A deep dive on body composition, puberty, and speed.
To get faster, you just need to get stronger.*
*Well, actually it needs to be the right type of strength. And it needs to be applied in a specific direction. And it needs to be applied at the right speed. And it needs to happen at the right time. And it depends on what the rest of your body is made of.
Okay, okay. Maybe getting faster isn’t as straightforward as the Twitter powerlifting bros tell you, but there is some truth there.
Speed is a factor of relative strength, that is relative to your bodyweight.
With all other factors being equal (direction, contact time, and timing), the more force you put into the ground with each step, the faster you’ll be.
An oversimplified way to think of this is: Strength / Bodyweight = Speed. (Don’t actually plug that into a calculator, it’s a concept, not a real equation).
Some of you are great at math, others not so much. You mathematicians might notice that there’s two variables in that equation that we can manipulate.
- If you increase Strength and keep Bodyweight the same, Speed will increase.
- BUT, if you keep Strength the same and increase Bodyweight, Speed will decrease.
If you want to improve your game speed and agility, you need to be aware of the role of body composition.
All mass isn’t created equal
When we measure body composition, we break down your mass down into two categories (mass is essentially another word for bodyweight).
- Fat mass
- Fat free mass, or lean mass
Lean mass consists of everything that isn’t fat. This can be organs, skin, bones, ligaments, and most important for this article, muscle.
Adding muscle mass increases the Bodyweight side of the equation, but it doesn’t make you slower. The gains in Strength outweighs the gains in Bodyweight, which results in an overall net increase in Speed.
Adding fat mass also increases the Bodyweight side of the equation, but it does make you slower. Fat doesn’t contribute to Strength, so there’s an overall decrease in Speed.
Puberty is unfair
Pre-puberty, girls and boys have essentially the same body composition. In late childhood (around 10 y/o), girls may develop a bit more body fat than boys, but its a very small difference.
Once puberty kicks in, everything changes.
For girls, lean mass stays the same, but fat mass shoots up. This results in body fat percentage going up significantly.
For boys, fat mass stays relatively the same, but lean mass shoots way up. This results in body fat percentage going down significantly.
The final verdict: puberty makes boys a whole lot faster and girls… the opposite.
When it comes to speed and agility, girls are fighting an uphill battle through puberty. The natural biologic process results in the ratio of strength to bodyweight going down.
It’s important to remember that these are averages, but you are an individual. Not all girls go through equal changes and not all boys go through equal changes.
I’m sure Myles Garrett worked hard in high school, but he didn’t work that much harder than everyone else on the planet to look like Godzilla out there compared to his peers.
I think puberty was just friendlier to him than others and he has a whole lot more testosterone coursing through his veins than the average human.
Some girls are genetically predisposed to laying down more breast tissue and accumulating more fat around the hips and thighs than others.
Some girls remain more slender and narrow, while others will naturally widen out in specific areas.
Yes, this is going to change your speed and agility capability, but it isn’t the only determinant. It’s just another factor in your Athletic Potential Range. In fact, there are some advantages in other areas for the wider-hipped individuals (see the questions section below).
Here’s what you can do:
For girls and boys, you should optimize your relative strength:
- Get really strong with squat and hinge patterns. (Bonus points if you get really strong on unilateral lifts).
- Eat like an athlete.
- Be aware of your body composition.*
For girls:
- Be extra vigilant on getting strong. Remember, most girls stop adding muscle mass during puberty. You can counteract this by training consistently, intensely, and intelligently in the weight room.
- You’re fighting a harder battle. This might mean that sometimes just not getting significantly slower is major progress.
- Run your own race. Don’t compare yourself to the girl next to you. You have different genetic codes, which means your bodies are going to respond in different ways. Identify your own superpowers and run with them.
For boys:
- You have been given a special gift. You go from having 10 ng/dL of testosterone in childhood, to up to 1,000+ ng/dL in your late teens. In other words, you have legal steroids coursing through your body. Get stupid strong during this this time period, but do it intelligently.
- Run your own race. Don’t compare yourself to the guy next to you. You have different genetic codes, which means your bodies are going to respond in different ways. Identify your own superpowers and run with them.
*I have to address some health concerns here.
- Being aware of your body composition is not the same as fixating on your body composition. If you’re anxiously stepping on the scale everyday or overly-concerned about your body composition, please seek help from a mental health professional.
- You need fat in order to survive. If you have too little body fat, you can run into some serious issues.
- Women need more body fat than men. In general, girls need to stay above 10-13%, while boys need to stay above 3-5%. HOWEVER, this number will be different for different athletes. Some girls may run into issues when they’re below 16-18% body fat.
Some additional common questions…
Why does puberty cause such a big difference in body composition?
It mostly comes down to steroids.
Boys get doused with testosterone and a little bit of estrogen. Girls get doused with estrogen and a little bit of testosterone.
Both estrogen and testosterone are steroids, but only testosterone is anabolic (anabolic = builds muscle).
I have athletes who will come in after being sick and tell me that they’re going to be so strong now, because their doctor “put them on steroids.”
I hate to be the one to burst their bubble (no I don’t), but steroids aren’t normally the muscle building kind. The only anabolic steroid in existence testosterone and synthetic derivatives of testosterone.
If your doctor put you on prednisone, you’re not turning into Barry Bonds.
Boys have an insane rise in testosterone levels once puberty kicks in, which plays a large role in why they develop so much muscle mass and girls don’t.
So, puberty makes all girls slower?
No!
Remember, we’re dealing with averages in research, but individuals in real life.
Some girls will get faster- a lot faster.
Is there any benefit for those with wider hips and more fat accumulation?
Yep! There are no solutions, only trade-offs.
If you have wider hips and more fat accumulation, a trade-off on one end is that you might not be built for speed. But, on the other end, you might be built for power.
This body structure can allow for more absolute strength and rotational power.