Strong Science #2

Thinking back about ten years ago, after tearing both pecs, I began a love affair with lower body training. What’s a guy (or girl) to do if you can’t bench, other than launch an all-out assault on lower body training? At the time, that made the main object of my affection without a doubt the barbell squat. With Valentine’s Day close behind us, I’ll stoke the fire of what will likely be a life-long romance with the barbell squat by filling this Strong Science post with three recent studies on the squat.

Limiting Ankle Dorsiflexion Range of Motion Alters Lower Extremity Kinematics and Muscle Activation Patterns during a Squat (1)

This study hit my radar thanks to a post on Mike Robertson’s site . The premise is simple; tight calves limit the ability of the lower limb to track properly during the squat. To test this the authors had subjects perform an unloaded squat exercise under two conditions: one where the foot was in a neutral position in the ground or the other with a wedge placed under the foot forcing it into 12 degrees of dorsiflexion relative to the ground.

With the foot in dorsiflexion there was an increase of one degree in the knee valgus angle (knee caving in) and EMG activity of soleus along with decreased peak knee flexion angle and quadriceps EMG. What’s interesting about the range of motion results is that the one degree change in knee valgus angle represented a 16% change from the non-wedged condition, identical to the 16% decrease in peak knee flexion angle between the two.

The authors were focused on the relationship of ‘tightness’ of the gastrocnemius and soleus to compensatory movement patterns and the potential for other problems to develop, namely patellofemoral pain syndrome. This probably explains the lack of load during the exercise in an attempt to mimic everyday life. Not too many patellofemoral pain sufferers load up the barbell for round after round of deep squats.

In the gym, how many times have you yourself, or a client you’ve worked with struggled with the knees caving in during the squat? We’re often quick to pinpoint the hip, assuming impaired glute function (not uncommon) but this study shows us we have to look down the chain to the ankle as well.

I’m also left wondering, how does a squat in forced dorsiflexion really work? Does it accurately reflect the effect of a tight calf complex (soleus, gastrocnemius), or simply a squat in a different foot position? In a previous study, Fry et al (2) altered movement of the knee in the forward direction (anterior, ‘over the toes’) by placing a board that limited the ability of the knee to move outside for the foot. The authors do acknowledge this limitation of their work, and also note that participants took a wider stance when in the wedged position. Are they making more room for the knees to collapse into?

Either way, both studies suggest that optimal squat technique requires movement of the knee around the foot and that the quality of the calf complex can contribute to impaired movement and potentially limit performance. Assess and address ankle mobility in your programming and start treating that soft tissue people!

Kinematic changes using weightlifting shoes on barbell back squat (3)

Interest in olympic lifts has exploded over the last five to ten years. With that we’ve seen increased use of olympic lifting shoes and there’s actually a pretty diverse selection on the market. I’d love to see how the sales numbers for these shoes have changed alongside the popularity of crossfit because as we all know, you can’t crossfit without the best footwear and you certainly can’t have the same colour shoes as the guy at the next rack over!

Nike Romaleo Shoes

As for the methodology of this study, there’s nothing incredibly complex here. Lifters were recruited to perform the back squat at 60% of their 1RM under two conditions: either wearing weight-lifting shoes or without. Markers were placed to help the investigators identify the foot, ankle, knee and hip as well as the end of the barbell, and all attempts were filmed to permit analysis of the movement.

Not surprisingly, the raised heel of the olympic shoe influenced the foot angle and  lead to a more upright trunk position during the squat, as has been consistently observed anecdotally, while there was no effect on peak knee flexion. It would have been nice to see how movement of the tibial portion of the leg was affected by the footwear, unfortunately the foot segment angle that they took would have only represented the effect of the heel of the shoe and not account for dynamic movements of the lower leg.

I’ve never spent much time on footwear personally. I’ve gone through Nike Frees and Chuck Taylors but for the most part now I stick with the New Balance Minimus. I’ve recently flirted with the idea of getting a pair of olympic lifting shoes just to see if it can reduce my hatred of the front squat. At this point I’ll try anything.

