Jody L. Clasey

A comparison of bone mineral densities among female athletes in impact loading and active loading sports

The purpose of this study was to compare bone mineral densities (BMD) of collegiate female athletes who compete in impact loading sports; volleyball players (N = 8) and gymnasts (N = 13), to a group of athletes who participate in an active loading sport; swimmers (N = 7), and a group of controls (N = 17). All of the volleyball, swimming, and control subjects were eumenorrheic (10-12 cycles/year), whereas two of the gymnasts were amenorrheic (0-3 cycles/year), eight were oligomenorrheic (4-8 cycles/year), and three were eumenorrheic (10-12 cycles/year). Lumbar spine, proximal femur, and total body BMD were measured with dual-energy X-ray absorptiometry. The groups were compared with respect to the following regions: lumbar spine (L1-4); femoral neck; Wards triangle; right and left arms; right and left legs; pelvis; and torso. When controlling for differences in height and weight the impact loading group (volleyball and gymnastic) had significantly greater BMD at the lumbar spine, femoral neck, Wards Triangle, and total body when compared to the active loading (swimming) and control groups. The regional analysis from the total body scan revealed that the gymnasts had significantly (p < 0.05) greater BMD than all other groups at the right and left arm sites. The impact loading groups (gymnastic and volleyball) had a greater BMD in the legs and pelvis than the active loading (swimming) and control groups. Furthermore, the impact loading group had a greater torso BMD than the control group. There were no differences at any site between the active loading group (swimming) and control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial.

