunk lean in weightlifting shoes at 60% 1RM. Weightlifting shoes may be the most appropriate option for athletes exhibiting a forward lean posture. Legg et al. (
28) used novice and experienced lifters with experienced being quantified as >1 year regularly using the back squat. A comparison between weightlifting and athletic shoes indicated that a more upright trunk posture was facilitated by wearing weightlifting shoes, providing further evidence that this type of footwear could be considered for those athletes presenting an excessive forward lean. Consequently, the use of weightlifting shoes could be considered as an additional strategy to facilitate a more upright torso position in the high-bar back squat.
THE “EXCESSIVE FORWARD LEAN”
Optimal alignment during a high-bar back squat is essential because of an increased injury risk that accompanies movement dysfunctions (21,24). Optimal positioning is characterized by the trunk and tibia running parallel to one another. This has been further demonstrated in Figure 1A by the dotted lines which will not intersect. By contrast, the excessive forward lean is characterized by the trunk and tibia becoming perpendicular to one another. As Figure 1B portrays, the tibia has increased vertically, whereas the trunk has assumed a more horizontal position. Once practitioners are clear on what constitutes an excessive forward lean visually, it is important to understand what may be instigating this compensation.
Reduced ankle range of motion could be a potential cause of this compensation. The tibia translating anterior in relation to the ankle is crucial for achieving optimal alignment during a high-bar back squat. Insufficient anterior translation of the tibia is often compensated with the forward trunk lean. Potential causes of this limitation include decreased mobility of the talocrural joint and shortened lower limb musculature (6). In the event of reduced talocrural joint mobility, restricted posterior talar glide may be present (19). This limits the ability of the tibia to translate anteriorly during dorsiflexion movements and may require increased mobility (discussed later) to optimize the high-bar squat technique. Previous literature indicates that the gastrocnemius may require increased lengthening to address this compensation (9). However, the “relative length change” in this muscle is small because of its origin above the knee joint. Essentially, although dorsiflexion occurs during a squat movement, the knee is also flexing which makes any relative length change in the gastrocnemius minor. However, the origin of the soleus is below the knee joint; thus, it is likely that any posterior tissue restriction is largely attributed to this muscle. Therefore, improving ankle mobility and reducing any posterior tissue restriction could be considered as appropriate strategies for enhancing back squat mechanics.
A second reason for excessive forward lean may simply be due to a weak “extensor profile.” This can be described as posterior chain muscles that perform extension movement patterns, namely the gluteal complex, hamstrings, and erector spinae. The gluteus maximus is the primary hip extensor and contracts eccentrically during the descent of a squat. An inability to gain sufficient depth in the back squat (parallel as a minimum requirement) could partially be due to the fact that the gluteal complex is not strong enough eccentrically as depth increases. Consequently, the body compensates by going into an excessive forward lean to avoid increased depth that the gluteal complex cannot sustain as previously reported (9). This is further supported by Isear et al. (22) and Caterisano et al. (7). Isear et al. (22) analyzed lower-body muscle activation patterns during an unloaded squat (to 90°) in 41 healthy males and showed a tendency for gluteal activation to increase as depth increased.
Caterisano et al. (7) investigated the effect of back squat depth on gluteal muscle activity in 10 experienced weightlifters (>5 years training age). Load was programmed at 100–125% of each subject's body mass with squat depths set at partial (2.36 radians at the knee joint), parallel (1.57 radians at the knee joint), and full (0.79 radians at the knee joint). Partial squats had significantly lower contribution from the gluteal muscles compared with both parallel and full range of motion (7). Strengthening the gluteal complex is likely a requirement for both athlete and nonathlete populations who exhibit an excessive forward lean and are unable to gain sufficient depth in the back squat. Similarly, the spinal extensors (erector spinae) may also require strengthening to encourage the torso to remain as upright as possible. With that in mind, variations of the back squat could be considered useful to strengthen the glutes at a sufficient depth and “retrain” appropriate spinal alignment for optimal high-bar squat technique.
