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5 Reasons Why You Keep Losing The Truck Pull

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The Science of Strongman: 5 Reasons Why You Keep Losing The Truck Pull

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By Mark Jones

A machine is anything with moving parts that uses energy to do work. Like in any mechanical system, no machine is ever 100% efficient. [1] This means that the energy put into the machine, is always greater than the work accomplished by the machine. Just because a machine requires the most energy input, does not mean that it accomplishes the most work.

Let’s look at the case where YOU are the machine, and pulling a big ass truck is the work. Winning a strongman competition does not make you the strongest athlete. It makes you the “best” competitor. The “best” competitor is the athlete who accomplishes the most relevant work, has a solid strategy, and doesn’t screw up.

I have no idea how to be the strongest athlete, but a little physics and engineering can certainly help us be the smartest and most efficient athletes we can be. Let’s take a look at some of the more glaring errors commonly seen during the truck pull.

      1. You jerk the truck

Newton’s first law of motion: “Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it” [2]

How does this apply to the truck pull? The whole point of strongman is to move objects that generally don’t want to move on their own. That said, you need to strongly encourage the truck to start its motion.  Big, jerky motions start and stop the truck with each tug. This uses WAY more energy than applying a constant force IF you even get the thing going at all. Once moving, the truck requires much less force to continue rolling.

Pulling with a constant force ensures that you only have to convince the truck to start moving once. IF you can generate a constant force, all of your efforts will continue rolling the truck rather than getting it going again. The best way to achieve this is to take short, alternating steps even if you feel like you are not moving. Keep the front rope taught and make sure the truck is always seeing force.

     2. You are too upright

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For the sake of simplicity and demonstration, let’s assume that any straps between the athlete and the truck are parallel to the ground. Given this assumption, the angle of your torso is a good approximation of the direction that you are actually pulling on the harness. This is represented by the red arrow. Since the truck only cares about the horizontal force pulling it forward, you want to be as low to the ground as possible. This will allow you to transfer more pulling force through the harness. Being low to the ground means that angle θ will be small. Let’s take a look at how important this angle is.

 

Let’s assume that strongman Stan is big and strong and has not yet read this article. He is capable of pulling with 600 pounds force, BUT he pulls the truck with his torso at 45⁰.

 

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600lbf.cos(45deg) = 424.264.lbf

Strongman Stan is effectively pulling the truck with about 425 pounds force.  

 

Now let’s look at strongman Dan who is weaker, but smarter, than strongman Stan. Strongman Dan can only generate 500 pounds force, BUT he pulls at a more efficient 30⁰.

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500lbf.cos(30 deg) = 433.013lbf

Strongman Dan is effectively pulling the truck with 433 pounds force.

Strongman Stan inputs more total energy into moving the truck, but strongman Dan effectively rolls the truck faster. Not only will strongman Stan probably lose the event, but he will expend MORE energy than strongman Dan, tiring strongman Stan for the next event. If all other factors are held the same, the physics says that strongman Dan should win every time.

     3. You’re tuggin’ all wrong

Not all competitions give you a harness AND a rope to pull, but when they do, you better use the damn thing. Tugging on the rope with your arms serves two main advantages.

1) The rope allows your upper body to generate force. This one is pretty obvious. The total force you can now exert is the sum of two forces: the force generated by your legs pushing on the ground, and your arms tensioning the rope.

2) Pulling on the rope mitigates slip and fall risk. In theory, if you could pull on the rope hard enough, the tension generated in the rope could hold your entire body off the ground for the duration of the pull. If you’re from planet earth, you’ll have to settle for picking a fraction of your body weight from the ground. In other words, keeping maximum tension in the rope makes you less likely to eat pavement and ruin your beautiful strongman face.

Reaching as far as possible for the rope keeps the number of arm “strokes” to a minimum and also keeps the tension more constant (see Newton’s first law of motion mentioned previously). By having long pulls and transitioning your hands quickly, you will have more overlap between strokes. This means that you will spend more time with BOTH of your arms pulling on the rope, rather than one at a time. Quick, efficient work on the rope can mean the difference between a huge win and a crippling loss.

