Effect of fingernail length on the hand dexterity.

All participants were healthy young adults, with a mean age of 21.4 years and a range of 21 to 22 years, so the findings may not apply to older adults or people with hand or neurological conditions. The same people were tested at 0 mm first and at 2 mm about 20 days later, so faster times could partly reflect practice or familiarity with the tasks. Only right-hand-dominant participants were tested, and only the right thumb, index and middle fingernails were cut to the two lengths. The study used timed object manipulation tasks, not patient-reported function or activities of daily living, so it does not show real-world benefit. The effect was not uniform: only some STEF subtests showed significant differences, and the mean time for the small sphere was longer at 2 mm than at 0 mm.

Do not tell patients to keep fingernails at 2 mm to improve hand function. The study only compared 0 mm and 2 mm nails in healthy young adults on timed object manipulation tasks, and the testing order could have produced a practice effect.