A third reason for the excessive forward lean compensation could be due to poor motor planning. This is perhaps more likely with less experienced athletes who have not been exposed to back squat training; thus, it is plausible that this issue may be “coached out of them” by practice. This may be the first step for any strength and conditioning coach to see whether improvements can be made with practice alone. Despite the paucity of literature pertaining to motor learning for the back squat specifically, research studies have highlighted the advantage of feedback in conjunction with practice (31). The use of immediate coach feedback (33) and visual feedback in the form of video analysis (15) may further enhance an athlete's learning if compensations are present. It is therefore suggested that the excessive forward lean may be a compensation that occurs because of 3 potential factors: reduced ankle mobility, a weak extensor profile, and/or poor motor planning in the exercise itself (Figure 2). It may well be a combination of these factors which is why an integrated approach to correcting technique is required and will be discussed next.
Figure 2.: Causes of the excessive forward lean seen during the back squat exercise.
ASSESSING ANKLE MOBILITY
Before discussing corrective strategies, it is essential that coaches understand how to assess for ankle range of motion. Ankle mobility is frequently measured using goniometry (17,25); however, it should be noted that such methods likely have a high margin of error. Goniometry is a precise skill, and coaches who are unfamiliar with the technique should not rely on this method given the reliability issues (11,18). As an alternative, the weight-bearing lunge test (Figure 3) offers a simple and reliable method of assessing ankle range of motion (20,25). Compensations noted during the squat pattern may be due to closed chain dorsiflexion mobility. Therefore, a closed chain assessment strategy likely retains more specificity to this task. This test can be easily administered adhering to a few simple steps.
Figure 3.: Weight-bearing lunge test with a rubber band placed on a stretch to ensure that the heel remains flat throughout (distance from the wall is measured in centimeters).
The foot and ankle complex should be set straight and in neutral to avoid any external rotation (which would provide “free range of motion” at the ankle). The heel must remain flat during the test, and coaches are encouraged to monitor this closely. A simple technique of placing a rubber band (on a stretch) underneath the heel will help to ensure that zero heel elevation occurs and a more accurate reading is obtained. Range of motion is measured from the end of the big toe to the wall in centimeters, and scores will vary depending on the available range of motion. Normative data would seem to be ∼12 cm for healthy adults (20), although this will likely differ dependent on the population in question.
STRATEGIES TO CORRECT BACK SQUAT TECHNIQUE
Figure 2 demonstrates 3 factors to address in correcting back squat technique. None of these causes of excessive forward lean will exist in isolation, but as part of an integrated program to optimize all aspects of back squat technique. Gaining strength within the squat pattern and correcting motor patterning are likely best served by practicing the squat pattern itself. If an athlete is unable to get into the correct position because of a lack of strength in the hip and spinal extensors, then alternatives to the back squat could be considered. The authors suggest starting with 2 potential variations before programming the back squat exercise: starting with a box squat, progressing to a “touch squat”, and then onto the full back squat exercise (Figures 1A and 4, 5). This method will address both the weak extensor profile and poor motor patterning issues. If athletes are struggling to gain enough depth, providing them with a box or bench to sit on will teach them to drive up from a deeper position that they cannot support on their own. In addition, it will also cue them to “sit back” using the hips, which has been suggested as a desired squatting trait (34,40). Finally, if athletes are really struggling to gain control in deep squat positions, the use of a platform behind them can be manipulated gradually until the desired technique has been achieved.
Figure 4.: Box squat which is part of the progressive squat series (box squat → touch squat → back squat) to correct back squat technique from an excessive forward lean.
Figure 5.: Touch squat which is part of the progressive squat series (box squat → touch squat → back squat) to correct back squat technique from an excessive forward lean.
