Deadlift is a compound exercise used for strength building and muscle growth. The exercise requires lifting “dead weight” off the floor without the use of momentum, hence its name. The activity involves the use of various muscle groups working together to complete the lift.
Performing a deadlift works several large muscle groups including the glutes, hamstrings, back, and core. The first half of the lift consists of bringing the barbell from the floor to the knees -- primarily targeting the quadriceps femoris muscles. The latter half of the activity involves bringing the bar from the knees to a lock-out which engages the lower and mid-back muscles, as well as the gluteal muscles and hamstrings.
The various muscle groups involved in performing deadlifts require understanding in order to optimize the workout. Engaging the right muscles in a deadlift also allows avoidance of injury.
What is a Deadlift?
A deadlift is a weight lifting exercise wherein a loaded bar is lifted off the ground until the trunk is upright and perpendicular to the ground, weights held at the hip level, before being placed back on the ground.
Along with squat and bench press, the deadlift is a type of resistance training. This exercise is usually used for improving physical fitness with the primary benefit of strengthening the posterior lower limb muscles. However, muscles of the core, back, and upper extremities are also involved in the movement.
What Muscles are Recruited in Doing Deadlifts?
From the beginning to the end of the movement, a properly performed deadlift requires rigid extension of the vertebral spine.
The initial stance begins with the lifter flexing the hips, knees, and shoulders going into an upright position demanding full extension of each of those joints, and recruiting different muscles throughout the movement.
One of the main components of the deadlift is being able to bring the torso upright to a lock-out position. The muscles responsible for this movement are the back extensors which allow the spine to move from a horizontal to an upright position. The primary back extensor involved here is the erector spinae muscle group composed of the spinalis, longissimus, and iliocostalis. From the beginning of the deadlift, these muscles are engaged, preventing the spine from rounding. These muscles pull the spine into normal extension and contract isometrically throughout the activity.
While the back extensors pull the spine upright as the weight is loaded, the trunk engages the core muscles (rectus abdominis, transversus abdominis, and internal and external obliques) to stabilize the spine, thus preventing hyperextension.
Hip and Leg Extensors
The most prominent movers of the deadlift are the hip and knee extensors. These muscles contract concentrically, producing enough force to counteract the bar’s weight and pull the legs into a standing position.
The quadriceps femoris, namely the vastus medialis, vastus lateralis, vastus intermedius, and the rectus femoris, are the muscles responsible for extending the knee. The knees simultaneously extend with the hips until the lifter is in a standing position.
Hip extension is primarily achieved through the contraction of the gluteus maximus muscle, assisted by the hamstring muscles (biceps femoris, semitendinosus, and semimembranosus), and the adductor magnus.
Shoulders and Arms
A technical principle in doing deadlifts is maintaining contact between the bar and the body. This is achieved as the lifter progresses into the lift where the latissimus dorsi pulls the upper arm to extend the shoulder and keep the bar against the legs. This movement acts against the downward pull of gravity acting on the bar to pull the arms straight.
The stability of the shoulder girdle is vital when doing deadlifts. The trapezius, a postural muscle which acts to prevent scapular depression is critical to the strength and stability of the shoulder complex. As the weight is held in the upright position, the trapezius muscle helps hold the shoulders in a neutral position.
The rhomboids assist the trapezius muscles in keeping the shoulder neutral while in the lock-out position. It retracts the scapula, preventing the shoulders to hunch forward.
The deadlift is an exercise that works on the strengthening of big muscle groups, but it is a grip exercise as well. The intrinsic and extrinsic muscles of the hand that contribute to grip strength, contract isometrically to hang onto the bar.
Deadlift Variations and Muscles Activated
Each variation of the deadlift will engage certain groups of muscles more or less than the others. These variations alter muscle activation to allow focus on areas that need development.
The sumo deadlift is performed with the feet set very wide with the toes slightly pointed out. It is considered to be a knee-dominant movement because the hips start closer to the barbell with the trunk more upright.
