Chang Mai Municipal Stadium - Muay Thai Gym?

anyone here familiar with the chiang mai municipal park of chang puak road? the one with the running track. i have been told theres a small muay thai gym there, i sauntered down for a look, asked around in pidgin thai and a guy said he thinks maybe 5 o'clock, i went back at 5pm but the place was locked up, appears from some of the equipment they must do other martial arts training in the building aswell, does anybody have any information? if not ill get a thai friend to ring and see what they can find out.