Adductor stretch

Key points

In 16 healthy men, the adductor longus was stiffer than at rest, a sign of being lengthened, at maximal hip abduction (the thigh moved out to the side)¹. It is one of the adductors, the inner thigh muscles that pull the leg in².
In the same men, the back part of the adductor magnus was lengthened only when the hip was also bent¹.
In 40 people with reduced hip adductor muscle length, one session of any of four stretching procedures raised hip abduction range by 1.0 to 1.7 degrees³. The authors called that change minimal³.
In a trial of 42 elite male youth soccer players, a 24-week programme included one stretch, the seated butterfly⁴. Range on a hip test did not change more than with usual training⁴.
Studies of hip abduction range before a season and later groin strain disagree^5,6.

Movement

The positions studies used

The adductors are the inner thigh muscles, which pull the leg in toward the other one. The group is the pectineus, adductor longus, adductor brevis, gracilis and adductor magnus². Studies stretch these hip adductors with hip abduction, which is moving the thigh out to the side^1,7.

The studies on this page used several versions^4,8,9:

Seated butterfly. The player sits, puts the soles of the feet together and presses the knees down with the arms⁴.
Machine-held stretch. One study used a seated hip abduction machine to hold a passive stretch that bore no body weight⁸.
Frog straddle. The same study compared it with an active, weight-bearing stretch similar to the frog straddle stretch⁸. Both aimed for a stretch sensation of 7 out of 10⁸.
Contract-relax. In one study, a passive stretch was followed by a 10-second contraction of the stretched muscles at half of maximum, then a further passive stretch⁹.

Why knee position matters

The gracilis is a long, thin muscle on the inner side of the thigh. Unlike the other adductors, which attach to the femur (thigh bone), it attaches to the upper inner tibia (shinbone)². It pulls the thigh inward and also bends the knee¹⁰.

A study of two textbook flexibility tests shows how knee position is read¹¹. Passive hip abduction with the knee straight is taken to measure the gracilis, the adductor that crosses two joints¹¹. With the hip at 90 degrees and the knee bent, the test is taken to measure the one-joint adductors¹¹.

What it loads

Which adductors lengthen

One study measured three parts of the adductors in 16 healthy men¹. It used shear wave elastography, an ultrasound method that estimates how stiff a tissue is¹. Stiffness is how much force it takes to stretch something by a given amount.

In 16 healthy men, the adductor longus was stiffer at maximal hip abduction than at rest in all five hip positions tested¹. Greater stiffness was a sign of being lengthened¹. The front and back parts of the adductor magnus, a large muscle on the inner side of the thigh, gave different results¹.

Muscle part	What was found at maximal hip abduction
Adductor longus	Stiffer in all five hip positions, with no difference between positions¹
Adductor magnus, back	Lengthened only when the hip was also flexed to 30, 60 or 90 degrees, and most at 90 degrees¹
Adductor magnus, front	No stiffer than at rest in any of the five positions, which the authors read as not being lengthened¹

The adductor longus and its tendon

The adductor longus arises from the front of the pubic bone, an attachment the adductor longus tendon page covers¹³. One study measured the bent knee fall out test in 60 male athletes with long-standing adductor-related groin pain¹⁴. This is groin pain that comes from the inner-thigh muscles and their tendons. The fall out distance fell from a median of 11.5 cm to 8 cm straight after the tendon was surgically cut¹⁴. The authors took this to show that the test reflects adductor longus flexibility in such athletes¹⁴.

The hip joint

At the hip, abduction is checked by two ligaments: the pubofemoral ligament and the inner band of the iliofemoral ligament¹⁵. A ligament is a tough band of tissue that holds bones together at a joint. In eight cadaver specimens (bodies donated for study), the pubofemoral ligament was strained by about 3% at maximal hip abduction¹⁶.

The authors of one study of flexibility tests state that the three hip ligaments are slack with the hip flexed to 90 degrees¹¹. They attribute a limit to abduction in that position mainly to the one-joint adductor muscles¹¹.

How the body adapts

After one session

Three studies measured range of motion (how far a joint moves) straight after one session of adductor stretching^3,8,17:

A randomised crossover study, in which each person tries every option in turn, included 40 people with reduced hip adductor muscle length³. A static (held) stretch and three other stretching procedures raised hip abduction range by 1.0 to 1.7 degrees³. The authors called the change minimal³.
In that study, static stretching, a modified lunge stretch and joint mobilisation did not raise range more than a control condition³. Multidirectional stretching did³.
A second randomised crossover study included 40 physically active adults with limited hip adductor flexibility⁸. Sixty seconds of passive or active static stretching raised hip abduction range by about 1 degree, and a time-matched control by 0.6 degrees⁸. The three conditions did not differ⁸.
In 45 female ballet dancers randomly assigned to three groups, four 30-second sets of static or contract-release stretching both raised hip adductor range¹⁷. The two methods did not differ, and a resting control group did not change¹⁷.

