Side-lying hip abduction

Key points

A systematic review (a study that sums up all the research on a question) of 23 EMG (electromyography, which measures muscle activity) studies of people without injury found this was the most studied side-lying exercise¹.
A meta-analysis (a study that pools earlier studies into one answer) of 8 studies in healthy people put activity in the middle part of the gluteus medius, a buttock muscle beneath the gluteus maximus (the large muscle of the buttock), at a moderate level^2,3.
Studies disagree on whether the clamshell variation works the gluteus medius less than the plain lift^4,5.
Turning the hip inward raised gluteus medius activity in two studies, while a third found hip rotation made no significant difference to the balance of muscles^6,7,8.
In one randomised trial (people assigned to groups by chance) of 31 healthy, active adults, six weeks of training raised strength in moving the thigh out to the side, with or without added load⁹.
Three studies that used the lift raised its load in different ways: after weekly strength tests, in two-week steps, or when effort was rated below “somewhat hard”^10,11,12.

Movement

What the movement is

Side-lying hip abduction is hip abduction (moving the thigh out to the side, away from the body’s midline) done while lying on one side¹. The gluteus medius and the gluteus minimus, a buttock muscle beneath the gluteus medius, work together as hip abductors¹³.

In a review of 23 EMG studies of people without injury, it was the side-lying exercise studied most often¹. The studies that used it had 197 people between them¹.

The versions studies have used

The studies on this page tested the lift in several forms^6,9,14:

Held still as an isometric lift, where the muscle works but the joint does not move, with the hip turned inward, neutral or outward⁶.
With an ankle weight of 5% of body mass¹⁵.
With the body rolled forward, in a neutral position, or rolled backward¹⁴.
With a 10-repetition maximum, the heaviest load a person can lift ten times, or with only the weight of the leg⁹.

The clamshell

The clamshell, or clam, is a side-lying variation that several studies compared with the plain lift^4,5. Studies tested it with the hip bent to 30, 45 or 60 degrees^8,16.

What it loads

The gluteus medius

One review put gluteus medius activity in the plain lift at a moderate level, and at a very high level when outside resistance was added². The review of 23 studies found the lift in nine of them¹. Gluteus medius activity ranged from 26.8 to 81.2% of maximum voluntary isometric contraction (MVIC), a muscle’s hardest effort while the joint stays still¹.

A meta-analysis found side-lying hip abduction was the most studied non-weight-bearing exercise for the gluteus medius². Across 8 studies of healthy people, pooled activity in the middle part of the muscle was about 40% of MVIC². Adding outside resistance raised activity further, to a very high level, though results varied widely between studies².

Two sources placed it near the top^1,4:

In 21 healthy, physically active people, it was the best of 12 exercises for gluteus medius activity⁴.
The review of 23 studies named it among three exercises with the highest gluteus medius activity, ranging from 81 to 103% of MVIC¹.

The review of 23 studies also found that weight-bearing exercises gave more gluteus medius and gluteus maximus activity than non-weight-bearing ones, such as side-lying exercises¹. Its authors put the spread in results down most likely to technique¹. They named the angle the leg was held at, the position of the pelvis, and whether the lifted hip was bent or extended¹.

How hip position shifts the work

The tensor fasciae latae is a small muscle at the upper outer thigh. It pulls on the iliotibial band (a long band of tough tissue running down the outer thigh). It is a synergist of the gluteus medius, a muscle that helps it make the same movement³. Two studies found that turning the hip inward favoured the gluteus medius^6,7:

In 20 healthy university students holding the lift still, turning the hip inward gave more gluteus medius activity than neutral or outward rotation⁶. It also gave a higher ratio of gluteus medius to tensor fasciae latae activity⁶.
In 19 people with gluteus medius weakness, turning inward raised gluteus medius activity, and turning outward raised tensor fasciae latae activity, compared with neutral⁷.

A meta-analysis of studies in healthy people found high middle gluteus medius activity in the lift with the hip turned inward, about 45% of maximum². With the hip turned outward, activity was moderate, about 38%².

One study did not find this⁸. In 13 healthy men, changing hip rotation did not significantly change the balance of gluteus medius to tensor fasciae latae activity⁸. The gluteus medius stayed the dominant muscle of the two⁸.

In 20 healthy distance runners with an ankle weight, turning the hip outward made the tensor fasciae latae the most active muscle measured¹⁵. The table gives that one study’s results as a percentage of each muscle’s maximum; hip flexors are muscles that bend the hip¹⁵:

Muscle	Plain lift	Lift with the hip turned outward	Loaded clamshell
Gluteus medius	70%¹⁵	53%¹⁵	33%¹⁵
Tensor fasciae latae	54%¹⁵	71%¹⁵	34%¹⁵
Front hip flexors	28%¹⁵	54%¹⁵	54%¹⁵
Gluteus maximus	25%¹⁵	32%¹⁵	34%¹⁵

The authors concluded the plain lift was better for targeting the gluteus medius¹⁵. In the other two exercises, other muscles were more active than the gluteus medius¹⁵.