Context The age-related decline of growth hormone secretion may play a role in sarcopenia and frailty. Content In this randomized trial, 65 healthy older adults were assigned to receive placebo or MK-677, an oral ghrelin mimetic that increased pulsatile growth hormone secretion to young-adult levels. Over 1 year, lean fat-free mass increased 1.1 kg with MK-677 and decreased 0.5 kg with placebo. MK-677 did not affect strength and function, but insulin sensitivity declined and mean serum glucose levels increased 0.28 mmol/L (5 mg/dL). Caution This short-term trial was underpowered to detect functional changes and adverse events. Implication An oral ghrelin mimetic increases pulsatile growth hormone secretion and alters body composition in healthy older adults. The Editors Aging is an inevitable process across all species. In humans, muscle mass declines after reaching its peak in the third decade of life. Muscle mass is important for physical fitness and metabolic regulation; sarcopenia is a major risk factor for frailty, loss of independence, and physical disability in elderly persons (1) and is associated with shortened survival in critically ill patients (2). As lifespans increase, more adults are becoming frail and dependent on others, which creates challenges for them, their families, and society. The decrease in fat-free mass correlates with the aging-associated decrease in growth hormone secretion (3, 4). Aging adults show decreases in fat-free mass and growth hormone secretion similar to those seen in growth hormonedeficient young adults (5). By the eighth decade, men and women lose approximately 7 and 3.8 kg of muscle mass, respectively (3), and gain intra-abdominal fat (6, 7). Previous trials in which growth hormone was administered to elderly persons were small, poorly controlled, or too short (8); in addition, growth hormone replacement does not restore pulsatile growth hormone secretion. MK-677, the first orally active ghrelin mimetic (a growth hormone secretagogue and growth hormone secretagoguereceptor agonist), increases pulsatile growth hormone secretion in older adults to levels observed in young adults (9, 10). Our primary objectives were to determine whether 25 mg of oral MK-677 daily would increase growth hormone and insulin-like growth factor I (IGF-I) levels in healthy older adults, prevent the decline in fat-free mass, and decrease abdominal visceral fat, with acceptable tolerability. Methods Design The General Clinical Research Center (GCRC) and the University of Virginia institutional review boards approved this study. All participants gave written informed consent. We performed a 2-year, randomized, double-blind, modified crossover trial in which healthy older men, women receiving hormone replacement therapy, and women not receiving hormone replacement therapy received oral MK-677, 25 mg, or placebo (in a 2:1 ratio) daily. After 1 year, participants receiving MK-677 were randomly assigned to continue receiving MK-677 (group 1) or change to placebo (group 2); participants receiving placebo were given MK-677 during year 2 (group 3). Appendix Figure 1 shows the study design. Supplement. Appendix Materials Setting and Participants We recruited healthy volunteers older than 60 years of age from the general population by advertisement and screened them by medical history, physical examination, and laboratory testing to rule out underlying disease. Exclusion criteria were body mass index greater than 35 kg/m2, strenuous exercise for more than 60 minutes per day, smoking, diabetes, history of cancer (other than some types of skin cancer), untreated hypertension or thyroid disease, or medications known to affect growth hormone secretion. We asked participants to maintain their typical diet and exercise throughout the study and to report any illnesses, medical procedures, or adverse effects. All participants were white, with the exception of 1 Hispanic and 1 African-American man. At baseline and every 6 months for 2 years, we admitted participants to the GCRC for measurement of body composition, body water, lipids, and bone mineral density; frequent blood sampling; and completion of quality-of-life questionnaires. We also performed tests of strength and function. During GCRC admissions, we standardized meals for caloric and nutrient content. Blood samples for growth hormone were drawn through an indwelling venous cannula every 10 minutes for 24 hours; participants were allowed to sleep after 9 p.m. Randomization and Intervention MK-677 and placebo tablets were provided by Merck Research Laboratories (Rahway, New Jersey) in a blinded manner and stored by a research pharmacist and dispensed in a blinded manner according to a randomization table with stratification for sex and hormone replacement therapy. Ten-mg tablets were provided for blinded back-titration. Participants were instructed to take the placebo or MK-677 tablets once daily between 7:00 and 9:00 a.m. (or at 9:00 a.m. during admissions). All research staff and volunteers remained blinded throughout the study and during data verification. We monitored adherence by pill counts. Outcome Measures We measured serum growth hormone and IGF-I levels in duplicate in the GCRC Core Laboratory. We assessed 24-hour mean growth hormone and endogenous growth hormone secretory dynamics by using the cluster method (11) and an automated multiple-parameter deconvolution method (9, 12). The Appendix provides details of all assay methods. We evaluated fat-free mass and total body fat by using a 4-compartment model (13) and dual x-ray absorptiometry (DXA) on a Hologic QDR-2000 (Hologic, Bedford, Massachusetts) in pencil-beam mode (14). Dual x-ray absorptiometry measurements included appendicular lean soft tissue of the arms and legs as an estimate of total appendicular skeletal muscle mass (TASM) (15); appendicular fat; and bone mineral density of the femoral neck, spine (L2L4), and total hip. We divided the DXA TASM estimates by height in square meters (TASM [kg]/m2) (15). We used this index of relative limb muscle mass to compute a T-score for each individual, relating the TASM/m2 to that of sex-concordant young adults (16). We defined sarcopenia as values more than 2 SD below values in young, sex-specific reference populations (17, 18). We used cross-sectional computed tomographic images to measure the areas of abdominal visceral and subcutaneous fat and midthigh skeletal muscle at predefined anatomical locations (19); we excluded data if the subsequent scan location differed or we had technical difficulties (4 placebo group recipients and 3 MK-677 recipients). One blinded observer analyzed the dual x-ray absorptiometry and computed tomographic scans. We measured total body water by using the deuterium oxide dilution technique (20) and extracellular water by using bromide dilution (21). We assessed intracellular water as the difference between total body water and extracellular water. To determine the relative relationships among total, extracellular, and intracellular water, we expressed each component in terms of kilograms of fat-free mass at each point. We chose the scale of measure for the analysis a priori. We also report the raw data in typical units for comparison. We determined concentric force during flexion and extension of the knee and shoulder every 6 months by using a Cybex II isokinetic dynamometer (CSM, Boston, Massachusetts). Participants performed 6 repetitions of maximal effort over 90 degrees at 60 degrees/s, and the mean of the last 5 repetitions was computed by using proprietary software (22). We calculated total work by multiplying the mean per repetition by 5. Function tests performed every 6 months included walking 30 meters as quickly as possible (best of 2 trials), walking as far as possible in 6 minutes on an indoor track, descending and ascending 4 flights of stairs, and rising and sitting 5 times from an armless chair with an 18-inch seat height. To compensate for differences in muscle mass between men and women, we analyzed all strength and function measurements in terms of kilograms of baseline appendicular skeletal muscle (lean) from DXA. We used arm lean and leg lean for shoulder and knee strength, respectively, and baseline TASM (sum of arms and legs) for the function tests. We chose the scale of measure used in this analysis a priori; the raw data are also reported. Participants completed 4 questionnaires every 6 months to assess quality of life and general well-being: the 20-item Short Form Health Survey, the Beck Depression Inventory, the Pittsburgh Sleep Quality Index, and the Body Cathexis Scale. The Appendix provides additional details of quality of life, muscle strength, and function assessments. We measured cholesterol, cortisol, and insulin sensitivity (estimated by the Quicki Index method [23] from fasting insulin and glucose) every 6 months. To determine whether the effects of MK-677 treatment were sustained for 2 years or reversed when changed to placebo, we analyzed several end points in a subgroup of participants who completed 24 months in each of the 3 treatment groups (Figure 1). Figure 1. Study flow diagram. FBG= fasting blood glucose; HRT= hormone replacement therapy; MI= myocardial infarction. Monitoring for Adverse Effects Each year, volunteers were seen monthly for the first 3 months and every 3 months thereafter for a physical examination, documentation of medications and vital signs, and questioning about side effects and overall well-being. We performed a complete blood count and chemistry panel and monitored levels of hemoglobin A1c (HbA1c) and fasting blood glucose in all participants and prostate-specific antigen and testosterone in men. Women received annual Papanicolaou smears and mammography. Statistical Analysis The 2 primary end points were fat-free mass and abdominal visceral fat. The study was powered for the pivotal first 12 months; the Appendix describes the power analysis in detail.

