Machine weights or free weights? While for some the controversy still rages, for most the issue has been settled decisively in favor of free weights. Free weights deliver more results – mass gain – than machine weights because the entire movement must be controlled, leading to more activation of the tiny ‘stabilizer’ muscles that would otherwise be left unstimulated by machines. However, machines weights are easier to use and more safe, especially if you do not have a spotter handy to help you through your workout.
There are a number of excellent free weight workouts that can accelerate muscle mass gain. Here are some of the most popular:
Bench press – Tried and true, this compound exercise targets muscles in the chest, shoulders, and triceps. These can be done either with dumbells or barbells.
Military press – This exercise targets the shoulders. Care should be taken when performing this exercise, as you have to hold the weights above your head.
Squat – This is another full body exercise, and as such it should always be done with the aid of a spotter. Primarily targeting the lower body muscles, including the quads, glutes, and hamstrings, this exercise requires the stabilizer muscles all throughout the upper and lower body.
Bicep curls – A favorite of many bodybuilders, this 
exercise isolates the bicep muscles on the front of the arm. You can really go hard on these, even without a spotter, as you’ll be in a better position to control the movement and prevent injury.
Rows – These exercises really target the back, along with some secondary stimulation of other muscles in the arms and chest.
