Toe-touch test. A measure of its validity.

The primary purpose of this study was to investigate the relationships between the vertical fingertip-floor distance (FFD) and the hip and vertebral components of trunk flexion during the toe-touch test. Measurements were taken from lateral photographs of each subject standing in the erect and maximally flexed positions. The subjects were healthy young men (n = 16) and women (n = 17). The mean FFD was 3 cm below floor level (-3 cm) with a standard deviation of 8 cm. Reliability of this measure was indicated by a test-retest correlation coefficient of .97. The FFD was a measure of both trunk (r = -.85) and hip flexion (r = -.79), but not of vertebral flexion (r = .10). At maximum trunk flexion, therefore, FFD is mainly a measure of the extensibility of the hamstring muscles that limit hip flexion when the knees remain extended. The toe-touch test was determined to be unsuitable for monitoring the effect of a treatment regimen to improve vertebral mobility because the partial correlation coefficient between vertebral flexion and FFD was -.64 (p less than .01), with the effect of hip flexion held constant. Although this correlation is significant, it means that less than half of the variation in FFD can be explained by changes in vertebral mobility. For this group of young adults, no significant correlations existed between the FFD and limb length and abdominal girth at maximum trunk flexion.