III.) Squatting Variations
-Are front or back squats better?
-What’s the deal with box squats?
-What are the benefits of doing a split squat?
-What about rear-foot elevated and front-foot elevated split squats?
These are questions that any strength coach gets routinely on a weekly basis. As with anything else, the answer you receive will depend on the person you ask. I feel the most important thing to remain cognizant of is to not marry one single squat variation. I will have some of my athlete’s front squat and some back squat- primarily depending on structure, injury history, and training goal (catching the theme yet…). I know several strength coaches, especially in the collegiate and high school realm, have a penchant for front squats over back because they are “more reflective of athletic movement.” I don’t disagree with that, however, in my experience it’s much more difficult to get someone in a good front rack position than it is to setup a back squat. This can quickly become a classic case of “square peg/round hole”, where we intuitively may believe front squats are superior for an athletic population, but if they can’t get into an appropriate front rack, are they really a better option? Nevertheless, let’s take an objective look at some of the differences between the two.
Front vs. Back Squat…
The primary difference, fundamentally, between front and back squats is found at the shoulder. An athlete’s ability to externally rotate at the shoulder will determine whether or not they can comfortably set-up in a back squat. Whereas with the front squat, the athlete must have the requisite lat flexibility, glenohumeral and thoracic mobility, and wrist flexibility/mobility to achieve a good front rack position. Personally, I can’t front squat worth a shit, but it has nothing to do with a lack of leg strength. I’ve broken both wrists multiple times over the years, and generally would not be someone you’d mistake for a gymnast…. my flexibility/mobility is atrocious for a front rack position. I’d have to spend WEEKS just cleaning up their front rack before we could ever load a front squat, which makes this cost/reward very low here. As we all know, time is precious, and in my opinion it’s just not a good return on investment scenario.
Just to be clear, I treat athletes with limited external rotation the same- we’re not gonna spend 6-weeks cleaning up external rotation simply for the sake of being able to back squat. The solution would be improving external rotation because it needs to be, and if we can get under a back squat in a few months, cool, if not, cool, keep using alternative methods for leg strength. A quick tangent, if you’re fortunate to be in a facility with a yolk bar, or cambered bar, then the shoulder conversation is pretty much null and void. Yolk bars are inherently my go to for athletes with poor shoulder mechanics and makes it a non-discussion.
The kinematic differences in the lower extremities are certainly noteworthy as well. According to a study by Fry et al., front squats have been shown to produce significantly lower maximal joint compressive forces at the knee, as well as reduced lumbar stress when compared to back squats. The authors went on to note that in this study, at least, there were no significant differences in hamstring activation, or presence of sheering stress at the knee between the two variations. The takeaway from this is that front squats may be a preferable option for athletes with ligamentous or meniscal injuries. In the same study, the authors also identified that quad activation may be slightly higher during front squats than back squats, making them a better option for athletes need to emphasize quad development. The back squat is going to be the preferred option for your athletes that fundamentally cannot achieve a good rack position, prefer a wide-stance foot position, and/or need to emphasize hip and glute strengthening. Also worth noting, although should be rather obvious, is that 9/10 athlete’s will be able to load heavier on a back squat. If the goal is simply to load the legs heavy, then back squats are likely the better option.
The caveat to the whole front vs. back squat debate that seems to be remiss in most debates regarding the two, is that the position of the trunk, along with tweaking foot position, knee and hip angles, are going to be the deciding factors for specific muscular adaptions, or injury avoidance. Generally speaking, we’re going to get greater angles of dorsiflexion and knee flexion on a front squat, whereas on a back squat we’re going to experience greater moments at the hip joint and surrounding musculature (5). Additionally, on back squats, we are able to achieve greater inclination of the trunk, so for athletes with a specific demand to do so, back squats are you’re go to.
-If they can’t get in to a proficient front rack, they can’t front squat. Period.
-If athletes can’t externally rotate at the shoulder, they can’t back squat. Period.
