Introduction : Oxidative stress is considered as one of the factors that can damage tissues . The aim of this study was to investigate the effect of short term dark chocolate supplementation pre-incremental exercise on vascular lipid peroxidation in active young girls.

  Methods : This is a semi-experimental study. 16 active girls in two groups of experimental (dark chocolate supplementation) and control ( avoiding the use of chocolate) participated in this study after completing consent forms. Experimental group consumed dark chocolate ( 80 grams per day ) three days before exercise. After that, the two groups participated in a session of incremental exercise. Venous blood samples were taken in three stages for measurement of H₂O₂ and MDA concentration prior to exercise test, immediately and 1 hour after exercise.

  Results : MDA and H₂O₂ concentration in both groups had no significant changes after incremental exercise and recovery in comparing to basal state (intra group comparison) (p≥0.05). But experimental group compared to control group had a lower H₂O₂ level in three stages of basal state (experimental: 1.25±0.45, control: 2.08±0.42) (p=0.004), after exercise (experimental: 1.68±0.30, control: 2.16±0.52) (p=0.05) and recovery (experimental: 1.51±0.30, control: 2.18±0.44) (p=0.006).

  Conclusion : Short term dark chocolate supplementation maybe effective in controlling the upward trend of the lipid peroxidation during incremental exercise in young active girls.