Association between bone mineral density (DXA), body structure,and body composition in middle‐aged men

The association between bone mass, body structure, and body composition was explored in 156 men, 40 years of AGE . Bone mineral density (total body, lumbar spine, left arm, and left leg) was obtained by dual‐energy X‐ray absorptiometry (DXA; Hologic QDR 4500A). Body structure was determined from a battery of anthropometric dimensions with a principal components analysis. Body composition was estimated with DXA. From the 24 anthropometric dimensions, three components were extracted and identified as muscle, fat, and skeletal length. Significant correlations between the muscle component and all BMD measurements (r = 0.28–0.44) were obtained. Except for BMD of the left arm, which correlated significantly, but negatively, with the fat component (r = ?0.16), no significant relations were found between the fat component and BMD. There were significant correlations between lean mass, fat mass, and BMD measurements. The correlations were higher between lean mass and BMD (r = 0.22–0.44) than between fat mass and BMD (r = 0.08–0.24). The multiple regression analysis revealed that except for BMD of the left arm only lean mass or the muscle component, and not fat mass or the fat component, were independent predictors of BMD. It is concluded that the principal anthropometric determinant of BMD in middle‐aged men is lean mass or muscle. Am. J. Hum. Biol. 14:735–742, 2002. © 2002 Wiley‐Liss, Inc.     

Aerobic power and pubertal peak height velocity in Belgian boys

Summary To determine the cardiorespiratory response to maximal exercise before, during and after the pubescent growth spurt, thirty boys were tested at yearly intervals over a period of six consecutive years. For each individual, peak height velocity (PHV) was determined. The age at PHV (¯X= 13.6 years) was taken as a standard of maturation. The results from all subjects at 1.5 and 0.5 years before and 0.5 and 1.5 years after PHV are presented. The highest oxygen uptake ( ) obtained during an incremental bicycle ergometer test to voluntary exhaustion was taken as peak oxygen uptake ( peak). Across each of the four years studied, mean peak (min=49.6; max=52.5 ml·kg^–1·min^–1) and mean heart rate (HR) at peak (min=190; max=192) did not change significantly as a function of PHV. On the other hand, the respiratory quotient at peak increased considerably from mean minima and maxima of 0.99 and 1.01 before PHV to 1.07 and 1.10 after PHV. Ventilatory equivalent for ( ), taken as an indicator of ventilatory economy, seemed to be unaffected by the maturation process. The steepest increase in circumpubertal oxygen pulse was found one year after PHV. Average stability coefficients (¯r), calculated from the inter-years correlations were high for height (¯r=0.95), weight (¯r=0.92), HR at peak (¯r=0.74), peak in 1/min (¯r=0.71), oxygen pulse (¯r=0.68) and tidal volume (¯r=0.64).     

A realistic 3-D gated cardiac phantom for quality control of gated myocardial perfusion SPET: the Amsterdam gated (AGATE) cardiac phantom

A realistic 3-D gated cardiac phantom with known left ventricular (LV) volumes and ejection fractions (EFs) was produced to evaluate quantitative measurements obtained from gated myocardial single-photon emission tomography (SPET). The 3-D gated cardiac phantom was designed and constructed to fit into the Data Spectrum anthropomorphic torso phantom. Flexible silicone membranes form the inner and outer walls of the simulated left ventricle. Simulated LV volumes can be varied within the range 45–200 ml. The LV volume curve has a smooth and realistic clinical shape that is produced by a specially shaped cam connected to a piston. A fixed 70-ml stroke volume is applied for EF measurements. An ECG signal is produced at maximum LV filling by a controller unit connected to the pump. This gated cardiac phantom will be referred to as the Amsterdam 3-D gated cardiac phantom, or, in short, the AGATE cardiac phantom. SPET data were acquired with a triple-head SPET system. Data were reconstructed using filtered back-projection following pre-filtering and further processed with the Quantitative Gated SPECT (QGS) software to determine LV volume and EF values. Ungated studies were performed to measure LV volumes ranging from 45 ml to 200 ml. The QGS-determined LV volumes were systematically underestimated. For different LV combinations, the stroke volumes measured were consistent at 60–61 ml for 8-frame studies and 63–65 ml for 16-frame studies. QGS-determined EF values were slightly overestimated between 1.25% EF units for 8-frame studies and 3.25% EF units for 16-frame studies. In conclusion, the AGATE cardiac phantom offers possibilities for quality control, testing and validation of the whole gated cardiac SPET sequence, and testing of different acquisition and processing parameters and software.An erratum to this article can be found at     

