By Stephen E. Alway, Ph.D., FACSM
Sometimes a busy life and schedule means it is harder than ever to find the time to keep your physique powerful, sharp and fat-free. Isolation exercises, as good as they are, do not help you solve the time-crunch problem. The solution? Compound movements that target multiple muscle groups at the same time, like Dumbbell Thrusters. Much of the challenge for this powerful exercise occurs because it activates most of the major muscles, large and small, in your body.
The initial parts of dumbbell thrusters recruit the gluteal and thigh muscles.
The gluteus maximus is the major hip extensor and it is the thickest muscle of all the hip muscles. The fibers of this muscle attach to the bones of the hip, the sacrum and along the lumbar area of the hip and lower back structures. This muscle finally attaches posteriorly to the femur bone of the thigh. When the thigh is fixed (i.e., your lower legs are firmly planted on the floor), and the hip joint is free to move, this muscle can also help to extend the lower back.
The quadriceps femoris thigh muscle group is strongly recruited during the squat part of dumbbell thrusters. This group is responsible for straightening the knee joint. The muscles making up the thigh include the vastus lateralis muscle from the lateral part of the femur; the vastus medialis muscle from the medial part of the femur; and the vastus intermedius muscle from the central, anterior part of the femur. The rectus femoris (rectus=straight) is the fourth muscle in the quadriceps group. It begins on the hip bone at the iliac crest and above the hip joint. Its fibers run straight down from the hip to the knee. The tendon from the vastus muscle combines with the tendon of the rectus femoris to form the quadriceps tendon. The quadriceps tendon attaches to the patella (knee cap) and continues inferiorly (toward the foot) as the patellar ligament to anchor on the tibia bone of the lower leg below the knee.
The final part of dumbbell thrusters activates the anterior and medial regions of the deltoid muscle of the shoulder. The anterior fibers of the deltoid begin along the lateral part of the clavicle (collar bone). The medial fibers of the deltoid attach along the acromion of the scapula. The fibers from the deltoid converge to attach to the anterior and upper portion of the humerus bone. The anterior fibers and middle fibers of the deltoid produce strong flexion of the humerus at the shoulder (bringing the humerus bone of the upper arm forward), and abduction of the humerus (raising the humerus away from the side of the body), respectively.
The top part of the press also activates the three heads of the triceps brachii. This muscle is responsible for extending (straightening) the elbow joint. The lateral head of triceps brachii begin on the posterior-lateral part of the humerus (upper arm bone) starting about 2/3 of the way toward the shoulder joint. The long head of the triceps brachii begins on the scapula (shoulder blade), just inferior to (below) the head of the humerus at the shoulder joint. The medial head of the triceps brachii attaches along the posterior humerus bone, a bit deeper and between the other two heads of the triceps. All parts of the triceps taper to attach to common triceps tendon that crosses the elbow joint to attach to the olecrenon on the ulna bone on the posterior forearm.
Additional Muscle Groups Activated
Other muscles are activated to various extents, including the abdominal and erector spinae muscles for supporting the torso in both upward and downward positions, and trapezius and serratus anterior muscles for rotating the scapula during the top of the movement.
THE EXERCISE: DUMBBELL THRUSTERS
1. Take a medium-light dumbbell (25-30 pounds) and clean them to your shoulders. Turn your palms into a pronated position (palms facing outward).
2. Place your feet shoulder-width apart. Keep your back flat, lower your hips and flex your knees so that you lower yourself to the place that your thighs are parallel to the floor.
3. Explode back up toward the starting position.
4. When you have reached the standing, press the dumbbells upward so that they end above your head with your elbows straight. In this position, you are pressing the dumbbells in an inverted ‘V’ position (wider at the shoulders, and narrower above your head).
5. Hold the top position for only one second, then lower the dumbbells to your shoulders, then go into your squat.
6. Repeat the upward movement in an explosive fashion (in about 2 seconds), but lower into the squat a little slower. Inhale on the way down and exhale at the top of the press.
Try to keep your weight toward your heels and not on your toes as you squat. This will prevent you from rocking forward on your toes and then having to rock backward onto your heels to drive your body upward. If instead, you rock forward and backward at the bottom of the thruster, the movement will be much slower and this will take away from the effectiveness of the upward power-generating piece of this exercise. Once you can do three sets of 15 reps, you can increase the weight on the dumbbells. However, do not think that this will be an easy exercise and one in which you can lift a lot of weight quickly.
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