when i get off my bike my legs collapse?

[dillon_redline]

hey when i get off my power lite bmx bike i me out of breath and my legs give out and i fall to the ground and my legs are shaking a while after that when i ride my bike i just do basic stuff like wheelie the fredmyers parking lot and bunny hop on to curbs so i dont see why my legs give out

ps i am very atheltic not some lazy kid thx