Slim Down Lifestyle

He has written a number of articles on biomechanics and apparently plans to release a book entitled The Physics of Fitness.  Apparently this book has received very positive advance reviews from such luminaries as Wayne Wescott, professor of exercise science and advocate of high intensity training, Jeffrey Mackey, professor of physics, sports psychologist Fred Hatfield, and neurobiologist Stephan Guyenet, among apparently well qualified reviewers.

I have found some value in some of Brignole's articles.  However, in an article entitled “Do You Know Squat” Brignole makes some claims about the physics (mechanics) of squatting that reveal that he probably does not understand some important aspects of the basic physics of squatting.

I will need to extensively quote this article in order to explain where he goes awry.

Brignol's Discourse on Levers

In order to explain Brignole's mistakes, I will need to refer to the background information he provides on levers.  After correctly discussing how the body is a system of levers, Brignole writes:

“A lever that is parallel with the direction of resistance is 'neutral.'  It provides zero load to its operating muscle. A lever that is perpendicular with the direction of resistance is maximally active. It provides 100% of the available resistance to its operating muscle. A lever that is in positions between parallel and perpendicular are percentages between zero and 100. 

“Let’s do a simple experiment, to illustrate this point. Put your arm on a table top, so that your upper arm is lying flat on the table (from elbow to arm pit). Then, bend your elbow so that your forearm is pointing straight up (vertical). Now put a weight in that hand.”

 

“What you’ll notice is that regardless of the weight you have in your hand, it does not require any force from your biceps, to maintain your forearm in a perfectly vertical position. This position is parallel with gravity - so it's neutral. This is the reason why light posts are vertical, as well as most support beams under bridges and in buildings.

“Now, allow your forearm to come almost all the way down, so that the dumbbell in your hand is a fraction of an inch away from touching the table. You’ll notice that this position requires considerable force, on the part of your biceps, to hold that position. This position is the 'maximally active' position. It is where the lever (your forearm, in this case) and the direction of resistance (gravity) are mostly perpendicular.”

“Every position in between, where your forearm is vertical and horizontal (neutral and maximally active), is percentages thereof. For example, a 45 degree angle is half way between vertical and horizontal - so it would result in 50% of the available resistance being loaded onto the biceps. This is the universal law of levers.”

Brignole's Description of Squatting

Brignole starts discussing the mechanics of squatting thus:

“If we were to watch someone who is performing a squat, from a side view, it would be easy to see the angle of the lower leg lever, the angle of the upper leg lever AND the angle of the torso. Keep in mind, we’ve already established that a vertical lever is neutral, a perpendicular lever is maximally active, and levers between vertical and horizontal, are percentages between zero and 100%.”

Brignole continues:

“In the photo above, we see a man in the descended position of a Squat. The red line indicates 'vertical', and is where the man’s lower legs, upper legs and torso would be, in the upright position. When in the upright position, the lower legs, upper legs, and torso are all in the neutral position - parallel with gravity.

“Now that he’s in the descended position, we can see the angle to which each of these three levers (lower leg, upper leg and torso) have moved, from the neutral position.

“The lower leg is at about a 60 degree angle, the upper leg is just below the horizontal position, and the torso is at about a 58 degree angle."

“It’s important to note that since none of these levers are perpendicular (in the descended position), none of them are neutral. They are all 'active' now (in this descended position), to varying degrees.

“The most 'active' is the upper leg (lever) - since it’s horizontal (perpendicular with the direction of resistance). It is being operated primarily by the Glutes.

“The lower leg (lever) is operated by the Quads, and it’s a little less than half-way between the neutral position and the fully active position. Therefore, this lever (the lower leg) is loading the Quads with a little less than half of the available resistance.”

Since he implies that the lower leg is loading the quadriceps, but with less than half of the available resistance,  I say he is "not even wrong" because in fact the lower leg is not providing any load to the quadriceps at all.  Let me repeat: the lower leg is transmitting no resistance whatsoever to the quadriceps, and this does not mean that the quadriceps are not subjected to a load.

First, just look at the photo.  There is no load attached to or force being applied to the lower leg anywhere.  Even if there was a load attached there, it would make no difference to the quadriceps.   When people add resistance to squats, they attach it to the shoulders or hips, not to the shins or ankles, because attaching a load at the shins or ankles will not make squatting more difficult.  The quadriceps are not resisting a load transmitted through the shin!

In writing "The lower leg (lever) is operated by the Quads..." Brignole gives the impression that he believes that the quadriceps can only operate (move) the lower leg lever. 

In fact, since the quadriceps attach to both the lower leg and the upper leg, they can operate either the lower leg or the upper leg (femur), depending on which lever (bone) is anchored and which is free to move.

In a seated leg extension (a so-called open chain movement), the femur is anchored and the lower leg is free to move.  When the quadriceps contracts, it pulls on the lower leg to open the knee joint into full extension where the tibia aligns with the relatively stationary femur. 

In contrast, in the case of squats (a so-called closed chain movement), the feet are anchored to the ground by gravitational and friction forces, limiting the lower leg to about 30º of motion, while the upper leg is free to traverse more than 100º of motion.  As a consequence, when the quadriceps contract, they will primarily move the loaded and most active lever, i.e. the upper leg (femur).  If this is not obvious to you at this point, I will prove it shortly when I discuss vertical shin squats below.

From Johnston BD, Prescribed Exercise.

“Yes - the knees are over the toes, due to the 60 degree angle of the lower leg. But if the knees were NOT over the toes, then the lower leg would be vertical - which is the neutral position. In other words, without the knees going over the toes, the Quads would get little if any resistance!”