Measurement of Weakness

Question 1

Why do we measure weakness?

Answer 1

1. To determine if weakness exists (either as part of an existing condition or if weakness may predispose to a developing problem)
2. To monitor changes in a patient’s condition over time (either for recovery or deterioration)
3. To assess the effectiveness of a treatment (measuring outcomes)

Question 2

What are the three ways to assess strength?

Answer 2

1. Manual muscle testing (MMT)
2. Dynamometry
3. Repetition maximum (RM) testing

Question 3

What is MMT?

Answer 3

This is physical manoeuvring done by the physiotherapist to the patient. MMT has different grades which describe the muscle contraction

Question 4

What is an MMT grade 0?

Answer 4

No observable or palpable muscle contraction

Question 5

What is an MMT grade 1?

Answer 5

Observable or palpable contraction, may be a small movement

Question 6

What is an MMT grade 2?

Answer 6

Full active range of movement, not against gravity

Question 7

What is an MMT grade 3?

Answer 7

Full active range of movement against gravity

Question 8

What is an MMT grade 4?

Answer 8

Full active range of movement against gravity and some manual resistance

Question 9

What is an MMT grade 5?

Answer 9

Normal: full active range of movement against gravity and full manual resistance

Question 10

What is dynamometry?

Answer 10

This can use machines or handheld devices for the process (a machine only process uses an isokinetic dynamometer). Isometric dynamometry works by standardising the body position for a subject (the angle of the joint and the gravity acting on the joint), the position of the dynamometer (same position on all patients), and the body position for the tester (allows for stability and mechanical advantage to make tester stronger than the patient)

Question 11

What is RM testing?

Answer 11

1RM is the maximal load that can be lifted through full range once but not more (with good form) – i.e. the patient must fail on the second attempt. 10Rm is the maximal load that can be lifted through full range 10 times but not more (with good form) – i.e. the patient must fail on the 11th attempt. We will often use 8-12RM but consider prescription intensity (particularly for very weak patients)

Question 12

How do we increase reliability in assessments of strength?

Answer 12

• Standardise testing
• Encourage maximal effort
• Point of application force (lever arm)
• Joint angle (if changed, changes length of muscle)