Daniels and Worthingham's Muscle Testing
Introduction
The Daniels and Worthingham's scale is a type of manual muscle strength testing.[1] This tool is commonly used to grade the severity of muscle weakness. Grading is based on a patient's ability to move a limb against gravity and resistance.[2]
History of the Scale
Manual muscle testing began in 1912 with Wright and Lovett, developed to assess polio patients.[1] They were the first to define a muscle testing procedure, taking into account the effects of gravity. Lovett described his method in a 1917 book, using gravity and resistance to rank muscle function from 0 to 6.[1] Other clinicians, such Lowman, Stewart, Legg and Merrill, and the Kendalls, built on this work over the following decades. They added the notion of range of motion (ROM) and rescaled it between 0 and 5, along with plus and minus symbols to further refine the grades.[1] In 1946, Daniels, Williams and Worthingham wrote what can be considered as the first exhaustive handbook on muscle testing methods.[1] Their work laid the groundwork that every later edition of Daniels and Worthingham's Muscle Testing has built on since.[1]
Daniels and Worthingham's Muscle Grading Scale
The table outlines the Daniels and Worthingham's Scale (0-5 muscle test grade).
| Grade | Description |
|---|---|
| 0 | Complete lack of discernable muscle contraction. The examiner is unable to feel or see any muscle contraction. However, EMG could still detect some muscle activity. |
| 1 | Faint or “flicker” muscle contraction without any movement of the limb.
The examiner can see or palpate some contractile activity of the muscle/s or may be able to see or feel the tendon “pop up” or tense as the person tries to perform the contraction. |
| 2 | Very weak muscle contraction with movement through complete range of motion in a position that eliminates or minimises the force of gravity. |
| 3 | Muscle can complete a full range of motion against only the resistance of gravity. |
| 4 | Able to complete the full range of motion against gravity and can tolerate some but not maximal resistance, displayed by breaking the test position. |
| 5 | Able to complete full range of motion and maintain end point range position against maximal resistance. The examiner cannot break the tested-person's hold position. |
Use of plus (+) and minus (-) symbols
Plus and minus signs are usually discouraged in muscle grading because they add unreliable subjectivity, especially at higher grades.[1] An exception is "2−," used for partial movement in a gravity-minimised position, since the jump between Grade 1 and Grade 2 is otherwise too large to capture small gains.[1] Therapists should still describe movement quality in their notes to support the grade given.[1]
Evidence
To date, recent peer-reviewed evidence on the Daniels and Worthingham scale are critically lacking. To best knowledge, in 2026, none could be found on the reliability and validity of the Daniels and Worthingham scale alone. A 2016 study reports that spina bifida guidelines recommend the Daniels and Worthingham protocol for its fine-grained strength grading, but note its psychometric properties have never been formally tested.[3] However, the study found that, with standardized training and forms, the Daniels and Worthingham protocol produced reproducible results for lower limb strength in children aged 6–18 with spina bifida.[3]
Daniels and Worthingham and the Oxford scale are sometimes used interchangeably by clinicians, as explicitly stated in a 2025 paper.[2] However, the Oxford, or Medical Research Council (MRC)[4] scale, does not mention the notion of complete or incomplete ROM, at least in the original published document,[5] suggesting that confusion subsists in the differentiation of those scales, even in published literature. There is therefore a crucial need for dedicated good quality studies to clarify the distinction and provide specific evidence on the use of the Daniels and Worthingham scale.
Summary
The Daniels and Worthingham's scale grades muscle strength from 0 to 5 based on ROM, gravity, and resistance. It has a long clinical history but limited modern research backing it. More studies are needed to strengthen the evidence base and clarify how it differs from related scales.
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 Avers D, Lott DJ, Brown M. Daniels and Worthingham's Muscle Testing: Techniques of Manual Examination and Performance Testing. 11th ed. St. Louis (MO): Elsevier; 2024.
- ↑ 2.0 2.1 Guatibonza AF, Solaque LE, Velasco A, Peñuela L. Daniels scale-based muscle strength prediction with neural networks. International Journal of General Systems. 2025 Aug 21:1-26.
- ↑ 3.0 3.1 Tan JL, Thomas NM, Johnston LM. Reproducibility of muscle strength testing for children with spina bifida. Physical & Occupational Therapy in Pediatrics. 2017 Aug 8;37(4):362-73.
- ↑ Roman NA, Miclaus RS, Nicolau C, Sechel G. Customized manual muscle testing for post-stroke upper extremity assessment. Brain sciences. 2022 Mar 28;12(4):457.
- ↑ Medical Research Council. Aids to the examination of the peripheral nervous system. Memorandum No. 45 (superseding War Memorandum No. 7). London: Her Majesty's Stationery Office; 1976.