-If they have disc degeneration or history of spinal surgeries, they shouldn’t back squat.
-Changing the stance, position, and trunk inclination will be determining factors for muscular activation, injury avoidance and force tolerance.
-If they can do both with proficiency, program both. If they have a specific need or demand for one vs. the other, program accordingly.
Well, no different than damn near everything else squat-related, box squats have been subject of heated debate and seem to have mixed reviews among top strength coaches. The primary backlash on box squats really focuses on the way in which they’re performed, more so than the exercise itself. Some coaches will be a bit reckless when having athletes perform box squats, whereby the athlete comes crashing down on to the box, losing all tension, and producing ungodly compressive forces on the spine. Obviously, this is a shitty thing to see, not only because this does impose true risk for the athlete, but it’s also overlooking proper squat mechanics as a whole. It does not take a spinal surgeon to discern that having 300 lbs. on the back of a 150 lbs. athlete and slamming down into a box is far from optimal. The compressive forces experienced at the spine are brutal in these instances, BUT, I can make the exact same case for any exercise on the planet… if we observe an athlete doing bench press and he/she is slamming the bar down into their sternum and bouncing the weight back up, nobody would argue the "safety concerns" for that exercise. For that reason, I think box squats get a little bit of an unfair wrap.
Personally, I love box squats, and think they certainly have a time and place. As alluded to, it is important that these are coached correctly, and they are only performed with athletes who have become reasonably proficient with traditional back squats. The way I cue box squats is to have the athlete “sit on a cloud” and to “be overly conscious about maintaining full body tension.” What I look for on a box squat is absolutely no presence of relinquishing tension while performing the squat. Be sure the athlete takes their breath at the top of the squat in-between each rep and holds that breath throughout the entire range of motion. We never want the athlete to disengage and reengage during any squat, but certainly not when box squatting. My primary reasons for programming box squats are as follows:
-Great for heavy training phases to help the athlete acclimate to heavier loads (i.e. 105-120% back squat 1-RM).
-Good option to emphasize quad strength and erectors when performed with slightly increased forward trunk lean.
-Great teaching tool for biofeedback and teaching appropriate bracing mechanics during squatting; namely, at the point of change of direction, which is the most imperative point of any movement.
**I will also use box squats for young/novice athletes, but this is not with any kind of external load, this is purely for kinesthetic awareness of fundamental squat mechanics.
Bilateral vs. Split Squats…
Split squats have a (somewhat) unique spectrum of versatility. For some of my athletes, split squats will completely supplant bilateral conventional squatting and will be used as our primary lower-body strength exercise. For others, they are a block two movement used more so as an auxiliary lift at lower intensities following back or front squats. Split squats can also be used with varying set-ups for specific adaptations, such as the front foot-elevated and rear foot-elevated variations. Whether it’s an injury management strategy, a performance or specificity strategy, there’s no question that split squats are extremely versatile, and certainly have a place for just about any athlete.
When compared to conventional bilateral squatting, split squats have been shown to promote increased hamstring, external oblique, and glute activation (6). Interestingly, at least in this study, there was no significant difference between bilateral or split variations when analyzing quad activation. Moreover, when compared to back squats in particular, split squats were shown to have similar muscle activation for rectus abdominis and erector spinae (5). Similar to my notes above on bilateral squatting with regard to muscular activation and forces experienced at specific joints, the split squat appears no different in that the step length (distance between front and back foot), trunk angle, and individual anatomical structure are typically the most influential factors.
