More than three thousand publications in the past have confirmed the efficacy of garlic for the prevention and treatment of a variety of diseases, acknowledging and validating its traditional uses.
Garlic is also used for the treatment of fatigue, although the mechanism involved remain unclear. The anti-fatigue function of garlic may be closely related to its many favorable biological and pharmacological effects. In animal studies, garlic has been shown to promote exercise endurance.
Differences in the methods of processing garlic result in differences in the intensity of its anti-fatigue effect.
In human studies, it has been confirmed that garlic produces symptomatic improvement in persons with physical fatigue, systemic fatigue due to cold, or lassitude of indefinite cause, suggesting that garlic can resolve fatigue through a variety of actions.
Recently, primarily in Japan, attempts have been made to measure the intensity of fatigue objectively and quantitatively using biomarkers. Currently available data strongly suggest that garlic may be a promising anti-fatigue agent, and that further studies to elucidate its application are warranted.
Source: http://www.ncbi.nlm.nih.gov/pubmed/17955479