In the world of exercise physiology, if a scientist wants to measure the how much the muscle is contracting, they will use what’s called EMG. An electromyogram (EMG) measures the electrical activity of muscles at rest and during contraction. Nerve conduction studies measure how well and how fast the nerves can send electrical signals. If you look at the example below, the harder the subject contracts his muscle, the larger the increase in EMG activity.
When you are training your chest, you have a limited amount of time in the gym to stimulate the chest muscle fibers, so you want to choose the exercises that activate the most muscle fibers. One of the beauties of EMG is that there are probably over 30 different exercises for the chest, so why waste time on the activities that don’t fully activate the chest fibers the most. In the book, Serious Strength Training by Dr. Tudor Bompa, which should be in all serious bodybuilders book collection. The results of the best exercises based on EMG.
Pectoralis Major (Chest)
Decline dumbbell bench press —————-93%
Decline bench press, Olympic bar(OB)———89
Push-ups between benches ——————–88
Flat dumbbell bench press ——————-87
Flat bench press (OB) ———————–85
Flat dumbbell flyes ————————–84
Pectoralis Minor (Chest)
Incline dumbbell bench press —————-91%
Incline bench press (OB) ——————–85
Incline dumbbell flyes ———————–83
Incline bench press (smith machine) ———81
Another study conducted by the American College of Exercise examined nine of the most commonly used exercises for strengthening the chest muscles. They reviewed the barbell bench press, bent-forward cable crossovers, seated chest press,
incline dumbbell flys, pec deck, dips, suspended push-ups, stability-ball push-ups, and standard push-ups. At the end of the study, they found that the bench press, pec deck, and cable flys were some of the top exercises to activate the chest exercise.