Cardiorespiratory fitness is positively correlated with cerebral white matter integrity in healthy seniors.

High cardiorespiratory fitness (CRF) is an important protective factor reducing the risk of cardiac-related disability and mortality. Recent research suggests that high CRF also has protective effects on the brains macrostructure and functional response. However, little is known about the potential relationship between CRF and the brains white matter (WM) microstructure. This study explored the relationship between a comprehensive measure of CRF (VO(2) peak, total time on treadmill, and 1-minute heart rate recovery) and multiple diffusion tensor imaging measures of WM integrity. Participants were 26 healthy community dwelling seniors between the ages of 60 and 69 (mean=64.79 years, SD=2.8). Results indicated a positive correlation between comprehensive CRF and fractional anisotropy (FA) in a large portion of the corpus callosum. Both VO(2) peak and total time on treadmill contributed significantly to explaining the variance in mean FA in this region. The CRF-FA relationship observed in the corpus callosum was primarily characterized by a negative correlation between CRF and radial diffusivity in the absence of CRF correlations with either axial diffusivity or mean diffusivity. Tractography results demonstrated that portions of the corpus callosum associated with CRF primarily involved those interconnecting frontal regions associated with high-level motor planning. These results suggest that high CRF may attenuate age-related myelin declines in portions of the corpus callosum that interconnect homologous premotor cortex regions involved in motor planning.

Body composition by DEXA in older adults: accuracy and influence of scan mode.

