I remember my first time in the weight room like it was yesterday. There I was, a young 14-year old high school freshman, eager to turn myself into a beast beyond typical high school proportions. I wanted to dominate the playing field and rule the weight room.
My first experience with weight training was in freshman P.E. class. Our gym teacher, whom I’ll call Mr. W. for short, wore a tight polo shirt and way-too-short tennis shorts. Before we were to venture off on our own to explore our physical limits and test our strengths (and egos) against our peers, we got some basic instruction about the proper way to lift weight.
Mr. W. discussed the basics of sets, repetitions, body part training, and equipment. I had no idea that our next topic that we were to go over would eventually turn into a four-letter word (at least in my mind).
We were taught that strict or “perfect” form is executing the exercise to the letter of the law. “This is how you should perform all of your exercises”, said Mr. W. Since I was just a lowly high school student and didn‘t know any better, I spent the next four years pounding away using absolutely perfect form. While I made modest gains over that four year time span, I was far from satisfied with my progress.
Fast forward two years. I was college junior, starting my fall semester. Having taken all my basic courses the first two years, it was now time to delve into the core work of my chosen major, exercise physiology. While immersed in my studies, I still toiled away in the weight room unsuccessfully. Unhappy with my progress in the gym, I tried to seek out a way of surpassing my stagnating level of development. I read every magazine and book I could get my hands on, and everyone said the same thing, “Use proper, strict form”. I began to get frustrated because this was nothing new to me; I learned that years ago in high school gym class.
In my biomechanics class, I learned about topics such as force production and lever systems. Force was basically mass x acceleration. If force = tension and increasing tension caused muscles to grow, then increasing either the mass moved (lifting heavier weight) or the acceleration of that mass moved would increase growth. By examining the different lever systems of the body and factoring in the rotational force, or torque, on each system, I could then devise a way of attacking each body part with biomechanically efficient form.
In bodybuilding terms, torque if often thought of as being a negative thing during exercise. Behind-the-neck presses put too much “torque” on the rotator cuff. Swinging the weights instead of using “perfect” form puts too much “torque” on the joints. I was now educated enough to see that this might not be the best use of the term.
Nonetheless, I found myself facing a conundrum; I have to increase torque to increase tension on the muscles, spurring new growth, but I have to limit excessive torque during the exercise which could be potentially harmful to the joints and connective tissue. How was I going to find that balance between optimal muscle stimulation and preventative joint health?
I first had to look at how torque is measured. Torque is simply a product of a force times the length of the torque arm. What the heck is a torque arm? Think of a see-saw. If you make the other side longer, you will have to work much harder to lift up the fat kid on the other side (not politically correct, but the fat kid better represents the heavier weight you need to use to grow from your efforts in the gym). The long side of the see-saw would be the torque arm.
One of the best lever systems of the body to examine this method is the elbow joint during biceps flexion (or performing a curl movement). Although the lever length (meaning your arm length) doesn’t change, the apparent torque arm length does. The point at which torque is the greatest is when the torque arm is the longest.
In this diagram, the thin black line (half-circle) is the possible path of the arm, the thick black lines are the arm itself as it moves along the path, and the blue, red, pink, green, and purple lines are the (x , y) components of the arm’s position. The x axis represents the length of the torque arm.
Remember that gravity only works in one direction, and for our purposes that would be in the negative y direction, or down, so the apparent length of the torque arm is the x component. This is why every free-weight exercise has a “sticking point” where the weight feels the heaviest. I’m sure we’ve all felt this phenomenon, when reaching the halfway point of a barbell curl, where the bar suddenly stops halfway up, and gets significantly easier once that point is broken.
The same happens during squats when the knees reach 90 degrees or during bench presses when the elbows reach 90 degrees.
Holding your arm down at your side, notice how there is very little if any tension on the biceps. This is because the torque arm is essentially zero. Now hold your arms with a 90 degree bend in the elbow. This is the point at which the point of resistance (where you hold the weight) is furthest away from the body, or where the torque arm is the longest. This is that sticking point.
If you can put more weight (or mass, for you physics nerds) onto a longer torque arm, then overall torque about the axis of movement (your elbow joint) is increased. What in the world does all this mean? It means that for most exercises, there is a point at which torque is at its greatest. I like to call this point the maximum force point or peak force point. If you can get more weight into that max. force point, then you will ultimately spur more muscle growth. For most exercises, this point comes where the joint forms a 90 degree bend during execution.
Think middle ROM for a squat, bench press, pull-up, row, curl, press down, calf raise, etc. Virtually all exercises form this 90 degree bend between the extreme stretched and contracted positions. But mechanically, the extreme stretched position is also the weakest. This means that in order for a weight to reach the max. force point, it must first get past the extreme stretched position.
