Strong Science #1

After roughly 6-7 months of blogging, I’m still working to find my voice and a good way to deliver my content. So while I’ve been experimenting with different formats of posts, this also means that I need to experiment with different LENGTHS of posts. I’ve started to build up quite the collection of overly-referenced monster posts but I need to add more short, to-the-point posts that are easily scannable. After receiving feedback from some readers I’ve created the Strong Science series to address individual research studies in a short and sweet fashion. I’ll recap studies in a few quick sentences and relate it to the world of strength training as a whole, without being riddled with technical terms and jargon. If the study title interests you, take the time to read on for details; if it doesn’t , skip to the next one. As always, I love feedback on anything to do with the site, so if I’ve hit a format you think is working (or not), feel free to let me know in the comments or send me an email.

With that out of the way, I’ll start the Strong Science series off with a good mix of both recent and older studies looking at the sweeter side of things nutritionally, everyone’s favourite exercise (the squat) and round it out with a study on the effect of bar size on forearm activation.

Carbohydrate does not augment exercise-induced protein accretion versus protein alone (1)

Carbs, protein and heavy weights. Sounds like the perfect combination, and for many of us it is. But for many carb-conscious folks, the idea of spiking your system full of sugar, even when consumed alongside a hearty dose of amino acids and timed with exercise, just doesn’t feel right. Fortunately for them new data suggests that cutting out carbs may not be compromising the goals of your peri-workout nutrition.

Staples et al (1) recruited college-aged, recreationally active men to perform two sessions of single-leg (unilateral) knee extensions (four sets at 8-12RM) separated by one week, with consumption of either 25g of whey protein alone or in combination with 50g of maltodextrin (carbs) following either bout. The authors measured mixed protein synthesis and breakdown, blood flow and metabolites in the period following the exercise and took biopsies to determine intramuscular signalling protein activity.

Not surprisingly, consumption of the carbohydrate-containing beverage increased plasma glucose and insulin compared to the protein-only drink. While this resulted in greater stimulation of the protein kinase Akt, a signalling protein thought to be pivotal to the elevation of protein synthesis, the additional carbohydrate did not elevate protein synthesis, or even reduce protein breakdown beyond what was seen with the protein-only drink. This suggests that elevated insulin was not additive to protein synthesis and breakdown when carbohydrate consumption occurs along with protein following a strength training bout. So it seems we have some relief for those low-carbers, and life is a little easier for the Paleos among us who were worried about how their ever-so-sweet peri-workout beverages were ruining their ketogenic or paleolithic lifestyles. Those extra carbs may not be necessary after all.

I’m sure some will be resistant to drop the carbs from their workout beverages, however, at least for those looking to lower calories (i.e. fat loss clients), these results suggest that sticking to a protein based beverage is sufficient. This only considers one aspect of muscle recovery (protein synthesis/breakdown), and not other factors that can impact performance, namely replenishment of muscle metabolites (glycogen). Those performing taxing exercise that results in depletion of muscle glycogen may still be interested in consuming carbs post-exercise to replenish glycogen more rapidly than without them (2,3).

High- and low-bar squatting techniques during weight-training (4)

This one is a classic that I first encountered doing an undergraduate biomechanics project, and was brought back to my attention in Bret Contreras’ latest post on T-Nation. The authors (4) recruited national level weightlifters and powerlifters to perform either the high-bar or low-bar squat respectively, where the bar was positioned just below the spinous process of C7 (high) or in line with the spine of the scapula (low). Powerlifters relied exclusively on the low bar position, which resulted in greater hip moments and a higher degree of hip flexion, indicating they sit back more in the squat, potentially engaging the posterior chain to a greater degree. Conversely, weight-lifters took the high-bar position and remained in a more upright position and had higher moments at the knee. Certainly fits with the common ideas that olympic lifters rely on a quad-dominant squatting pattern while powerlifters focus on the posterior chain.

