WHY BOX SQUAT?
Why Box Squat?
By: Ab Campbell
MSc Kinesiology
Introduction
Although a book could be written on box squats; I will keep this somewhat brief. Box squatting has multiple utility in various contexts from beginners, intermediate, and to the elite. Box squat’s benefits can be applied to the general population, both raw & geared powerlifting, injury prevention, rehabilitation, and athletics. So first let’s examine the history of box squatting; followed by a “how to” guide to the box squat, the mechanisms of the box squat, its application in various contexts, a research-based narrative review and finally a take home message/Conclusion
Box Squatting History: A brief historical overview and origin
In the 1960’s a strength athlete by the name of Bill West of the original Westside Barbell in Culiver City, California was thought to be the inventor of the box squat (Simmons, 2016). West primarily used box squatting with his athletes. An elite level athlete, named George Frenn (a world class hammer thrower who also appeared on the cover of sports illustrated in the early 1970s) achieved an 853 lbs squat at a body weight of 242 lbs in the early 1970’s (remember no supportive powerlifting “gear” during that era, Frenn wore only a pair of shorts). Frenn performed the box squat with a particular technique that differs from today’s modern box squat. Frenn would descend to the box, rock backwards, and once seated on the box; Frenn would lift his feet off the floor and slam them back down, driving upwards as fast as possible in an explosive manner. Box squatting performed in this manner allowed Frenn to achieve the great feat of an 853lbs free squat (Simmons, 2016).
Many years later, Louie Simmons popularized the box squat which is observed today. Louie Simmons’ Westside Barbell was named to honor the original Westside Barbell in Culiver City. Culiver City Westside Barbell was alleged to be way ahead of its time using techniques such as box squatting and “board pressing” which is now supported in modern exercise science. Westside Barbell has had multiple 1000lbs squatters (ie., Matt Dimel squatted 1010lbs and Chuck Vogelpohl squatted a 1025lbs at bodyweight of 220 lbs). Both powerlifters’ regularly box squatted in preparation for powerlifting meets (remember although they were geared lifters, the “gear” didn’t provide as much support or assisted carryover as it did in the 2000’s era). This is just an example of many of the lifters at Westside who have had tremendous success with the box squat including all time world record holder in multiply powerlifting, Dave Hoff (Simmons, 2016). Even Louie Simmons himself has experienced great success with a 920 lbs squat after a complete patellar rupture. The box squat can also transfer to “raw” powerlifters and athletes’ squat performance and its training effect is now observed on an international front. The box squat is used in both “elite raw” and “geared” powerlifting athletes’ training in addition to athletes from a variety of sport disciplines at Westside Barbell (Simmons, 2016).
Box Squats: Applications, “A how to guide,” and Box Squat Mechanics
Applications
Often the box squat is performed incorrectly; an individual may “squat to a box,” or bounce off a box and/or “touch and go squat” off a box or any or all these variations. However, a box squat is performed much differently from the traditional squat or free squat. It is also executed much differently than the aforementioned variations of a “box squat.” Additionally, depth is a consideration with a box squat; generally, a beginner would want to start off with a high box (thigh to a parallel position; that is hip and knee joint forms approximately a ~90-100 degree angle; the intermediate/elite may also use this height depending on a specific context or application). Anecdotally, when a box squat is adjusted for depth as compared to the traditional/free squat it is suggested that one can perform ~10% more in the free squat than the box squat (ie., one can free squat more than the box squat when adjusted for squat depth because of the reduction of aid of the stretch-shortening cycle or “stretch reflex). However, high boxes still allow one to develop the strength output of both a low box squat and free squat through a variety of mechanisms which will be detailed shortly. Additionally, strength radiates plus or minus (+/-) 5 degrees, therefore what you may squat on a box at 17” will carry-over to a box squat at 12” and even a free squat. Although, the load will differ because of the increased range of motion (however there are caveats to this ie, “sticking points,” biomechanical considerations, muscular activation patterns, inter- and intra- muscular co-ordination, velocity, acceleration etc). Anecdotally, it is also speculated that an inch difference in range of motion can differ in loading parameters 25-50 lbs in both the squat/box squat.