A bigger question I’ve had is how we can manipulate small technique modifications to help those who have technical limitations in certain exercises, or previous injuries and pain that is produced by certain positions. In the case of squat-related back pain, the usual solution is to drop barbell squats in favour of single leg solutions to minimize spinal loading. This is often a successful solution to keep loading the legs, but for many, single-leg solutions don’t cut it and they continue to grind through the pain.

Pisarenko Upright Olympic Squat

But if we combine back squats with a high bar position and olympic lifting shoes (pic above), you’ll probably have a technique with the least amount of trunk flexion possible. This would definitely alter the positioning from the now popular powerlifting style low-bar back squat with high trunk flexion angles and increased moment arms at the hip and lower back (L5/S1) (4). At the very least this may be a good first step when reintroducing people to the exercise who have previously suffered squat-related back pain once before. If their goal is ultimately to move as much weight as possible, you can gradually progress them back to a low-bar, power-lifting squat with increased trunk flexion.

Influence of weight distribution asymmetry on the biomechanics of a barbell back squat (5)

In case you haven’t heard, squats and milk may not be the cure all the internet bro-scientists have made it out to be. To make matters worse, training bilaterally may not actually ‘even out’ the muscular asymmetries you have.

Sato et al (5) set out to determine how weight-distribution asymmetries influence technique in lifts that are bilateral and assumed to be symmetrical, in this case the squat. These weight-distribution asymmetries are really just a fancy term to acknowledge that when standing, most of us tend to choose a ‘favourite’ leg that ends up supporting more of our bodyweight than the other.

The study looks at whether these weight-distribution asymmetries carry over from standing and persist during a barbell squat. Participants were divided into either a symmetrical group, where the difference in bodyweight distributed to each leg was less than 4%, or an asymmetrical group where a difference of greater than 6% existed. Each group performed two sets of five reps at 60% and 75% 1RM on two force plates (one for each foot). The barbell was marked and all lifts recorded with video cameras to measure bar angular displacements.

The results demonstrated that weight-distribution asymmetries persisted despite loading, and that adding increased load (from 60% to 75% 1RM) did not increase the asymmetries further. Those who were asymmetrical held the bar on an angle (both vertically and anterior/posterior), although the difference was roughly one degree either way. Increased loading didn’t influence any measures. It seems that asymmetrical weight distributions lead to minor technique modifications resulting in different vertical ground reaction and minor rotation of the bar (one degree).

So we now know that someone that doesn’t distribute their weight evenly between each leg when standing will also lift asymmetrically, even if the lift is bilateral. The differences in technique (barbell position) was small, often around only one degree, so the ultimate question is how does this affect performance and muscle activity? I’m sure some will see this as support for single leg and asymmetric training to promote muscular balance instead of assuming bilateral lifts get the job done, but much more work needs to be done before we can make that leap.

What have you experimented with?

As always, I’d love to hear your thoughts about these studies so shoot me an email, find me on twitter, or use the comments below to share your thoughts. Next month, after having a blatantly obvious bias for studies on the squat I’ll take a break and bring some different work to the table. If you have any requests for topics, let me know.

References Show

Get an evidence-based inbox

Submit your email to get regular updates on how the latest developments in exercise science can help you maximize your physical potential.

Comments

  1. Kevin Thomas says

    You misread your third reference, "Kinematic changes using weightlifting shoes on barbell back squat". There WAS a statistically significant difference in foot segment angle. The WL shoes had about 3.5 degrees more than the running shoes.

  2. says

    Hi Kevin, Thanks good find and I've corrected the text. While of course lifting in a raised heel will influence the degree of plantar flexion the foot is in, I garbled this up with my argument that it would be more interesting to track tibial translations than the angle of the foot that they calculated in the study. Thanks for reading.

Trackbacks

Leave a Reply

Your email address will not be published. Required fields are marked *