How the body and pelvis shift the work

Body position and the pelvis also changed which muscles worked^14,17,18:

In 21 people with gluteus medius weakness, rolling the body forward gave more gluteus medius and maximus activity than other positions¹⁴. Tensor fasciae latae activity was lower¹⁴.
In 19 participants, a block that stopped side-to-side pelvic movement made no significant difference to gluteus medius activity¹⁷. Tensor fasciae latae and quadratus lumborum (a deep muscle of the lower back) activity was modestly lower with the block¹⁷.
In 24 women with gluteus medius weakness, ankle loads raised quadratus lumborum activity from 49% to 82% and 92% of maximum¹⁸. The ratio of gluteus medius to quadratus lumborum activity fell¹⁸.

The gluteus minimus

A meta-analysis found only one study of the gluteus minimus in this exercise². That study recorded moderate activity in the front segment, 38% of maximum, and high activity in the back segment, 44%². The review listed the exercise among those that can target the back segment².

In 12 healthy men, the back part of the gluteus minimus and the gluteus medius were most active with the hip extended and turned inward¹⁹. That peak, 55% and 59% of maximum, came late in the lifting phase¹⁹. MRI is a scan that shows soft tissue such as muscle in detail. In an MRI study of 10 healthy, active people, the lift with the hip turned outward was tested²⁰. It worked the gluteus minimus more than a single-leg bridge, clamshell or reverse clamshell²⁰.

The gluteus maximus

The gluteus maximus also works in this lift¹. In the nine studies in the review of 23, its activity ranged from 21.3 to 51.1% of MVIC¹. Pooling all side-lying variations, that review found average activity of about 30% for the gluteus maximus and 42% for the gluteus medius¹.

How the clamshell compares

Studies disagree on how hard the clamshell works the gluteus medius^4,5. Several found less activity than in the plain lift^1,4:

In 21 healthy, active people, two types of clam gave 40% and 38% of MVIC, significantly less than the lift’s 81%⁴.
The review of 23 studies found four clam variations gave the lowest gluteus medius activity of the exercises reviewed, 12 to 18% of MVIC¹.
A meta-analysis found low to moderate middle gluteus medius activity, 17 to 28% of maximum, across studies that differed widely in technique².
In 10 healthy, active people scanned by MRI, the lift with the hip turned outward activated the gluteus medius more than the clamshell²⁰.

One study did not find a difference⁵. In 11 men, gluteus medius activity did not differ significantly between the lift, the clamshell and a hip abductor machine⁵. Tensor fasciae latae activity was greater in the lift than in the other two⁵.

The balance between the gluteal muscles (the three muscles of the buttock) and the tensor fasciae latae also varied by study^8,15. In 13 healthy men, the ratio of gluteus medius to tensor fasciae latae activity was far greater in the clamshell than in the lift⁸. In 20 healthy people doing 11 exercises, the clam scored highest on an index comparing gluteal with tensor fasciae latae activity²¹. In the loaded clamshell of the distance-runner study, though, the front hip flexors were more active than the gluteus medius and tensor fasciae latae¹⁵.

How far the hip is bent in the clam also gave mixed results^2,16:

A meta-analysis reported that hip angle and trunk position made little difference to average gluteus medius activity².
In 13 healthy men, hip angles of 30, 45 or 60 degrees did not significantly alter the gluteus medius to tensor fasciae latae ratio⁸.
In 30 healthy women, the gluteal to tensor fasciae latae activation index was higher at 60 degrees than 45, and at both than 30¹⁶.

Studies also measured other hip muscles in the clam^2,20. A meta-analysis pooling two studies found low gluteus minimus activity². In the MRI study, the clamshell and outward-turned lift worked the obturator internus, a deep hip muscle, more than a single-leg bridge or reverse clam²⁰. The clamshell also activated the piriformis, a small muscle deep in the buttock, more than the reverse clamshell²⁰.

The gluteal tendons

The gluteus medius and minimus reach the femur (thigh bone) through the gluteal tendons^22,23,24. The greater trochanter is a bony knob at the top of the thigh bone. A facet is a small flat area on a bone. In studies of cadaver (donated body) hips, the gluteus medius tendon attached to the trochanter at its side and upper back facets^22,23. The gluteus minimus tendon attached to the front facet^22,24.

