Garlic has been used medicinally for centuries for its antibacterial and antifungal properties. The active ingredient in garlic that provides these benefits is allicin, a sulphur-based compound. A Chinese study has found that allicin may also reduce muscle damage as a result of exercise.
A double-blind placebo controlled study was conducted on well-trained athletes to investigate the effects of allicin supplementation on exercise-induced muscle damage (EIMD). In the study, athletes were randomly assigned to one of two groups; those who received an allicin supplement, and those who received a placebo, for 14 days before and two days after a downhill treadmill run.
Running downhill is particularly known for its ability to induce a significant amount of EIMD due to its high frequency of eccentric muscle contractions. EIMD is chracterised by such symptoms as swelling, muscle soreness, and an increase in inflammatory markers such as cytokines that are released in response to damaged muscle fibers.
Both before and after the exercise, a number of factors were measured; plasma creatine kinase (CK), muscle-specific creatine kinase (CK-MM), lactate dehydrogenase (LDH), IL-6, superoxide dismutase (SOD), total antioxidative capacity (TAC), and perceived muscle soreness.
When compared with the control group, the group who received the allicin supplementation was found to have significantly lower levels of creatine kinase, a muscle damage marker, and also lower levels of IL-6, an immune marker, suggesting less biochemical stress to the body. In addition, the allicin group showed a higher level of total antioxidant concentration at rest, a level that remained high 48 hours after exercise. Finally, those athletes who received the allicin supplementation reported significantly less perceived muscle soreness after exercise than the control group.
Allicin is produced by an enzymatic reaction when raw garlic is either freshly crushed or otherwise injured. The enzyme, alliinase, stored in a separate compartment in garlic, combines with a compound called alliin in raw garlic to produce allicin. Allicin itself is very unstable and decomposes into other compounds quickly, so it must be either eaten fresh and raw, or taken as a stabilised supplement.
Though more studies are needed to fully explore the anti-inflammatory and antioxidant effects of allicin, these findings point to allicin as being a possible aid in reducing muscle damage and soreness after exercise.