Re: electric shock-like feeling in arm
Sounds to me like the suppination (twist) of the wrist may be putting pressure on a nerve . Not real serious but you may want to avoid this. The form you use with suppination at as you go through the movement puts the bicep in optinmal position to recruit muscle fibers - unfortunatly it hurts.
Try this - using dumbells or a barbell start with the elbows back and the bar parallel to the floor - move the bar up, into bicep flexion - KEEP THE MOVEMENT LINEAR. Do not move the shoulder joint or the elbow joint and skip the rotation at the end of the exercise.