Furthermore, the box squat also has practical applications in injury prevention and rehabilitation. For example, in an ACL injury (tear/repair) the posterior chain; more specifically the hamstring’s insertions around the knee; biceps femoris, semitendinosus, and semimembranosus counteract the anterior dislocating forces of the quadriceps. The function of the ACL is to reduce the anterior displacement of the tibia and provide rotational stability of the knee. Therefore, balancing the strength ratio between the torque of quadriceps and hamstring is of importance for injury prevention of the knee and its connective tissue and ligamentous systems. Li et al., (2022) suggests that box squats result in greater hamstring activity than seated knee extensions thus resulting higher rotational knee stability. Therefore, rehabilitation therapists treating ACL deficient patients (and internal-external knee rotation intolerant patient and/or subjects that have other injuries of knee structures’ Medial Collateral Ligament (LCL), Lateral Collateral Ligament (LCL), Posterior Collateral Ligament (PCL) or popliteofibular complex) may opt for a box squat during exercise selection for rehabilitation interventions (Li et al., 2022).
In the context of injury prevention, the box squat aids in learning and acquisition of squat mechanics and technique. Box squatting results in minimal tibial anterior displacement due to the reduction in knee torque force/moment arm and the increases hip torque/moment arm. The result is less knee shear force, “wear and tear” on the tibiofemoral joint (knee). Theoretically, this would improve the knee’s long-term “health” and associated “longevity.” In rehabilitation contexts, when squatting causes knee discomfort/pain either due to overuse, injury or in post-operative contexts; the box squat may provide additional benefit by reducing the torque force, anterior displacement, and joint shear of the knee by a greater activation/moment arm of the hip/posterior chain (muscles of the hips, glutes, hamstrings). This allows one to strengthen the musculature of the lower extremities without causing further inflammation, joint shear, and/or pain. Anecdotally, I have observed many individuals unable to perform a conventional squat either for performance-based training or in the context of rehabilitation that were able to box squat pain free and strengthen the musculature of the lower extremities and improve function and return to athletics or daily-living associated tasks. Additionally, the general population and rehabilitative patients can also benefit from the box squat as it enhances proprioceptive cues in the squat, rather than “squat with the knees” the individual will learn how to squat with the hips, reach a consistent depth, and build psychological confidence with the safety of a box. The individual can then translate the box squat mechanics to a free squat or continue to box squat dependent on goals, preference, and exercise/sport specificity.
How to perform the box squat
A box squat is performed as the following in summary (at least in my interpretation/version, although see Louie Simmons article, “How to Execute a Box Squat Correctly!” https://www.westside-barbell.com/blogs/the-blog/how-to-execute-a-proper-box-squat). Essentially, a box squat is executed as follows; adduction of the scapula (pinch shoulder blades together), place the barbell on the traps not on the neck; take a wide grip on the bar or narrow depending on mobility and preference (generally wider is better) contract the lats, elbows following the angle of the torso or whatever mobility permits (generally point elbows down and work on mobility ie., horizontal external rotation unless of some type of joint restriction etc, one can also use a safety squat bar, cambered bar, marrs bar, or bow bar) make your torso as rigid as possible this is accomplished by taking a big breath of air using the diaphragm and breathing from the stomach not the chest and pushing the air into your stomach (think about giving oneself a “giant belly” do not breathe from the chest). This increases intra-abdominal pressure, stabilizes the torso, and protects the low back and vertebrae from injury. Slightly, arch the back, ie., lead with hips; both thoracic and lumbar basically ie., keep spine in extended position; this is dependent on individual posture; (is the individual already in anterior pelvic tilt or posterior tilt, hip shift etc?) Descend lowering the glutes to the box both back and down on the lowering phase (eccentric); control the descend as much as possible (don’t crash the box or bounce!) maintain a vertical shin angle (or close to!) with little anterior displacement (this will differ based on the anthropometrics of the individual). Maintain muscle tension throughout the movement, until the glutes contact the box; maintain muscle tension throughout the lower extremities, displace approximately 60% of your weight on the box by releasing tension in the hips/glutes. Initiate the concentric or ascending phase by displacement of force throughout the foot and spread toes apart (maintain this throughout movement) drive foot laterally and down producing two force vectors, ie., vertically into the floor and lateral/horizontally. Reverse the action by thrusting the hips forward and contract/flex hard at the hips/glutes, ie., simultaneous extension of all the extremities involved. One repetition has now been completed. Generally, the box squat can be performed in 1-5s for max effort or 2s for speed-strength, box squats can also be performed with the repetition method (6-12) if maintaining proper posture/technique. Although, generally rep schemes like 5 x 5, 10 x 3, 10 x 2 etc 2-3s are best for technique and to build volume. It is recommended more sets should be completed with low repetitions instead of conventional rep schemes 3x10, 4x12, etc. Hypertrophy can also be utilized during box squats; 6-12 reps if technique is maintained. The repetition method (6-12+) can be performed on the box squat dependent on program, context, specificity, and goals of the individual. But generally, 1-5 reps are advised with multiple sets (Simmons, 2016).
