Increase Power and Strength
If you are looking to increase the amount you can bench press, take a wide grip on the bar. This is pure science here folks... A wider grip means you have less distance to push the bar and also have more of a mechanical advantage. By taking a wider grip you utilize more of the larger pectorals muscle as well. This is an excellent way to increase the weight you can lift thus increasing raw power and strength.
Focus on Shoulders and Triceps
By simply adjusting your grip more narrow, you can change the muscle focus. The closer your grip, the more shoulders and triceps you will work. By taking a narrow grip on the bench press (hands almost touching one another on the bar) you will incorporate more of the shoulders and triceps to lift the weight. The narrow grip also creates an unstable bar which will cause stabilizer muscles such as the lats (back) and biceps to work as well.
Focus on Upper and Lower Chest
You can also change the angle of the bench to effectively target specific areas of the chest. By increasing the angle of the bench to 45 degrees you will target more of the upper chest area as well as the anterior deltoid (shoulders). By increasing the angle more than 45 degrees you will minimize the chest involvement in the lift and incorporate more shoulders and triceps. By decreasing the angle of the bench to a decline, you will target more of the lower pectorals region of the chest.
For the first few attempts at changing the grip or angle of your bench press, I usually recommend using the Smith Machine or have someone spot you to ensure proper form and safety
*Consult your physician before attempting this or any other fitness program to ensure you are in good health and able to complete strenuous activity. Contact myself or a Certified Personal Trainer for a demonstration and to ensure your form is correct.