One of the most common tools for testing hand-muscle strength is the hand-held (or hand-grip) dynamometer.Digital Hand Dynamometers can be both digital and mechanical. The growing trend is toward digital and away from mechanical. To use a hand-held dynamometer, the patient is required to squeeze down on a grip (often resembling the grip on a hand gun). The dynamometer grip is equipped with gauges (digital) or cables (mechanical) that measure the force of the squeeze and convert that force into a number. The number is then used to determine the patient’s muscle strength.
Several recent studies show the value of using more than one type of hand-held dynamometer to assess a patient’s muscle strength. One such study can be found on the website for the U.S. National Library of Medicine. This study tested the Jamar Hand-Held Dynamometer against the Takei Dynamometer and the EMG System Manual Transducer. The study was primarily concerned with the significantly different shapes of the dynamometers and found stark differences between the results obtained from the Jamar Dynamometer when compared with the two other dynamometers. The Jamar Dynamometer uses a hydraulic technology and, when squeezed, has a smooth hydraulic motion to it. The other two instruments are more springy as they rely on cables instead of hydraulics. The study concluded that the differences in results could be attributed to: (1) differences in the shape of the hand grips on the instruments, and (2) differences in the calibration (hydraulics v. cables) of the instruments.
This study shows that determining a true hand-muscle strength may require more than one type of hand-held dynamometer. A patient may be more comfortable using one type of instrument over another. There may also be a mental component to how hard a patient thinks he or she can squeeze one instrument over another.