Written by: Kevin Cann
Training is first and foremost a physics problem. Understanding concepts such as force, potential energy, kinetic energy, velocity, acceleration, and work are critical to the coach being able to write effective programs, but also to be able to utilize the various tools at his or her disposal more effectively.
Understanding how biomechanical structure has an impact on recovery is important. A lifter with a longer ROM on deadlifts, will be doing more work, even if the weights are lighter. I did this math for Instagram, but a 600lb deadlift moving 24 inches is 1626.92 joules. A 700lb deadlift moving 18 inches is 1423.89 joules, and 800lbs moving 12 inches is 1074.53 joules.
The equation for potential energy is mass * gravity * height. Potential energy is converted into kinetic energy which we use as elastic energy in movements. A taller lifter, due to the height variable, will need to enhance this quality more than a shorter lifter. The lifters that speak negatively about speed work tend to have much smaller ROM than those that argue for it. You should be able to see how this picture is painting itself for those with favorable leverages in the sport.
Bands and chains do not do the same things. Remember that the goal of training is to increase force which is mass * acceleration. We can’t just adjust the mass to impact acceleration due to the peak contraction principle which states that peak contraction occurs at the angles of least leverage, but then as leverages improve deceleration occurs. The velocity of the barbell is 0 at the top. Deceleration can occur in weights as high as 85% of 1RM with more explosive athletes, but others it may be avoided at 75%. This is why most coaches encourages loads above 85% to improve strength, and science tends to back this up. Volume falls in that 75% to 85% range because this minimizes deceleration.
Exercises like pauses can change the strength curve of an exercise, but for me, this is not optimal because a decrease in velocity also decreases force, the thing we are attempting to build. Instead of pauses we would do Anderson style lifts where the bar is in the bottom of the lift resting on pins at the start. We also use boxes in the squat.
The box has a collision between the hamstring and glute tissue and the box. This is technically an elastic collision and creates a neurological response, as well as a response in absence of the nervous system, to utilize that elastic energy. If we bring the bar down to pins instead, we lose this elastic collision because the collision occurs between the bar and pins, and also comes with deceleration, lowering forces. You are still training, so of course these efforts will work for a bit, they might improve positions, but coordination tends to follow a force specificity curve. The closer to 1RM the more intra and inter muscular coordination that is developed. Under maximal velocities we see similar coordination strategies implied.
We can utilize muscular contraction powered by the food that we eat to move weights. This would be utilizing chemical energy. We can also utilize kinetic energy through the elastic rebound in the lifts. We can alter how we train these pieces by using bands and chains.
The first question that we have to ask is whether we want to adjust the mass or velocity of the lifts. The equation for kinetic energy is 1/2mass * velocity^2. Force is also mass * acceleration. Again, we cannot just decrease barbell mass to increase acceleration (rate of change of velocity over time) because of the deceleration occurring during the lifts. However, if we replace barbell mass with the mass of chains on the barbell we can accomplish this.
Chains still have a velocity that is equal to gravity, but they accommodate the resistance in a way that deceleration is avoided. This allows for the lifter to apply more force to the bar, and over time develop the ability to apply more force to the bar. Proprioception happens at the top before the lift is even begun. The body needs to produce overcoming forces upon changing directions. This is why it is known as the overcoming phase.
There is a collision with your feet into the ground here when you reverse directions in a squat. The force applied to the barbell at this point needs to be enough to overcome the increasing chain weight on the bar. This trains the bottom of the lift, not the top. This is contingent upon having adequate chain weight, which needs to be between 20% and 30% of the lifter’s 1RM. Less than that is ineffective.
Bands are different because they increase the velocity of the barbell faster than gravity. They basically slingshot the bar down to the earth. This increases the kinetic energy and develops our ability to utilize that kinetic energy as elastic energy when we reverse directions. This is using the energy already present in the barbell and decreases our need for chemical energy.
We want our elastic system to initially move us into positions where the muscles have more optimal lengths to then contract and finish the lift. If we are poor at utilizing elastic energy, stronger muscular contraction needs to happen at less than optimal muscle lengths which can increase the stress on the tissue and lead to difficulties in recovery. In my experiences, the less “athletic” people tend to have higher amounts of nagging pains.
A box squat with bands is really stressing our abilities to utilize elastic energy through the collision with the box as well as the bands increasing the velocities of the weights. This doesn’t mean that we ignore straight weight and chains. Lebron James is very elastic, but I am sure that I can out squat him.
All methods should be utilized in a well-rounded program. The adaptations of dynamic effort work may be difficult to notice at first because they probably take the longest to develop if there was not a more explosive athletic background in the person’s relatively immediate past.
The lack of emphasis on developing elastic qualities may be why we see higher frequencies struggle a bit more for longevity. The ones that do last with a high volume of barbell lifts tend to be those with favorable leverages. They are just always at muscle lengths close to optimal, decreasing the work, and allowing for better recovery. Specificity is not about what the lift looks like. It is about the factors that impact how the lift is executed and this is first and foremost a physics problem.