The impact of variation in the device used to measure grip strength on the identification of low muscle strength: Findings from a randomised cross-over study

Grip strength is commonly used to identify people with low muscle strength. It is unclear what impact the type of dynamometer used to measure grip strength has on the identification of low muscle strength so we aimed to assess this. Study participants were 118 men and women aged 45-74y from a randomised, repeated measurements cross-over study. Maximum grip strength was assessed using four hand-held dynamometers (Jamar Hydraulic; Jamar Plus+ Digital; Nottingham Electronic; Smedley) in a randomly allocated order. EWGSOP2 cut-points were applied to estimate prevalence of low muscle strength for each device. Agreement between devices was compared. Prevalence of low muscle strength varied by dynamometer ranging between 3% and 22% for men and, 3% and 15% for women. Of the 13 men identified as having low muscle strength by at least one of the four dynamometers, only 8% were identified by all four and 54% by just one. Of the 15 women classified as having low muscle strength by at least one of the four dynamometers, only 7% were identified by all four and 67% by only one. Variation in the measures of grip strength acquired by different hand-held dynamometers has potentially important implications when identifying low muscle strength.