The Mechanics of the box squat
Mechanistically, the box squat separates the eccentric-concentric phase and during the amortization or translation phase of a repetition which reduces the stretch-shortening cycle or stretch reflex. This is the elastic ability of muscle to stretch and recoil to produce force. One may consider that you would want to produce a great stretch reflex to produce greater force. Wilson et al., (2003) study demonstrated that a stretch reflex can be held up to 8 seconds while sitting on a box (Simmons, 2016). The most difficult phase of any movement is the concentric phase; while it has been suggested that the eccentric phase allows individuals to handle 20-30% greater loads eccentrically than concentrically. Therefore, concentric only movements allow greater increases in strength while eccentric movements are thought to increase muscle mass.
The box squat incorporates “static overcome by dynamic” and “relaxed overcome by dynamic.” Basically, what this means is that although the box squat is thought to be dynamic movement there is a moment where musculature is neither shortening nor lengthening. This is referred to as the static phase, whereas the box squatter would have a moment of partial relaxation of the hips before the dynamic phase would occur when the squatter ascends in an explosive manner concentrically. This helps develop both explosive, reversal, and absolute strength in the squat (Simmons, 2016).
The mechanics/biophysics of box squat will be detailed next; when one lowers on to the box potential energy is converted into kinetic energy. When one contacts the box, this is referred to as a collision, lowering to the box eccentrically (potential energy) lasts for approximately 0.5 seconds, this is representative of an inelastic collision between two objects of mass, whereas momentum is conserved but deformation occurs in the atoms and this results into the transference of energy into another object. Kinetic energy depends on two factors mass and speed (velocity). Greater mass and speed equals greater kinetic energy. The eccentric portion of a conventional or free squat can last up to 1 second approximately twice as long as the box squat. Hence, the box squat is twice as fast as the conventional squat, therefore if speed was tripled for example nine times more kinetic energy would be produced during the collision (as kinetic energy depends on the velocity of the object squared). More kinetic energy is therefore produced during the box squat. One can complete more work in a lesser amount of time corresponding to a greater amount of power output. Power is defined as the amount of work completed in a given period of time (Simmons, 2016).
When a conventional squat is executed; the three phases of a repetition are completed: the eccentric phase, the static (amortization) and the concentric. Musculature lengthens during the eccentric phase, then transfers to the static (amortization or transference stage) where there is little change in length, and finally to the ascending (concentric) phase during a squat under a load one must contract concentrically to produce force while the musculature is held statically for a moment. The box squat breaks up these phases and force can be redirected more efficiently during the concentric phase of the squat. This produces a more effective concentric phase as a large amount of energy can be transferred into the more difficult phase/weaker phase of the squat allowing one to improve both explosive and maximal strength (Simmons, 2016).
A Narrative Literature Review: The Box Squat
As previously mentioned, the examination of “high box squats” (ie., partial range of motion training) mechanisms, practical applications, and the implications on strength attributes will be detailed. Partial range of motion training or “accentuation principle” was initially documented by Soviet weightlifting coach Zatsiorsky. Zatsiorsky’s accentuation principle states that training should occur in a limited range of motion where force production is greatest (Massey et al., 2004). Therefore, implementing partial range of motion ie., high box in the most mechanically advantageous position may demonstrate a positive effect on strength performance outcomes. This hypothesis will be examined using an evidence-based approach extracted from peer-review scientific literature.
