Garlic has been used for years to reduce heart disease, high blood pressure, and have positive health benefits.  Recently, garlic and garlic constituents prepared by various means have been shown to have antioxidant, anti-inflammatory and various other biological actions. High intensity exercise results in an enhanced rate of free radicals production that initiates skeletal muscle damage. Researchers from China reported that administration of 80 mg of allicin (the main bioactive component of garlic), increased muscle anti-oxidant levels and blunted eccentric exercise-induced muscle damage.  Allicin reduced plasma CK (including CK-MM), LDH and IL-6, and alleviated muscle soreness. A higher pre-exercise total anti-oxidant levels, that may be induced by allicin supplementation, appears to also contribute to reducing the exercise induced muscle damage.

u QS, Tian Y, Zhang JG, Zhang H. Effects of allicin 
supplementation on plasma markers of exercise-induced
 muscle damage, IL-6 and antioxidant capacity. 
Eur J Appl Physiol. 2008 Jun;103(3):275-83.