Enter the grip dynamometer readings from a set of trials. This tool gives you the coefficient of variation and a plain reading of what that number does and does not prove about effort.
Type each trial reading, separated by commas or spaces. Any unit is fine, as long as they all match. Three or more trials.
Cut-off and diagnostic numbers from Shechtman O. The coefficient of variation as a measure of sincerity of effort of grip strength, Part II. J Hand Ther. 2001;14(3):167-176. PMID 11511013.
Above the 15 percent cut-off is a rule-in with teeth. For a three trial grip test, specificity at this cut-off is 0.94. Very few full effort people scatter that much by chance, so a positive result is real evidence of submaximal effort. It is evidence, not proof. Weigh it with the rest of the exam.
At or below the cut-off clears nobody. Sensitivity is only 0.55, so the test misses almost half of the people who are actually holding back. A tight, consistent set of readings is a weak rule-out, not a clean bill.
Trial count matters. The area under the curve is 0.79 for three trials and 0.87 for five, so more trials give a more reliable read. And the 15 percent cut-off with these numbers is specific to the grip dynamometer, not to every effort test.
Want the full walk through of where grip testing and single camera video both fall short? Read the research teardown.