Massey et al., (2004) study examined partial range of motion training (PROMT) on maximal strength (1RM) in the bench press. All groups (n=3) ie., full range of motion (n=11), partial range of motion (n=15), and a mixture of both methods (n=30) improved 1 RM of the bench press. However, there was almost no difference between partial range of motion and full range of motion training with both groups experiencing similar increases in the mean of 1RM of the bench press (m= 25lbs and 24.33 lbs) after a 10-week duration (Massey et al., 2004). Although this was demonstrated in the bench press; similar results may potentially be expected from a compound multi-joint extension movement which similarly matches the ascending strength curve (ie., the high box squat set at the most biomechanically advantageous position). The PROMT group’s partial range of motion was defined as 2-5 inches from full extension of the elbows referred to as the “sticking point” (Elliott et al., 1989). Interestingly, training within this range of motion the PROMT group produced similar outcomes of 1RM as compared to the full range of motion (FROM) group. How is this mechanistically possible?
PROMT has demonstrated increased levels of cardiac and metabolic stress, such as increases in heart rate, blood PH, lactate, and psychological variables ie., the rate of perceived exertion (Sullivan et al., 1996). A biomechanical analysis of PROMT also revealed that greater torque values were produced in contrast to full ROM training resulting in greater work being completed in a duration of time resulting in an increase in the training effect (Sullivan et al., 1996 as cited in Massey et al., 2004). Additionally, Mookerjee & Ratamess (1999) propose that PROMT may enhance motor learning, neural inhibition, and improve co-ordination of primary and stabilizing musculature in the execution of a movement pattern. Furthermore, the researchers postulate that trainees’ which exclusively use full ROM fail to train at an optimal biomechanical advantage where maximal force development occurs, thus also eliminating “the sticking point” during execution of a movement pattern (Mookerjee & Ratamess, 1999). Interestingly, Elliot et al., (1989) suggest the “sticking point” during ROM may be related to a force-reduce transition phase between a strain energy-acceleration phase and a mechanically advantageous maximum strength region in contrast to the moment arm surrounding a joint or by the minimization of muscular activation. Mookerjee & Ratamess (1999) also suggest that PROMT may also have applicability to the advanced trainee to overcome plateaus with the incorporation of supramaximal loads in a methodical periodization progression.
Bazyler et al., (2014) research found similar outcomes in the application of partial range of motion in combination with full ROM squat performance resulting an increase in maximal strength (1RM) in subjects with previous strength training experience. Results from the study suggested that augmenting PROMPT training in combination with full ROM training led to superior outcomes in comparison to full ROM training alone (Bazyler et al., 2014). Bazyler et al., (2014) force-time characteristics also indicated that the PROMPT and the full ROM group had superior outcomes in the force-time curve demonstrating a larger increase in impulse scaled at earlier time points suggesting an improvement in the rate of force development (RFD). Additionally, Bazyler et al., (2014) research also indicated that participants in the PROMPT and full ROM group versus full ROM only group trained a higher intensity during the last 3 weeks of the training intervention suggesting superiority in training adaptations. Thus, also offering an explanation to the improvement strength outcomes and explosive strength (RFD). Swinton et al., (2012) examination of box squatting kinematics also supported an improved in the RFD of box squatting 3-to-4 fold as compared to the traditional squat and wide-stance powerlifting squat. Bazyler et al., (2014) also propose that PROMPT can be implemented as a novel training stimulus for experienced lifters and could be incorporated in the strength-speed mesocycle for competition preparation for a strength-power athlete. In summary, Bazyler et al., (2014) findings suggest that combined training is likely to be superior to full ROM training for maximal strength development and RFD, however more research in needed in this area. Similarly, Swinton et al., (2012) suggest that box squatting be used as a tool to improve mechanical efficiency of the wide stance powerlifting squat. The researchers also suggest familiarizing the athlete with a higher box gradually reducing box height as technical proficiency improves to improve the powerlifting free squat. Additionally, box squats elicited large values in RFD therefore it is suggested that the box squat be implemented in the development of explosive strength. Swinton et al., (2014) suggest multiple set parameters in the range of 3-6 repetitions. This low rep multiple set scheme has been implemented extensively for decades by Simmons (2016) during speed-strength waves in the development of RFD in athletes also incorporating accommodating resistance in a progressive method using “wave-loading.” McBride et al., (2010) analysis of the box squat resulted in significantly greater peak power at 70% of 1RM and 80% of 1RM as compared to the free squat. However, biceps femoris (hamstrings) and vastus lateralis (quadriceps) activity was significantly greater at 60% and 70% of 1RM. However, no difference in muscle activity was demonstrated between 80% of 1RM in between the box squat and the free squat. The researchers suggest that a box squat can provide a similar stimulus to the lower extremities and low back musculature as the free squat. McBride et al., (2010) research suggests that the box squat is likely just as an effective at eliciting strength gains during a training cycle as the free squat. However, because of the removal of the stretch-shortening cycle the box squat may be a more favorable option for athletes for concentric only movements in sport and for eliciting greater peak power outputs as compared to the free squat.
