Gaining muscle mass is not easy it takes time to build muscle. Prolonged muscle contraction is the key stimulus for increasing muscle size. This method is called Time under tension-(TUT) total time it takes to do a series of muscle contractions. The idea that lifting heavy weights for a few reps develops plenty of tension but stress doesn't last long. Many athletes are taught that lifting heavy weight stimulates strength and muscle growth. This is good for strength but not muscle gain. Training higher volumes Lifting slowly helps maximizes metabolic stress, increasing growth hormones levels, that builds muscle mass and cutting fat. There have been many studies about the benefits of lifting moderate weight and slowly pushing muscles to the max resulting in more muscle mass. Traditional lifters do 3 sets of 10 repetitions lifting fast without controlled movement. (TUT) is all about timing, which indicates that the weight is lowered for 4 seconds, paused for 1, and finally lifted over a duration of 2 seconds. But, play around with the tempo that you’re using as you go about your weight lifting exercises. Muscle should be under tension for between 40 and 70 seconds on any given set. Rest time should be between 30 seconds to 1 minute. This method will cause you only to complete about 5 to 8 reps with good form. So next time you’re looking for a way to change up your workout and gain muscle mass, consider time under tension.