This deadlift variation relies on the hip musculature with less emphasis on the spinal extensors as compared to a conventional deadlift. The deeper initial squatting position puts more focus on the gluteus maximus and adductor magnus muscles. Because of the wide stance of this lift, the sumo deadlift requires strong external rotators of the hip (gluteus medius). The muscles at the inner thigh (vastus medialis) are activated to avoid tracking of the patella off the center of the knee.
The Romanian deadlift starts out with the lifter holding the bar at hip level with the feet shoulder width apart. The bar is lowered to the knees by moving the hips backward while keeping the spine straight. Upon reaching the knees, a concentric contraction of the hip extensors occurs to bring the lifter back to the starting position.
This variation engages the gluteal muscles the most. The gluteus maximus eccentrically contracts to control the descent of the weight as the hip is flexed when bringing the bar down to the knees. The hamstrings work with the gluteal muscles to extend the hip as the weight is lifted back up to the hips.
Stiff Leg Deadlift
Unlike the Romanian deadlift where the barbell is lowered down to the knee level only, the stiff leg deadlift is performed until a feeling of stretch is felt in the hamstrings and gluteal area.
The stiff leg deadlift engages the hamstrings greater than the other variations. Although the gluteal muscles still work to aid hip extension, the hamstrings contract to facilitate hip extension more when the knees are straight. The hamstrings also act as synergists throughout the full movement of the activity since the knees are kept only slightly bent.
Trap Bar Deadlift
The trap bar deadlift is similar to a conventional deadlift in terms of stance, but a trap bar deadlift is performed using a specialty bar that allows for a more neutral grip. This modification reduces the demand on back extensors. This primarily engages the gluteus maximus muscle with assistance from the quadriceps and adductor magnus.
A deficit deadlift is performed while standing on a short platform usually 1 to 4 inches high. It can be done using a conventional deadlift or a sumo deadlift, and targets the same muscle groups for each variation.
The increased range of motion recruits more of the posterior chain muscle group and the quadriceps femoris. The additional joint flexion on the hips and knees helps develop maximal tension and strength at the end ranges.
Factors Affecting Deadlift Performance
Deadlift performance is affected by a number of intrinsic biomechanical factors. The biomechanics varies from an individual to another as it is dictated by physiological features unique to that person. To be able to perform a deadlift correctly and without pain, these components must be considered. The most important to note of these physiological differences is that of varying body proportions.
There is a greater distance between the shoulders and hips of an individual with a longer torso. This makes the lever arm longer, requiring the lower back muscles to exert more effort to keep the torso upright.
Another aspect is an individual’s ape index (or ape ratio), which is a measure of an individual’s wingspan relative to their height. The typical ape index is 1. A number greater than 1 signifies that an individual’s wingspan is greater than their height, and a lesser number means that their height is greater than their wingspan.
A higher ape ratio would make it much easier to set-up on a deadlift as lesser movement would be required from the hip and knee joint to reach the bar. Lesser ape indices would make a conventional deadlift set-up more challenging as more mobility from the hip and knee joints is required.
Risk of Injury
Because deadlifts involve carrying heavy weights, there is a great possibility of injury that comes with the exercise. However, the weight of the barbell may not be the inherent cause of injury.
Hyperextension of the spine is one cause of injury when doing deadlifts because this movement increases the weight placed on the lumbar spine, thus increasing disc pressure. On the other hand, placing the barbell too far from the body may also cause injury as this recruits the wrong muscles for lifting.
Overtraining and lifting weights that are too heavy may also be sources of injury. The former does not allow ample time for muscles to recover leading to excessive fatigue that makes injuries more likely to occur. The latter, however, may lead to poor technique creating an imbalance in the load carried by the hips and the lower back.
Generally, the risk of getting injured due to deadlifts may be lowered by simply performing the movement using proper form and staying within the body’s limitations at a certain point in time.
The deadlift is more than just a lower extremity exercise as it engages major muscle groups in the hips, knees, back, core, shoulders, and arms. Breaking the bar from the floor would require more engagement from the knee extensors while bringing the hip towards the bar would utilize more of the gluteal muscles. Regardless of deadlift variation, the back extensors contract isometrically, stabilized by the core muscles to keep the spine in a neutral extended position. Proper engagement of all the muscles used helps in achieving optimal workout outcomes and preventing possible injuries.