   4. You wear your dad’s lawn cutting shoes

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Any time something wobbles, slips or compresses you are wasting energy through that action. Not only does this “lost” energy not move the truck, but it also tires you out along the way. During a truck pull, this applies most directly to your feet and shoes.

You might be thinking “how big of a difference could compression or wobble in my shoe REALLY make?” The answer is: a non-negligible amount. Yes, the energy wasted in a single step by your crappy shoes is small, but that small amount of energy adds up quickly when you consider how many steps it takes to complete a truck pull. If each of your steps is 3”, then you will take about 200 steps in a 50’ truck pull. When you multiply out that seemingly small amount of waste from a single step, you can imagine how quickly the energy savings add up. A small increase in the efficiency of your stroke can easily add up to a win in this event.

To put the most energy into moving the truck and not into compressing your shoe, you should ditch your old running shoes and find shoes that are flat, firm and with sufficient traction. Get yourself some rock climbing shoes. Rock climbing shoes are generally accepted as the ideal truck pull footwear for a number of reasons. The sole usually goes way up over the toe, which makes them ideal for maintaining traction in a leaned over position (remember small θ.) The soles are usually very stiff and will not compress. I recommend going to your local rock gym and trying them on to ensure a snug fit. And yes, they are supposed to hurt your feet.

      5. Your steps are too ambitious

You’re not going to move a truck 50’ in one big pull on level ground. If you can, you shouldn’t be competing against mere mortals anyway. The truck pull is more closely represented the summation of many smaller pulls. This model allows for a more constant applied force that is more likely to keep the truck moving when compared to a lesser number of larger steps.

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When you take a large step forward, you are placing your front foot in a disadvantaged position. Your leg is much more powerful in its “almost straight” position. A good example of this concept is the common quarter-squatter. Ever notice how the top quarter of a squat is much easier than the bottom quarter? Keeping more of your leg stacked under your body (as opposed to a large knee bend) means that there is less torque required to return your legs to their straightened position. The truck pull is a similar concept, but applied in the unilateral condition. Keeping your steps small enough such that your leg stays “almost straight” puts you in a powerful position. This will translate more of your energy into moving the truck instead of overcoming torque to straighten the leg.

 

By taking many smaller steps, you are also keeping your resultant pulling force at a shallower angle, which means a more efficient pull. If you forgot why this is important, scroll back up and reread #2. Basically, you should make your body look like as much like a horizontal line as possible throughout the duration of the pull.

 

[1]http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/seclaw.html

 

[2]http://hyperphysics.phy-astr.gsu.edu/hbase/newt.html

 

By Mark Jones

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Mark is a lightweight amateur strongman, long time powerlifter, practicing mechanical engineer and owner of your favorite stone sleeve company, 4Armour LLC. As a student at The Pennsylvania State University, Mark studied mechanical engineering, mechanics, red beard growing and was an athlete on the Penn State Powerlifting team. Since then, Mark has been working as a mechanical engineer, and directly applying his knowledge of physics to lifting smarter both in the gym, and wherever heavy things may be hiding from him.

Check out his hand-crafted, American made stone sleeves in the Starting Strongman store!

 

http://startingstrongman.com/shop/products/4armour/ 

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3 Comments
  1. Noah permalink

    This is great… last year I pulled a 28,000bus 70′ in 41seconds… this year… I “tried some new stuff” and I pulled the same bus 16′ and blew out my left calf. Summed up… no efficiency… wrong boots… new equipment that put me in a bad position.

    I train on 24,000lb freighliners up to 42,000 freightliner with trailer. I’ve been looking for some a “how to”.

  2. Faith Simms permalink

    Great article! Pulling trucks is my favourite!!! So far worked my way up to 67,000lb. These tips will help me pull faster and heavier THANKS!!

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