I think you could say , hay que estar listo, en la punta del pie. (tip of the foot, literally)

It is the "Bola del pie".

Sorry I wouldn't understand this position. Can you explain, wwht you want to say, George'

Cherry,
"Bola del pie" is a very literal translation. Perhaps that is the right solution. But I am concerned that it may not be understood. My friend from Costa Rica told me it might not be a common term. He recommended "de puntillas". But when I looked it up in the dictionary the translation was "brad, a small nail".

I want something that the Mexican children and their parents will understand. I will leave photo copies of the descriptions of the baseball skills with them. In the ready position the defensive player is not flat footed. They are ready to move in any direction; their knees are bent and their weight is on the "balls of the feet". Their weight is not onn their toes and not on their heels.

In this case, the "ball of the foot" is the area behind the toes and before the arch. If there is a specific term that would be used in Mexico or across Latin America, that is what I am looking for.

Thanks!
George

Heidita,
Please see the reply I left for Cherry. I hope I explained it well enough.
Thanks,
George

Really, I don't think there is a term for this. One should be able to understand:

iniciando el salto (ready to jump)

dispuesto para saltar

posición de alerta

Ah, I just asked a specialist in the matter:

estar en tensión sobre la punta de los pies

Let's see if this can help you.

Hi, i think ready position would be easier to understand as "posición de listo/preparado". Or perhaps "posición inicial".
And about "ball of the foot" well, you can say "en la punta de los pies" but you must remark that it's not on the toes but on the feet.