I'm Jeremy Shore for Livestrong.com, and this is how to create mass in the pectorals. Nick Tumminello, owner of Performance University, recommends following these simple guidelines when trying to create mass in the pecs. First, make sure to perform at least 12 sets of exercise with 8 to 15 repetitions for each set. You also want to make sure that during each set your tempo is such that it takes at least 40 seconds to complete the set ensuring that there is adequate time under tension for adaptations to occur. When choosing chest exercises, Nick recommends staying in the horizontal plank. Exercises like a bench press, dumbbell chest press and variations of the fly keep the focus on the pectorals and off muscles that may try to assist in the movement like the shoulders. Instead of changing your angles, change up the resistance factor. For example, when performing a dumbbell fly on a flat bench the greatest amount of resistance occurs when the dumbbells are out to the sides away from the mid line of the body. However, when you perform this same exercise using cables, the greatest point of resistance happens when you are further into the movement as the hands draw closer to the mid-line of the body. I'm Jeremy Shore for Livestrong.com, and this has been how to create mass in the pectorals.