Flexibility may be expressed as the maximum passive physiological range of motion in a given joint movement. Flexibility is specific to both joint and movement. The Flexitest, originally described in 1980, allows for the flexibility measurement of 20 joint movements, using a progressive scale of integer numbers from 0 to 4, and provides a global score called Flexindex. Assuming that it is possible to obtain the same Flexindex by different combinations of scores in the 20 movements, an objective study of the variability of the results was required. Based on data obtained in 2,426 men and women ranging from 5 to 88 years of age, this paper proposes five new variability indices based on the scores from the Flexitest: a) intermovements, b) interjoints, c) flexion-extension, d) between segments, and e) distal-proximal. The two first indices do not depend on age, gender, and Flexindex magnitude. The other three, as a result of ratios between mean values of groups of measurements, tend to show values close to 1, while differing between genders, specially in relation to score dispersion around the central tendency. A distal-proximal variability index lower than 1.15 (men) and 1.04 (women) was observed at least three times more frequently in subjects younger than 50 years old, thus providing an infantile-juvenile pattern. Calculation methods, percentile ranges of scores for homogeneous, somewhat heterogeneous, and highly heterogeneous, as well as the major aspects of interpretation of each one of the indices are presented.
Flexibility; Joint mobility; Joint lassitude; Functional assessment; Kineanthropometry
