Biceps Muscle Testing: Procedure, Interpretation, and Self-Assessment

How Do You Muscle Test Your Biceps?

Manual muscle testing (MMT) of the biceps brachii assesses the strength and integrity of this key elbow flexor and forearm supinator, providing insights into muscle function and neurological health.

Understanding Manual Muscle Testing (MMT)

Manual muscle testing is a clinical and rehabilitative technique used to evaluate the strength of individual muscles or muscle groups. It involves applying resistance to a specific movement while the subject attempts to hold the position, allowing the examiner to grade the muscle's ability to contract and generate force. For the biceps brachii, MMT evaluates its primary actions: elbow flexion and forearm supination. This assessment can help identify weakness, asymmetry, or neurological deficits affecting the musculocutaneous nerve, which innervates the biceps.

Anatomy of the Biceps Brachii

To effectively test the biceps, a foundational understanding of its anatomy is crucial:

• Origin: The biceps brachii has two heads:
  • Long Head: Originates from the supraglenoid tubercle of the scapula, its tendon passing through the shoulder joint capsule.
  • Short Head: Originates from the coracoid process of the scapula.
• Insertion: Both heads merge to form a common belly, inserting primarily onto the radial tuberosity of the radius and, via the bicipital aponeurosis, into the fascia of the forearm.
• Primary Actions:
  • Elbow Flexion: Bending the elbow.
  • Forearm Supination: Rotating the forearm so the palm faces upward.
  • It also assists in shoulder flexion due to its scapular origins.
• Innervation: Musculocutaneous nerve (C5, C6).

Preparing for Biceps Muscle Testing

Proper preparation ensures an accurate and safe assessment.

• Patient Positioning: The individual should be comfortably seated or supine, with the arm to be tested fully exposed and free to move. Ensure the shoulder is relaxed and not elevated.
• Examiner Positioning: Position yourself to have good leverage, a stable base, and clear visibility of the muscle being tested. Your hands should be placed to apply resistance effectively and stabilize adjacent joints.
• Clear Instructions: Explain the procedure clearly to the individual. Instruct them on the movement they need to perform and how you will apply resistance. Emphasize that they should "hold" their position against your force.
• Contraindications and Precautions: Avoid MMT if there is acute injury, recent surgery, unhealed fractures, severe pain, or any condition where resistance could cause further harm. Always prioritize the individual's comfort and safety.

The Biceps Muscle Test Procedure

This procedure outlines the standard manual muscle test for the biceps brachii, typically performed by a trained professional.

• Step 1: Patient Positioning for Optimal Contraction
  • Have the individual flex their elbow to approximately 90 degrees.
  • Ensure the forearm is fully supinated (palm facing upward). This position isolates the biceps more effectively for both elbow flexion and supination, as the brachialis is a pure elbow flexor and the brachioradialis is active in neutral forearm rotation.
• Step 2: Stabilize the Proximal Joint
  • Place one of your hands to stabilize the individual's humerus (upper arm), just above the elbow. This prevents unwanted shoulder movement and ensures that the force is concentrated on the elbow joint.
• Step 3: Apply Resistance
  • Place your other hand on the anterior aspect of the individual's forearm, just proximal to the wrist joint.
  • Instruct the individual to "hold this position, don't let me move you."
  • Apply a gradually increasing, sustained resistance in the direction of elbow extension and forearm pronation. Apply force perpendicular to the forearm.
• Step 4: Observe and Palpate
  • As you apply resistance, observe the individual's ability to hold the position. Look for any "giving way" or shaking.
  • Simultaneously, palpate the biceps muscle belly to feel for contraction and assess its quality. You can also palpate the biceps tendon in the cubital fossa to feel for its integrity.
• Step 5: Grade the Muscle Strength
  • Muscle strength is typically graded on a scale of 0 to 5, where:
    • Grade 5 (Normal): Completes full range of motion against gravity and maximal resistance.
    • Grade 4 (Good): Completes full range of motion against gravity and moderate resistance.
    • Grade 3 (Fair): Completes full range of motion against gravity but no added resistance.
    • Grade 2 (Poor): Completes full range of motion with gravity eliminated (e.g., arm supported on a surface).
    • Grade 1 (Trace): Evidence of slight contraction, but no joint movement.
    • Grade 0 (Zero): No evidence of muscle contraction.

Interpreting Muscle Test Results

The findings from biceps MMT provide valuable diagnostic and prognostic information:

• Weakness (Grades < 5): Can indicate a variety of issues including:
  • Nerve Impingement or Damage: Specifically, the musculocutaneous nerve (e.g., C5/C6 radiculopathy).
  • Muscle Injury: Strain, tear, or rupture of the biceps muscle or tendon.
  • Disuse Atrophy: Weakness due to lack of use.
  • Referred Pain or Inhibition: Pain from an adjacent joint (e.g., shoulder or elbow) may inhibit muscle activation.
• Pain During Testing: Localized pain can pinpoint an issue:
  • Muscle Belly Pain: Suggests a muscle strain or overuse.
  • Tendon Pain (Proximal): Could indicate biceps tendinopathy or a superior labral tear (SLAP lesion).
  • Tendon Pain (Distal): Suggests distal biceps tendinopathy or rupture.
  • Joint Pain: May indicate underlying elbow or shoulder pathology.
• Asymmetry: Comparing the strength of the left and right biceps can highlight unilateral weakness or imbalance.
• Correlation with Symptoms: Always interpret MMT results in the context of the individual's reported symptoms, functional limitations, and other clinical findings.

Self-Testing Considerations

While formal MMT requires a trained professional for accurate grading, individuals can perform a simplified self-test to gain a gross understanding of their biceps strength:

• Procedure: Sit or stand, flex one elbow to 90 degrees with the palm facing up. Place the palm of your opposite hand firmly on the front of the testing forearm, just above the wrist. Attempt to flex your bicep and supinate your forearm while resisting with your other hand.
• Purpose: This self-test can help identify significant weakness or asymmetry between arms. It's useful for tracking general strength changes or identifying a major deficit that warrants professional evaluation, but it cannot provide objective grading.

Practical Applications and Beyond Testing

MMT of the biceps is more than just a diagnostic tool; it's integral to various aspects of health and fitness:

• For Fitness Professionals: Helps identify muscular imbalances, guides exercise selection and program design, and monitors progress in strength development or rehabilitation.
• For Clinicians and Therapists: Crucial for diagnosing neuromuscular disorders, assessing the extent of injury, guiding rehabilitation protocols, and evaluating recovery.
• Rehabilitation: Post-injury or surgery, MMT helps track improvements and determine readiness for progression to more advanced exercises.
• Performance Enhancement: Identifying subtle weaknesses can lead to targeted training, improving overall upper body strength and reducing injury risk in sports and daily activities.

While muscle testing provides valuable information, it is one component of a comprehensive assessment. It should be combined with a thorough history, observation, palpation, and other specialized tests to form a complete clinical picture.