The term "children with severe motor and intellectual disabilities (SMID)" is a classification based on the degree of disabilities, but not the name of a disease. Suzuki (1995) indicated the presence of children continuously requiring respiratory care, such as mechanical ventilation, tracheotomy, suction, and oxygen ther

BACKGROUND: The activity of deep trunk muscles (psoas major; PM, quadratus lumborum; QL, transverse abdominis; TrA, and lumbar multifidus; MF) in response to external perturbation is not clearly known. OBJECTIVE: This study aimed to record the onset and amount of activity of the deep trunk muscles during sagittal plane perturbations. METHODS: Fourteen healthy males participated in this study. The activity of the right deep trunk muscles was recorded using wire electrodes. In standing, the participants performed three tasks: a pendulum impacted from anterior with predictable and unpredictable and posterior with unpredictable. RESULTS: In predictable anterior perturbation, the TrA and PM demonstrated feedforward activation, while all deep trunk muscles demonstrated feedback activation in unpredictable anterior and posterior perturbations. In the anticipatory postural adjustment phase, the activity of the TrA was large in predictable anterior perturbation, while that of all deep trunk muscles was slight in other perturbations. In the compensatory postural adjustment phase, the activity of the PM, QL, and TrA in unpredictable anterior perturbation and those of the PM, QL, and MF in unpredictable posterior perturbation were large. CONCLUSIONS: These results showed that the onset and magnitude of deep trunk muscle activity changed depending on both predictable or unpredictable perturbation and the direction of perturbation.

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Objective: The aim of this study was to elucidate the activities of the hip flexor muscles during straight leg raising (SLR) in healthy subjects. We also investigated the activities of these muscles during SLR with deep flexion, abduction, and external rotation. Methods: The ten dominant right legs of ten male volunteers were analyzed in this study. Twelve SLR motion tasks were performed; these comprised combinations of hip flexion at 30°, 45°, and 60°; abduction at 0° and 20°; and external rotation at 0° and 30°. The activities of the psoas major (PM) and iliacus (IL) were measured using fine-wire electrodes, whereas the activities of the rectus femoris, sartorius, adductor longus, and tensor fasciae latae muscles were measured using surface electrodes. The percentage of the maximal voluntary isometric muscle contraction (%MVC) during SLR was calculated for each muscle and used for data analyses. The Friedman test and the Wilcoxon signed-rank test were performed for statistical analyses. The significance level was set at P <0.05. Results: The %MVCs for the PM and IL at 60° flexion were significantly larger than those at 30° or 45° flexion. Moreover, for a constant hip flexion, the %MVC values for the PM and IL showed no significant changes when hip abduction and external rotation were added. For the other muscles, the %MVC values showed no significant change with increasing hip flexion with or without added abduction and external rotation. Conclusion: Our findings suggest that subjects who perform SLR of up to 60° mainly activate the PM and IL at larger hip flexion angles, whereas the other muscles included in the analysis do not contribute greatly to increased flexion angles during SLR.

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