Tina was caught off gaurd when the dragon starting charging  back. She may have been strong enough to push him when he was standing still, but he was heavy enough that if he was charging at her she wouldn't last long. She stopped charging, looking around for some how to get out of his way. The only option she saw was either stopping his charge or jumping off the platform. She gritted her teeth and put her arms up, prepared to atleast try to stop him.