The role of the upper limbs in the common plank exercises is considered a limiting factor in targeting the core muscles The purpose of this study was to investigate the core muscles activation in plank with and without support on upper limbs during different body angles. Twenty-one healthy men 20-30 years participated in this study. The subjects performed the plank in two positions with support on the upper limb (by the TRX suspension device) and without support on the upper limb (by the researcher made device) at 20, 40, 60 and 80 of body angles. Each eight test was repeated twice for 5 seconds. The activity of rectus abdominis, external oblique, multifidus, erector spinae lumbar, and rectus femoris muscles were measured and compared. Repeated measures analysis of variance was used to examine the effects of upper limb on our outcomes. The results showed that there is no difference on core muscles activity between plank with and without support on upper limbs during different body angles (p=0.821). Changing the body angle (20, 40, 60 and 80 degrees) showed a main different on the core muscles activity in the both plank positions with and without support on upper limbs (P≤0.05). Not using the upper limbs in the plank exercises does not change the activity of the core muscles, and also the level of their activity increases through the gradual addition in the body angle.