Dual energy x-ray absorptiometry (DEXA) measures bone mineral content (BMC), bone mineral density (BMD), fat-free mass (FFM), and provides estimates of percent body fat. Changes in scan mode geometry (pencil beam vs array) may impact these measures and body composition estimates using multi-compartment models. Forty-one adults, ages 59-79 yr, were scanned in each mode and also underwent hydrostatic weighing and measurement of total body water (tritiated water dilution). The effect of scan mode on measurement of DEXA BMC, BMD, FFM, and percent body fat (DEXA %Fat) was examined. The effect of scan mode on percentage body fat determined by a 4-compartment body composition model (4 Comp %Fat) and comparison of DEXA %Fat and 4 Comp %Fat were also examined. BMC and DEXA %Fat were greater (1.3% and 3.9%, respectively, P < 0.01), and BMD and FFM were lower (1.1% and 1.9%, respectively, P < 0.01) with the array scan mode. The 4 Comp %Fat was significantly greater (0.2%) when the array scan mode measurements of total body bone mineral were used; however, these differences were physiologically inconsequential. Comparison between DEXA %Fat and 4 Comp %Fat measures revealed a total error of +/-5.0% in the older adults examined. These results indicate significant scan mode differences in total body BMC, BMD, FFM, and DEXA %Fat measurements and demonstrate the importance of using a single DEXA scan mode for clinical investigation, particularly with longitudinal studies. For all investigations with DEXA, the scan mode should be reported. Furthermore, the error associated with using DEXA alone to estimate percent fat in an older population suggests that this technique is unacceptable in a research setting.

Contributions of exercise, body composition, and age to bone mineral density in premenopausal women

The purpose of this cross-sectional study were to determine whether exercisers have greater bone mineral density (BMD) than nonexercisers, whether aerobic dancers have greater BMD than walkers, and to determine the contributions of energy expenditure, body composition, and dietary factors to spine and femur BMD. Measurements were obtained on 93 eumenorrheic women (walkers N = 28; aerobic dancers, N = 34; nonexercisers, N = 31) ages 25-41 yr; lumbar spine and proximal femur BMD, body composition, physical activity, and nutrient intakes. Mean height, weight, and body mass index and median age and calcium intakes were similar for the three groups. Mean (+/- SD) values of the spine, total femur, and femoral neck BMD, respectively, were: walkers (1.092 (+/- 0.098), 0.947 g.cm-2), dancers (1.070 (+/- 0.124), 0.990 (+/- 0.104), 0.908 (+/- 0.106) g.cm-2), and nonexercisers (1.020 (+/- 0.112), 0.887 (+/- 0.073), 0.792 (+/- 0.089) g.cm-2) multiple regression analyses indicated that exercise contributed to spine (P = 0.018), total femur (P =0.012), and femoral neck (P < 0.0001) BMD, whereas type of exercise (aerobic dance vs walking) did not (P > 0.05). Total femoral BMD was influenced by exercise (P = 0.012) and energy expenditure (P = 0.023), while vertebral BMD was influenced by age (P = 0.0067), body weight (P = 0.017), and exercise (P = 0.018). These findings suggest that walking and aerobic dance exercise may provide physically active premenopausal women with greater lumbar and femoral BMD than sedentary females.

Relationship between regional bone density measurements and the time since injury in adults with spinal cord injuries

OBJECTIVES To determine the bone mineral density (BMD) of the legs, arms, and trunk region of a group of adults with spinal cord injury (SCI) and to determine the relationship between regional BMD values and the time since injury. DESIGN BMD measurements were determined by total-body, dual-energy x-ray absorptiometry scans and percentage values (percentage-matched BMD), based on manufacturer-supplied normative data for age, sex, body weight, and ethnic group. The relationship between percentage-matched BMD values and time since injury was determined by linear regression analyses. SETTING Research laboratories in a university setting. PARTICIPANTS Twenty-nine subjects (21 men, 8 women; mean age, 38.5 y) who had sustained an SCI a mean of 10.6 years earlier (range, 0.6-35.3 y). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES The relationship between percentage-matched BMD values and the time since injury. RESULTS There was a significant inverse relationship between percentage-matched BMD leg (r2 = -.76), arm (r2 = -.45), and trunk (r2 = -.38) values and the log of time since injury. CONCLUSION Despite the varying levels of SCI and other relevant BMD contributing factors, the regional percentage-matched BMD values were significantly inversely related to the log of time since injury.

