Mouse Shoulder: A Painful Ailment for PC Gamers

What is rat shoulder?

Mouse shoulder is a condition that occurs at the tendon insertion proximal to the long head of the biceps brachii (near the center of the body). The biceps brachii is involved in elbow and shoulder flexion. As the name suggests, PC gamers are more susceptible to this injury from using a mouse.

Due to misuse and imbalance, the fiber orientation of tendons is disrupted. This dysfunction is called tendinopathy , and it is different from tendonitis , a common misnomer for the condition. We discuss this difference in more detail in the pathophysiology section below.

Related anatomy

It's important to understand some basic anatomy of the shoulder in order to understand the mouse shoulder. First, the affected tendon in the mouse shoulder was the tendon proximal to the long head of the biceps muscle .

The biceps brachii has two parts ( bi- means two parts):

• Long head : The longer of the two parts of the biceps runs in front of the shoulder and attaches above the shoulder joint on the scapula (shoulder blade)

• Short head : The shorter part of the biceps brachii also attaches to the scapula, but this attachment point is more medial, below the collarbone (clavicle)

Distally (away from the center of the body), the two halves of the biceps converge and attach to the radius , the bone on the thumb side of the forearm.

Pathophysiology

This injury is tendinopathy ! It is not inflammatory in nature and the term tendonitis is inappropriate! This is critical in determining appropriate prevention and rehabilitation.

Mouse shoulder occurs when there is at least one of two imbalances in muscle contraction. If one or both of these imbalances occur over time, degradation of collagen (a protein found in connective tissue) can occur. This results in disruption of tendon fiber orientation in the biceps tendon.

The strong fibers of the tendon should be aligned parallel to each other. In tendinopathy, these fibers become disorganized or disorganized —often described as adhesion formation —causing pain and affecting the movement of the tendons and shoulder joint.

• Concentricity and eccentricity imbalance
  • Concentric : shortening phase of muscle contraction
    • Computer Gamers: Lifting your arm forward and upward to grasp the mouse is a concentric movement that includes the biceps
    • Lifting Example: Upward Phase of Bicep Curl (Raising Dumbbells to Shoulders)
  • Eccentric : The lengthening phase of muscle contraction
    • In the game, there is no abnormal shrinkage, and that's the problem!
    • Lifting Example: Descending Phase of Bicep Curl (Controlled Return of Dumbbells to Hips)

• Agonist vs Antagonist Imbalance
  • Agonist : A muscle that is active in a specific sport
    • PC Gamers: The agonists are the muscles involved in shoulder flexion; this includes the biceps
  • Antagonist : A muscle that opposes an agonist; this muscle (or group of muscles) will relax during the contraction of the agonist
    • PC Gamers: Antagonists are the muscles involved in shoulder extension; these include the latissimus dorsi and posterior deltoid muscles ; these muscles are not challenged with any significant resistance during PC gaming

For console gamers , these imbalances have nothing to do with the mouse shoulder. Imbalances in console games are more likely to cause medial epicondylosis, or gamer's thumb.

Concentricity and eccentricity imbalance

When concentric contractions occur too frequently without balance from eccentric contractions, collagen begins to degrade through chronic shortening. Eccentric contractions—the lengthening of muscles and tendons under tension—help maintain the direction of tendon fibers.

Mechanical loading, especially during the eccentric phase , protects tendons from injury!

Agonist vs Antagonist Imbalance

When the agonist muscles act too frequently without balance from the antagonist muscles, an imbalance in the strength and tension of the joints involved occurs. When strength and tone are imbalanced, muscles can become overworked and injuries become more common.

A concentric vs. eccentric imbalance is usually the direct cause of any tendinopathy, but an imbalance of agonists vs. antagonists may exacerbate the disease and prolong healing time.

signs and symptoms

If you are affected by mouse shoulder, you may experience the following symptoms:

• pain
  • Most often, you will feel pain in your shoulder and front of your upper arm
  • Forward and upward movement of the shoulder joint may increase pain; for example, pushing forward or lifting overhead
  • Extending your arm backwards may be uncomfortable due to stretching of the biceps tendon

• weakness
  • Pushing or overhead movements may feel weak; however, the weakness you feel is more likely due to pain rather than true muscle weakness

Other common findings may include:

• More pronounced symptoms of shoulder flexion (e.g., when using a mouse)
• Symptoms worsen after rest
• Symptoms relieved or improved after warming up

Note: Mouse shoulders are considered tendinopathic and do not show inflammation . Inflammation is classified as painful, with swelling, redness, and warmth (warm to the touch).

If you notice these signs of inflammation, you're experiencing something different than simple mouse shoulder tendinopathy. If you are concerned about these symptoms, you should talk to your doctor.