What I will add to the advantages of using a split squat that for some reason is less discussed is what occurs at the ankle/foot/big toe. Honestly the primary reason that I’m sure to use some split squat variation with every athlete I work with is because of the effects on the foot and ankle complex. When we perform a traditional split squat (i.e. both feet on the ground), irrespective of how it’s loaded, I love the demand for controlled dorsiflexion, the presence of big toe extension- which isn’t exactly commonly trained but highly important, and the ability to isometrically control the foot. All of these alone are enough for me to make split squats a staple in programming. Again, these are not always easy traits to train, but are each wildly important for athletic performance. I also feel that by training them in a split squat, it is highly reflective of sport action, and a very natural movement. The strain that’s placed on the plantar (or “arch”) is also something I covet with split squat variations, and also why I particularly prefer to do split squats without shoes.
Everyone, and I mean EVERYONE, should get out of their shoes to train, at least once in a while. But split squats are the quintessential exercise for barefoot training. On the front foot, we’re working the intrinsic muscles of the foot by actively gripping or squeezing the ground and promoting kinetic stability and maintaining a neutral foot with even weight distribution, whereas on the back foot we’re getting all the qualities mentioned above. But big toe extension and loading the arch specifically are reasons enough to get your athletes split squatting.
In my personal opinion, I don’t think bilateral vs. unilateral squatting has any reason whatsoever to be debated… I truly do not understand why that topic generates so much interest. I mean truth be told I perceive them as COMPLETELY different exercises (mind blowing, I know), but there are qualities that I want from bilateral squatting that aren’t present in unilateral, and vice versa equally. Don’t overthink this kind of shit, unless you have a very specific reason as to why one is better than the other, or why someone is a good or bad candidate for one or the other, then just program both. Trust me.
What the hell are RFE and FFE all about…
Rear foot-elevated (RFE) and front foot-elevated (FFE) split squats are movements commonly utilized in the athletic performance realm, and for good reason. Although each appear to be single-leg movements, I do not coach them as such. What I’m looking for with RFE split squats is to keep the back leg active by dorsiflexing the foot into the pad and finishing the ascent portion of the lift by firing the back glute in an effort to create co-contraction at the hips. This also outlines why I do not recommend using a bench for RFE split squats, as it takes away the ability to stabilize the hips accordingly. As for the front leg, we want to have an active front foot by squeezing the toes down and slightly rotating the foot outward and think “push through the quad” as we ascend. The tibia usually translates forward over the toe more in RFE split squats than in other variations, which is another reason why I love RFE set-up. As for the trunk position on RFE split squats, I typically coach this by saying “mirror your shin angle”, meaning, I want the trunk inclination to be parallel to the shin angle while we perform the movement. I stole this from someone, but for the life of me I honestly cannot recall where I heard this. But if you happen to be reading, thank you, and my bad.
With the FFE split squat, we again are going to coach this as a two-legged movement, with just a shift in distribution between legs. In the FFE split squat, I will coach the athlete by instructing them to “push through the quad on the front, and the big toe in the back”, again with the emphasis of co-contraction at the hip in the forefront of my mind. Typically, dorsiflexion angles are preserved during FFE split squats, which will be reflected by a more upright torso position. This makes FFE split squats an advantageous squatting option for athletes with poor or impaired dorsiflexion. I also like the FFE split squat because it demands deeper ranges of hip flexion, making them great options for baseball, softball, and combat athletes. Deep angles of hip flexion are hard to come by in training, the FFE split squat requires this and usually without issue. Remember, your hip flexors probably aren’t “tight” as much as they are “weak”. Similarly, with deeper angles of hip flexion we’re going to likely experience deeper angles of knee flexion as well. This makes FFE split squats great options for those with knee ligamentous or patellar injuries, whereby we can re-acclimate them to some deeper ranges of motion without forcing it.
For both RFE and FFE split squats, these will most often be second and third block options for me and treated as accessory lifts (i.e. never programmed with corresponding percentages). I will use both options, mostly in a 1:1 fashion, with just about every athlete I see. I think that both are tremendous variations, with unique qualities you cannot replicate elsewhere. One important note I want to tack on here is that RFE and FFE variations are not for everyone. For athletes with significant anterior pelvic tilt, RFE split squats probably aren't a good option, as this position will exacerbate present issue of anterior tilt. Similarly, FFE variations probably aren’t a good option for athletes with excessive posterior pelvic tilt or excessive lumbar flexion in their resting posture.
