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Objective: To determine if estimates of functional muscle strength from a novel progressive lateral-step-up test (LSUT) are feasible, reliable, and related to physical activity in children with cerebral palsy (CP). Design: Cross-sectional; test-retest reliability Subjects/Patients: Children with CP and typically developing control children (n = 45/group). Methods: An LSUT with 10, 15, and 20 cm step heights was completed. It was repeated 4 weeks later in 20 children with CP. A composite score of LSUT was calculated based on the step height and number of repetitions completed. Physical activity was assessed using monitors worn on the ankle and hip. Results: Only 4 (13%) of the children with CP were unable to complete a lateral step-up repetition without assistance. All children were able to complete at least 1 repetition with assistance, though more than twice as many children with CP required assistance at 15 and 20 cm step heights than at the 10 cm step height (p < 0.01). Children with CP had 59 to 63% lower LSUT performance, 37% lower physical activity assessed at the ankle, and 22% lower physical activity assessed at the hip than controls (all p < 0.01). The intra-class correlation coefficient ranged from 0.91 to 0.96 for LSUT performance at the different step heights and was 0.97 for the composite score. All LSUT performance measures were positively related to ankle physical activity in children with CP (r range = 0.43 to 0.47, all p < 0.01). Only performance at 20 cm and the composite score were positively related to hip physical activity (r = 0.33 and 0.31, respectively, both p < 0.05). The relationship between the LSUT performance and physical activity at both the ankle and hip increased when age and sex were statistically controlled (model r range = 0.55 to 0.60, all p < 0.001). Conclusion: Estimates of functional muscle strength from a novel progressive LSUT are feasible, reliable, and positively related to physical activity in children with CP. [ABSTRACT FROM AUTHOR]

Children with cerebral palsy (CP) exhibit impaired motor control and significant muscle weakness due to a brain lesion. However, studies that assess the relationship between brain activity and performance on dynamic functional muscle strength assessments in CP are needed. The aim of this study was to determine the effect of a progressive lateral step‐up test on prefrontal cortex (PFC) hemodynamic activity in children with CP. Fourteen ambulatory children with spastic CP (Gross Motor Function Classification System level I; 5–11 y) and 14 age‐ and sex‐matched typically developing control children completed a progressive lateral step‐up test at incremental step heights (0, 10, 15 and 20 cm) using their non‐dominant lower limb. Hemodynamic activity in the PFC was assessed using non‐invasive, portable functional neuroimaging (functional near‐infrared spectroscopy). Children with CP completed fewer repetitions at each step height and exhibited lower PFC hemodynamic activity across step heights compared to controls. Lower PFC activation in CP was maintained after statistically controlling for the number of repetitions completed at each step height. PFC hemodynamic activity was not associated with LSUT task performance in children with CP, but a positive relationship was observed in controls at the most challenging 20 cm step height. The results suggest there is an altered PFC recruitment pattern in children with CP during a highly dynamic test of functional strength. Further studies are needed to explore the mechanisms underlying the suppressed PFC activation observed in children with CP compared to typically developing children. [ABSTRACT FROM AUTHOR]

Valid methods for assessing regional muscle mass in children are needed. The aim of this study was to determine whether dual-energy X-ray absorptiometry (DXA) can accurately estimate midthigh muscle mass from MRI ([muscle.sub.MRI]) in typically developing children and children with quadriplegic cerebral palsy (CP). A mathematical model predicting [muscle.sub.MRI] from midthigh, fat-free soft tissue mass from DXA ([FFST.sub.DXA]) was developed using 48 typically developing children (6- 13 y) and was validated using the leave-one-out method. The model was also tested in children with quadriplegic CP (n = 10). The model produced valid estimates of midthigh muscle mass ([muscle.sub.DXA]) in typically developing children, as indicated by a very strong relationship between [muscle.sub.DXA] and [muscle.sub.MRI] ([r.sup.2] = 0.95; SEE = 68 g; P < 0.001), no difference in [muscle.sub.DXA] and [muscle.sub.MRI] (P = 0.951), and visual examination using a Bland-Altman plot. [Muscle.sub.DXA] was very strongly related to [muscle.sub.MRI] in children with CP ([r.sup.2] = 0.96; SEE = 54 g; P < 0.001); however, [muscle.sub.DXA] overestimated [muscle.sub.MRI] by 15% (P = 0.006). The overestimation of [muscle.sub.MRI] by [muscle.sub.DXA] was strongly related to the lower ratio of [muscle.sub.MRI] to [FFST.sub.DXA] ([muscle.sub.MRI]/[FFST.sub.DXA]) in children with CP ([r.sup.2] = 0.75; P = 0.001). The findings suggest that the DXA-based mathematical model developed in the current study can accurately estimate midthigh muscle mass in typically developing children. However, a population-specific model that takes into account the lower [muscle.sub.MRI]/[FFST.sub.DXA] is needed to estimate midthigh muscle mass in children with quadriplegic CP. J. Nutr. 140: 2260-2265, 2010. doi: 10.3945/jn.110.126219.

Bone mineral needs of women can be positively affected by nutrition and physical exercise. Research shows that nutrients such as vitamin D and calcium lower bone loss rates in both premenopausal and postmenopausal subjects, while high-load exercise generates bone mineral enhancement through stimulus. Exercise also reduces fracture risk by improving strength and balance.

Assessment of physical activity in clinical bone studies is essential. Two bone-specific physical activity scoring methods, the Bone Loading History Questionnaire (BLHQ) and Bone-Specific Physical Activity Questionnaire (BPAQ), have shown correlations with bone density and geometry, but not architecture. The purpose of this study was to determine relationships between physical activity scoring methods and bone architecture in non-Hispanic white adolescent females (N = 24; 18-19 years of age). Bone loading scores (BLHQ [hip and spine] and past BPAQ) and energy expenditure (7-day physical activity recall) were determined from respective questionnaires. Estimates of trabecular and cortical bone architecture at the nondominant radius and tibia were assessed via magnetic resonance imaging. Total body and regional areal bone mineral density (aBMD), as well as total body fat mass and fat-free soft tissue (FFST) mass were assessed via dual energy X-ray absorptiom-etry. Pearson's correlations and partial correlations adjusting for height, total body fat mass, and FFST were performed. Hip BLHQ scores were correlated with midtibia cortical volume (r = .43; p = .03). Adjusted hip and spine BLHQ scores were correlated with all midtibia cortical measures (r = .50-0.58; p < .05) and distal radius apparent trabecular number (r = .46-0.53; p < .05). BPAQ scores were correlated with all midtibia cortical (r = .41-0.51; p < .05) and most aBMD (r = .47-0.53; p < .05) measures. Energy expenditure was inversely associated with femoral neck aBMD only after statistical adjustment (r = .49, p < .05). These data show that greater load-specific physical activity scores, but not energy expenditure, are indicative of greater midtibia cortical bone quality, thus supporting the utility of these instruments in musculoskeletal research. [ABSTRACT FROM AUTHOR]