A laboratory and clinical study of pneumatic 'grip strength' devices.

The use of inflated bags or cuffs to measure grip strength is now a well established technique. The method does have a number of problems. Bags of different diameter and volume were seen to give statistically significantly different pressure readings when squeezed by the same subjects. Different initial pressures (from 20 mmHg to 60 mmHg) also gave significantly different results both in laboratory tests on a materials testing machine and when patients with rheumatoid arthritis squeezed the bag. The technique of squeezing also affected the results. Despite the intrinsic drawbacks of the system, it is likely to remain in general use because of familiarity and convenience. We recommend the minimum details required when pneumodynamometer-derived data are published.