By Stephen E. Alway, Ph.D., FACSM
The stiff-leg deadlift is an effective basic exercise that has superior effects for firming the erector muscles of the spine.1 The deadlift is mechanically simple, but it requires a strong effort and careful attention to exercise form. It can be both a blessing and a curse. If you do the exercise correctly, the back will become strong and straight, and even the hamstrings will benefit from each repetition.2,3 However, if you do it sloppily, it can induce an injury that never had to happen. Like anything else in life, doing things correctly is better than doing them quickly or without much thought, as the latter choice will almost always come back in the form of a “gluteal bite.”
The back muscles, which together are called the erector spinae,4 are positioned around the spine in doublets, with one muscle on the right side of the vertebral column and the other muscle on the left side. The iliocostalis muscle is the most lateral of the erector spinae group. It begins from the iliac crest of the hip-bone, and runs upward to insert into the ribs.4 The intermediate muscle of the erector spinae group is the longissimus muscle, which runs almost the entire length of the back. The spinalis has short muscle bundles that run from spinous process (the protruding bump on the vertebrae) below to spinous process above it. This muscle extends from the thoracic to the cervical vertebrae in the neck. When both left and right parts of these back extensors contract together, the vertebral column is extended4 (i.e., from a flexed bent-over position to an upright standing position). If only the left half of the muscle contracts, the vertebrae will be rotated to one side.
You might not think that the hamstrings have much to do with deadlifts, but because they are anchored on the lower hip bones, they are very active during each lift.5 The hamstring muscles consist of the long head of the biceps femoris, semimembranosusand semitendinosusmuscles.4 The long head of the biceps femoris begins on the ischial tuberosity, which is the bony part of your hip that you sit on when you are in a chair. The fibers of the short head of the biceps femoris start on the lower one-third of the femur bone just above the knee. Both heads of the muscle fuse into a thick tendon, which crosses the lateral side of the knee joint to attach to the fibula bone (and some ligaments) on the knee.4 The muscle fibers of the semitendinosus anchor to the ischial tuberosity and inserts on the medial side of the tibia (the large medial bone of the leg). The semimembranosus muscle also begins on the ischial tuberosity and it attaches to the posterior part of the medial condyle of the tibia just below the knee joint.4 While the hamstring muscles flex the knee, they also extend the thigh at the hip joint4 and this is the primary action involved in straight-leg deadlifts.3
1. Before doing the exercise, you should spend a few minutes stretching the hamstrings, and back.6
2. Place a light barbell on the floor. Your feet should be approximately shoulder-width apart and under the bar, with your knees bent and the middle back flat and tight. Grab the bar with both hands in a pronated position (palms towards the floor) with slightly more than a shoulder-width grip. Looking slightly upward places your neck and back in a line that reduces shearing forces through the intervertebral disks.
3. With bent knees, slowly lift the bar from the floor by extending the trunk and the knees. Straighten your knees as you come to an upright (erect) position. Your knees should remain straight except for the initial lift from the floor at the beginning, and when you put the weight back on the floor at the end of the set.
4. Keep your eyes forward and head up as you lower the weight towards the floor. Never look at the floor during the lift, otherwise the middle of your back will become rounded and this invites injury by destabilizing the spine.
5. Just before hitting the barbell on the floor, start back upwards to a standing position (but now with straight knees). Pull the shoulders back at the top position, but do not lean backwards, as this could compress the intervertebral disks.
6. On the last repetition of your set, bend both trunk and knees, and drop your hips as you lower the barbell to the floor.
The erector spinae and the hamstrings all strongly contract during the lift upward (extending the vertebral column). These same muscles will undergo an eccentric (lengthening) contraction as the bar is lowered back towards the floor. The hamstring muscles are most active in the lower one-third of the movement.
Deadlifts are used as part of the assessment and rehabilitation for heart patients7,8, so this is not an exercise that is likely to kill you (although it can be tough enough to feel like it). In general, deadlifts can develop strong and balanced back extensor muscles, which will reduce the chance for injury, while at the same time develop outstanding posture. Nevertheless, you must stay very alert when you are lifting and avoid twisting when the bar is in your hands, especially when your knees are straight and you are raising the weight upwards. Be strong and be safe with your deadlifts, as this strategy will build you outstanding back strength and posture.
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