Cold has been the post-exercise modality of choice for more than 30 years. Pitchers and javelin throwers, for example, often applied ice bags to their shoulders after practice or competition.
A study led by Jerrold Petrofsky from Loma Linda University found that heat worked slightly better than cold for reducing post-exercise muscle soreness and decreases in performance. Researchers applied ThermaCare cold or heat wraps following 15 minutes of squatting. The four immediate treatment goals include: preventing further damage, reducing spasm and pain, reducing bleeding and swelling, and promoting healing.
Ice reduces bleeding, but it also decreases inflammation, angiogenesis (new blood vessel formation) and release of tissue growth factors. Ice decreases pain and spasm following an injury, but it might delay healing and eventual return to the playing field. Applying ice or heat after intense training is better than doing nothing, but heat works slightly better.