The touch squat is a similar exercise and still has a box or bench positioned behind the athlete as a target to aim for. However, the athlete does not physically “sit down” in this exercise (such as the box squat), but descends until the glutes lightly touch the surface before driving up to finish the repetition. Coaches should be mindful of 2 things for this exercise. First, athletes should not “bounce” off the platform behind them as this will likely cause unwanted jarring forces through the spine. Second, by “not sitting down,” a small amount of depth will be lost in this variation. If possible, the box or bench should be lowered slightly so that when touching at the lowest point, the athlete is squatting to a comparable depth as when seated in the box squat position. In Figures 4 and 5, the bench is positioned on a decline (and cannot be lowered further); however, the feet have been walked further forward for the touch squat (Figure 5) to facilitate the required extra depth.
Once the touch squat has been mastered at an appropriate depth, coaches should be able to remove the box and get athletes' back squat to parallel without anything behind them. It is not known how long this process takes to complete before competency in the back squat is evident and will likely vary from athlete to athlete. It seems logical that 4-week blocks for each of these variations could be considered so that athletes are back squatting without a box after approximately 8 weeks. The authors are unaware of any motor planning studies that have specifically enhanced the high-bar back squat. Eight weeks has been shown to enhance functional movement inclusive of the squat pattern (23) and reduce lower back pain (10) in comparable motor control literature.
In addition, strategies should be incorporated that focus on improving ankle mobility, should this be deemed a problem. A 4-step approach inclusive of foam rolling posterior muscles below the knee, enhancing flexibility to the soleus, mobilizing the talocrural joint, and incorporating functional exercises that challenge dorsiflexion dynamically will assist in improving long-term ankle range of motion. Details of important points accompanying these methods are provided in the Table.
Table: Summary of key points for each exercise when aiming to correct back squat technique
Table-A: Summary of key points for each exercise when aiming to correct back squat technique
Improvements in flexibility can be addressed in multiple ways; however, this article will provide suggestions for athletes who can be performed without the use of support staff such as strength and conditioning coaches or athletic trainers. Foam rolling provides an easy method of targeting trigger points within a muscle and has been said to relieve soreness and correct muscular imbalances (29,37), which are likely restricting a muscle's extensibility. Second, static stretching the soleus muscle may allow some acute increases in ankle range if the muscles of the lower limb are causing a restriction in anterior movement of the tibia during the squat pattern. Step 3 should incorporate a mobility exercise such as the knee-to-wall drill, where dorsiflexion can be optimized once any posterior tissue restriction has been addressed. Integrating more functional exercises such as the RFESS allows dorsiflexion to be targeted for each ankle individually which will likely be needed to get into the desired back squat position. Furthermore, the instability of a RFESS will enhance overall foot stability and has been shown to be an appropriate exercise choice for hip extensor muscle activation (32), also critical for optimal back squat mechanics.
PRACTICAL APPLICATIONS
Multiple strategies are suggested to enhance back squat technique related to excessive forward lean. This article has provided key points that coaches should be mindful of when implementing with their athletes (Table 1). Most recommendations to optimize ankle mobility are remedial in nature; thus, are likely to be performed as part of a warm-up routine aiming to correct an athlete's motor patterning. These bilateral squat variations (box squat, touch squat, or back squat) should be programmed in the aforementioned order for 4 weeks separately, until optimal back squat technique can be maintained (Figure 1A).
CONCLUSION
In summary, excessive forward lean is a movement compensation that many athletes may exhibit. The cause may be attributed to reduced ankle mobility, insufficient strength, poor motor patterning, or a combination of these factors. An integrated approach that addresses these issues is suggested to correct technique. Improving ankle mobility in isolation may not be enough to automatically correct technique. A progression sequence using different bilateral squat variations may simultaneously allow strength and motor patterning to be developed over time. Once sufficient technique has been achieved, coaches should ensure that athletes continue to train throughout full range of motion, as this will likely be sufficient to maintain adequate mobility within the squat pattern.
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