What often gets missed in this study is the high activation of the quadriceps in the low-bar squat, where rectus femoris activation was significantly higher than in the high-bar position. The authors mention that the powerlifters were heavier and lifted more weight, which could potentially explain the higher EMG, but as the signal was referenced to a baseline contraction with the same load that might be unlikely. We’ve seen the concept of coactivation in previous posts on my blog, and here might be a perfect example. The low-bar position results in high activation and force production from the posterior chain muscles, clearly higher than the high-bar and this increased hamstring activation across the knee requires elevated quadriceps activation and force to stabilize and protect the joint. The posterior chain is certainly getting all the glory these days, but this demonstrates that we can’t neglect the contribution of the quadriceps to the movement, regardless of squatting style.

Effect of knee position on hip and knee torques during the barbell squat (5)

Squat technique has seen a shift in recent years, originally a quad dominant technique with upright posture popularized by olympic weightlifters and bodybuilders, to a lower-bar technique with greater hip flexion and an emphasis on sitting back, showing the influence of prominent powerlifters on the fitness industry as a whole. This study tested the commonly held belief that the lower leg (shank) should be kept near vertical throughout the squat exercise, ensuring that the knee does not pass the toe throughout the range of motion (5).

Recreationally active men were recruited to perform high-bar squats with a barbell equivalent to their bodyweight under two conditions. The first, an unrestricted squat where the knees were free to move beyond the toes and the second a restricted condition, where a vertically placed board stopped the knee from moving beyond the toes, ensuring the shin remained near vertical as compared to the unrestricted condition. The results of the study were limited simply to torques about the knee and hip, but are interesting nonetheless. The restricted condition resulted in significantly greater torque about the hip with greater hip flexion and drastically reduced torque at the knee compared to the unrestricted condition. This position is shown below and condition ‘B’, the restricted squat, would be anything but desirable form for a squat. Seems that high-bar position and near vertical shins don’t seem to mix when it comes to squats.

Free vs Restricted Squat

The influence of bar diameter on neuromuscular strength and activation: inferences from an isometric unilateral bench press (6)

The idea is simple, so simple that most wouldn’t think to question it. If an object is hard to hold onto, more work is required to hold on to it and more muscle mass is activated in the process. Sounds good in theory, however in practice the scientific literature paints a different picture. Fioranelli and Lee (6) put this theory to the test with an isometric bench press exercise (pressing against an immovable bar) with the elbow joint in two positions, either 45 or 90 degrees. Using EMG (represents muscle activity) the authors found that for this particular pressing exercise, the thicker bar actually resulted in reduced activity of the forearm flexors at both angles. Building on that, EMG activity was lower for the Pectoralis Major with the thick bar at one angle tested, however maximal strength was similar regardless of the bar used. So the claims on many equipment manufacturer’s sites may be a bit grandiose based on what the scientific literature has to say about it.

There are limitations to this work. It would have been nice to see other exercises, particularly pulling-based lifts given that previous literature has demonstrated reduced strength in these exercises with oversized bars (7). The authors used an isometric exercise, not a staple of the average gym-goer’s routine, but a necessary component for accurate force determination and EMG work in the lab. It would be nice to see how bar diameter alters the kinematics and muscle activation of a dynamic lift, but this may be asking a bit much experimentally. Nevertheless, I’m not trading in my collection of oversized bars just yet. If anything, it provides another level of variation in your training, and various anecdotal reports (myself included) find reduced elbow pain in many exercises when using these bars.

References Show

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Comments

  1. Adam says

    Regarding the Fry study, with which I was very taken when I read it: it certainly demonstrates the loads borne by the hips (and presumably low back) in a vertical shank squat. I think they found something like 2000% increase.

    I can’t remember the researcher, but a study that Bret Contreras reviewed compared the squatting styles of competitive lifters vs. recreational ones. The most relevant thing I remember is that better squatters utilized wider stances, which allowed a more vertical torso. I have long femurs even for 6’1″ and this is definitely my experience.

    One could also suggest that the maxim to keep the shin vertical is bogus unless you’re geared. I think it’s more a cue to keep people from just shoving their knees (and weight) forward.

    Also, homeboy appears to be wearing lifting shoes with a positive heel, which isn’t exactly conducive to hip-dominant squatting (along with the bar position, which you pointed out).

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