Reliability and Validity of Individual Finger Flexor Strength Measurement Using the Martin Vigorimeter

Objective While numerous tools exist for grip strength measurement, there is a lack of research for assessing the individual finger flexor strength. This study aimed to evaluate the test-retest reliability of measuring individual finger flexion strength in healthy adults using the smallest bulb of the Martin Vigorimeter (MV). Methods Grip strength of 100 adults without hand pathology was measured using the large bulb of the MV, while individual finger flexor strength was assessed using the small bulb. Measurements were repeated after 3 weeks to evaluate test-retest reliability. Contribution of each finger flexor was calculated and compared to the previously reported values obtained using specialized equipment or protocol. Results The MV showed excellent reliability for grip strength (intraclass correlation coefficient > 0.9) and good-to-excellent reliability for individual finger flexor strength (intraclass correlation coefficient = 0.805–0.914). The middle finger contributed the most (approximately 30%), followed by the index and ring fingers (25%–26%), which were comparable to values previously reported using specialized equipment or protocols. Normalized minimal detectable change values for finger flexor strength ranged from 9.7% to 14.2%. Conclusions These findings suggest that the smallest bulb of the MV is a reliable and accessible tool for measuring individual finger flexor strength in healthy adults, with results comparable to those obtained using specialized equipment or protocols.