The Big Butt Theory: Women and Bodyweight Training

Mar 15, 2015

Ladies, if you think this post is going to give you more ammunition to use as an excuse for not being able to do a single pull up, then you can stop reading right now.

I hear all the time that bodyweight training is too difficult for women. My news feed is full of guys doing crazy feats of bodyweight strength. If you search for tutorials on calisthenics moves, 99.9% are made by guys for guys.

This is bullshit! There are a few women out there kicking ass in this field (Fi Silk, Gayle Pocock my fellow GMB trainer, Sara-Clare from Agatsu, Adrienne Harvey who teaches at the PCC to name a few) but there should be more. Women can totally do this stuff.

Women can do pull-ups

Let's start with pull-ups. There are so many women out there that believe that this move is a physical impossibility for them. Their centre of mass is too low and they are built with insufficient upper body strength.

What. The. Fuck?

My PhD in Astrophysics gives me the authority to say that this is bullshit. In order to pull yourself over the bar you must exert an upward force on your body greater than the gravitational force that is pulling you down. The gravitational force is equal to mass times gravitational acceleration regardless of how far the mass is from your arms.

Warning: Science-y stuff ahead

pull up on earth

For pull-ups, the acceleration is due to the gravitational pull of the earth on your body. If you want to be picky, the gravitational force is slightly less the further your centre of mass is from the centre of the Earth (i.e. for men). However, shifting yourcentre of mass from your butt to your chest would give a difference of 0.000003139% in acceleration. So, fairly trivial in technical terms. This would be similar to doing pull-ups on a higher versus lower bar.

The scientist in me wanted to further validate the accuracy of this so I undertook an experiment. I performed weighted pull-ups using two methods:

Method 1. Pull-ups wearing a 10lb weighted vest.

Method 2. Pull-ups with 10lbs attached to my feet.

I performed my max reps using each method. To increase the accuracy of this, I repeated this 5 times. Two days later I reversed the order of the sets and did the experiment again. This made my results statistically significant using a student's t-test (this is not true).

IMG_5151

The startling results showed that the height of the extra weight made no difference whatsoever. So big butts are not a liability for pull-ups. Yes we are naturally built with less upper body strength than guys but there is no reason why we can't build strength and kick the guys' asses at these (so to speak). Remember that they likely have a greater overall mass to lift.

Why I still can't do my front lever

So now we have all nailed the pull-ups. What about levers, planches and flags?

If Force = mass x acceleration why should it matter if I have a big butt?

Let's talk about torque. Torque is a measure of how much a force acting on an object causes it to rotate about a pivot. In a pull-up, we are pulling vertically up and the gravitational force is in the opposite direction so there is no torque.

However, in a front lever for example, the pivot point is your shoulders and to stay in the lever you must resist this torque.

1862Rings1

Since the body is perpendicular to the force acting on it, the magnitude of the torque in this case will be equal to the force x distance (of the mass to the pivot)*. To simplify the formula we can approximate that the entire mass, and the force acting on it, is at the gymnast's centre of mass.

Using a highly sophisticated calculation I guessed that mycentre of mass was 30cms from my shoulders and if I were a guy (of my height) it would be 22cms (i.e. women have a longer lever arm). The torque is therefore 1.36 times greater as a female rather than a male. Which to be honest is less than I expected given the number of women that I have seen performing a full lever (= exactly one; Alex Puccio, a professional climber).

*Note: All these calculations are approximate. There is also a pivot at the hands but I am trying to keep things as simple as possible.

Levelling the playing field

What can we do about this? Well it is simple get stronger than the guys or find ways to shift your centre of mass. Bend your legs, straddle your legs or pike your legs. There are variations of all these skills in different shapes and positions and some of the straddle flags that I've seen from women are the prettiest flags I've ever seen.

I see these variations successfully working when I teach. In my GMB gymnastics classes, the guys and girls are evenly matched when it comes to tucked front levers. Leah, one of my kick ass students has nailed the tucked front lever and is now working on harder variations. Using a progressive approach, we can slowly lengthen the lever and nail the full skill.

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Using your butt to your advantage

Beyond twerking, your butt and lower centre of mass will actually give you some advantages.

The closer yourcentre of mass is to the ground the better your balance - this is why surfers bend their knees and get low on the big waves. You will be more stable when landing jumps and skills. Also my internet research suggests that as a woman you can bend over and touch your head against a wall and then pick up a chair! Wow! Guys can't do this.

In all seriousness, quit using your gender as an excuse for not being able to get certain skills. You can get those skills with a lot of work, some tweaking (and twerking) and the right mindset.