Foot and Ankle Strength Assessment Using Hand-Held Dynamometry: Reliability and Age-Related Differences

Abstract

Background: Age-related reduction in lower limb muscle strength has been shown to be related to disability, falls and loss of independence. While there have been a number of studies on age-related changes in muscle strength, they have concentrated on more proximal muscle groups with little research into how ageing affects the muscles of the foot and ankle. Objective: To evaluate the intra- and interrater reliability of hand-held dynamometry for the assessment of foot and ankle strength, and to compare the values obtained between young and older people. Methods:The muscle groups which perform ankle dorsiflexion, plantar flexion, inversion, eversion and plantar flexion of the hallux and lesser digits were recorded for 36 young participants (17 males, 19 females, mean age 23.2 ± 4.3 years) and 36 older people (17 males, 19 females, mean age 77.1 ± 5.7 years) using a Citec hand-held dynamometer. Differences in muscle strength between the groups as well as intrarater and interrater reliability of two assessors were determined. Results: The reliability of the hand-held dynamometry procedure was excellent for both intrarater (ICC_3,1 = 0.78–0.94) and interrater (ICC_3,1 = 0.77–0.88) comparisons. There were significant differences between the muscle strength of the young and older participants for all muscle groups tested (p < 0.001) with older participants being weaker than the young participants by a magnitude of between 24 and 37%. Conclusions:Hand-held dynamometry is a reliable instrument to measure the foot and ankle strength of young and older adults. Ageing is associated with a reduction in strength of between 24 and 37% for the muscles responsible for movement of the foot and ankle.