IV.) Joint-by-Joint Kinematics (Important items to be aware of)
Alright so I’m not gonna bust out my inverse dynamics chart and TI-89 for this, I promise, that part of my tutelage is behind me. But there are some important kinematic observations at each joint in the lower extremities we should take particular note of. I’ll go joint-by-joint here, but just gonna keep this to bullet point fashion.
Ankle and Foot:
-Primary action of the talocrural joint is to facilitate dorsiflexion and plantarflexion; normative values for dorsiflexion are ~20° and ~50° for plantarflexion (1).
-The primary function of the subtalar joint is to maintain positional stability and resist inversion/eversion translation during squat (1).
-Peak ankle moments have been shown to be around 50-300 Nm during squatting (5).
-Speed or velocity of squat has significant influence on the function of the lower leg. Namely, gastroc and soleus. During higher velocities, gastroc and tibialis anterior co-contract to provide stability. While at more standard velocities, the gastroc works mostly eccentrically, and the soleus more isometrically (3).
-Lacking strength in medial gastroc, TA, or posterior tibialis may reduce ability to control knee valgus and foot collapse (overpronation) (6).
-Tightness of lateral ankle muscles (peroneals) can contribute to or exacerbate medial (valgus) knee collapse (6).
-Unilateral or split-stance squat variations require increased demand for foot stability, preventing overpronation, and ankle stability. Split squats also increase demand on big toe extension and arch strain when performed in traditional setup.
-Hamstrings behave paradoxically during closed-chain movements, such as squatting, by co-contracting with quads.
-Peak ACL forces typically occur during 15-30° of knee flexion (5).
-Forces on ACL/PCL actually decrease during deeper ranges of flexion; debunking the myth that deep squats are bad for the knees (5).
-Deep squats are highly demanding on menisci and articular cartilage but are also great for glute and hip development.
-A narrow stance is generally more demanding on the knees, as forward translation and shear stress is greater.
-Forward lean has significant impact on squat mechanics and force tolerance. Hip torque is significantly increased during restricted squatting in which knees do not travel past toes.
-Hamstrings are only moderately active during squatting; about 50% of EMG activation as compared to RDL or hamstring curl (5).
-For most, adductors and glutes will be primary working muscles during squatting.
-The length of the hamstrings during squatting remains almost net neutral, which is the same for the rectus femoris for the quads.
-Peak hamstring activation has been shown to occur between 10-70°, depending on structure and set-up (5).
-Studies have yet to discern a difference in hamstring activation based on depth.
V.) Depth, Transfer and Specificity
In this last segment, I want to just add a few notes on depth, how different squat variations transfer, and what we can do to increase specificity for our athletes. Most of this I actually wound up touching on throughout the material above, nevertheless, I want to wrap this up by hitting some key points I often consider while coaching.
-If we can squat to parallel without pain, I think it’s best to use that most often. I do, however, feel that quarter and half squats should absolutely be programmed and utilized throughout your training cycle. Don’t overthink the specificity conundrum… watch their sport, observe the angles, use them in the gym. If you have a basketball player, offensive lineman, or volleyball player, half and quarter squats should be programmed frequently. If you have catchers, combat athletes, or running backs, deeper squats should be programmed frequently. I promise you, it’s not as tough as most make it seem.
-Moreover, if you look at the literature, there really isn’t anything essential about working to parallel, I actually believe that this is one of those undying rites of passage for training- “squat to depth or be stoned to death.” But in all seriousness, I think it’s a bit overblown. You can absolutely have proficient technique in a slightly above parallel squat, and frankly you’ll get about the same amount of work out of them. The best way to approach squat depth in my opinion, is if they can access it, then it’s fair game. If it’s forced, cut the range of motion. But I digress.
