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Baseline and Jamar hydraulic dynamometers measure grip strength equivalently. In contrast, Baseline and B&L Engineering pinch gauges do not measure pinch strength equivalently and therefore must not be used interchangeably.
Key words: hand strength measurement instruments * grip strength * pinch strength * hand rehabilitation
Abstract
This study compared different types of grip and pinch strength measurement devices to determine their inter-instrument reliability and concurrent validity. The study included 40 females and 40 males who were tested on 2 types of grip and pinch strength measurement devices using a repeated measure design. Results indicated that the Jamar and Baseline hydraulic dynamometers have acceptable inter-instrument reliability and concurrent validity (i.e., they measure grip strength equivalently) and can be used interchangeably. Thus, therapists using the Baseline dynamometer are justified in using published normative data that were collected with the Jamar dynamometer. In contrast, Baseline regular and hydraulic pinch gauges did not measure tip, key, and palmer pinch strength equivalently with the B&L Engineering pinch gauge. As a result, therapists using Baseline pinch gauges are not justified in using published normative data that were collected with the B&L Engineering pinch gauge. Therapists should not interchange different types of grip and pinch strength measurement devices unless there is evidence that they measure equivalently.
Therapists measure grip and pinch strength for various reasons. The measurements are used to evaluate a client's strength relative to some normative standard (Mathiowetz, 1991) and to document the improvement or deterioration in a client's clinical course (Janda, Geiringer, Hankin, & Barry 1987). The information collected may be used to motivate clients and to facilitate communication among other prof essionals (Ager, Olivett, Johnson, 1984). Grip strength data have been used to characterize upper extremity strength impairment (Bohannon, 1998) to predict recovery of arm function in individuals poststroke (Sunderland, Tinson, Bradley, & Hewer, 1989) and to determine sincerity of effort (Hildreth, Breidenbach, Lister & Hodges, 1989, Niebuhr & Marion, 1987).
There are a number of grip and pinch strength measurement instruments available commercially. However, the Jamar dynamometer and the B&L Engineering pinch gauge are recommended most frequently. The standard Jamar dynamometer, first introduced by Bechtol (1954), is recommended by the American Society of Hand Therapists (ASHT, 1992) and by others (Fess, 1987; Kirkpatrick, 1956; Mathiowetz, 1990)...