Hand-held Dynamometry

Original Editor - Mason Trauger
Top Contributors - Mason Trauger

Purpose[edit | edit source]

Handheld Dynamometry (HHD) is a method utilized to assess muscle strength. Although other dynamometers were utilized to assess grip strength, this version of a dynamometer is set up or held by the therapist to derive an objective measurement of force.

Procedure[edit | edit source]

Unlike traditional manual muscle testing as a "break test," the preferred method for HHD is to utilize a "make test" format. This assessment requires the subject to exert a maximum isometric force while the dynamometer is held stationary. [1]

An example procedure is as follows (however, there is some variety in procedures performed; it is important to clearly document the procedure and positioning utilized to ensure consistency and reproducibility):

  • The examiner keeps the dynamometer stable
  • The patient/client/subject produces maximal force against the instrument while the examiner matches this force
  • Verbal commands provided include "push as hard as possible," and "push, push, push, push"
  • Each trial is performed over a 3-4 second hold, with 2-3 trials being performed
  • The average and individual trial numbers should both be reported
    • Common units: pounds (lbs), Newtons (N), or kilogram-force (kgf)
    • Can be expressed as a percentage of the unaffected/less impaired extremity (e.g., R knee extension 90% of L knee extension)

The following video demonstrates the use of a hand-held dynamometer in various positions: [2]

Benefits[edit | edit source]

  • Decreased subjective interpretation (compared to manual muscle testing grades beyond a 3/5)
  • Reliable, objective testing of muscle strength
  • Not gravity-dependent in its interpretation
  • Minimizes the tester's contribution to error (make test principle)

Drawbacks[edit | edit source]

  • No present universal, standardized positions
  • Questionable inter-tester reliability (related to lack of standardized positions)
  • Error if subject strength greater than tester (concentric contraction)
    • Important for tester to ensure good body mechanics for maximum efficiency
  • Other devices are more appropriate for assessing Grip Strength

Evidence[edit | edit source]

  • In healthy adults aged 20-53 years of age, HHD demonstrated weak-to-moderate concurrent validity (r value 0.37-0.51, p≤0.05) with the "gold standard" measure of muscle strength assessment, isokinetic dynamometry (IKD) for peak torque values in hip extension [3]
  • The American Academy of Physical Medicine and Rehabilitation published a systematic review which supports the use of HHD as a reliable and valid measure of muscle strength that is easy to use, portable, and more cost-affordable than IKD, but does question its efficacy for larger joint use such as the knee [4]
  • The ActivForce Digital Dynamometer and microFET2 HHDs were found to have similar levels of intra- and inter-tester reliability and criterion validity for assessing shoulder muscle force production of internal rotation, external rotation, and forward elevation. Reported intraclass correlation (ICC) values for intra- and inter-rater reliability were high (0.85-0.99) [5]
  • A proposed HHD measurement of 31.1% knee extension force (normalized to bodyweight) was established as necessary for independence in performing a sit to stand in hospitalized adult populations [6]
  • In healthy populations, external stabilization of the HHD using a belt (to avoid examiner strength as a confounding variable) has been shown to be reliable and valid for the assessment of hip and knee strength assessment
    • Intrarater reliability was excellent (ICC = 0.8-0.96) for hip adductors, abductors, flexors, extensors, right internal rotators, external rotators and the knee extensors, and moderate for bilateral knee flexion (ICC = 0.62–0.66) and left hip internal rotation (ICC = 0.70). Correlation with IKD was moderate to high (r=0.6-0.90)[7]

The following videos demonstrate the use of external fixators (belts, straps, or an alternative dynamometer design) to assess muscle force production: [8] [9]

Resources[edit | edit source]

References[edit | edit source]

  1. Bohannon RW. Make tests and break tests of elbow flexor muscle strength. Phys Ther. 1988 Feb;68(2):193-4.
  2. HOGGANScientific. Handheld Dynamometry with HOGGAN Scientific’s microFET2. Available from: https://www.youtube.com/watch?v=8G2x1VYsFGU [last accessed 2/29/2024].
  3. Keep H, Luu L, Berson A, Garland SJ. Validity of the Handheld Dynamometer Compared with an Isokinetic Dynamometer in Measuring Peak Hip Extension Strength. Physiother Can. 2016;68(1):15-22.
  4. Stark T, Walker B, Phillips JK, Fejer R, Beck R. Hand-held dynamometry correlation with the gold standard isokinetic dynamometry: a systematic review. PM R. 2011;3(5):472-9.
  5. Karagiannopoulos C, Griech S, Leggin B. Reliability and Validity of the ActivForce Digital Dynamometer in Assessing Shoulder Muscle Force across Different User Experience Levels. Int J Sports Phys Ther. 2022;17(4):669-676.
  6. Eriksrud O, Bohannon RW. Relationship of knee extension force to independence in sit-to-stand performance in patients receiving acute rehabilitation. Phys Ther. 2003;83(6):544-51.
  7. Martins J, da Silva JR, da Silva MRB, Bevilaqua-Grossi D. Reliability and Validity of the Belt-Stabilized Handheld Dynamometer in Hip- and Knee-Strength Tests. J Athl Train. 2017;52(9):809-819.
  8. Physique Management. Using the Activforce 2 Digital Dynamometer Belt for an Accurate Strength Measurement. Available from: https://www.youtube.com/watch?v=lnm5YhuNx7M [last accessed 2/29/2024].
  9. Meloq. Measuring the Isometric Muscle Forces of Knee Extension - EasyForce Digital Dynamometer. Available from: https://www.youtube.com/watch?v=F5vDj3gY4Y8 [last accessed 2/29/2024].