How firm is your stability ball?

mklap1

Cathlete
When I press down on my stability there is quite an indent. I sort of sink into it on any exercise on my back. I'm thinking it needs to be inflated but how much? How can you tell?
 
I have DH look when I sit to see if my deflation rate looks similar to what is shown on screen or when I'm on it I look to see if my knee and thigh look to be at the same angle as demonstrated.

Sounds to me like yours is deflating and could use some more air!
 
I agree ~ I think you need to inflate it more.

Mine is firm enough to actually be a bit uncomfortable on my chest when I'm face down on it. I like it that way because it rolls so much better.
 
I actually measure mine to see if they are the size they are stated to be - I've got a 55 cm and a 65 cm. Using a tape measure or yardstick it's pretty easy to do. They are very firm this way, I only get a little indent from either one.
 
The proper circumference for a 55 cm ball is 173 cm. You have to find the circumference of a sphere to get the right inflation. If you have a ball bigger than 55 cm, just do a google search for a circumference formula calculator, then plug in your ball's circumference. The calculator will do the rest.
 
easy to calculate circumference yourself, if you want to

It's simple to calculate the circumference yourself with any calculator. The formula is 2 * PI * radius. So for 55 cm this is 55 * 3.14159 (using a common approximation of PI; also the diameter of 55 is equal to 2 * radius).

Anyway we just measure the diameter with a yardstick and it works nicely. We find this a lot easier than trying to measure the circumference.
 

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