Reliability and concurrent validity of an alternative method of lateral lumbar range of motion in athletes

Abstract

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