I have a pulled muscle or charlie horse, would a hot or cold compress work?

Varies: It varies somewhat. Cold is usually used to decrease swelling and inflammation to an area and can also provide some pain relief by numbing the superficial structures somewhat. Heat, particulary moist heat can help to relieve muscle spasm and can bring increased blood flow to an area. Most of the time, moist heat seems to work best for muscle injuries in my opinion. Thank you.

Muscle pull: Generally speaking, ice followed with moist heat helps. Also consider gentle massage of the muscle belly.