The effect of school bag design and load on spinal posture during stair use by children

This is an Accepted Manuscript of an article published by Taylor & Francis in Ergonomics on 22/11/2011, available online: http://dx.doi.org/10.1080/00140139.2011.615415.Thirteen male children ascending and descending stairs with loads that equalled 0%, 10%, 15% and 20% of their body weight were the subject of our research: the boys were wearing an asymmetrical single-strap athletic bag or a symmetrical double-strap backpack during our experiments with them. The maximum spinal tilt to the loading side and to the support side, and the range of spinal motions, were obtained by using a motion analysis system. Our results showed that symmetry of spinal posture was observed both when they ascended staircase with all loads and descended in a backpack. When carrying an athletic bag with 15% and 20% of their body weight while ascending the staircase, the lateral spinal tilt to the supporting side was significantly increased. We concluded that a symmetrical backpack with a load not exceeding 20% or an asymmetrical single-strap athletic bag with a load not exceeding 10% should be recommended for school children in order to promote safer staircase use. Statement of Relevance: Children carrying heavy school bags may develop spinal problems. This study suggested that when they are using stairs, a symmetrical backpack with a load within 20% body weight is acceptable for them. When they are carrying an asymmetrical single-strap athletic bag, the bag's weight should not exceed 10% of the body weight in order to avoid excessive spinal tilt

Differentiating Cantonese-Speaking Preschool Children With and Without SLI Using MLU and lexical Diversity (D)

Purpose: In this study, the authors examined the diagnostic accuracy of a composite clinical assessment measure based on mean length of utterance (MLU), lexical diversity (D), and age (Klee, Stokes, Wong, Fletcher, & Gavin, 2004) in a second, independent sample of 4-year-old Cantonese-speaking children with and without specific language impairment (SLI). Method: The composite measure was calculated from play-based, conversational language samples of 15 children with SLI and 14 children without SLI. Scores were dichotomized and compared to diagnostic outcomes using a reference standard based on clinical judgment supported by test scores. Results: Eleven of 15 children with SLI and 8 of 14 children with typical language skills were correctly classified by the dichotomized composite measure. The measure’s sensitivity in this second sample was 73.3% (95% confidence interval [CI] 48%–89%); specificity was 57.1% (95% CI 33%–79%); positive likelihood ratio was 1.71 (95% CI 0.87–3.37); and negative likelihood ratio was 0.47 (95% CI 0.18–1.21). Conclusions: The diagnostic accuracy of the composite measure was substantially lower than in the original study, suggesting that it is unlikely to be informative for clinical use in its present form. The value of replication studies is discussed