Research on the box squat would suggest its efficacy in the development of maximal strength, rate of force development, power output, and concentric-only movements in sport (Bazyler et al., 2014; McBride et al., 2010; Swinton et al., 2012). Cleary there is some efficacy when implementing even a “high box” ie., PROMT when developing these strength attributes (the development of maximal strength, rate of force development, power output, and concentric-only strength) (Mookerjee & Ratamess, 1999; Bazyler et al., 2014; Swinton et al., 2014).
In summary, box squats’ mechanisms of action include mechanical adaptation to greater loads resulting in musculoskeletal/physiological adaptations to increased loads at a full range of motion. This results in greater musculoskeletal adaptations (ie., strengthening of connective tissue such as tendons, ligaments, hypertrophy of muscle fibers and increased bone density). Neuromuscular components are also proposed to contribute to box squats’ efficacy ie., development of intra- and extra- muscular co-ordination (sensory/afferent muscle receptors activity; golgi tendon organ and muscle spindle mechanisms) under increased loading parameters. Additional proposed factors that may contribute to box squats efficacy are the enhancement of motor learning, neural inhibition, and improve co-ordination of primary and stabilizing musculature in the execution of a movement patterns (Mookerjee & Ratamess, 1999). Other proposed mechanisms may be rooted in other neurological determinates associated with neural efficiency of movements, such as rates of motor firing and motor unit synchronization (Gabriel et al., 2006). However, more research is needed before any conclusions can be inferred.
Biomechanical factors also play a role in box squatting, perhaps box height selection (partial range of motion training) based on the anthropometrics of the individual can facilitate the reduction of force-reduce transition phase between the strain energy-acceleration phase ie., the sticking point during the squat to enhance performance (Elliot et al., 1989). Furthermore, Box squats have also shown to enhance the rate of force development (Bazyler et al., 2014). Therefore, one would surmise at the level of the motor neuron pool a greater number of fast-fatigable motor units (Large/fast motor neurons “wired” into type II muscle fibers) may be recruited if RFD is improved (ie., increased motor unit recruitment). Additionally, the concentric movement action of the box squat (and the ability to overcome inertia) is likely to lead to a greater peak force, increases in maximal strength, explosive power (RFD), and peak power via the inhibition eccentric-concentric chain (although it still exists it is prolonged); Therefore, based on both scientific evidence and anecdotal reports one may infer that the box squat is a practical and efficacious tool. The box squat can be implemented to enhance squat performance and attributes of strength during various phases of training cycles (ie., Conjugate, Block training ie., maximal strength, power, speed strength (Rate of Force Development etc.)
Take Home Message/Conclusion
Summing up the main points and drawing some conclusions are as follows:
· Box squatting is an old exercise, only recently has it entered mainstream use and often an area of controversy, although academic research supports its application.
· Box squats are a good selection for individuals new to the squat and/or prior knee injuries/post-surgery who are trying to minimize anterior displacement of the knee.
· Box squatting is a safe alternative to the free squat, or it can be used in place of the conventional squat for the general population. The box squat can also be used in performance-based applications for the rate of force development in athletics and explosive-strength development in strength sports.
· Although in terms of specificity dependent on goals; both the box squat and the conventional squat may be programmed in strength training programming, especially weeks leading up to competition where proprioceptive/technique cues are paramount. Although, a free squat maybe be selected closer to competition whereas the law of exercise specificity is of particular importance.
