Not always, but only when handled carelessly. Shock induced muscle tetany is the most important effect of current on the muscles. If a person touches the energized conductor, fore arm muscles contracts forcefully and fingers bend. So the person involuntarily holds the conductor. Therefore the victim will be unable to take the hand from the conductor.
As you know, electricity is the flow of electrons through a conductor from its source to the destination. If the conductor offers less resistance, the flow current will be fast and if the conductor has some resistance, the flow of electrons will be obstructed leading to slow movements which generate heat through friction.
Human skin is a semiconductor for electricity and current passes through the body to the ground just like the flow of current through the electric wire. This flow of current causes burning and shock. If the skin resistance is low, the chance of shock hazard is very high. Some people are more sensitive to current while others are less sensitive. Electrical safety measures are necessary while dealing with high voltage AC available from the power grid. Ignorance can lead to a fatal shock or fire hazards.
Remember, Electricity travels at the speed of light. Its flow is around 299,460 kilo meters per second so you will not get time to react because you can’t move faster than electricity. So the best way is staying out of its way.