Deadlift

Movement

The main movers

A narrative review of powerlifting injuries describes the hip, knee and back extensors as the prime movers in the deadlift¹. An extensor is a muscle that straightens a joint, or bends the spine backward. A prime mover is the main muscle that makes a movement.

A systematic review of deadlift studies adds a purpose². A systematic review searches for the research on a question in a set, checkable way and sums it up. It states that the lift is often done to strengthen the thigh and posterior chain muscles, naming the buttock muscles, hamstrings, erector spinae and quadriceps².

What the joints do in two styles

Two studies on this page compare two styles of the lift, called conventional and sumo^3,4. One study filmed lifters at a national powerlifting championship and worked out the joint moments in each style⁴. A joint moment is the turning effect of a force around a joint. At the ankle, the conventional style generated a plantar flexor moment, the kind that points the foot down⁴. The sumo style generated a dorsiflexor moment, the kind that pulls the foot up⁴:

Joint	Conventional style	Sumo style
Hip	Extensor moment4	Extensor moment4
Knee	Extensor and flexor moments4	Extensor moment4
Ankle	Plantar flexor moment4	Dorsiflexor moment4

Hip moments did not differ significantly between the two styles⁴.

How knee bend shifts the work

A study of both styles in 13 college football players tracked muscle activity as the knees bent and straightened³. Some muscles were more active when the knees were more bent, and others when they were straighter³:

• More bent knees: the quadriceps (four front thigh muscles that straighten the knee), tibialis anterior (a shin muscle) and hip adductors (inner thigh muscles)³.
• Also more bent knees: the gluteus maximus (buttock muscle), the middle trapezius (upper-back muscle), and paraspinal (beside the spine) muscles at two levels³.
• Straighter knees: the hamstrings (three long muscles at the back of the thigh), the gastrocnemius (calf muscle nearest the skin) and the upper trapezius³.

What it loads

Which muscles work hardest

A systematic review looked at 19 studies that used EMG (electromyography) with sensors on the skin². EMG measures a muscle’s activity by picking up its electrical signals. The review’s rules required healthy, trained participants². The review concluded that the erector spinae and quadriceps were more activated than the gluteus maximus and biceps femoris². This held for the deadlift and most of its variants².

The review concluded that the erector spinae and quadriceps were more activated than the gluteus maximus and biceps femoris.

The biceps femoris and semitendinosus are two of the three hamstring muscles, with the semimembranosus⁵. The Romanian deadlift was the exception to the review’s main pattern². In it, erector spinae activation was lower than biceps femoris and semitendinosus activation². Within the hamstrings, the semitendinosus showed slightly greater activation than the biceps femoris during deadlift exercises².

What each main muscle does

The four muscle groups the lift is often done to strengthen each have a known job^2,5,6,7:

Muscle	What it does
Erector spinae	Makes up most of the back’s muscle mass and is the main extensor of the spine5
Gluteus maximus	Built to extend the hip and turn it outward, and to help move the thigh out to the side6
Hamstrings	Extend the hip and bend the knee5,7
Quadriceps	Straightens the leg at the knee, acting through the kneecap5

The gluteus maximus and the hamstrings work together to extend the hip⁸. When the body rises from a full forward bend of the trunk, most movement in the first half happens at the hip⁶. The gluteus maximus and hamstrings produce it⁶.

How style shifts the thigh and calf muscles

In 13 college football players, style changed which leg muscles were more active³. They lifted a 12-repetition maximum, the heaviest load they could lift 12 times³. In the sumo deadlift, the vastus medialis, the vastus lateralis and the tibialis anterior were more active³. The vastus medialis and vastus lateralis are the quadriceps muscles on the inner and outer sides of the thigh⁵. The conventional deadlift drew more activity from the inner head of the gastrocnemius³.

The belly muscles and a lifting belt

The same study compared lifting with and without a lifting belt³. With a belt, activity was greater in the rectus abdominis, the long, flat muscle down the front of the abdomen³. Activity was lower in the external oblique, the outermost flat muscle on each side of the abdomen³. The rectus abdominis is the main muscle for bending the spine forward, as in sitting up⁵.

The lower back

A study of 57 competitors, 13 women and 44 men, at a national powerlifting championship estimated loads on the L4/L5 joint⁹. That is the joint between the fourth and fifth lumbar vertebrae. Average squeezing (compressive) loads there were estimated at up to 17,192 newtons, a unit of force⁹.

In a model-based analysis of lifters at that championship, the sumo style had a 10% lower L4/L5 joint moment than the conventional style⁹. It also had an 8% lower shear (sliding) force there⁹.

In 13 male university track-and-field athletes, parts of the spine bent more as the load rose¹⁰. They deadlifted 60% to 90% of their one-repetition maximum, the heaviest weight a person can lift once¹⁰. Flexion (bending) of the lower thoracic and upper lumbar spine increased with the load¹⁰. The backward tilt of the pelvis also sped up with heavier loads¹⁰.

