Reliability and concurrent validity of an alternative method of lateral lumbar range of motion in athletes
Background: Cricket bowling involves combined spinal movements of side bending and rotation and, consequently, injury to the low back is a common problem. Therefore the assessment of lumbar spine kinematics has become a routine component in preseason screening. This includes static measurement of lateral spinal flexion as asymmetrical range of motion may predispose an athlete to low back injury.
Objectives: This study examined intra-rater reliability and concurrent validity of the fingertip-to-floor distance test (FFD) when compared to a criterion range of motion measure.
Methods: Thirty-four junior-level cricket players aged 13‑16 years were recruited. Lumbar spine lateral flexion was measured simultaneously with the fingertip-to-floor distance test and digital inclinometry methods. Relative and absolute intra-rater reliability were investigated with intraclass correlation coefficients (ICC3,1) of agreement, standard error of measurement (SEM) estimates, Bland and Altman bias estimates and 95% limits of agreement, respectively. The concurrent validity of the fingertip-to-floor distance test, compared to digital inclinometry measures, was examined with Pearson correlation coefficients.
Results: Intra-rater reliability demonstrated substantial agreement for both measures (ICC3,1 > 0.84). The fingertip-to-floor distance test SEM values ranged from 1.71‑2.01 cm with an estimated minimum detectable change (MDC) threshold of 4.73‑5.55 cm. The inclinometry SEM values ranged from 1.00‑1.09° with minimal detectable change estimates of 2.77‑3.01°. There were strong correlations between the index test and criterion measure outcomes (r > 0.84, p < 0.001).
Conclusions: This study’s results support the intra-rater reliability and concurrent validity of the finger-to-floor distance test, suggesting it to be a suitable surrogate measure for lumbar lateral flexion testing.
Keywords: authenticity, efficacy, range of motion, lumbar spine