Adolescent physical performance and adult physical activity in Flemish males

Limited information is available about the associations between adolescent fitness levels and adult physical activity. In the present study, these associations are investigated using different indicators of physical activity. It is hypothesized that both health‐ and performance‐related fitness characteristics, observed during the adolescent period, contribute equally to the explained variance in adult physical activity levels. Subjects were 109 Flemish males followed over a period of 27 years from 13 to 40 years of age in the Leuven Longitudinal Study on Lifestyle Fitness and Health. Performance and health‐related fitness characteristics were observed during the growth period and at 40 years of age. The Work Index, Leisure Time Index, and Sport Index of the Baecke questionnaire were used as indicators of physical activity together with triaxial accelerometry. Multiple regression and discriminant analyses contrasting extreme quintiles of activity groupings were used to analyse the associations. Only the Baecke Sport Index showed consistent significant associations (R² = 0.03 to R² = 0.23) with adolescent fitness levels observed at 13, 15, and 18 years. When upper and lower quintiles were contrasted, fitness characteristics observed at the three age levels during adolescence were significantly different for each of the three indices of the Baecke questionnaire at 40 years of age. Lowest associations (R² = 0.09 to R² = 0.17) were found for the Work Index, followed by the Leisure Time Index (R² = 0.12 to R² = 0.28) and Sport Index (R² = 0.25 to R² = 0.43). Highest associations were evident for the 18‐ to 40‐year interval. Performance‐ and health‐related fitness characteristics explain equally well the variance in physical activity indicators. Am. J. Hum. Biol. 13:173–179, 2001. © 2001 Wiley‐Liss, Inc.     

Effect of Heat Treatment on the Microstructure and Performance of Cu Nanofoams Processed by Dealloying

Cu nanofoams are promising materials for a variety of applications, including anodes in high-performance lithium-ion batteries. The high specific surface area of these materials supports a high capacity and porous structure that helps accommodate volume expansion which occurs as batteries are charged. One of the most efficient methods to produce Cu nanofoams is the dealloying of Cu alloy precursors. This process often yields nanofoams that have low strength, thus requiring additional heat treatment to improve the mechanical properties of Cu foams. This paper provides the effects of heat treatment on the microstructures, mechanical properties, and electrochemical performance of Cu nanofoams. Annealing was conducted under both inert and oxidizing atmospheres. These studies ultimately reveal the underlying mechanisms of ligament coarsening during heat treatment.     

Associations between daily physical activity and physical fitness in Flemish males: A cross-sectional analysis

The relationship of physical activity to several components of physical fitness was investigated in a sample of 166 males 40 years of age. In addition to Pearson correlations, multivariate canonical correlations were calculated. Physical activity during work (work index), sport (sport index), and leisure time (leisure time index) was assessed by the Baecke questionnaire. Physical fitness included cardiorespiratory fitness measures, the body mass index (BMI), the sum of seven skinfold thicknesses (SKI), percentage body fat (PFAT), balance, and several tests of muscle strength and endurance, flexibility, and speed of limb movement. More than 86% of the variance was shared by the two first canonical variables. The first canonical variable can be interpreted as a health-related fitness function. Carciorespiratory fitness, balance, speed of limb movement, explosive strength, and trunk muscle strength are clearly related to this function. From the physical activity measures, the Baecke sport index correlated significantly with this health-related fitness function. The second canonical variable can be explained as a fatness function, since body weight, BMI, SKI, and PFAT showed the highest correlations with the variable. The Baecke work index was inversely related to this canonical variable. The sample was also divided into physical activity groups in order to look for differences in physical fitness. The data indicate that physical activity during work was modestly, but inversely related to adiposity. Sport activity was beneficially associated to several fitness components, including cardiorespiratory fitness, trunk muscle strength, and upper body muscular endurance. Am. J. Hum. Biol. 11:587–597, 1999. © 1999 Wiley-Liss, Inc.     

Influence of participation in high-impact sports during adolescence and adulthood on bone mineral density in middle-aged men: a 27-year follow-up study

This study examined whether participation in high-impact sports during adolescence and adulthood contributes to bone health in males aged 40 years. Data were analyzed on 154 Belgian men aged 13 years at study onset in 1969 and aged 40 years at the end of the 27-year follow-up. In a second analysis, subjects were divided into three groups according to their sports participation history: participation during adolescence and adulthood in high-impact sports (HH; n=18), participation during adolescence in high-impact sports and during adulthood in nonimpact sports or no sports (HN; n=15), and participation during adolescence and adulthood in nonimpact sports or no sports (NN; n=14). Body mass and impact loading during adulthood were significant predictors of total body bone mineral density (BMD) and lumbar spine BMD. Analysis of variance revealed significant differences for lumbar spine BMD between the HH (1.12 g/cm2) group and the HN (1.01 g/cm2) and NN (0.99 g/cm2) groups (F=5.07, p=0.01). Total body BMD was also higher in the HH group at age 40 years, but not significantly (F=3.17, p=0.0515). Covariance analyses for total body BMD and lumbar spine BMD, with body mass and time spent participating in sports as covariates, confirmed these results. Continued participation in impact sports is beneficial for the skeletal health of males aged 40 years.