A different study used videofluoroscopy, a moving X-ray, to watch the lumbar vertebrae of four experienced powerlifters doing conventional deadlifts¹¹. Except in one trial of one lifter, the lumbar spine stayed 1.5 to 13 degrees short of full flexion¹¹. The authors concluded that the ligaments did not stretch enough to resist the trunk’s forward bend much¹¹. In their view, that job fell to the muscles¹¹.

How the body adapts

Strength after training other lifts

One study tested deadlift strength after training two other exercises¹². Untrained college-aged adults did 9 weeks of hip thrust or back squat training¹². Strength gains favoured the exercise each group trained¹². Deadlift strength improved similarly in both groups¹².

Thigh muscle size early in training

One study of 10 weeks of resistance training, not a deadlift study, measured the cross-sectional area of a thigh muscle¹³. Cross-sectional area is the size of a slice cut straight across a muscle. In ten untrained young men, vastus lateralis cross-sectional area was about 2.7% larger in the third week¹³. The authors propose that early rises like this are not purely hypertrophy, growth in the size of a muscle¹³. Swelling from oedema (fluid build-up), probably from muscle damage, may account for a large share of the rise¹³.

By the end of 10 weeks, the area was about 10.4% larger than at the start¹³. The same authors conclude that a rise in this area, especially early on, should not be called hypertrophy without a measure of swelling or damage¹³. A review puts forward the idea that swelling from muscle damage explains most of the rise in the first four or so sessions¹⁴. In that view, modest hypertrophy follows after about 10 sessions, and true hypertrophy is not seen until after about 18¹⁴.

What happens without load

In two bed-rest studies, parts of the erector spinae and gluteus maximus lost volume^15,16. In 24 healthy adults, 60 days of head-down-tilt bed rest cut lumbar erector spinae volume by 11.2% on average¹⁵. In that set-up, people lie in bed for weeks with the head slightly below the feet. The exception was at L5/S1, between the fifth lumbar vertebra and the sacrum, where volume rose¹⁵. The sacrum is the triangle-shaped bone at the base of the spine.

In a bed-rest study of men, upper gluteus maximus volume in those who did not exercise stayed 7.4% below its starting level¹⁶. That was 14 days after 60 days of bed rest¹⁶. By 90 days after bed rest, volume was no longer significantly reduced in any group¹⁶.

Injuries reported with the deadlift

A narrative review found few studies describing how the deadlift might be associated with specific injuries¹. It found one case report (a report on one patient), two case series and one retrospective study (one that looked back at past cases)¹. A case series is a report on a group of patients with the same condition, without a comparison group. The injuries those studies reported were¹:

• A stress fracture of the acetabulum (hip socket)¹.
• A rupture (tear) of the pectoralis major, the large, fan-shaped muscle at the front of the chest¹.
• Hamstring muscle ruptures¹.
• Avulsions, tears in which a tendon or ligament pulls away from the bone, at the anterior superior iliac spine (the hip point)¹.
• Knee meniscus (knee cartilage) injuries, and lumbosacral injuries, where the lower spine meets the sacrum¹.

A questionnaire study of 104 Swedish subelite (below the top level) powerlifters looked at lumbopelvic (lower back and pelvis) injuries¹⁷. A current lumbopelvic injury was significantly associated with the injury having started during deadlift training, with an odds ratio of 4.03¹⁷. An odds ratio shows how many times higher the odds of an outcome are in one group than in another. Of the 21 lifters with a current lumbopelvic injury, 11 said it started during deadlift training¹⁷.

Progressive overload

A 2026 position stand describes progressive overload as the need to increase the stimulus placed on the muscle throughout a training programme¹⁹.

A rule for adding load to the trap bar deadlift

In a randomised trial of recreationally active women, one group trained the trap bar deadlift twice a week for 8 weeks, unsupervised²⁰. They did 4 sets of 4 repetitions, starting at 85% of their pre-test one-repetition maximum (1RM)²⁰. They were told to add 2.5 to 10 kg when they could do more than four repetitions²⁰. When they could not finish all four, the weight came down by 2.5 to 5 kg on the next set²⁰.

Across the 22 women, trap bar deadlift 1RM rose by an average of 18.4 kg in this group²⁰. It rose 11.7 kg in a group that trained the barbell half squat²⁰.

Repetitions, effort and tempo in the Romanian deadlift

A randomised 6-week trial of 32 healthy young adults had one group do the Romanian deadlift twice a week²¹. That variant lowers the bar by bending at the hips, with the knees only slightly bent. Effort was set by RPE (rating of perceived exertion), a score for how hard effort feels²¹. A metronome paced the eccentric, or lowering, phase²¹:

Weeks	Sets and repetitions	Effort (RPE)	Lowering phase
1 and 2	From 3 sets of 3 up to 3 sets of 421	From 5 up to 721	4 seconds in week 1, 5 seconds in week 221
3 to 6	4 sets of 421	8 to 921	6 seconds21

Load went onto the barbell in steps of about 2.5 kg to hold effort at RPE 8 to 9²¹. The other group did the Nordic hamstring exercise, and the two groups did not differ²¹. Across both, biceps femoris long head fascicle length rose 9% and hamstring cross-sectional area 10%²¹. Fascicle length is the length of the bundles of fibres in a muscle.

