What is weight training? what must skeletal muscles do to move?

Weight training is when you excersise with heavy objects such as dumbbells, barbells, medicine balls or other heavy objects. When someone signs up to a gym you usually see squat racks bench presses and dumbbells. All of the people using that type of equipment are weight training. Each excersise works different muscles. Bench press works the pecs (chest muscles) dumbbell curls work biceps and so on.

The answer would be age 18.