In 50 healthy recreational athletes, two goniometer tests of passive hip abduction had a minimal detectable change of 5.9 and 6.2 degrees¹¹. A goniometer is a tool for measuring joint angles. A smaller change between two measurements could be measurement error¹¹.

A meta-analysis (a study that pools the results of several earlier studies) looked at single bouts of stretching¹⁸. Range rose on sit-and-reach, hamstring and calf tests, but not on a hip adductor test¹⁸.

Two sources report how long a gain lasts^19,20. In eight male volunteers, contract-relax stretching of six lower-limb muscle groups, the adductors among them, raised hip abduction range by 17%¹⁹. The gain was still present 90 minutes later¹⁹. A review of single-session stretching found that range improvements typically lasted less than 30 minutes²⁰.

In the 40 physically active adults, neither kind of 60-second static stretch reduced maximal isometric strength measured straight afterwards⁸. Isometric means the muscle works but the joint does not move.

Over weeks

One trial placed the seated butterfly inside a longer programme⁴. For 24 weeks, elite male youth soccer players did five adductor and core strength exercises and this one stretch⁴. In the trial’s 42 players, bent knee fall out range did not change more with the programme than with usual training⁴. Hip adduction strength on the left side rose more in the programme group⁴.

In 45 active adults randomly divided into training and control groups, 8 weeks of Copenhagen adduction training raised hip abduction range by about 7%²¹. Range returned to baseline after 4 weeks without training²¹.

Progressive overload

In resistance training, progressive overload means raising the stimulus on the muscle as a programme goes on²². The youth soccer programme progressed its seated butterfly by sets alone⁴. Each set was five 20-second holds with 10 seconds of relaxation, and sets were 60 seconds apart⁴.

Weeks	Sets of the seated butterfly
1 to 8	2⁴
9 to 16	3⁴
17 to 24	4⁴

Reviews of static stretching programmes in general have looked at dose^23,24. One meta-analysis found that flexibility gains were larger with more repetitions in a session and more total time under stretch²³. Another, of 189 studies in adults, found gains were greatest at 10 minutes of stretching per week²⁴.

Flexibility and groin injury

Flexibility measured before an injury

Studies that measured players before a season and then recorded groin injuries disagree^{5,6,25,26,27,28}.

Who was followed	What was found
306 male football players in Iceland’s two highest divisions	Lower hip abduction range before the season was a predictor of groin strain, as was a previous groin strain⁵
120 male professional soccer players from six Australian clubs	The eight with an adductor strain had a lower mean preseason hip range of movement: 44.7 against 53.7 degrees²⁵
146 male professional soccer players in Belgium	Preseason adductor flexibility did not differ significantly between the 13 later injured and the uninjured²⁶
47 players on one National Hockey League team, over two seasons	Preseason adductor flexibility did not differ between the eight who had adductor strains and the others²⁷
1292 National Hockey League players	Total hip abduction flexibility did not predict groin or abdominal strain injury⁶
438 male professional soccer players in Qatar, screened with pain, range and strength tests	Previous hip or groin injury and eccentric adduction strength (measured as the muscle lengthens) were associated with injury risk; no other screening test was²⁸

Reviews have read this kind of evidence in different ways^29,30:

A 2007 systematic review of groin strain in sport described the role of adductor length as debated²⁹.
A 2009 review found some low- to moderate-level evidence linking flexibility and strength to injury risk in particular sports³¹. It stated that randomised controlled trials are needed to establish the link³¹.
A systematic review of screening tools in team sports concluded that a decreased range of hip abduction may predict leg injuries³².
A systematic review with meta-analysis pooled two prospective studies, which follow people forward in time³⁰. It found moderate evidence that hip abduction flexibility is not a risk factor in developing sports-related groin pain³⁰.
Another systematic review found strong evidence that hip abduction range was not associated with groin pain in athletes³³.

In athletes who already have pain

A meta-analysis of two high-quality case-control studies compared athletes with and without hip or groin pain¹². Such studies compare people who have a condition with similar people who do not. Those with pain had less range on the bent knee fall out test, by 3.6 cm on average¹². The authors of that 2015 review noted that no study had examined whether the test predicts who goes on to develop pain¹².

A trial that included the stretch

The trial of 42 elite male youth soccer players also counted cases of groin pain syndrome⁴. It was found in 14.3% of the programme group and 28.6% of controls⁴. The difference was not statistically significant⁴. The athletic groin pain page covers trials in athletes who already had adductor-related groin pain, including one whose comparison group did stretching³⁴.

Connections

In 16 healthy men, maximal hip abduction lengthened the adductor longus, one of the hip adductors¹. The adductor longus arises from the front of the pubic bone, where the adductor longus tendon page picks it up¹³. At the hip, the pubofemoral ligament is one of the checks on abduction¹⁵.

Related exercise pages include the Copenhagen adductor plank, after which hip abduction range rose in one trial of 45 active adults²¹. The athletic groin pain page covers the condition most often studied alongside adductor flexibility³³.