Biomedical subjects

J S Skinner

Publications and source records attributed to J S Skinner.

At least 19 recordsLinked to original sources

PubMed1999

Familial aggregation of resting blood pressure and heart rate in a sedentary population: the HERITAGE Family Study. Health, Risk Factors, Exercise Training, and Genetics.

The familial aggregation of resting systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) was assessed in 98 white families, who participated in the HERITAGE Family Study, and were selected to be sedentary, and primarily nonobese and normotensive. In the present study, 522 family members were sedentary at baseline examination, and resting SBP, DBP, and HR measured during this examination were investigated. If physical activity level is a potent environmental factor, then we expected that the relative contribution of environmental factors to the familial aggregation of blood pressure (BP) would be somewhat reduced, because activity was controlled for in this study. Using a familial correlation model, maximal heritabilities were estimated to be 54%, 41%, and 32% for resting SBP, DBP, and HR, respectively, in these families; and they were 51%, 42%, and 34% for resting SBP, DBP, and HR, respectively, when the data were adjusted for body mass index. The estimates are somewhat higher for BP but similar for HR to those reported in previous family studies, suggesting that the distribution of the underlying etiologic factors in these sedentary families may be similar to those in the general population. There was substantial spouse resemblance in this study, which may be explained by a higher concordance for correlated lifestyle factors including diet, similar activity levels, or by assortative mating for relative weight or dietary preferences.

Adolescent↗

PubMed1999

Differential expression of genes encoding the light-dependent and light-independent enzymes for protochlorophyllide reduction during development in loblolly pine.

The expression patterns of the two distinct subfamilies of genes (designated porA and porB) encoding the light-dependent NADPH:protochlorophyllide oxidoreductases (PORs) in loblolly pine (Pinus taeda L.) were examined. Transcripts arising from both gene subfamilies were shown to be present at high levels in the cotyledons of dark-grown pine seedlings and to a lesser extent in their stems. Exposure of dark-grown seedlings to light resulted in increased levels of both porA and porB transcripts, as well as increased levels of mRNAs encoding other photosynthesis-related gene products, suggesting that they are under a common mode of regulation. Relative levels of the porA and porB transcripts were similar in seedling cotyledons and primary needles of two-month-old pine trees, whereas only porB transcripts were present at a significant level in mature secondary needles of two-year-old trees. Immunoblot analysis showed that the 37 kDa PORA protein was most abundant in dark-grown tissues, decreased dramatically upon exposure to light, but could still be detected at low levels in light-grown seedlings. In comparison, levels of the 38 kDa PORB protein were not significantly changed upon transfer of dark-grown tissues to light. While both PORA and PORB were detected in cotyledons and primary needles, only PORB could be detected in mature needles. Transcripts derived from the three plastid genes, chlL, chlN, and chlB, encoding subunits of the light-independent protochlorophyllide reductase were detected in the cotyledons and stems of dark-grown seedlings, and in mature needles. The highest levels of chlL, chlN, and chlB transcripts were detected within the top one-third of the stem and decreased gradually towards the stem/root transition zone. Correspondingly, the highest levels of light-independent chlorophyll formation took place near the top of the hypocotyl. A similar pattern of expression was observed for other photosynthesis-related gene products, including porA and porB. Our results suggest that many aspects of the light-dependent, tissue-specific and developmental regulation of POR expression first described in angiosperms were already established in the less evolutionarily advanced gymnosperms. However, unlike angiosperms, light is not the dominant regulatory factor controlling porA expression in these species.

Algal Proteins↗

PubMed1999

Accuracy of prediction equations to estimate submaximal VO2 during cycle ergometry: the HERITAGE Family Study.

UNLABELLED: It was hypothesized that more accurate equations for estimating submaximal VO2 during cycle ergometry could be developed if more independent variables were used in the equation. PURPOSE: The purposes of this study were: (1) to develop new equations for estimating submaximal VO2 during cycle ergometry; and (2) to examine the accuracy of the newly developed equations and those of the American College of Sports Medicine (1995), Berry et al. (1993), Lang et al. (1992), Latin and Berg (1994), and Londeree et al. (1997). METHODS: Subjects (715 men and women, ages 16-65 yr, from the HERITAGE Family Study) completed a maximal cycle ergometry test, two submaximal trials at 50 W and 60% of VO2max, hydrostatic weighing, and stature and body mass measures before and after 20 wk of cycle ergometry training. Regression analysis generated prediction equations using pretraining data from the 60% trials. RESULTS: No equation with more independent variables was better than an equation that used only power output. This equation, HERITAGE-1, with only power output was cross-validated using the "jackknife" technique. Paired t-tests, mean differences, SEEs, and Es were used to compare the VO2 estimated by HERITAGE-1 and those of previously published equations with the measured VO2 at 60% of VO2max. CONCLUSIONS: HERITAGE-1 was slightly better than the equations of ACSM, Lang et al., and Latin and Berg using pretraining data but was not better when using post-training data. All four of these equations were superior to the equations of Berry et al. and Londeree et al.

Adolescent↗

PubMed1998

Acute coronary syndromes in the United States and United Kingdom: a comparison of approaches. The Antithrombotic Therapy in Acute Coronary Syndromes Research Group.

BACKGROUND: Patients with coronary artery disease are managed differently in different countries. HYPOTHESIS: These variations in patient management may affect clinical outcome, a possibility that should be taken into consideration in multicenter studies. METHODS: In a binational, 3 months study of antithrombotic treatment of patients with unstable angina and non-Q-wave infarction (ATACS), we compared the experience in the four enrollment centers in the United States (US) with the three centers in the United Kingdom (UK). The 59 US patients and the 299 UK patients were similar with regard to age, rates of prior revascularization, prior positive exercise tests, medication use, and aspirin use. RESULTS: US patients were more commonly women (45 vs. 28%), diabetic (30 vs. 4%), or hypertensive (52 vs. 31%), and had a prior coronary angiogram (30 vs. 18%). After enrollment, coronary angiography was performed more frequently in the US than in the UK (61 vs. 22%). