Considerations When Performing Muscle Testing of the Trunk and Lower Limbs

Original Editor - Lenie Jacobs based on the course by Shala Cunningham

Top Contributors - Lenie Jacobs, Jess Bell and Tarina van der Stockt

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Introduction[edit | edit source]

Muscle strength testing is an essential component of a physical examination. It is used by healthcare professionals to measure strength deficits, monitor rehabilitation progress and assess readiness to return to work, sport and other activities. The strength assessment offers crucial insights into an individual's physical capabilities, neurological status, and certain diseases. For instance, quadriceps strength is considered a robust predictor of functional decline and mortality associated with coronary artery disease and chronic obstructive pulmonary disease.[1] This article explores how certain factors, such as age, neurological conditions and being critically ill, can impact the assessment of trunk and lower limb strength.

Age and Developmental Stage[edit | edit source]

Older Persons[edit | edit source]

Our muscles progressively change as we age. These changes are associated with decreased muscle strength and mass.

Frailty is a growing issue in ageing populations. Frailty is a clinical state that is associated with an increased risk of fractures, recurring falls, harm events, institutionalisation, care needs and disability/death.[2][3] It has been found that reduced lower limb muscle strength is associated with increasing age and frailty.[4] Accurately measuring muscle strength is, therefore, essential for the diagnosis, prevention and management of frailty.[5]

Sarcopenia is characterised by the loss of muscle mass, strength, and physical function. It is linked to ageing and results from a combination of genetic, environmental, and physiological factors. It is associated with an elevated risk of health problems, including disability, reduced function, increased fall risk, increased length of hospital stay and mortality.[6] While the loss of muscle mass has traditionally signalled sarcopenia, recent research highlights muscle strength as a more effective indicator of the adverse health outcomes of sarcopenia.[7] Another study of older adults revealed a strong association between hand grip strength and lower limb strength, with significant correlations across examined muscle groups, except for the ankle dorsiflexion muscles.[8]

Paediatric population[edit | edit source]

When assessing strength in children, it is important to consider the child's age, developmental stage, and cognitive status, as well as their emotional and behavioural state at the time of the assessment.[9]

Infants and toddlers: when assessing infants and toddlers, strength is primarily assessed through observation. Instead of isolating muscles, the focus is on observing movements across muscle groups. To determine if a baby has the necessary strength to explore their environment, specific muscle actions during movements against gravity are observed.

Children: manual muscle testing can be used in children as young as 3 years if they are able to follow directions / instructions.[9] Other reliable measures of muscle strength and function in children aged 6-9 years include the leg press, hand grip, squat jump, and long jump tests (without familiarisation).[10] The sit-to-stand test requires familiarisation to ensure adequate reliability.[10] Specific tests that can be used in children are shown here.

Pain[edit | edit source]

Musculoskeletal pain can influence descending motor drive and muscle activation. Experimental studies have revealed reduced voluntary activation, decreased motor unit firing, and altered intracortical network excitability during experimentally induced muscle pain.[11]

Patients with pain often report weakness in their extremities. While the American Medical Association Guides recommend manual muscle testing to determine strength deficits, it has been found that this method may fail to detect strength losses of up to 50%. Thus, using this method of testing in individuals with pain can be problematic, particularly if the strength deficit is 25% or less.[12] If available, other methods, such as dynamometry, may offer a more precise strength evaluation.[12]

Cerebral Palsy (CP)[edit | edit source]

Muscle weakness is common in individuals with cerebral palsy and it can impact function. When assessing the strength of an individual with cerebral palsy (CP), it is important to take into account factors such as altered tone / spasticity levels, muscle imbalances, and decreased motor control and coordination. Therapists may need to make adjustments to testing procedures to ensure accurate results.

In clinical practice, the Oxford Scale (also known as the Medical Research Council Scale (MRCS)) is usually used for manual muscle testing in individuals with CP. In cases where a more detailed quantification of muscle strength is needed, clinicians might use dynamometers if they are available.[13] The Functional Strength Measurement - Cerebral Palsy (FSM-CP) also appears to be a reliable and valid method to measure functional strength in individuals with cerebral palsy.[14]

Individuals who are Critically Ill[edit | edit source]

Depending on the diagnostic criteria, neuromuscular complications develop in 9-87% of patients in intensive care units (ICU). This can lead to prolonged mechanical ventilation, extended hospital stay, rehabilitation time, and potentially increased mortality.[15]

Muscle strength assessments for patients in ICU include manual muscle testing and functional assessments. However, several factors need to be considered for this patient population:

  • endurance - a patient may not be able to complete multiple muscle strength tests in one session; thus, it is advisable to conduct only one or two tests per session
  • contractures - it is essential to compensate for any muscle contractures that have developed by appropriately supporting the limb; any adaptations made during testing should be documented
  • lines - it's important to be mindful of lines / attachments, such as arterial lines, internal jugular catheters for dialysis, and central venous catheters; consider any contraindications to assessment and document any adaptations to testing

The physiotherapy assessment for patients in ICU, including the strength assessment, is discussed in more detail here.

References [edit | edit source]

  1. ↑ Sahu PK, Goodstadt N, Ramakrishnan A, Silfies SP. Test-retest reliability and concurrent validity of knee extensor strength measured by a novel device incorporated into a weight stack machine vs. handheld and isokinetic dynamometry. PloS one. 2024 May 22;19(5):e0301872–2.
  2. ↑ Buxton S. An Introduction to Frailty Course. Physiopedia Plus. 2020.
  3. ↑ Xu W, Zhao X, Zeng M, Wu S, He Y, Zhou M. Exercise for frailty research frontiers: a bibliometric analysis and systematic review. Frontiers in medicine. 2024 May 1;11.
  4. ↑ Batista FS, Gomes GA, Neri AL, Guariento ME, Cintra FA, Sousa Mda L, D'Elboux MJ. Relationship between lower-limb muscle strength and frailty among elderly people. Sao Paulo Med J. 2012;130(2):102-8.
  5. ↑ Swales B, Ryde GC, Fletcher I, Whittaker AC. The reliability and suitability of strength assessments in frail and pre-frail older adults: recommendations for strength testing in older populations. BMC Geriatr. 2023 Dec 8;23(1):820.
  6. ↑ Pedauyé-Rueda B, García-Fernández P, Maicas-Pérez L, José Luis Maté-Muñoz, Hernández-Lougedo J. Different Diagnostic Criteria for Determining the Prevalence of Sarcopenia in Older Adults: A Systematic Review. Journal of clinical medicine. 2024 Apr 25;13(9):2520–0.
  7. ↑ Ito S, Hiroshi Takuwa, Saori Kakehi, Someya Y, Hideyoshi Kaga, Nobuyuki Kumahashi, et al. A genome-wide association study identifies a locus associated with knee extension strength in older Japanese individuals. Communications biology. 2024 May 20;7(1).
  8. ↑ Strandkvist V, Larsson A, Pauelsen M, Nyberg L, Vikman I, Lindberg A, et al. Hand grip strength is strongly associated with lower limb strength but only weakly with postural control in community-dwelling older adults. Archives of Gerontology and Geriatrics. 2021 May;94:104345.
  9. ↑ 9.0 9.1 APTA Pediatrics. FACT SHEET Strength Testing in Pediatric Physical Therapy. Available from: https://pediatricapta.org/includes/fact-sheets/pdfs/11%20StrengthTraining%20in%20Ped%20PT.pdf?v=1.1 (last accessed 5 June 2024).
  10. ↑ 10.0 10.1 Thams L, Hvid LG, Damsgaard CT, Hansen M. Test-Retest Reliability of Muscle Strength and Physical Function Tests in 6–9-Year-old Children. Measurement in Physical Education and Exercise Science. 2021 Jun 20;1–9.
  11. ↑ Myles Calder Murphy, Ebonie Kendra Rio, Whife C, Latella C. Maximising neuromuscular performance in people with pain and injury: moving beyond reps and sets to understand the challenges and embrace the complexity. BMJ open sport & exercise medicine. 2024 May 1;10(2):e001935–5.
  12. ↑ 12.0 12.1 Ambroz A, Zucker R, Ambroz C. Strength Testing in Pain Assessment. Pract Pain Manag. 2006;6(8).
  13. ↑ Physiopedia. Evaluating the Child with Cerebral Palsy.
  14. ↑ Aertssen W, Smulders E, Smits-Engelsman B, Rameckers E. Functional strength measurement in cerebral palsy: feasibility, test–retest reliability, and construct validity. Developmental Neurorehabilitation. 2018 Sep 12;22(7):453–61.
  15. ↑ Ciesla N, Dinglas V, Fan E, Kho M, Kuramoto J, Needham D. Manual Muscle Testing: A Method of Measuring Extremity Muscle Strength Applied to Critically Ill Patients. Journal of Visualized Experiments. 2011 Apr 12;(50).
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