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The purpose of this study was to quantify the inter-session reliability of force–velocity–power profiling and estimated maximal strength in youth. Thirty-six males (11–15 years old) performed a ballistic supine leg press test at five randomized loads (80%, 100%, 120%, 140%, and 160% body mass) on three separate occasions. Peak and mean force, power, velocity, and peak displacement were collected with a linear position transducer attached to the weight stack. Mean values at each load were used to calculate different regression lines and estimate maximal strength, force, velocity, and power. All variables were found reliable (change in the mean [CIM] = − 1 to 14%; coefficient of variation [CV] = 3–18%; intraclass correlation coefficient [ICC] = 0.74–0.99), but were likely to benefit from a familiarization, apart from the unreliable maximal force/velocity ratio (CIM = 0–3%; CV = 23–25%; ICC = 0.35–0.54) and load at maximal power (CIM = − 1 to 2%; CV = 10–13%; ICC = 0.26–0.61). Isoinertial force–velocity–power profiling and maximal strength in youth can be assessed after a familiarization session. Such profiling may provide valuable insight into neuromuscular capabilities during growth and maturation and may be used to monitor specific training adaptations. [ABSTRACT FROM PUBLISHER]

Background: Vitamin C (ascorbate) is likely to be essential for skeletal muscle structure and function via its role as an enzyme cofactor for collagen and carnitine biosynthesis. Vitamin C may also protect these metabolically active cells from oxidative stress. Objective: We investigated the bioavailability of vitamin C to human skeletal muscle in relation to dietary intake and plasma concentrations and compared this relation with ascorbate uptake by leukocytes. Design: Thirty-six nonsmoking men were randomly assigned to receive 6 wk of 0.5 or 2 kiwifruit/d, an outstanding dietary source of vitamin C. Fasting blood samples were drawn weekly, and 24-h urine and leukocyte samples were collected before intervention, after intervention, and after washout. Needle biopsies of skeletal muscle (vastus lateralis) were carried out before and after intervention. Results: Baseline vastus lateralis ascorbate concentrations were ~16 nmol/g tissue. After intervention with 0.5 or 2 kiwifruit/d, these concentrations increased 3.5-fold to 53 and 61 nmol/g, respectively. There was no significant difference between the responses of the 2 groups. Mononuclear cell and neutrophil ascorbate concentrations increased only ~1.5- and ~2-fold, respectively. Muscle ascorbate concentrations were highly correlated (P < 0.001) with dietary intake (R = 0.61) and plasma concentrations (R = 0.75) in the range from 5 to 80 μmol/L. Conclusions: Human skeletal muscle is highly responsive to vitamin C intake and plasma concentrations and exhibits a greater relative uptake of ascorbate than leukocytes. Thus, muscle appears to comprise a relatively labile pool of ascorbate and is likely to be prone to ascorbate depletion with inadequate dietary intake. [ABSTRACT FROM AUTHOR]

Aim: To investigate the bone health and associated risk factors of a group of South Asian women living in New Zealand. Studies on the Indian subcontinent suggest a high incidence of low bone mineral density in women with poor vitamin D status and low dietary calcium intake. Methods: Subjects were women of South Asian origin (n = 91) living in Auckland, New Zealand. Subjects were stratified by menopausal status. They completed a 4-day food diary, and provided a fasting blood sample. Bone mineral density was measured in the lumbar spine and proximal femur using dual X-ray densitometry. Results: Mean age of premenopausal (n = 71) and postmenopausal (n = 20) women was 39.8 ± 7.8 and 55.3 ± 5.4 years, respectively. Osteoporosis ( T-score ≤−2.5) was present in 32% of postmenopausal and 3% of premenopausal subjects, but only in the lumbar spine. Adequate 25(OH)D levels (>50 nmol/L) were found in only 22% of premenopausal, and 26% of postmenopausal women. A body mass index in the overweight or obese category was found in 61% of premenopausal and 75% of postmenopausal women. Conclusion: The high incidence of osteoporosis in the postmenopausal group could be associated with the early age of oophorectomy or menopause together with low vitamin D status. [ABSTRACT FROM AUTHOR]