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A strength-endurance index for power grip
D W Jones1, L D Robertson, S F Figoni
1Department of Kinesiology, California State University, 1250 Bellflower Blvd., Long Beach, CA, 90840-4901, USA. djones9@csulb.edu
Introduction:
The purpose of this study was to quantify muscle strength and endurance in power grip.
Method:
Workers (74 M and 74 F, 18-72 years) squeezed a dynamometer for a 60 s, 18-cycle test. Initial strength (IS) and final strength (FS) were calculated as the mean peak force for cycles 1-3 and 16-18, respectively. Endurance was defined by the strength decrement index (SDI) where SDI = (IS - FS)/IS x 100. A grip strength-endurance analyzer was constructed from IS and SDI data which were depicted on two parallel, linearly scaled axes. Discrete IS and SDI scores were connected on each axis with a vector. The vector (Vmag) was measured directly from the analyzer and its direction identified from its slope. Integer scales transformed discrete IS and SDI scores into individual strength-endurance performance scores (SEPS).
Results:
Better than 95% of the sample (n > or = 141) scored within acceptable test ranges defined as the combined sample mean +/- 2SD, for SDI, Vmag and SEPS. Vmag was the best predictor for SEPS. Linear regression for SEPS was SEPS (combined) = 0.09 (Vmag) - 0.29: (SEE = 0.829). The analyzer revealed individual scores outside acceptable ranges for injured and uninjured efforts.
Conclusion:
The development of a power grip strength-endurance analyzer provided a simple method to graph individual power grip performances. Converting strength and endurance scores to integers and summing them (SEPS) provided a simple means to represent individual estimates of power grip strength-endurance performance.
