Eccentric exercise often causes acute and chronic inflammation, as well as local muscle damage [1]. Chronic inflammation arises from the activation of leukocytes, which is closely related to the increase of oxidative stress, clinical muscle fatigue and muscle pain [2]. Therefore, it is possible to improve the clinical symptoms and promote muscle repair by reducing the oxidative stress. Garlic is widely used as a natural medicine in ancient civilizations [3]. Recent scientific studies have shown that many pharmacological effects of garlic are often related to its antioxidant properties [4]. The antioxidant capacity, plant polyphenols and free amino acids are greatly reinforced in black garlic made from raw garlic within a special environment; great improvement has been observed in the emergence of S-allyl-cysteine and a large number of Maillard compounds that are not found in raw garlic [5]. Therefore, the ant oxidative performance and the effect of alleviating inflammation and accelerating the recovery of muscle fatigue of black garlic are noteworthy. The purpose of this study was to investigate the effects of black garlic supplementation on muscle injury, inflammatory response and the recovery of muscle fatigue caused by an acute eccentric exercise.

20 healthy, nonsmoking and untrained males were recruited and assigned to either a black garlic group (n=11, GG) or a placebo group (n=9, PG), by a randomly double-blind method, with the similar age and body mass index. One week before and after an acute exerciseinduced injury experiment, totally lasted for 14 days, the subjects were continuously asked to take black garlic balls (200 mg/ball, 15 balls/time, 3 times/day, equivalent to 11.2 g black garlic every day) or placebo balls (consisted of starch, completely identical in weight and appearance to the BG balls) orally. An arm curl machine was used for the eccentric exercise protocol. Subjects performed 3 sets of 10 repetitions, with each repetition lasted 6 s, at 70% of their eccentric one-repetition maximum using only the non-dominant arm. At the 7 d pre-exercise (T1), immediately pre-exercise (T2), immediately post exercise (T3), 6 h post-exercise (T4), 1 d post-exercise (T5), 3 d post-exercise (T6) and 7 d post-exercise (T7), blood sampling (7 times), urine collection (5 times) and muscle function tests (6 times) were performed.

Serum oxidative stimulation (d-ROMs) values in PG showed a significant increase (P<0.05 ~ 0.01) at T3 and T5, while in GG a significant decrease at T5 and T6 (P<0.05) were observed. Serum antioxidant capacity (BAP) values after one week supplementation were found no significant changes in PG, but it increased significantly (p<0.05) in GG. The maximal voluntary contraction strength in two groups decreased by about 35% immediately after exercise, but it recovered more quickly on the 7th day after exercise in PG. Circumference of biceps brachii around working arm flexors was significantly lower on day 10 (T6) and day 14 (T7) in GG than in PG (P<0.05, both). Muscle soreness and range of motion exhibited significant changes post-exercise (time effects: P<0.05, respectively), but finally recovered to the baseline level, with no differences between groups. A significant increase after exercise (time effect, p<0.05) in LDH was seen and both CK and LDH peaked at T6, but CRP and G-CSF exhibited no significant changes in either group during the study period. Exercise induced significant leukocytosis post-exercise, with significant time effects in leukocytes, lymphocytes and monocytes. Compared to the baseline (T1), leukocytes with peak values 6 h post-exercise increased 18.1% to 23.3% in GG and 26.1% to 32.1% in PG, respectively and then almost recovered to baseline (+5% approximately) in GG, while still greater (approximately+12.6% ~ 18.4%) in PG 1-3 d post-exercise. The increase in lymphocytes positively correlated with circumference change at 6 h post-exercise (r=0.52, P<0.05), as did neutrophil count with blood d-ROMs immediately postexercise (r=0.47, P<0.05). Although no time effect and supplement × time effect were observed in blood LP, a significant supplement effect (P<0.05) was found and GG had significantly lower values at T6 and T7 than PG (P<0.05, both). 8-iso-PGF2α level indicated significant supplement effect, time effect and supplement × time effect (P<0.05, all), GG had lower values than PG post-exercise at T4, T5, T6 and T7 (P<0.05, all).

Black garlic supplementation at 11.2 g per day for 14 days indicated that it effective to, 1) promote the recovery of local edema caused by eccentric exercise, but had no significant effect on the recovery of strength; 2) curb exercise-induced oxidative stress significantly; 3) decrease urinary 8-iso-PGF2α and blood LP concentrations markedly; and 4) inhibit the increases in blood LDH and CK levels caused by exercise. In conclusion, BG supplementation can be expected to improve some physiological responses, such as chronic inflammatory responses (edema) and mitigate the extent of muscle injury due to eccentric exercise through decreasing oxidative stress. These results suggest that, black garlic supplementation might be useful to prevent metabolic syndrome, including obesity, diabetes, hypertension and hyperlipidemia, because the accumulation of oxidative stress and chronic inflammation are closely related to the occurrence and development of these diseases.