The lower you drop your chest, the more muscle toning benefits you will reap.
Breast tissue is made up largely of fat. Ligaments hold the breasts in place and over time will stretch and cause sagging. Exercise can neither firm nor lift your breasts. Some high-impact activities like running actually can damage the breasts by weakening ligaments, your breasts' natural support system. With the proper type of exercise, you can firm the underlying muscles of the chest wall which can offer a more desirable appearance in this area. Exercise also can improve posture and lead to the illusion of more lifted breasts.
Breasts are mostly comprised of fat, and exercise won't firm them up. However, improved posture can make them appear more perky.
Show Some Support
The University of Portsmouth conducted a study on the causes of breast strain while exercising by tracking the distance between two points. A group of women ran on a treadmill while their breasts' movement patterns were dissected to ascertain where support was most needed. The study determined that breasts move in more of a figure eight pattern, not just up and down. Unsupported breasts increase the tension in the ligaments and skin. Over time this leads to stretching of the breasts' natural support system and could cause permanent damage. While exercising, you always should wear a proper supportive bra. The level of support should be rated for the type of activity. It is imperative to make sure you wear maximum support for high-impact activities such as running and kickboxing.
Tone Your Pecs
Toned pecs are crucial for improving the aesthetics of your physique. Embarking on a new or enhanced fitness program may result in an increase in lean muscle and a loss of fat which in itself can change the size and appearance of your breasts, resulting in more desired physical proportions. According to a study at the University of Wisconsin-LaCrosse, the barbell bench press has been shown to activate the highest level of muscle fibers. Lie on your back on a flat bench with your head fully supported, feet flat on floor or resting on the bench with bent knees. Place hands slightly wider than shoulders, upper arms in line with your body. Grip the bar firmly and slowly lower to touch chest. Press the barbell back up in a natural, fluid arc from your nipple-line to eye-level, fully extending your elbows. Bend elbows and slowly return to starting position. Repeat six to 10 times. Rest briefly and do two more sets.
Push 'Em Up
Doing pushups on your knees is a great way to build strength while maximizing range of motion to effectively tone your chest. You eventually can progress to full body pushups. Starting on your knees, walk your palms out until your body forms a straight line from your crown to your tailbone. Keeping your shoulders over your wrists, lower down by bending at your elbows and leading with your chest. Draw your navel up and keep your tailbone tucked. Press back up, extending your elbows. Do a set of 10 to 15 reps, rest briefly, then try a second set of two counts down and two counts up, slowing down the movement but keeping it fluid. Repeat five to eight times.
Pick a Pec
Use caution while using your gym's pec deck. This machine externally rotates the shoulder joint and may not be appropriate for those with a history of shoulder issues. Adjust the wings so that your elbows are in front of your shoulders. Set your weights so that they are relatively light. You should feel some resistance and be able to move your arms smoothly. Place your feet on the floor, your back against the backrest. Bend elbows at shoulder level and place against the wing pads. With control, push wings toward the center until almost touching. Do two sets of 10 to 15 reps.