Common injury mechanisms

For gamers, mouse shoulders are more common for PC users as they lift their arms or raise their arms to use the mouse. Common risks for PC users include:

• Poor chair or table setup
  • If your desk is too high, you will need to raise your arms further to reach your mouse
  • Likewise, the same problem can occur if your chair is too low

• lack of eccentric contraction
  • As noted above in pathophysiology , actions performed in PC games do not include eccentric contractions or extensor lengthening
  • The imbalance of muscle shortening and not lengthening under tension leads to tendon fiber rupture

• lack of antagonist muscle contraction
  • Also described in Pathophysiology above , you are less likely to perform pulling or rowing movements during play
  • Lack of strong shoulder extension can lead to overactivity of the shoulder flexors, including the biceps, perpetuating shortening and fiber breakage of the tendons

prevention

The most common mechanism of injury to the mouse shoulder is an imbalance in movement and body positioning (posture and ergonomics). Therefore, correcting posture and balancing muscle contraction and activation are simple but very effective preventive measures.

In addition to these preventative measures for mouse shoulders, be sure to take breaks to help prevent overuse tendinopathy.

Concentric and Eccentric Muscle Contractions

The lengthening phase of muscle contraction is the most important ! Below, we've listed exercises that may help with this condition. Performing the eccentric or "descending phase" portion of these exercises slowly and with control is an absolute must!

Resistance exercises that add eccentric action to the biceps include:

Pronation and anterior elevation

In the following exercises, lift the weight with both arms and lower the weight with only one arm (the affected side) .

1. Use dumbbells or small weights
2. Using your arms , lift the dumbbell or weight directly in front of you to shoulder height
3. For the affected side, just : Keep your palm facing up and your elbow straight. Slowly and under control, return the weight to the starting position
4. Repeat steps 2-3 for 3 sets of 8 times each

(tilt) bicep curl

If possible, perform this exercise on an incline bench to further stretch your biceps tendon. The slope should be approximately 45 to 60 degrees. If you don't have an inclined bench, standing or sitting upright can still be useful.

1. Hold a dumbbell or small weight in your hand
2. Keeping your palms facing up, bend your elbows and bend the dumbbells up toward your shoulders
3. Slowly and under control, return to starting position
4. Repeat steps 2-3 for a total of fifteen (15) times

Agonist vs Antagonist Muscle Activity

Balancing muscle activity in any joint will help keep all mechanical structures healthy. For PC gamers, shoulder flexion is a strenuous movement; therefore, it is important to perform shoulder extension exercises and stretches.

Shoulder stretches and stretches include:

Anti-excretion

1. Using dumbbells or a barbell, bend forward so your chest faces the floor
2. Start with your arms straight in front of you, then pull the weight toward your abs
3. Slowly lower the weight back to the starting position
4. Repeat steps 2 and 3 for a total of fifteen (15) times

sleeper stretch

1. Lie on your side with your arms at 90 degrees to your torso and your elbows bent at 90 degrees
2. Use your other arm to press your forearm down toward the surface you're lying on; you should feel a stretch in the back of your shoulder
3. Hold this stretch for 10 seconds
4. Perform this stretch 3 times

rollback

To effectively address rat shoulder problems, you must first identify and correct the original cause. For example, if your body is in a bad position while gaming, or you are not performing eccentric bicep movements outside of gaming, the protocol may not be effective due to continued deterioration.

Step One: Aggressive Cross-Friction Massage

The provider should use a firm surface (such as thumb pressure or knuckles) to apply moderate pressure to the biceps tendon and scrape vertically across the tendon. Unfortunately, this procedure tends to be moderately painful.

This will loosen the tendon matrix, making it more malleable for the next part of the treatment.

Step 2: Hypervolt+

Compared to muscles, tendons consume about 7.5 times less oxygen due to limited blood flow, which is one of the reasons why tendons heal more slowly.

In order for your body to heal any tissue, blood is needed to remove toxins and cellular waste, bring oxygen to working cells, and provide nutrients (in other words, building materials) to damaged tissue.

The Hypervolt+® tool is added during this step to stimulate all soft tissue in the area of ​​the affected tendon to increase blood flow. As blood flow increases, oxygen and nutrients increase to promote healing; toxins will also be removed from the healing process more quickly.

Step Three: Heavy Eccentric Loading

After cross friction has loosened the tendon matrix, resistance must be added to lengthen the tendon under tension. This resistance should be moderate to considerable in order to properly tighten the tendon fibers.

For mouse shoulders, the best exercise is the incline dumbbell curl. The provider should place the weight in the patient's hands, with the elbow flexed, and the patient pulls the tendon against the weight downwards.

Step 4: Continuous perfusion of blood through heat therapy

The use of hot compresses or other heat therapy (e.g., infrared laser) on the affected area should conclude this protocol. Typically, the heat pack should be used for 10-15 minutes. Adding a damp towel between the heat pack and the affected area will increase its effectiveness by creating moisture that penetrates further into the body.

Often, people believe in icing their ailments to relieve pain. However, ice can relieve inflammation, which, as mentioned before, is not the cause of pain . So ice won't help the situation. In fact, icing the affected area may prolong the healing process.

Heating the area increases blood flow, which increases the oxygen and nutrients needed for recovery. For overuse tendinopathy, heat is more helpful than ice. Once resolved, continuing to implement these protocols can prevent this from happening again.