The purpose of this study was to determine the effect of vertical whole-body vibration (WBV) on heart rate (HR), mean arterial pressure (MAP), femoral artery blood flow (FBF), and leg skin temperature (LSk(temp)) during static exercise. These parameters were examined: seated next to the WBV device (passive, unloaded), with feet secured onto the WBV platform (knees 90 degrees flexion) and while standing in a semi-squat position (static, loaded, knees 120 degrees flexion); both with and without WBV. Conditions involved 1 min bouts separated by 1 min rest, repeated 15 times followed by 10 min recovery. WBV in the seated condition had no effect on the responses examined. The static semi-squat without WBV increased MAP 9 mmHg (P < 0.05) with no significant effect on HR, FBF, or LSk(temp). Similarly, WBV static semi-squat increased MAP 8-14 mmHg (P < 0.05), FBF 135-180 mL/min, and LSk(temp) 1.8-3.1 degrees C (P < 0.05). However, only the LSk(temp) was increased above the no-WBV semi-squat position (P < 0.05). The addition of WBV to repeated intermittent static semi-squats does not appear to be a significant cardiovascular stressor.
Many children may have insufficient serum concentrations of vitamin D, which could prevent optimal muscle development and function. Vitamin D deficiency in animal models results in negative effects on muscle fiber structure and calcium/phosphorus handling, suggesting an integral role of vitamin D in skeletal muscle function. While there is a dearth of data in humans, the available evidence demonstrates a positive association between vitamin D status and muscle function. This review focuses on the important role of vitamin D in muscle function in children and adolescents who live in North American regions where exposure to ultraviolet B radiation is limited and who are thus at increased risk for vitamin D insufficiency. The effects of vitamin D on muscle cell proliferation and differentiation, muscle fiber structure, and calcium and phosphorus handling are discussed. Moreover, the roles of vitamin D and the vitamin D receptor and their genomic and nongenomic actions in muscle function are explored in depth. Future research should aim to establish a vitamin D status consistent with optimal musculoskeletal development and function in young children.
Objective: To examine the associations between near and distant visual acuity and biomarkers of Hg, Pb, n-3 fatty acids and Se from the local diet of fish-eating communities of the Tapajós River in the Brazilian Amazon. Design: Visuo-ocular health and biomarkers of Hg (hair, whole blood, plasma), Pb (whole blood), Se (whole blood and plasma) and n-3 fatty acids (plasma total phospholipids) were assessed in a cross-sectional study. Setting: Lower Tapajós River Basin (State of Pará, Brazil), May to July 2006. Subjects: Two hundred and forty-three adults ($15 years) without diagnosed agerelated cataracts or ocular pathologies. Results: Near visual acuity was negatively associated with hair Hg and positively associated with %DHA, with a highly significant Log Hg 3 age interaction term. Stratifying for age showed that while young people presented good acuity, for those aged $40 years, clinical presbyopia was associated with hair Hg $ 15 mg/g (OR 5 3?93, 95 % CI 1?25, 14?18) and %DHA (OR 5 0?37, 95 % CI
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