The trial ended with 2 weeks of detraining, the loss of training gains when training stops or falls too low²¹. By then, fascicle length was back at baseline, but hamstring cross-sectional area stayed raised²¹.

Setting the load by feel or by percentage

In one randomised trial, two deadlift groups did identical sets and repetitions, with loads set by RPE or by fixed percentages of 1RM²². Deadlift 1RM rose by 12.3 kg in the RPE group and 10.8 kg in the percentage group²². Only the RPE group had lower scores for fatigue before sessions²².

A crossover study of 8 trained men compared two 8-week blocks, each man doing both²³. In one block, each day’s loads came from a first set taken to failure at 85% of the starting 1RM²³. The other used fixed percentages²³. Both improved deadlift 1RM, with no significant difference between them²³.

Connections

The muscles it loads

The deadlift works four muscles and muscle groups that the studies on this page measured²:

• The erector spinae, the long muscles beside the spine that straighten the back^2,5.
• The gluteus maximus, the large muscle of the buttock^2,6.
• The hamstrings, including the semitendinosus and biceps femoris^2,5.
• The quadriceps, including the vastus medialis and vastus lateralis^3,5.

The trunk muscles it works

The rectus abdominis and external oblique were both measured in deadlifts with and without a belt³.

Other muscles the studies measured

• The gastrocnemius, whose inner head was more active in the conventional style, and which was more active with straighter knees³.
• The tibialis anterior, more active in the sumo style and with more bent knees³.
• The hip adductors, more active with more bent knees³.
• The trapezius, whose middle and upper parts shifted in opposite directions with knee bend³.

Sources

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2. Martín-Fuentes I, Oliva-Lozano JM, Muyor JM (2020). Electromyographic activity in deadlift exercise and its variants. A systematic review.. PLoS One. doi:10.1371/journal.pone.0229507 PMID 32107499
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4. Escamilla RF, Francisco AC, Fleisig GS, Barrentine SW, Welch CM, Kayes AV, Speer KP, Andrews JR (2000). A three-dimensional biomechanical analysis of sumo and conventional style deadlifts.. Medicine and Science in Sports and Exercise. doi:10.1097/00005768-200007000-00013 PMID 10912892
5. Betts JG, Young KA, Wise JA, Johnson E, Poe B, Kruse DH, Korol O, Johnson JE, Womble M, DeSaix P (2022). Anatomy and Physiology 2e. OpenStax. Link
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10. Shoji K, Nakayama K, Shiouchi M, Manabe Y (2025). Load-dependent increase in lumbar kyphosis is associated with posterior pelvic tilt during deadlift.. Frontiers in Sports and Active Living. doi:10.3389/fspor.2025.1682991 PMID 41195113
11. Cholewicki J, McGill SM (1992). Lumbar posterior ligament involvement during extremely heavy lifts estimated from fluoroscopic measurements.. Journal of Biomechanics. doi:10.1016/0021-9290(92)90242-s PMID 1733981
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13. Damas F, Phillips SM, Lixandrão ME, Vechin FC, Libardi CA, Roschel H, Tricoli V, Ugrinowitsch C (2016). Early resistance training-induced increases in muscle cross-sectional area are concomitant with edema-induced muscle swelling.. European Journal of Applied Physiology. doi:10.1007/s00421-015-3243-4 PMID 26280652
14. Damas F, Libardi CA, Ugrinowitsch C (2018). The development of skeletal muscle hypertrophy through resistance training: the role of muscle damage and muscle protein synthesis.. European Journal of Applied Physiology. doi:10.1007/s00421-017-3792-9 PMID 29282529
15. De Martino E, Hides J, Elliott JM, Hoggarth MA, Zange J, Lindsay K, Debuse D, Winnard A, Beard D, Cook JA, Salomoni SE, Weber T, Scott J, Hodges PW, Caplan N (2022). The Effects of Reconditioning Exercises Following Prolonged Bed Rest on Lumbopelvic Muscle Volume and Accumulation of Paraspinal Muscle Fat.. Frontiers in Physiology. doi:10.3389/fphys.2022.862793 PMID 35774286
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20. Hagerupsen K, Pedersen S, Giller NB, Thomassen NK, Heitmann KA, Sagelv EH, Osborne JO, Johansen KR (2024). Comparison of resistance training using barbell half squats and trap bar deadlifts on maximal strength, power performance, and lean mass in recreationally active females: an eight-week randomised trial.. BMC Sports Science, Medicine and Rehabilitation. doi:10.1186/s13102-024-00911-8 PMID 38816857
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Every source the library cites

Changes

• October 23, 2026 Added a Progressive overload section.
• September 29, 2026 Added a figure showing where it sits, links to the exercise pages that load it, and tighter wording in a few places.