Here’s a really good blog for polo players and even riders: Prof. Martin’s Perez’s Physical Training for Polo Players. Martin brings a lot of valuable content about physical training for polo players to his blog. He details exercises for horse-riding muscles, balance and stretching exercises, all applicable to all riders, not just polo players.
Martin spent a little time in Malaysia this season, working with players. He really knows his stuff. Hope you enjoy his blog too.