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Michael J. Ormsbee, Brandon D. Willingham, Tasha Marchant, Teresa L. Binkley, Bonny L. Specker and Matthew D. Vukovich

urine samples, body composition via dual-energy X-ray absorptiometry, a graded treadmill test to measure peak aerobic capacity (VO 2 peak), and a one-repetition maximum (1-RM) test to measure dynamic strength. Following baseline measurements, study participants were matched for strength and randomly

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David A. Greene, Geraldine A. Naughton, Julie N. Briody, Allan Kemp, Helen Woodhead and Nathalie Farpour-Lambert

This study compared tibial bone and muscle geometry and total body and regional bone mineral content (BMC) in elite female adolescent middle-distance runners (n = 20, age: 16 ± 1.7 years) and age- and sex-matched controls (n = 20, 16 ± 1.8 years) using magnetic resonance imaging and dual-energy X-ray absorptiometry. Significant advantages were found in athletes compared with controls in bone and muscle geometric values for distal tibial cortical, medullary cavity, distal tibial total muscle and dorsi flexor muscle compartment cross-sectional area, and regional BMC. Results imply mechanical loads associated with middle-distance running might be beneficial to musculoskeletal health in adolescent females.

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Nicole Gero, Jacque Cole, Jill Kanaley, Marjolein van der Meulen and Tamara Scerpella

This longitudinal study evaluates the role of impact activity in bone accrual in premenarcheal girls. Twenty-eight gymnasts and 20 controls underwent 1-year analysis; fifteen gymnasts and 8 controls underwent 2-year analysis. Bone mineral density (BMD) was measured yearly by dual energy X-ray absorptiometry. For the 1-year analysis, BMD accrual rates were greater in gymnasts than controls at the forearm only (p < .05). For the 2-year analysis, gains in BMD were 1.5 to 1.9 times greater at the forearm, total hip, and femoral neck for gymnasts (p < .05). These findings confirm the positive effect of impact activity on bone accrual in premenarcheal girls.

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Bernadette L. Foster, Jeff W. Walkley and Viviene A. Temple

The purpose of this study was to describe and compare the bone mineral density of women with intellectual disability (WID) and a comparison group (WOID) matched for age and sex. One hundred and five women, ages 21 to 39, M = 29, were tested for their bone mineral density levels at the lumbar spine and three sites of the proximal femur using dual energy X-ray absorptiometry. No significant difference between groups existed (λ = 0.94, F(4, 98) = 1.68, p = .16, η2 = .06); however, one-sample t tests revealed that bone mineral density for the WID group (n = 35) was significantly lower than zero at the Ward’s triangle (p < .01) and the lumbar spine (p < .05). Approximately one-quarter of WID had low bone density at these two sites, suggesting that WID may be at risk of osteoporotic fracture as they age.

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Ann V. Rowlands, Sarah M. Powell, Roger G. Eston and David K. Ingledew

This study aimed to determine the relationship between bone mineral content, habitual physical activity, and calcium intake in children. Fifty-seven children, aged 8–11 years, wore pedometers for seven days to assess activity. Calcium intake was estimated by a 4-day food diary. Bone mineral content (BMC) and areal density (BMD) were measured at the total proximal femur and femoral neck using dual energy X-ray absorptiometry. Regression analysis was used to assess contributions of physical activity and calcium intake to BMC, residualized for bone area and body mass. Physical activity explained 11.6% of the variance in residualized BMC at the proximal femur and 14.3% at the femoral neck (p < 0.05). Calcium intake added to the variance explained at the proximal femur only (9.8%, p < 0.05). This study provides evidence for an association between BMC and habitual physical activity.

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Jeanne F. Nichols, Karen P. Nelson, Katrina K. Peterson and David J. Sartoris

The purpose of this investigation was to determine the effects of high-intensity strength training on bone mineral density (BMD) of 34 non-estrogen-repleted, active women over 60 years of age. The study was designed as a randomized, nonblinded trial in which subjects were stratified into rank-ordered pairs by level of physical activity, then randomly assigned into either a weight training (WT) or a control (CON) group. BMD of the spine (L2–L4), hip, and total body was assessed at 0, 6, and 12 months by dual energy x-ray absorptiometry. Group-by-time repeated-measures ANOVA demonstrated no effect of weight training on BMD, despite marked gains in muscular strength for all exercises. The high-intensity weight training utilized in this study did not induce positive changes in BMD of the hip and spine of previously active, non-estrogen-repleted older women. However, the protocol was safe, enjoyable, and highly effective in increasing muscular strength.

