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Single-Arm Pec Deck

By RealJock Staff

This exercise provided courtesy of Mike Clausen, founder and co-owner of DIAKADI Body training gym, voted best personal training gym in San Francisco by CitySearch in 2006.

This variation of the standard pec deck asks you to do the exercise one arm at a time—helping you further isolate and focus on the center valley of your chest while still working the full pectorals.

Muscles Worked

Starting Position
Sit at a pec deck machine (the accompanying photos show a grip handle machine, but you can do this exercise on the pad-style machine if the grip handle is not available). Set the bench height such that your hands, when gripping the handles (or forearms when on the pad machine), will be at the level of your chest. Grasp the handle to your left with your left hand, leaving your right arm at your side. Keep your shoulders back throughout. This will generate a slight arch in your back, which is fine provided you support by engaging your abs (see Photo 1).


  1. From the starting position, bring your left arm and the machine’s corresponding arm in a straight arc just past the center line of your chest. Control this movement so that it is continuous; avoid starting with a jerking motion. On the grip handle machine, the lower portion of your hand should have the most pressure; for a pad machine, your elbow will carry more pressure than your hand (see Photos 2 and 3).
  2. From the flexed position, reverse direction and bring your arm back to the starting position. Be very careful to control this movement; your arm should not come further back than straight to the side, and as you near full extension you should be careful to go slowly and keep your chest muscle flexed to protect your shoulders and prevent injury (see Photos 4 and 5).
  3. After a full set with the left arm, switch to the other side and repeat with the right.
About Mike Clausen: Clausen is the founder and co-owner of DIAKADI Body training gym, voted best personal training gym in San Francisco by CitySearch in 2006. He has been actively involved in sports and weightlifting since high school, and continues to use that knowledge when training his clients. Clausen is both A.C.E. and N.A.S.M. certified and has been training clients professionally for six years. He enjoys making his clients stronger, both physically and mentally, giving them the tools to create an efficient body and to do things they thought were not possible.