· It is recommended to squat from variable depths, so the ability to modify box height is important. Keep that in mind when purchasing or constructing a box.
· Breaking up the eccentric-concentric chain has benefit in explosive strength, although in muscle hypertrophy the goal is to elicit more eccentric loading in muscle tension.
· Box squatting aids the psychological component of training building confidence in the squat as well as physiological adaptations.
· Box squatting is safe when executed properly. Improper technique may cause injury as in any exercise endeavor.
· Evidence from academic publications support box squat’s utility and supports anecdotal reports of its various utility in strength training (Bazyler et al., 2014; McBride et al., 2010; Mookerjee & Ratamess, 1999; Swinton et al., 2012)
· Both raw and geared powerlifters can benefit from the box squat, contrary to popular belief as Louie Simmons’ Westside Barbell/Conjugate system was designed to be trained “raw.”
· Box squatting can be used for max effort (ME) and dynamic effort (DE) method whereas DE is used in conjunction with accommodating resistance to enhance rate of force development and explosive strength. (It can also be used in ME training in conjunction with accommodating resistance (ie., bands/chains) for mechanical overload and to enhance power output and maximal strength)
· And finally, Louie Simmons and Dave Tate say to box squat (Good enough reason for me!)
References
Bazyler, Caleb D, Sato, Kimitake, Wassinger, Craig A. Lamont, Hugh S. Stone, Michael H. The Efficacy of Incorporating Partial Squats in Maximal Strength Training, Journal of Strength and Conditioning Research: November 2014 - Volume 28 - Issue 11 - p 3024-3032 doi: 10.1519/JSC.0000000000000465
Elliott, B. C., Wilson, G. J., & Kerr, G. K. (1989). A biomechanical analysis of the sticking region in the bench press. Medicine and science in sports and exercise, 21(4), 450–462.
Gabriel, D.A., Kamen, G. & Frost, G. Neural Adaptations to Resistive Exercise. Sports Med 36, 133–149 (2006). https://doi.org/10.2165/00007256-200636020-00004
Li, P., Li, C., Wang, C., Kernkamp, W. A., Yang, C. H., Hu, H., & Tsai, T. Y. (2022). In-vivo tibiofemoral kinematics of the normal knee during closed and open kinetic chain exercises: A comparative study of box squat and seated knee extension. Medical engineering & physics, 101, 103766. https://doi.org/10.1016/j.medengphy.2022.103766
Massey, C & Maneval, Mark & Moore, Melissa & Johnson, J. (2004). An Analysis of Full Range of Motion vs. Partial Range of Motion Training in the Development of Strength in Untrained Men. Journal of strength and conditioning research / National Strength & Conditioning Association. 18. 518-21. 10.1519/13263.1.
McBride, J. M., Skinner, J. W., Schafer, P. C., Haines, T. L., & Kirby, T. J. (2010). Comparison of kinetic variables and muscle activity during a squat vs. a box squat. Journal of strength and conditioning research, 24(12), 3195–3199. https://doi.org/10.1519/jsc.0b013e3181f6399a
Mookerjee, S., & Ratamess, N. (1999). Comparison of strength differences and joint action durations between full and partial range-of-motion bench press exercise. The Journal of Strength & Conditioning Research, 13(1), 76-81.
Swinton, Paul A.1; Lloyd, Ray2; Keogh, Justin W. L.3,4; Agouris, Ioannis1; Stewart, Arthur D.5 A Biomechanical Comparison of the Traditional Squat, Powerlifting Squat, and Box Squat, Journal of Strength and Conditioning Research: July 2012 - Volume 26 - Issue 7 - p 1805-1816 doi: 10.1519/JSC.0b013e3182577067
Sullivan, J. J., Knowlton, R. G., DeVita, P., & Brown, D. D. (1996). Cardiovascular Response to Restricted Range of Motion Resistance Exercise. Journal of Strength and Conditioning Research, 10(1), 3–. https://doi.org/10.1519/1533-4287(1996)
Simmons, L. (2016, October 18). Retrieved from https://www.westside-barbell.com/blogs/2005-articles/box-squatting-benefits
Simmons, L. (2016, October 13). Retrieved from https://www.westside-barbell.com/blogs/2014/how-to-execute-a-proper-box-squat
