Muscle Strength

Original Editor - The Open Physio project.

Top Contributors - Pieter Jacobs, Naomi O'Reilly, Jo Etherton, Alistair James and Claire Knott  

Introduction

An assessment of muscle strength is typically performed as part of a patient's objective assessment. This should assist the physiotherapist's clinical reasoning and enable them to reason an appropriate point to begin strengthening rehabilitation from. Muscle strength can be assessed by a number of methods: manually, functionally or mechanically. [1]

The Oxford Scale

The Oxford scale is commonly used by physiotherapists to manually assess muscle strength. According to the Oxford scale, muscle strength is graded 0 to 5. The grades are summarised below:

  1. Flicker of movement
  2. Through full range actively with gravity counterbalanced
  3. Through full range actively against gravity
  4. Through full range actively against some resistance
  5. Through full range actively against strong resistance
[2]

There are a number of limitations to the usefulness of the Oxford scale [3].   These include:

  • Poor functional relevance;
  • Non-linearity i.e. the difference between grades 3 and 4 is not necessarily the same as the difference between grades 4 and 5;
  • A patient's variability over time i.e, alternating between grades due to fatigue;
  • Intra-rater reliability;
  • Only assesses muscles when contracting concentrically;
  • The difficulty of applying the Oxford Scale to all patient's in clinical practice (so that strength is rarely assessed throughout full range as many patients assessed by physiotherapists do not possess full range due to their respective pathology.

Due to these shortcomings, physiotherapists commonly use modified versions of the Oxford scale in clinical practice. [1]

Performing Manual Muscle Tests

Check out strength testing by muscle group

Upper Extremities Lower Extremities
Shoulder Flexion Hip Flexion
Shoulder Extension Hip Extension
Shoulder Abduction Hip Abduction
Shoulder Horizontal Adduction Hip Adduction
Scapula Elevation Hip External Rotation
Scapular Retraction/ Adduction Hip Internal Rotation
Elbow Flexion Knee Flexion
Elbow Extension Knee Extension
Wrist Flexion Plantarflexion
Wrist Extension Dorsiflexion
Ankle Eversion
Ankle Inversion
Some guiding principles:

References

  1. 1.0 1.1 Porter S. Tidy's Physiotherapy. Edinburgh: Churchill Livingstone, 2013.
  2. Physiotutors. MRC Scale⎟Muscle Strength Grading. Available from: https://www.youtube.com/watch?v=LjlqP1uMUo0
  3. Cuthbert SC, Goodheart GJ. On the reliability and validity of manual muscle testing: a literature review. Chiropractic & Osteopathy 2007; 15:4