Electronic dynamometers read about 4–5 kg higher than hydraulic or spring devices
Do different grip dynamometers give different results?
The finding
Electronic dynamometers (Jamar Plus+, Nottingham) read 4–5 kg higher than the hydraulic Jamar or the Smedley spring device. Jamar hydraulic and Smedley differed by only 0.2 kg (95% CI −0.8 to 1.3).
- Authors
- Lessof C, Cooper R, Wong A, et al.
- Published
- PLoS ONE 18(12):e0289052 · 2023
- Evidence
- Read in the primary source; numbers checked.
- Source
- doi.org/10.1371/journal.pone.0289052
How it was studied
Randomised cross-over study: 118 adults aged 45–74, each tested on four devices.
The numbers
Other studies disagree on the hydraulic-versus-spring gap. In 467 adults aged 69–89, the Smedley read 3.09 kg lower than the Jamar in men and 2.60 kg lower in women (Kim and Shinkai, Geriatr Gerontol Int 2017). In 67 adults with a mean age of 76, the Jamar read 27.4 kg and the Smedley 23.4 kg on day one (Benton et al., PLoS ONE 2022).
Limits of agreement between devices were wide in every pair, so one person can differ by more than the average gap.
What it does not show
The Jamar-versus-Smedley gap is inconsistent between studies, from 0.2 kg to 4 kg. None of these studies tested low-cost consumer digital dynamometers.
What Longstanding does with it
The reference tables were collected on hydraulic and spring devices. A digital dynamometer can read several kilograms high, which is enough to move a percentile. The app records the device with each grip result and asks you to use the same one every quarter, so your own line stays comparable even if the percentile is off.