I am stuck at level 13 cause I can't do the one arm push up exercise on level 14
Are you asking for a solution or just making a statement. I'm sorry, it's just that sometimes I don't understand correctly. Well, if you are looking for a solution I can share with you something that has worked for me and many others. Rotate around levels 11, 12, and 13 until your strong enough for the one arm push-up. Shuttle push-ups and tigerbend push-ups are also great for strengthening several different muscles in your arms. You can do them in your burnout routines if you wish. NOTE: I recommended rotating around levels 11, 12, and 13 because you don't want to just stay on one or two levels doing only certain exercises. You need to work out differently. Well, I hope you keep progressing Bro. Time to get those one arm push-ups! Good luck!