Reverse Curls
Take the barbell and hold it down at your thighs, gripping it a shoulder’s length or perhaps an inch or two narrower. Make sure that you have a reverse grip, which means that your palms are facing away from you, not toward you. Keeping your elbows locked into your sides, slowly lift the bar toward your torso.
You should stop when your forearms are completely contracted, which means that your hands should be across from your shoulders. Slowly let the weight bring your arms back to the starting position – down at your legs – while you squeeze your forearm muscles during the negative motion. Try 8-10 reps for three sets.
Forearm exercises are extremely important to me as I enjoy rock climbing quite a bit. Using something like a 3-5 lb weight with your arms extended and your palms facing down simply lift the weight by flexing at the wrist. Then also in the other direction with your palms facing up.
Then to prevent the soreness after a climb or in your case polo I stretch out my forearms using the same movements however with no weights and just a clenched fist.
ever tried those powerball gyro's? theyre pretty damn good. mainly works out the wrists but does a good job on the forearms. its soo simple too. you can get em on ebay.
try a gyroscope. I think t here is one called a powerball or something, i bought one for the bf because it looked like a cool toy but it reallly reallly works out your forearms..