Can My Growth Spurt Make Me Faster Than Usain Bolt?

[Gus Timmer]

I ran 60 meters in 8,53 seconds today, but the thing is, I don't work out, I just started my growth spurt (I'm 160cm tall now but my doctor predicted I'll grow to be 185cm tall) and my body fat percentage is probably near 15%.
I calculated what nu speed would be if I was 185cm talk but without taking into effect gravity and other factors like that
185/160=1,15625
1,15625^3=1,54580688476562
60/8,53=7,0339765533411 m/s (average speed 60m)
7,03397655411*1,54580688476562=
10,8732020030407m/s (average speed at 185cm)
100/10,8732020030407=
9,19692285419096s (on 100m at 185cm)

I don't expect these calculations to be correct so I'm asking you.
My weight is 47kg at the moment if that is tot any relevance

 

[A.T.]

1,15625^3

Why do you think your speed will grow with the cube of your height?

 

[jim mcnamara]

Let's look at this, not your calculations:

60 meters in 8,53

is your time for 60m. Correct? You predict 9.19s.

so:

9.19 - 8.53 =  .66

Therefore you would have to run the last 40m in .66 seconds, whereas you the previous 60m in more than 8 seconds. Or, you would have to the last 40m about sixteen times faster than you did the first 60m. Sound logical to you?

It is useful to do a sanity check on your result before worrying about anything else.

 

[Gus Timmer]

As I said, I don't expect my calculations to be correct but I figured my speed would increase alongside my muscle mass.

 

[Gus Timmer]

Let's look at this, not your calculations: is your time for 60m. Correct? You predict 9.19s.

so:

9.19 - 8.53 =  .66

Therefore you would have to run the last 40m in .66 seconds, whereas you the previous 60m in more than 8 seconds. Or, you would have to the last 40m about sixteen times faster than you did the first 60m. Sound logical to you?

It is useful to do a sanity check on your result before worrying about anything else.

I don't think I am faster than Usain bolt as of now, I think I can be faster when I am 185cm tall

 

[jim mcnamara]

Well, you would have to be 10X times taller... using your approach. It still says that you would have to find a way to go faster by a large factor, and growing another 15% of height won't do it. @A.T. pointed out some issues for you. I'm suggesting that in general, a critical look at a result can give you an idea if you are in the correct ball park to start with. Your time with your new future height would need to be ~5.7s for 60m as a rough guess.

 

[Drakkith]

As I said, I don't expect my calculations to be correct but I figured my speed would increase alongside my muscle mass.

Not quite. Muscle mass increases directly proportionally to the volume of your muscle. But muscle strength only increases proportionally to the cross sectional area of the muscle. As you grow, your muscles increase in both length and width, but the volume (and thus mass) increases faster than the cross sectional area. So if your muscle mass doubles, you aren't doubling your strength. At best, I'd expect perhaps a 1.5x increase in your strength, but I haven't done any detailed calculations. It could be a little more, or a lot less.

In addition, speed isn't directly proportional to muscle strength. I can do squats and other leg exercises to increase my leg strength, but my speed will have only a marginal increase, if any.

And if that weren't enough, we'd also have to include the fact that your muscles require oxygen and fuel to burn as you run that 100 meters. Your body can't provide enough of either of these as you run (which is why you tire out), so your muscles have to store some of this to use when needed. So average speed over some distance also depends on your muscles ability to store and process this oxygen and fuel. But I don't know how much they can store and I don't know how it increases with different types of exercises.

Long story short, this is a complicated topic and simply calculating muscle mass/strength won't do you much good.

 

[A.T.]

I figured my speed would increase alongside my muscle mass.

Mass means inertia, which limits how fast you can swing your legs, while muscle strength depends on crosssection.