Squats, lunges and leg presses work just about everything below the waist except for your abs. Of the three, leg presses are probably the easiest to master for beginners and the least likely to cause injury. Add weight or change the muscle focus as you progress. If you're a serious presser, do leg presses on a plate-loaded incline press at your local gym. No matter your level of skill, though, performing leg presses delivers health benefits you'll notice.
Quads and Hamstrings
The the prime mover muscles on a leg press machine are the quads at the fronts of your thighs. The hamstrings at the backs of your thighs are worked as stabilizers. Your quads are responsible for straightening your leg, while your hamstrings are responsible for bending your leg -- movements involved in just about everything you do with your lower body. Strong quads and hamstrings take the strain off your knees when walking, running, squatting or climbing stairs. They also take the strain off your back when lifting heavy objects. If you get into working with barbells, strong quads and hamstrings will be essential to avoiding back injury.
Your gluteus maximus assist in the leg press. Your major concern with this muscle -- the largest one in your body -- may be how you look in that black knit dress, but the gluteus maximus has many more benefits. It plays a major role in everyday movements like sitting and rising from a chair, walking and maintaining good posture so your back doesn't arch. Weak glutes are associated with knee and low-back problems. Strong glutes provide a basis for good exercise form and technique making it possible to walk fast, run and lift with less chance of injury.
The technical names for your calf muscles are the gastrocnemius -- located just under your knee -- and the soleus -- which runs down your leg, slightly to the outside. Together, they give your lower leg its shape, but they also are responsible for your foot and ankle motion. The soleus muscle acts as an assister in leg presses, while the gastrocnemius is a stabilizer. Strong calf muscles are important in avoiding injury, like sprains, caused by weak ankles.
Leg presses in and of themselves won't improve cardio fitness. However, one of the major health benefits of strong legs and glute muscles is the ability to engage in longer and more intense cardio workouts. Whether you choose power walking, running, biking or working out on a treadmill or elliptical, you'll be hard-pressed to build cardio endurance if your legs tire quickly. By strengthening the entire leg, presses will help you stay with your cardio longer.
Like any exercise, the benefits will be quickly negated if you do leg presses improperly. Whether the machine is lever action, in which you push the plate away from you, or sled action, which requires that you push away from the plate, you should not bend your knees to more than 90 degrees. It is also important to choose a weight you can control on the return. Allowing the weight to snap back will not only be less effective, it could put you out of commission. Leg presses are generally safe even if you have knee pain and may be recommended for recovery from an injury. In that case, you'll want to limit your range of motion to even less than 90 degrees. Follow your doctor's guidance.
- ExRx.net: Lever Seated Leg Press
- ExRx.net: Sled 45° Leg Press
- SAPT: It's All About Glutes
- Sports + Spinal Physical Therapy: Gluteus Maximus: More than Just a Seat Cushion
- Personal Fitness Training: Theory & Practice, Second Edition; Mary Yoke
- Medioimages/Photodisc/Photodisc/Getty Images