-Having your knees go past your toes is 100% ok. Let me reiterate- having your knees go past your toes is about the most ‘sport-specific’ thing there is! It is a fundamental requirement of any sport I can think of. I can’t wrap my head around why this is still a thing. Turn on any athletic event, watch for 5 minutes and tell me you don’t see athletes with their knees over their toes… I’ll wait. What we don’t want to see is the knees travel over the toes while the hips are still underneath us or have the knees divebomb over the toes as the initiating action of the squat pattern. Yes, those are bad patterns that need to be cleaned up. But if the rest of the squat looks solid, and the knees travel over toes as a manifestation of that, that’s a beautiful squat. Knee over toe is also what I WANT to see during most unilateral squatting. Again, it doesn’t get more sport-specific than this.
-I do not recommend squatting beyond parallel in a bilateral, front or back squat, very often, or very heavy. I just don’t think this is a position the knees are meant to be in under heavy load. The exceptions to this are outlined above. Unless it's required in sport, for deep knee flexion angles, use unilateral options.
-Conversely, for football and basketball players, whose sports are predominantly played at low degree knee flexion angles, I will actually program as many quarter and half squats, and box squats as I will parallel; and with the same intensities applied. You rarely, aside from pre-snap stance, see an offensive lineman in a deep knee flexion or beyond parallel position. Use good judgement and apply it logically.
-As I hit on earlier, you need to use an array of squat variations. Even if you are a power lifter or Olympic weightlifter, I would recommend sprinkling in a blend of front and back squats, split squats, and RFE and FFE variations. When it's conducive to your programming, I think each has a specific quality to offer and each helps to build a more robust, stronger athlete.
-This is purely anecdotal but I’ve actually had success with taking Oly lifters off their typical programming for 8-12 weeks and hammered them with as much non-sagittal or ‘specific’ work as I could. The results have been quite successful. Including mitigating chronic minor injuries such as tendinitis, IT band syndrome, non-functional asymmetrical imbalances.
-Apply tempos to your squatting. Regularly. Need more on this? Follow this link.
-Pistol squats suck. There I said it. Use a skater squat instead, or just stick with FFE and RFE variations.
-If you can do them properly, overhead squats are one of the best exercises out there. Problem is, I’d guess like 5% of athletes can properly overhead squat. For those of us who cannot overhead squat well (yours truly included), I will use an overhead set-up for split squats, FFE and RFE split squats and lunges often. I just think it’s great whenever we can make movements more ‘total body’ oriented. Squatting is no exception to that. But seriously, overhead squats are tough, and highly demanding on the shoulder, thoracic spine, and lumbo-pelvic complex. Use good judgement.
Finally, thank you for reading. I know this one was a monster, but I had a ton of fun putting this one together. Truth be told I learned some new things myself and was reminded of a few things I had lost sight of. Just because an exercise is common, doesn’t mean it’s “basic”, there is a ton of shit going on while doing squats, we need to give this movement the respect it demands.
1.) Baechle, TR. Earle, RW., (2008). Essentials of Strength Training and Conditioning (4th ed.). Champaign, Il: Human Kinetics, 2008.
2.) Dietz C, Peterson, B., (2012). Triphasic Training. Hudson, WI: Bye Dietz Sport Enterprise.
3.) Fry, AC, Smith, JC, and Schilling, BK. Effect of knee position on hip and knee torques during the barbell squat. J Strength Cond Res. 17: 629–633,2003.
4.) McKean, MR. Burkett, BJ. Does segment length influence the hip, knee and ankle coordination during the squat movement? J Fit Res. 1(1), 2012.
5.) Schoenfeld, BJ. Squatting kinematics and kinetics and their application to exercise performance. J Strength Cond Res. 24(12): 3497–3506, 2010.
6.) Senter, C and Hame, SL. Biomechanical analysis of tibial torque and knee flexion angle: Implications for understanding knee injury. Sports Med. 36: 2006.