How to differentiate between abductors and adductors?

The abductor and adductor muscles are in your hips and thighs, working in sync to allow you to move your legs to the sides. The abductors are responsible for moving the leg away from the midline of the body, while the adductors are responsible for moving the leg towards the midline of the body.

You’ve probably seen the machines to train these muscles in your gym. Both are similar in design and target areas, although they have a big difference. The abductor machine involves pushing the legs apart against resistance, while the abductor machine brings the legs together. Below you will find out all about these antagonistic muscles.

Functions of the abductors

Abduction refers to the movement of the limbs away from the middle of the body by the contraction of the abductor muscles. The physiological function of a muscle is related to the length of the fiber and the area of ​​the cross section. Abductors have been found to generally have a shorter muscle fiber length (overall) than an adductor muscle.

There are many examples of abductor muscles in the human body. Some are even named in part for the action they take. For example, in the hands, the abductor pollicis brevis and abductor pollicis longus, which are two muscles that act on this finger and cause abduction. The abductor pollicis longus, as its name implies, is a long muscle that attaches to the bones of the forearm and thumb. The dorsal interossei are muscles between the long bones that cause the fingers to abduct.

Part of the deltoid muscle is also responsible for abduction of the arm, as is the supraspinatus muscle. The deltoid muscle covers the shoulder region and the supraspinatus is attached to the shoulder blade (scapula) and the bone of the upper arm (humerus).

In the legs we find them in the hips. They include the gluteus minimus and gluteus medius which are found in the gluteal region. The gluteus medius is the larger of these two muscles and is very important for keeping the hips stable when walking. The abduction muscles allow you to move your legs to the side and also work to stabilize the hip joint. The abductor muscles in the hip region contract to produce a lateral movement of the pelvic region of the body. Any weakness of the abductor muscles found in the hip region can cause abnormal walking.

mujer entrenando los abductores

What is the adductor good for?

On the other hand, adduction refers to the movement of the limbs towards the middle of the body by the contraction of the adductor muscles.

The adductor muscles typically have a longer average muscle fiber length compared to the abductor muscle. Longer fibers and fibers with greater cross-sectional area produce greater force , even within one type of muscle. Thus, science has shown that the adductor magnus, which is longer and has a greater cross-sectional area than the adductor longus and adductor short, also has greater strength.

The fingers and toes are brought together by contraction of the adductor muscles. The adductor pollicis is a muscle that acts on this finger. The latissimus dorsi is a muscle in the back that helps in adduction of the arm. The pectoralis major is also a very large pectoral muscle that participates in the adduction of the arms.

In the case of the legs, there are three very important adductor muscles found in the human thigh. These are the adductor magnus, long and short. These muscles attach to the lower parts of the pelvic bones and the long bone (femur) of the upper leg. Contraction of the adduction muscles moves the leg inward toward the middle of the body, allowing you to move the thighs together.

mujer estirando los abductores

Main differences and similarities

Now that we know the function of each one separately, the truth is that they are similar and different to a great extent. Both are muscles that help move parts of our body and can contract on their own. In addition, they are located throughout our body, both arms and hands and legs.

The abductor and adductor muscles are two types of muscles that pull parts of your body toward the midline of your body, respectively. While the abductor muscles of the hip, for example, are located on the outside of the hips, the adductor muscles are located on the inside. The most common is to work these muscles with the machine for the inner thigh in the gym, but that is not the only movement that works them. Sumo squats, for example, also target your hip adductor muscles as they work to maintain strength and stability by squatting wider than usual.

They move on a different axis

As we have already discussed, this is the most important difference. And the one that can be applied to all the groups of abductor-adductor muscles of the body (not only those of the legs), such as those of the thighs, hands, fingers, thumbs, feet, eyes, etc.

Abductors are those that have the mechanical function of separating a part of the body from your axis. That is, they perform external movements. This, in the case of the legs, translates into lateral movements that separate one leg from the other. On the other hand, the abductor muscles are those that have the mechanical function of bringing a part of the body closer to your axis, that is, of making internal movements. This, in the case of the legs, would occur when joining one with the other.

They are in different areas

The differences are the most relevant at the sporting level. The abductor muscles, to allow these movements away from the legs, are located on the outer face of the thigh (they look out), from where they perform the contractions that allow the abduction movements that we have already detailed.

On the other hand, the adductor muscles, to allow these movements of approximation between both legs, are located on the inner face of the thigh (they look inwards), from where they perform the muscular contractions that are translated into these adduction movements that allow the approach to the axis.

The abductors and adductors are antagonists

The abductor and adductor muscles are antagonists, since they perform totally opposite functions. The abductors separate and the adductors unite.

But this does not mean that they are “enemies”, quite the contrary. The abductors need the adductors and vice versa. And it is precisely the fact that they perform opposite functions that allows, in the region of the body in which they are located, a perfect mechanical and physiological balance between the movements of separation and approach to the axis. In fact, if there is a muscle imbalance, the antagonist muscle may be overloaded.

The abductors are more numerous

Returning to the muscles of the lower extremities, there is a clear difference in the total of muscles. While the abductor muscles of the leg are a total of six (gluteus maximus, sartorius muscle, tensor fascia lata, pyramidal muscle, gluteus minimus and gluteus medius), the leg adductors are five (pectineus muscle, adductor magnus, short adductor, long adductor and gracilis muscle). Each of them is independent but complements the muscle group to allow abduction or adduction, respectively.