Bullets & Dump Trucks

September 15, 2021

Remember high school physics class? Besides building rocket launchers that could fire an egg down the block, the knowledge of Newton's Laws proved an invaluable staple to strength and conditioning and the success of our services. Force, friction, inertia, momentum, leverage, and good ole' gravity play a crucial role in performance gains and overall fitness.

In case physical phenomena are a bit fuzzy to recollect, let me review Newton's 3 Laws:

  1. An object at rest or in motion will stay in said state unless acted upon by another force
  2. The vector sum of forces on an object is equal to its mass multiplied by its acceleration
  3. Every force action has an equal and opposite reaction force

Think of a back squat. Gravity of the barbell and weight is acting directly downwards on your body and will continue to do so unless you produce force to counter it. Your muscle contraction produces force acting against a solid floor which in turn act upwards against you and the barbell. If said force is greater than the force of gravity and barbell, the barbell will change direction and proceed upwards.

Simplified physics with extreme application. What coaches want to know is how much force their athletes can produce and how fast they can produce it. As strength and conditioning specialists, we need to be able to break down the science and create better athletes.

A Bullet and A Dump Truck

Let's break this down. Force=Mass x Acceleration (F=ma). Increasing one of the two variables (mass or acceleration) will then increase the vector sum of force. Turning to strength training, we associate mass with maximal strength (how much weight can we move) and acceleration with dynamic strength (how fast can we move said weight).Let's use an example of a bullet and a dump truck. One weighs 32 tons, the other only a couple grams.

A dump truck in motion can certainly make an impact, even when travelling slow. Although acceleration is minimal, the mass of the object is incredibly high resulting in a greater force production. A bullet is barely heavy enough to make the needle on the scale move but when fired can travel almost 2500 feet per second. The acceleration is superior to its mass which in turn reflects its high force production. Mass and acceleration determine force production, no matter which side of the equation is favored.

Maximal Strength & Dynamic Strength

Taking the 2nd Law into consideration for strength training means examining how much mass can be moved and how fast one can move said mass. We know the body adapts to training and that different stimuli result in different adaptations, especially with speed and strength. We assume that if you want to get faster, you simply train at higher velocities.

Although this has lots of truth, remember the 2nd Law. Increasing one of the variables can then increase the result of the remaining variables. Training maximal strength capacity will improve its dynamic counterpart and vice versa.Let's say you have 2 athletes, Tom and Jerry. Tom can squat 500lbs for 1RM and Jerry can squat 200lbs 1RM. You ask Tom and Jerry to find a weight they can lift for 3 reps as fast as possible while challenging themselves. Tom does 300lbs and Jerry does 85lbs. Both are moving at the same rocket speed, but Tom is moving more mass. His dynamic strength seems greater because his maximal strength is also greater.

Another example would be looking at a deadlift and a power clean. The deadlift is more maximal in nature whereas the O-Lift is all about speed of the bar. If Tom can deadlift 800lbs, power cleaning 300lbs shouldn't be an issue. If Jerry can only deadlift 500lbs, 300lbs may prove to be a struggle. On the flip side, if Jerry can power clean 150lbs extremely fast, it's likely Jerry can deadlift 400lbs. Being able to accelerate more mass faster leads us to look at the Force-Velocity Curve and assume that more mass could be moved at a slower speed. Put simply, moving towards more force means slower velocity. Moving towards increased velocity means a decrease in force.

How Do I Adapt?

The training process varies but the goal for most athletes is the same. Continually train at higher intensities more frequently to increase maximal force production at the fastest rate possible. Although practical on paper, the neurological recovery from max effort and dynamic effort training is quite substantial, sometimes upwards of 72 hours. It's easy to see why athletes believe intense strength training isn't as demanding on the body with such low volumes. The truth is that although volume and perceived exhaustion levels after a session may seem low, your central nervous system is begging for a break.

Strength is the ability for one to exert/resist force. To produce greater force requires the body to recruit more motor units to innervate and contract musculature. This innervation process is quite demanding and requires sufficient time to recuperate. If you were to include additional practices, games and daily activities, that's a heavy workload for one's body, hence why appropriate planning and recovery is encouraged. For the average exerciser, picking one big lift to go heavy on is sufficient if done every week or two. Ensure form first and then start stacking on the plates to really crank up your session.

Once substantial gains have been made, you may wish to try decreasing loads to focus on the speed of your lift. Although not as necessary for the average exercise, power development can still lead to many health benefits and improved quality of life.If you're an athlete, consult your strength coach. A professional strength coach will be the best resource to dictate the effort (maximal, dynamic, etc.) and lifting volume being implemented throughout each month of your season. Switching exercise variations, adding bands/chains and changing tempos can get a bit confusing and, if used incorrectly, can lead to reduced gains or chance of injury at the wrong times. A strength coach will ensure you're progressing and recovering appropriately so as to peak your strength and power gains for the right times.

The Take Home

I'm not trying to give the impression that a powerlifter who can squat 800lbs is going to run the 100m dash in under 9 seconds. The point I'm trying to get across is that maximal strength assists dynamic strength and vice versa. If you want to improve power, increase your maximal strength. If you want to improve max strength, lift loads faster. if F=ma, you need to increase "m" or "a", to improve performance.The key is in the education.

Too many coaches, athletes and fitness enthusiasts assume doing the same training at higher velocities will lead to better results but unfortunately this isn't always the case. Being able to move more mass (in whatever direction) means being able to move less mass faster. Athletes of all backgrounds need to be appropriately maxing out to improve performance irregardless of their respective sport. The ability to generate more force and strengthen tendons, bones and joints mean a healthier and more powerful specimen. Consider this next time you're sitting under the apple tree.

Coach Matrixx Ferreira

Matrixx specializes in adolescent athletic development. He coaches some of the top athlete prospects coming out of high school in the Niagara region. He also works with dedicated members of the community who are passionate about improving personal fitness. Matrixx is also the author of The Iron Guide to Building Muscle.

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