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Saori I. Braun, Youngdeok Kim, Amy E. Jetton, Minsoo Kang and Don W. Morgan

The purpose of this study was to determine if bone health at the femoral neck (FN) and lumbar spine (LS) can be predicted from objectively-measured sedentary behavior and physical activity data in postmenopausal women. Waist-mounted ActiGraph GT1M and GT3X devices were used to quantify levels of sedentary and moderate-to-vigorous intensity behavior during a 7-day period in 44 older females. Bone health (normal and osteopenia/osteoporosis) of FN and LS was derived from T scores generated using dual energy x-ray absorptiometry. Binomial logistic regression analysis indicated that sedentary time and number of breaks in sedentary behavior were significant predictors of osteopenia/osteoporosis at the FN, but not at the LS. Adherence to physical activity guidelines was not a significant predictor of bone health at the FN or LS. Our findings suggest that more frequent interruptions in sedentary behavior are associated with improved bone health in postmenopausal women.

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Élvio R. Gouveia, Bruna R. Gouveia, José A. Maia, Cameron. J. Blimkie and Duarte L. Freitas

The aims of this study were to describe age- and sex-related differences in total body skeletal muscle (TB-SM) mass and to determine the variance explained by physical activity (PA). This cross-sectional study included 401 males and 402 females, aged 60–79 years. TB-SM was determined by dual-energy x-ray absorptiometry (DXA) and PA by Baecke questionnaire. Statistical analysis included t test, ANOVAs, Pearson correlations, and multiple regression analysis. TB-SM mass was higher in the youngest age group when compared with the oldest in males and females. Males had greater TB-SM values than females. PA made a significant and positive contribution to the variation in TB-SM, β = 0.071; p = .016. Sex, height, fat mass, and PA explained 77% of the variance in TB-SM. The oldest cohorts and females had lower TB-SM than the younger cohorts and males. This study suggests that PA exerts a significant role in the explanation of TB-SM.

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Cédric R.H. Lamboley, Donald Royer and Isabelle J. Dionne

The aim of this study was to determine the effects of oral β-hydroxy-β-methylbutyrate (HMB) supplementation (3 g/d) on selected components of aerobic performance and body composition of active college students. Subjects were randomly assigned to either an HMB (n = 8) or a placebo (PLA) group (n = 8) for a 5-wk supplementation period during which they underwent interval training 3 times a week on a treadmill. Aerobic-performance components were measured using a respiratory-gas analyzer. Body composition was determined using dual-energy X-ray absorptiometry. After the intervention, there were significant differences (P < 0.05) between the 2 groups in gains in maximal oxygen consumption (+8.4% for PLA and +15.5% for HMB) and in respiratory-compensation point (+8.6% for PLA and +13.4% for HMB). Regarding body composition, there were no significant differences. The authors concluded that HMB supplementation positively affects selected components of aerobic performance in active college students.

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Richard B. Kreider, Robert Klesges, Karen Harmon, Pamela Grindstaff, Leigh Ramsey, Daryll Bullen, Larry Wood, Yuhua Li and Anthony Almada

This study examined the effects of ingesting nutritional supplements designed to promote lean tissue accretion on body composition alterations during resistance training. Twenty-eight resistance-trained males blindly supplemented their diets with maltodextrin (M), Gainers Fuel® 1000 (GF), or Phosphagain™ (P). No significant differences were observed in absolute or relative total body water among groups. Energy intake and body weight significantly increased in all groups combined throughout the study with no group or interaction differences observed. Dual energy x-ray absorptiometry-determined body mass significantly increased in each group throughout the study with significantly greater gains observed in the GF and P groups. Lean tissue mass (excluding bone) gain was significantly greater in the P group, while fat mass and percent body fat were significantly increased in the GF group. Results indicate that total body weight significantly increased in each group and that P supplementation resulted in significantly greater gains in lean tissue mass during resistance training.