Testing grip strength is a popular assessment used by occupational therapists in a range of clinical settings. It is fast, easy to perform, reliable and produces a result which is simple to record. Results of grip strength testing have been used to determine a baseline measure of performance against which change can be compared, as well as comparison of results to normative data. This article reviews the literature associated with the measurement of grip strength. It addresses the purposes of grip strength measurement; the instruments used and their reliability and accuracy; the testing position and protocol suggested for use and aspects of these which may influence results; the use of normative data and factors which influence grip strength, including age, gender and occupation; and various methods to determine level or sincerity of effort. Recommendations are made regarding these issues to enable clinicians to conduct grip strength assessments and interpret the results with confidence.

Handgrip strength testing: A review of the literature

Grip Strength Testing Reliability

Objective Several studies have indicated that changing body positions results in altered grip strengths. Although one might expect that grip strength would be influenced by the position of the forearm during gripping due to the biomechanical properties of the forearm and hand muscles, no investigations of this variable have been undertaken. Method This study examined the effect on grip strength of moving the forearm among supinated, neutral, and pronated positions while maintaining the standard position recommended by the American Society of Hand Therapists. The mean of three grip trials in each position was recorded for each of 106 subjects. Results Grips in forearm supination were the strongest, followed by grips in the neutral position. Grips in pronation were the weakest. Conclusions The changes in grip strength observed with variations in forearm position further support the necessity of a standard position for testing grip strength. The knowledge of how changes in body position affect the strength of the grip can be used to design environments and tools to maximize biomechanical abilities.

How Forearm Position Affects Grip Strength

The average of three consecutive measurements is the most frequently used method for grip strength assessment. The purpose of this study was to compare the consistency of the maximum value with that of the average value of three consecutive measurements of grip strength. One hundred healthy volunteers participated in this study. Three measurements of grip strength were taken on two occasions separated by 2 weeks. For each hand, two average values and two maximum values were obtained. Ninety-five per cent limits of agreement for the average method were - 8.3 (-23%) to +7.2 (+20%)kg and for the maximum method were - 8.8 (-23%) to + 8 (+21%)kg. Both methods of grip strength assessment were found to be highly consistent with no statistically significant difference.

Average versus maximum grip strength: which is more consistent?

The effects that normal aging have on adult hand function and functional performance are not well understood. An empirical study was conducted examining relationships between prehension pattern type and frequency, hand strength, and performance time in functional tasks. Four groups of 10 adults were selected by age and gender, ranging from 24 to 87 years. Subjects were asked to pour milk into a cup and remove money from a wallet while being videotaped. Prehension patterns were identified with a functionally based classification system. Grip and three types of pinch were measured with a dynamometer and a pinch gauge. Prehension pattern selection did not seem to differ with age. Statistically significant differences in age were found for prehension pattern frequency, hand strength, and performance time. Nondysfunctional older subjects were observed resetting identical prehension patterns secondary to lateral pinch weakness, which contributed to increased prehension pattern frequency and performance time. Hand function seemed to remain stable until age 65 years, after which it diminished slowly. After age 75 years, age differences in performance were most apparent.

Effects of aging on adult hand function.

We implemented a tridirectional survey to begin the standardization process for grasp and pinch terminology and protocols for testing and to improve the communication between rehabilitation professionals who assess hand strength. We surveyed the literature, occupational therapy clinics across the country, and occupational therapy educational programs. Our results reveal the current use, teachings, and recommendations of pinch and grasp strength measurement. The results confirm that the standardization of grasp and pinch terminology and protocols for testing are vitally needed. Specific recommendations to continue this standardization process are recommended.

Margie Wadlington Benge

Papers

Pinch and grasp strength: standardization of terminology and protocol.