Your biceps are among several synergist muscles during a lat pulldown.
The lat pulldown is a cable-based exercise machine that targets your latissimus dorsi -- a large muscle that extends across the top of your rib cage and that aids in shoulder adduction and extension. Because the lat pulldown relies on the biceps to assist the motions of your lats, you might have heard it referred to as a bicep lat pulldown. While strength training routines such as this one won't necessarily help you lose weight, they can play a helpful role in building lean, healthy muscle.
Target Muscle Strengthening
The lat pulldown primarily targets your latissimus dorsi. You'll likely feel some tension in these muscles as you lift, and when you allow the weight to return to its starting position the tension will lessen. As you pull down on the bar, your lats are engaged to help move your shoulders down and lift the weight. Heavier weights, of course, will mean a more intense workout that can ultimately yield more muscle development.
Synergist Muscle Strengthening
Synergist muscles are muscles that help to stabilize your latissimus dorsi, aiding in its movement. The degree to which specific muscles are used depends upon your form, the amount of weight you're lifting and whether you have any muscle weaknesses that other muscles must compensate for. You'll gain some strengthening benefits in synergist muscles such as the biceps, deltoids, rhomboids, trapezius and pectoral muscles.
Alleviating Pain and Tension
Hunching over a computer all day can cause tension in your back and shoulders due to underuse of your lats and other nearby muscles. Regular muscle-strengthening exercise, however, helps strengthen these muscles, potentially improving your posture, reducing pain and improving the overall health of your muscle tissue. The U.S. Centers for Disease Control and Prevention recommends at least two days of strength training per week.
Benefits of Muscle Development
Every time you exercise your lats, you produce tiny tears in the muscles. As the body heals these tears, you build more muscle tissue, which is why regular exercise can help you look toned. Building up your muscles can boost your metabolic rate, because muscle burns more calories than fat. Regular strength training can also help reduce your risk of chronic illnesses such as osteoporosis and arthritis.