Why can’t I lift as much as that guy?

At an event I attended and presented at this weekend, I was watching a friend of mine compete at powerlifting.  He did great considering he took 1st in his category but one thing that struck me was when he was squatting and benching, how much farther the bar was travelling than some of his competitors due to him being quite tall and narrow.  This was especially true with the females, who were using a very wide grip (which is perfectly legal for powerlifting) but had massive torsos and huge legs so the bar did not have to travel nearly as far.  Even the other guys were quite a bit shorter and stockier, which tends to be the trend with power lifting.

So the inner geek in me decided to do some math and see if there was a big proportional difference between what my friend did and for example, what pound for pound another competitor would do if they were simply a different shape or the bar didn’t travel as far.  There’s some very interesting results, but first I’m going to embrace my inner geek and go through some very basic math and physics for you:

A Joule is a unit of energy or work that factors in weight, distance and time and gives us a formula to derive the work done moving one Newton of force through a distance of one meter.  We’re going to assume that for our purposes today, the bar that they were using was travelling at the same speed for everyone.  I thought about getting into acceleration and stuff like that but my head started to hurt thinking about all of the parameters.  So, today let’s assume that the time taken to lift is a constant 1-second per foot of distance for everyone.

For a squat, we need to factor in the fact that the load is on the back, and that means that the weight involved is not only what is on the bar, but the bodyweight of the person in question as well.  They are exerting Joules into the floor.  So my friend puts 100 kilograms on his back at a bodyweight of 85 kilos for a total of 185.  He drops down and then lifts it a total of three feet or one meter over three seconds.

J = 185 * 1 / 9 for a total of 20.55 joules

Competitor number two lifts the same weight – 100 kilograms, but only lifts it two feet or .66 meters over two seconds (because it doesn’t travel as far).

J = 185 * .4356 / 4 for a total of 20.14 joules

So they are roughly the same.  Not a big deal in terms of the amount of force.  However, when another parameter changes, let’s see what happens:

My friend suddenly lifts the bar the three foot distance, but over the same two seconds of time.

J = 185 * 1 / 4 for a total of 46.25 joules

This is 229% more power generated than what the previous person did.  Simply because he lifts the bar further over the same amount of time.  For the second competitor to generate the equivalent amount of Joules, considering that he can only lift the bar two feet over two seconds, he would have to lift 424 kilograms – over 900 pounds!

We can really see how factors like acceleration; displacement and velocity come into play, especially when it comes to lifting things.  This is a very simple example for you not to take anything for granted when generating power on a bar or lever.  That person lifting significant amounts of weight can generate a surprising amount of power, which is the whole idea behind power lifting in the first place.  Hope you enjoyed this little display of how physics can be applied into proper lifting, but also consider things like how far the bar is travelling and at what speed when it comes to your own lifting.

Also, increasing your strength is a very slow process and should be.  Don’t get discouraged when you see guys in the gym lifting a lot more than you are.  Likely they have been doing those lifts for a lot longer, and have other factors into play (like the above) that make it a bit easier for them.  Do what your body allows and is designed to do properly, and keep everything healthy to stay strong and fit another day.  Think about the goal and then just keep moving towards it.  Hope you enjoyed this and feel free to comment and subscribe.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s