The purpose of the present study was to evaluate the effect of different rest intervals between sets on markers of muscle damage in professional bodybuilders. Therefore, ten male athletes voluntarily participated in four sessions of resistance trainings. At the first session, 1RM of participants evaluated. In other sessions, the subjects performed four sets of squat and bench press to fa ilure with 85% of 1RM. In each session one of the rest intervals of 60s, 90s and 120s between sets used random ly. To determination of serum lactate and enzymes concentrations (CK ،CK-MB and LDH), Blood samples were taken from the subjects before and immediately and 30 minutes after the training. For statistical analysis of data, one-way repeated measures and LSD post hoc were used. No significant differences were found in the training volume and levels of serum enzymes (CK ،CK-MB and LDH) and lactate between three groups (P>0.05). However, there were significant elevation in serum enzymes levels immediately after and 30 min after exercise in the three groups (P<0.0 5). The results of the present study showed that 60, 90, and 120 seconds rest duration between resistance training sets don’t affect levels of CK ،CK-MB and LDH and training volume.