Meal‐related Changes in Ghrelin, Peptide YY, and Appetite in Normal Weight and Overweight Children

Objective: Ghrelin and peptide YY (PYY) are two gut hormones that have effects on appetite. Our objectives were to characterize the patterns of secretion of these hormones in response to feeding in school‐age children and determine whether there were differences between normal weight (NW) and overweight (OW) subjects.

A new BIA equation estimating the body composition of young children.

Bioelectric impedance analyses (BIA) provides a valid and reliable measure of body composition in field, clinical, and research settings if standard protocol procedures are followed, and population‐specific equations are available and utilized. The objective of this study was to create and cross‐validate a new BIA body composition equation with representative healthy weight (HW), overweight (OW), and obese (OB) young children. Participants were 436 children who were 5–11 years of age. Dual‐energy absorptiometry fat‐free mass (FFM) was used as the criterion measure and a single frequency tetra‐polar BIA device was used to create the new BIA equation. The new BIA equation explained 95.2% of the variance in FFM with no statistical shrinkage upon cross‐validation. The use of this equation may help to identify effective intervention strategies to prevent or combat childhood obesity, and may assist in additional conditions or treatments where information concerning body composition measures would provide greater accuracy and sensitivity measures for preventing or combating disease.

Body Composition Assessment in Spinal Cord Injury Clinical Trials

Body weight and composition impact almost every aspect of rehabilitation and community reintegration for the person with spinal cord injury (SCI), but they have received fairly little attention from the rehabilitation community. In particular, sarcopenia (muscle wasting) and fat accumulation due to paralysis significantly impair activities of daily living, community mobility, cardiopulmonary health, bowel and bladder function, skin integrity, and spasticity and can contribute to morbidities associated with obesity including atherosclerosis, diabetes, dyslipidemia, hypertension, chronic pain, depression, and societal isolation. Usual methods of body composition assessment typically underestimate body fat in SCI and are relatively insensitive to changes that may occur from exercise and nutritional interventions. Current body composition assessment techniques are reviewed for their appropriateness in use with the SCI population, and limitations of those techniques are discussed. Recommendations are made for ...

The effect of a novel tactical training program on physical fitness and occupational performance in firefighters

Abstract Pawlak, R, Clasey, JL, Palmer, T, Symons, TB, and Abel, MG. The effect of a novel tactical training program on physical fitness and occupational performance in firefighters. J Strength Cond Res 29(3): 578–588, 2015—Structural firefighting is a dangerous and physically demanding profession. Thus, it is critical that firefighters exercise regularly to maintain optimal physical fitness levels. However, little is known about optimal training methods for firefighters, and exercise equipment is often not available to on-duty firefighters. Therefore, the purpose of this study was to determine the effect of a novel supervised on-duty physical training program on the physical fitness and occupational performance of structural firefighters. Twenty professional male firefighters were divided into a supervised exercise group (SEG; n = 11) and a control group (CG; n = 9). The SEG participated in a 12-week circuit training intervention. The SEG exercised for 1 hour on 2 d·wk−1. At baseline and after the intervention, subjects performed a battery of physical fitness tests and a simulated fire ground test (SFGT). At baseline, there were no significant differences (p = 0.822) in the completion rate of the SFGT in the SEG (82%) vs. the CG (78%). After the intervention, a significantly greater proportion of the firefighters in the SEG completed the SFGT compared with the CG (SEG = 100% vs. CG = 56%; p < 0.013). In addition, the SEG demonstrated significant improvements in body mass, fat mass, and body mass index (p ⩽ 0.05). The findings of this study indicate that training with firefighter equipment improved occupational performance and anthropometric outcomes in incumbent firefighters. Furthermore, implementing a supervised exercise program using firefighter equipment can be done so in a safe and feasible manner.