Let’s say you typically perform “perfect” or strict dumbbell curls with 50lb. dumbbells. Imagine holding an 80lb. dumbbell with your arm bent at 90 degrees. Pretty tough huh? It should be difficult, but possible because at 90 degrees the biceps are at their strongest mechanically.
Now hold that 80lb. dumbbell with your arm hanging strait down to your side and try to curl it up with zero movement other than that of the elbow joint. Might be near impossible. If we know that having that 80lb. dumbbell in the max. force point causes the most growth but the bottom of the movement is the limiting factor, we can conclude that to stimulate maximum growth in the biceps that we have to somehow bypass the weak extreme stretch position to get that heavy dumbbell into the max. force point.
You could hypothetically just use assistance to get the dumbbell into the 90 degree position and hold it there, but a static hold does very little in terms of growth because it neglects one important factor of physics; movement.
Force = mass x acceleration. If acceleration is zero, then force = zero, torque = zero and ultimately growth = ZERO.
To bypass the weak stretched position but still keep the heavy dumbbell accelerating (remember, increase mass and acceleration and we increase force), slight movement of the hips and back can put a small amount of momentum into that dumbbell, making that 80lbs. feel like 50lbs.
Simply swinging up the weight with no regard to muscle control will yield less total torque because you will then have a 50lb. dumbbell in the max. force point, causing less stimulation. Barely swinging the dumbbell will not give it enough momentum to get it out of the stretched position. The answer then is finding a compromise between heavy weight and strict form. This will make the dumbbell feel like 50lbs. in the weakest position but feel like 80lbs. during the max. force point. The best of both worlds, movement in a full ROM and maximum torque.
On movements like curls, triceps extensions, lateral raises, rows, calf raises and pulldowns, a slight bit of movement from other muscle groups will allow more stress to be put into the max. force point of each exercise. For the biceps/triceps and quads/hams, it’s when you are halfway through a curl or extension movement. For shoulders, it’s when you are near the top of lateral raises or halfway up on an overhead press (elbows at 90 degrees). For chest and back, it’s when your arms reach a 90 degree bend in the elbow (imagine during a bench press when the upper arm becomes parallel to the floor). For calves, it’s when your ankles form a 90 degree angle.
So what does this mean? Well, it means that a little bit of body English at the bottom of a movement isn’t necessarily a bad thing (as long as it is performed safely and under muscular control). It also means that the negative portion of the repetition shouldn‘t be ignored since the negative portion includes another pass through of the max. force point.
Because the negative, or eccentric portion of the repetition is stronger, it could also be assumed that the occasional use of negative only training (by which you use a heavier weight than can be completed during the positive portion of the rep) can increase torque even more than traditional means.
Also, because the negative portion is stronger, it will increase time-under-tension (TUT) by slowing down the negative considerably. This is another important piece in the muscle growth puzzle. Again, because the negative can be performed slower, it is assumed that the weaker, positive portion must be performed faster to be successfully completed. This increases the acceleration portion of the Force = mass x acceleration equation.
Another factor to consider then is rep timing. Normal, cadenced rep speed proves to be less effective than strategically speeding up or slowing down certain portions of the rep because a loss of torque is experienced if the load is left in the weak point of the lift for extended periods of time. There’s no need for a peak contraction, and don’t pause to feel the stretch. This will limit total torque about the joint during the duration of the set.
While this would generally mean pausing at the top or bottom is undesirable, in certain circumstances pausing at the top or bottom can prove to be more useful in allowing more pass throughs of the max. force point.
In a curl, a pause at the bottom of each rep allows for a brief instance of ATP regeneration (the muscles’ immediate fuel source) and can increase the TUT during the set, again allowing for more pass throughs of the max. force point. Pausing at the top of the squat can allow the lifter a moment to catch their breath, as tiring quicker than desired often causes the set to end before full muscular stimulation is achieved.
Extending a set past positive failure (the point at which complete reps can’t be completed) by incorporating partial reps close to the max. force point can again increase the number of pass throughs of this ever important muscle building biomechanical point.
The simple lesson for this all is that from a strictly biomechanical sense, the point of greatest stress on a muscle is always at the point where the limb in use is perpendicular to the force (or at 90 degrees), so spending time at the stretch and contraction are not necessarily helpful, though a significant range of motion is usually necessary.
During your next workout, try using a bit of momentum on your lateral raises or dumbbell curls to get through that max. force point, and feel it again on the way down. Don’t waste energy feeling that contraction at the top or the stretch at the bottom.
Allowing your body to move naturally in its own biomechanical groove can prove to be more perfect for muscle growth that using “perfect“ form. Above all, be safe about it. Strive to constantly reach that happy medium between heavy weight and the form you need to maximally stress the given muscle