BACKGROUND:Heavy physical exercise causes relative hypoxia. In hypoxic condition, the cell's energy comes from anaerobic metabolism that produces lactic acid. An increment of oxygen need leads to ischemia-reperfusion, triggers free radical formation and damages muscles. Creatine kinase (CK) is a marker of muscle tissue damage. Red dragon fruit (RDF) has potential as antioxidant to reduce free radical formation.

AIM:This study aims to determine RDF extract potential to reduce the lactic acid level and CK activity after heavy physical exercise.

METHODS:A total of 32 male rats (Rattus Norvegicus) were randomly divided into 4 groups: group NORDF, treated heavy physical exercise and distilled water; group RDF100, treated heavy physical exercise and at 100 mg/kg BW RDF extract; group RDF200, treated heavy physical exercise and at 200 mg/kg BW RDF extract and group RDF300, treated heavy physical exercise and at 300 mg/kg BW RDF extract. The rats swam for 20 minutes, 3 times a week for 3 weeks.

RESULTS:RDF300 group showed lower lactic acid level and CK activity as compared to that of NORDF (p = 0.00) and RDF100 (p = 0.00) groups, but RDF300 are not significantly different for lactic acid (p = 0.45) and for CK (p = 0.68).

CONCLUSION:Red dragon fruit extract has potential in lowering lactic acid level and CK activity in male rats receiving heavy physical exercise.