I threw a ball towards my dogs in order to hit them
Why would you try to hit them with a ball?
Long story short I wanted to see what would they do if ball hits them.
That is just cruel. You should not hit your pet. It is just going to make them fear you in the future.
I need to test their reflexes.
There is a better way to do that rather than hitting them with a ball. Don't be so abusive towards them.