Hip adduction, moving the thigh toward the body’s midline, can raise the pressure of the iliotibial band on tissue over the greater trochanter²⁵. In 18 unfixed bodies and 12 people having hip replacement, force beneath the band there rose with adduction and fell with abduction²⁶. It rose by up to 106 newtons at 40 degrees of adduction²⁶. Neither group was doing side-lying hip abduction, and no study here measured this force during the lift²⁶. Any link to this exercise runs through hip position alone^25,26.

How the body adapts

Strength after six weeks

A randomised trial assigns people to groups by chance and then compares the groups. One such trial of this exercise enrolled 31 healthy, physically active adults⁹. For six weeks, one group trained with a 10-repetition maximum and the other with only the weight of the leg⁹. Isometric and eccentric (done while the muscle lengthens) hip abduction strength rose by 11 to 23%⁹. The gains did not differ between the groups⁹.

What is known about tendon

A review of hip tendon problems described mechanical load as a key signal for tendon, driving both breakdown and building²⁵. That point is general; no study here measured how the gluteal tendons change with this exercise²⁵.

Progressive overload

A 2026 position stand describes progressive overload as the need to increase the stimulus placed on the muscle throughout a training programme²⁷. Three studies that used this lift raised its load in different ways^10,11,12:

Who trained, and for how long	How the load was set and raised
29 symptom-free volunteers, 5 weeks	Ankle weights at 80% of measured strength¹⁰. The load was adjusted at each weekly strength test¹⁰
86 people with knee osteoarthritis, 10 weeks	A sandbag at the ankle, raised every two weeks from 50% to 90% of the 10-repetition maximum¹¹
Recreationally active adults, 6 weeks	Bands, ankle weights or dumbbells, added whenever effort was rated below “somewhat hard”¹²

Load set from a strength test

One randomised trial enrolled 29 symptom-free volunteers with knee valgus, the knee angling inward, toward the other knee¹⁰. Their thigh bones were also turned inward¹⁰. The strengthening group did 3 sets to failure (until another repetition isn’t possible), every other day, for five weeks¹⁰. All of it was done unsupervised, with training diaries¹⁰.

Hip abductor strength rose 35% in this group, and 27% in a group doing a functional motor control programme¹⁰. The two groups did not differ significantly¹⁰.

Load raised in steps, with a hold

A randomised trial enrolled 86 people with osteoarthritis (a joint disease in which cartilage wears away) on the inner side of the knee¹¹. One group added side-lying hip abduction to quadriceps exercises¹¹. The leg was lifted to 45 degrees and held for 10 seconds, with a sandbag strapped at the ankle¹¹. The exercise was done as 4 sets of 10, morning and evening, 3 days a week¹¹.

Both groups improved over 10 weeks, and knee scores did not differ significantly between them at 2 to 10 weeks¹¹. The group with the hip exercise improved 2 to 4 weeks sooner in pain, symptoms, daily function and knee-related quality of life¹¹. The authors called that effect small¹¹.

Load raised by rated effort

In a 6-week study of recreationally active adults, the strength programme included side-lying hip abduction and the clam¹². Each exercise was done as 3 sets of 12¹². Training was 3 sessions a week, one supervised and two at home¹².

In the 9 people in this group, clam strength changed from the start to 6 weeks, and from the start to 12 weeks¹². Only this group changed hip-abduction strength from the start to 6 weeks¹². There was no overall group effect, and no change from the start to 12 weeks¹².

Load or no load

In the six-week trial of 31 healthy, physically active adults, gains with a 10-repetition maximum and with leg weight alone did not differ⁹. In EMG studies of healthy people, outside resistance raised gluteus medius activity to a very high level². Results varied widely between those studies². In 24 women with gluteus medius weakness, ankle loads also raised quadratus lumborum activity¹⁸. In 11 healthy, active people, adding elastic resistance to the clam significantly changed tensor fasciae latae activation²⁸.

Connections

The tendons it loads

The gluteus medius and minimus, the hip abductors studied in this exercise, attach to the femur through the gluteal tendons^13,22,23,24. The force beneath the iliotibial band at the greater trochanter rose with hip adduction in a study that did not test this exercise²⁶.

The muscles it works

The gluteus medius, moderate, or very high with added resistance².
The gluteus minimus, especially its back segment².
The tensor fasciae latae^3,5.
The gluteus maximus, at lower average levels than the gluteus medius across side-lying exercises¹.
The quadratus lumborum¹⁸.
In the clamshell, the front hip flexors and the piriformis; in both the clamshell and the lift with the hip turned outward, the obturator internus^15,20.

The review of 23 studies placed the side plank with hip abduction, like this lift, among three exercises with the highest gluteus medius activity¹.