Scott B Going

PMID: 16283062;Abstract:

The aim of this study was to examine the association of exercise frequency and calcium intake (CI) with change in regional and total bone mineral density (BMD) in a group of postmenopausal women completing 4 years of progressive strength training. One hundred sixty-seven calcium-supplemented (800 mg/ day) sedentary women (56.1 ± 4.5 years) randomized to a progressive strength training exercise program or to control were followed for 4 years. Fifty-four percent of the women were using hormone therapy (HT) at baseline. At 1 year, controls were permitted to begin the exercise program (crossovers). The final sample included 23 controls, 55 crossovers, and 89 randomized exercisers. Exercisers were instructed to complete two sets of six to eight repetitions of exercises at 70-80% of one repetition maximum, three times weekly. BMD was measured at baseline and thereafter annually using dual-energy X-ray absorptiometry. Four-year percentage exercise frequency (ExFreq) averaged 26.8% ± 20.1% for crossovers (including the first year at 0%), and 50.4% ± 26.7% for exercisers. Four-year total CI averaged 1,635 ± 367 mg/day and supplemental calcium intake, 711 ± 174 mg/day. In adjusted multiple linear regression models, ExFreq was positively and significantly related to changes in femur trochanter (FT) and neck (FN), lumbar spine (LS), and total body (TB) BMD. Among HT users, FT BMD increased 1.5%, and FN and LS BMD, 1.2% (p 0.01) for each standard deviation (SD) of percentage ExFreq (29.5% or 0.9 days/week). HT non-users gained 1.9% and 2.3% BMD at FT and FN, respectively, (p 0.05) for every SD of CI. The significant, positive, association between BMD change and ExFreq supports the long-term usefulness of strength training exercise for the prevention of osteoporosis in postmenopausal women, especially HT users. The positive relationship of CI to change in BMD among postmenopausal women not using HT has clinical implications in light of recent evidence of an increased health risk associated with HT. © International Osteoporosis Foundation and National Osteoporosis Foundation 2005.

PMID: 8338157;Abstract:

Previous studies have shown that children have a higher aqueous fraction of the fat-free body mass (FFM) than young adults. In older adults, methodological differences among studies limit evaluation of potential age- related differences in the water content of the FFM (W/FFM). Therefore, we determined W/FFM in 28 healthy white prepubescent children (age = 5-10 yr), 31 young adults (age = 22-39 yr), and 62 older adults (age = 65-84 yr), using ²H2O dilution to estimate total body water and a multicomponent approach based on body density, total body water, and regional bone mineral density to estimate FFM. To quantify the extent to which variation in W/FFM affects percent fat estimation error, differences in percent fat between our multicomponent approach and the Siri two-component model were related to W/FFM. Prepubescent children (72.7 ± 1.6%) and older adults (72.5 ± 1.4%) were found to have significantly higher (P 0.01) mean W/FFM than young adults (70.8 ± 1.2%). Differences in percent fat between the multicomponent and two-component models ranged from -10 to 6% fat and were significantly associated with W/FFM (r = -0.62, P 0.0001). We conclude that prepubescent children and older adults, on average, have a higher W/FFM than young adults, and that, in adults, individual differences in W/FFM account for a substantial portion of the percent fat estimation errors associated with the use of two-component body composition models.

PMID: 8503351;Abstract:

The ability of dual-energy x-ray absorptiometry (DEXA) to detect small changes in body composition was studied in 17 men and women during a dehydration-rehydration protocol. Scale weight (BW) and total mass (TM) from DEXA were highly related (r > 0.99) as were estimates of fat-free mass (r = 0.99) and percent fat (r = 0.97) from DEXA and densitometry. Changes in BW of ≈1.5 kg due to fluid loss and gain were highly correlated (r = 0.90) with both changes in TM and soft-tissue mass (STM) by DEXA but less so (r = 0.67) with changes in lean-tissue mass (LTM). Mean changes in TM, STM, and LTM were not different (P > 0.05) from changes in BW. Estimates of bone mass and fat were unaffected by changes in hydration. We conclude that DEXA is able to detect small individual changes in TM and STM and is also useful for detecting group changes in LTM.

PMID: 14636810;Abstract:

Background. Inadequate opportunities for physical activity at school and overall low levels of activity contribute to the high prevalence of overweight and obesity in American-Indian children. Methods. A school-based physical activity intervention was implemented which emphasized increasing the frequency and quality of physical education (PE) classes and activity breaks. Changes in physical activity were assessed using the TriTrac-R3D accelerometer in a subsample of 580 of the students (34%) randomly selected from the Pathways study cohort. Baseline measures were completed with children in second grade. Follow-up measurements were obtained in the spring of the fifth grade. Results. Intervention schools were more active (+6.3 to +27.2%) than control schools at three of the four sites, although the overall difference between intervention and control schools (∼10%) was not significant (P > 0.05). Boys were more active than girls by 17 to 21% (P ≤ .01) at both baseline and follow-up. Conclusions. Despite the trend for greater physical activity at three of four study sites, and an overall difference of ∼10% between intervention and control schools, high variability in accelerometer AVM and the opportunity to measure physical activity on only 1 day resulted in a the failure to detect the difference as significant. © 2003 American Health Foundation and Elsevier Science (USA). All rights reserved.