Muscle functional MRI analysis of trunk muscle recruitment during extension exercises in asymptomatic individuals.

The present study examined the activity levels of the thoracic and lumbar extensor muscles during different extension exercise modalities in healthy individuals. Therefore, 14 subjects performed four different types of extension exercises in prone position: dynamic trunk extension, dynamic-static trunk extension, dynamic leg extension, and dynamic-static leg extension. Pre- and post-exercise muscle functional magnetic resonance imaging scans from the latissimus dorsi, the thoracic and lumbar parts of the longissimus, iliocostalis, and multifidus were performed. Differences in water relaxation values (T2-relaxation) before and after exercise were calculated (T2-shift) as a measure of muscle activity and compared between extension modalities. Linear mixed-model analysis revealed higher lumbar extensor activity during trunk extension compared with leg extension (T2-shift of 5.01 ms and 3.55 ms, respectively) and during the dynamic-static exercise performance compared with the dynamic exercise performance (T2-shift of 4.77 ms and 3.55 ms, respectively). No significant differences in the thoracic extensor activity between the exercises could be demonstrated. During all extension exercises, the latissimus dorsi was the least activated compared with the paraspinal muscles. While all extension exercises are equivalent effective to train the thoracic muscles, trunk extension exercises performed in a dynamic-static way are the most appropriate to enhance lumbar muscle strength.

Prevalence of traumatic brain injury among children, adolescents and young adults: prospective evidence from a birth cohort.

BACKGROUND: Little is known about the incidence and prevalence of traumatic brain injury (TBI), particularly for infants, children and young adults. PRIMARY OBJECTIVE: The purpose of this study was to provide an accurate estimate of the incidence and prevalence of TBIs for individuals between 0-25 years of age. METHOD AND PROCEDURES: A birth cohort of 1265 individuals was used, for which information regarding TBI events, both hospitalized and non-hospitalized, had been recorded. MAIN OUTCOMES AND RESULTS: The average incidence for this age group ranged from 1.10-2.36 per 100 per year, with an overall prevalence of approximately 30%. The most common source of injury was falls for individuals 0-14 years of age and contact sports and motor vehicle accidents for 15-25 year olds. Approximately one third of the individuals who experienced a TBI went on to have one or more additional injuries. CONCLUSIONS: The incidence rates reported here are much higher than those previously found. It is clear that TBIs constitute a major health issue and therefore it is important to have accurate information to enable planning for primary healthcare services and to inform prevention programmes.