MRI-derived body segment parameters of children differ from age-based estimates derived using photogrammetry.

Body segment parameters are required when researching joint kinetics using inverse dynamics models. However, the only regression equations for estimating pediatric body segment parameters across a wide age range were developed, using photogrammetry, based on 12 boys and have not been validated to date (Jensen, R.K.

Stride width discriminates gait of side-fallers compared to other-directed fallers during overground walking.

Purpose: The purpose was to identify differences in gait characteristics between older fallers with a tendency to fall sideways compared to those who do not fall to the side.

Method: The authors conducted a prospective, case control study of ambulatory adults older than 70 residing in retirement communities. Measurements included spatial and temporal gait parameters and prospective fall surveillance.

The effects of hormone replacement therapy and resistance training on spine bone mineral density in early postmenopausal women.

This study evaluated the additive effects of hormone replacement therapy (HRT) and a 1-year site-specific resistance-training (RT) program involving two free weight exercises (i.e., squat and deadlift) 2 days/week as a strategy to reverse or attenuate bone loss at the lumbar spine in early postmenopausal women.

Site-specific response of bone to exercise in premenopausal women.

We studied the response of bone at specific skeletal sites to either lower body exercise alone or complemented with upper body exercise in premenopausal women. Thirty-five exercisers and 24 age-matched controls completed the 12-month study. Exercising women (N = 35) were randomly assigned to either lower body resistance plus jump exercise (LOWER) (N = 19) or to lower and upper body resistance plus jump exercise (UPPER + LOWER) (N = 16).

Oral contraceptive use in young women is associated with lower bone mineral density than that of controls.

Osteoporosis is a skeletal disease affecting 44 million Americans. A primary strategy to prevent osteoporosis is to develop a high peak bone mass in youth. Oral contraceptives (OCs) alter hormones in women and could affect bone mass development.

The association between hormone therapy use and changes in strength and body composition in early postmenopausal women.

Objective: To prospectively examine potential differences in upper- and lower-body muscle strength, lower-body power, lean muscle mass, total body fat, intra-abdominal fat, and energy expenditure (METS) variables in early postmenopausal women. Measurements were taken at baseline and 12 months.

Design: Prospective, 1-year non-randomized [self-selected hormone therapy (HT) and non-HT-replaced], longitudinal study with participation from 136 normally active, early [14.

One year of oral calcium supplementation maintains cortical bone density in young adult female distance runners.

We conducted a double-blind, placebo-controlled, randomized trial to determine whether 1 year of supplemental calcium intake would augment hip [greater trochanter, GT, femoral neck (FN), total hip (TH)], spine (LS), and femoral mid-shaft (Fmr) BMD in female distance runners. Twenty-three women (age: 23.7 +/- 4.

Spine bone mineral density increases in experienced but not novice collegiate female rowers.

Purpose: There is evidence that rowing exercise targets the spine, but the dose of exercise required to build bone is poorly understood. To further explore this topic, we studied the bone response at the spine in novice and experienced female collegiate rowers over their 6-month competitive season. We hypothesized that, with rowing strokes similar between groups during training, experienced rowers would produce greater force at the spine than novices and thus, gain more bone mineral density (BMD).

Musculoskeletal response to exercise is greatest in women with low initial values.

Introduction: The "initial values" principle of exercise training states those with the lowest initial values of a physiologic system have the greatest capacity for improvement in response to training. We sought to determine whether initial values predicted the musculoskeletal response to training in premenopausal women (N = 31) who participated in a 1-yr program of resistance and jump training designed to improve physical indices of fracture risk. Significant improvements in trochanteric bone mineral density (BMD), hip abductor strength, power, and postural stability occurred in response to training.

Bone health across the lifespan--exercising our options.

Exercise is frequently extolled as an osteoporosis treatment. In reality, the use of exercise as an osteoporosis intervention lies more in its ability to: 1) maximize peak bone mass attained in youth; 2) maintain bone mass or reduce age-related bone loss; and 3) preserve muscle strength and postural stability to reduce the risk of falling and fracturing in the later years.

Morphological and functional characteristics of skeletal muscle fibers from hormone-replaced and nonreplaced postmenopausal women.

We tested the hypothesis that cross-bridge mechanisms of contraction differed in early postmenopausal women who did or did not receive hormone replacement therapy (HRT). Vastus lateralis biopsies were obtained from 17 postmenopausal women (49-57 years old), 8 of whom were on HRT for the previous 24 +/- 5 months and 9 of whom were never on HRT. Electrophoresis and enzyme histochemistry revealed that fiber myosin heavy chain (MHC) isoform distribution, the cross-sectional area (CSA) of slow and fast fibers, and the relative CSA occupied by each, were similar for HRT and non-HRT groups.

Physical activity, body fat, and serum C-reactive protein in postmenopausal women with and without hormone replacement.

The objective was to determine whether higher physical activity is associated with lower serum C-reactive protein (CRP), independent of oral hormone replacement therapy (HRT) status and body fatness, in 133 postmenopausal women using a cross-sectional exploratory design at a university research laboratory. The subjects were 133 postmenopausal women, age 50-73 years, with no evidence of coronary artery disease or diabetes. The main outcome measures were: serum CRP, physical activity as measured by Stanford 7-day activity recall, body fat (both total and regional) as measured by dual energy X-ray absorptiometry (DXA), and anthropometry (waist and hip circumference).

Gains in hip bone mass from high-impact training are maintained: a randomized controlled trial in children.

Objectives: We previously reported significant gains in hip and spine bone mass after 7 months of high-impact training in 89 prepubertal children. Our aim in this investigation was to evaluate the bone response to 7 months of "detraining" in this cohort of children.

Study Design: Seventy-four boys and girls (n = 37 jumpers, n = 37 controls) from the original cohort completed follow-up testing.

Seasonal interaction of serum vitamin D concentration and bone density in alpacas.

Objective: To evaluate temporal changes in bone mineral density associated with seasonal variation in serum vitamin D, calcium, and phosphorus concentrations in alpacas.

Animals: 5 healthy mature neutered male alpacas.

Procedure: Metacarpal bone mineral density was measured at 4 times during a year.