beginning the study. Figure 1 —Experimental design. VITD = 5,000 IU of vitamin D 3 ; PTH = parathyroid hormone; fT = free testosterone; tT = total testosterone; SHBG = sex hormone-binding globulin; IGF-1 = insulin-like growth factor 1; DXA = dual-energy X-ray absorptiometry. Participants Male and female
Michelle S. Rockwell, Madlyn I. Frisard, Janet W. Rankin, Jennifer S. Zabinsky, Ryan P. Mcmillan, Wen You, Kevin P. Davy and Matthew W. Hulver
Monica Klungland Torstveit, Ida Fahrenholtz, Thomas B. Stenqvist, Øystein Sylta and Anna Melin
squared in meter (kg/m). Body composition was measured using dual-energy X-ray absorptiometry (Lunar Prodigy, EnCore v. 15; GE Medical Systems, Madison, WI). All measurements were completed in a fasted state between 06:00 and 09:00 a.m. Maximal Oxygen Uptake VO 2max was predicted by asking the subjects
Xiaomin Sun, Zhen-Bo Cao, Kumpei Tanisawa, Satomi Oshima and Mitsuru Higuchi
coefficient of variation for the cross-sectional area at the umbilical level was 0.4%. Dual-energy X-ray absorptiometry (DXA; Hologic QDT-4500, DXA Scanner; Hologic Inc., Waltham, MA) was used to measure the body fat percentage. The fat-free mass was calculated from the body weight and body fat percentage
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
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.
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.
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.
Christie L. Ward, Rudy J. Valentine and Ellen M. Evans
Adiposity, lean mass, and physical activity (PA) are known to influence physical function in older adults, although the independent influences are not completely characterized. Older adults (N = 156, M age = 68.9 ± 6.7 yr, 85 men) were assessed for body composition via dual-energy X-ray absorptiometry, PA by accelerometer, and physical function via timed up-and-go (UP&GO), 30-s chair stand, 6-min walk (6-min WALK), and Star-Excursion Balance Test. In the absence of percentage-body-fat by PA interactions (p > .05), main effects existed such that a higher percentage body fat was associated with poorer performance in UP&GO, 30-s chair stand, and 6-min WALK (p < .05). No significant main effects were found for PA and functional performance. Adiposity explains 4.6–11.4% in physical functional variance (p < .05). Preventing increases in adiposity with age may help older adults maintain functional independence.
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.
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.