Weight training burns a significant amount of calories, while at the same time building up muscle bulk. For this reason, weight training is popular with those who want to increase the size of their legs, arms and torsos. There are three free weight exercises that are the most popular and target these areas: squats, curls and presses.
Squats are classic, multi-joint (knees and hips) exercises that target a variety of the body's muscle groups, with emphasis on the back and lower body. There are several variations of the squat, but the most common is the parallel back squat. This squat involves placing a barbell across the upper shoulders and back, squatting until the thighs are parallel to the floor, and returning to a standing position. Squats burn a tremendous amount of energy, and activate the following muscle groups:
Many people don't think of the squat as a back exercise, but the erector spinae group of muscles plays a vital role in lateral stability while squatting. They contract isometrically (without shortening or lengthening) to control rotation of the torso.
The gluteus maximus muscle plays a vital role during squats. During the downward phase of the squat, the gluteus maximus contracts while lengthening. This allows the squatter to control the speed and range of descent. During the upward phase of the squat, the muscle contracts while shortening to transfer power to the quadriceps and hamstrings necessary to return to a standing position.
Along with the quadriceps, hamstrings provide the power needed to perform squats. In concert with the gluteus maximus, the hamstrings contract while lengthening during downward movement and contract while shortening on upward movement to facilitate hip extension.
The quadriceps muscle group turns muscle activity into knee extension, which provides the motion necessary to perform squats. While in the downward motion of the squat, the quadriceps contract while lengthening, and contract while shortening when returning to the starting posture.
Curls are a classic weight lift that involves holding a weight in an upward facing palm at a dead hang and then raising the weight to the shoulder. This exercise is used to develop arm musculature and is utilizes these muscle groups:
The goal of curls is to develop the biceps; therefore, it is logical that this is the primary muscle group used. The bicep muscles contract while shortening during the upward lifting phase of the exercise. The muscles contract while lengthening as the weight is being lowered back to the starting position. In this manner, they control the angle of the elbow, which controls arm movement.
Within the range of motion where the biceps is at a mechanical disadvantage, the brachioradialis muscle assists in maintaining elbow motion and control. Like the biceps, the brachioradialis contracts while shortening during lifting and contracts while lengthening as the weight lowers.
The bench press is a very simple motion wherein an individual removes a weighted barbell from an overhead position with arms extended, lowers the weight to his or her chest, and pushes the weight back to the extended position. The bench press is an intense exercise, and makes use of several muscle groups:
The pectoral muscles allow a weight lifter to lift by controlling the motion of the shoulder. As the pectoral muscles contract while shortening, they pull the shoulders forward, which in a supine position, moves the arms upward. While controlling the downward rate of descent and range of motion, the pectoral muscles contract while lengthening.
The deltoid muscles, being much weaker than pectoral muscles, assist the pectoral muscles in shoulder rotation.
The triceps muscles provide upper arm extension and control during the lifting phase of the exercise as they contract while shortening.
The biceps provide lateral stability during the press exercise, alternating between shortening and lengthening as necessary to control the weight which is being lifted.
Muscles Make it Happen
The human body is a fascinating piece of machinery. An individual's ability to lift or control weight is dependent upon the angles of joints which are connected to rigid bones. It is change of these angles that makes limbs move. These angles are controlled by gravity and muscles, which often oppose each other. By working out the muscles listed above, they grow stronger and can exert more force on these joints, which translates to more strength and an increased ability to lift heavier objects.