From Ergo Log
The push-up may well be the first exercise that humans thought up to make their body stronger. Athletes who train at home can build up a surprising amount of strength with this simple exercise. For this group therefore, research published ten years ago by physiotherapists at the Mayo Clinic is doubly interesting. The study showed that you can get more out of your push-ups if you place your hands closer to each other on the ground.
The researchers got 40 test subjects to do a push up after placing electrodes on their chest muscles and triceps. This way they could measure the electrical activity in the muscle groups. The higher the electrical activity, the more intensively the muscle was being stimulated. Sports scientists use this method when they want to determine which variation of an exercise stimulates a muscle group better.
The subjects placed their hands in three different positions: shoulder width base (SW) (A), wide base (WB) (B) en narrow base (NB) (C).
The figure below shows the total electrical activity during the three variations in the triceps and the pectoralis major. Doing push-ups with your hands placed wide apart scores a little worse than the other variations; a push-up with your hands next to each other scores better.
The figure above shows averages. In some individuals the differences in electrical activity between the exercises was greater. Like the subject for whom you see the activity of the pectoralis major, here below.
In popular fitness manuals you can read that a push-up variation where your hands are close together on the ground is a better way of training your triceps. This is correct. But you can achieve the same with your chest. “If an individual uses the push-up as a form of upper-extremity exercise to strengthen the pectoralis major and triceps brachii, we recommend using the narrow base hand position”, the researchers conclude.
J Strength Cond Res. 2005 Aug; 19(3): 628-33.