Concurrent and Criterion-Referenced Validity of Trunk Muscular Fitness Tests in School-Aged Children

Low back pain (LBP) has been shown to commence during childhood or early adolescence and some evidence suggests that back pain in youth has a high predictive value for back pain in adulthood. And a frequent cause of decreased physical activity levels in youth and adults is the presence of LBP. Indeed, proposed correlates of LBP in youth include poor physical fitness, decreased physical activity, poor hamstring flexibility, increased sedentary behaviors including TV and computer time, and rising overweight and obesity rates. Therefore, proper assessment of low back function in physical education settings is needed to identify children who may be at risk. The purpose of this study was to determine the concurrent and criterion-referenced validity of field tests of low back and core muscular endurance in school-aged children.

The sample consisted of 4^th through 10^th grade students (N = 370) who completed low back and core muscular fitness tests on four separate testing days during their physical education classes. Field measures related to low back function included the Box 90° Trunk Extension (Box 90°) and the FITNESSGRAM Trunk Extension (FG-TE). Field measures related to overall core function consisted of a Lateral Plank, Prone Plank, and a Static and Dynamic Curl-up. Criterion measures of low-back muscular endurance included the Parallel Roman Chair Dynamic Trunk Extension (PRC-DTE) and the Parallel Roman Chair Static Trunk Extension (PRC-STE).

Multivariate analysis using canonical correlations showed moderate correlations between low back and core measures (P < .001). The Lateral Plank, Prone Plank, and Dynamic Curl-up had moderate-to-strong canonical cross-loadings with the low back measure variate. The FG-TE displayed an insignificant canonical coefficient, and weak canonical loadings and cross-loadings. Measures of overall core function also significantly agreed with the criterion measures in classifying students into ranked tertile groups (P < .001).

In conclusion, this paper suggests that the FG-TE, a commonly used assessment in FITNESSGRAM for lumbar strength and flexibility, should not be used as a measure of low back muscular endurance in school-aged children. This study also supports that measures of overall core muscular endurance can be useful assessments to examine specific low back muscular endurance.

Article by Ryan D. Burns, et al, from USA.

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Image by David Cross, from Flickr-cc.