Lethal Sjaak

Hey guys, I recently came back to play RS once in a while. A lot has been changed to the game. I am a bit familiar with the new combat system. Currently I am f2p and I am a bit bored with increasing my firemaking xp. Strength is one of the f2p skills in which I haven't got 99 yet. What is the best place for me to train and what is the xp/h? I have 99 attack and 99 defence. I hope you can help me out! - Lethal Sjaak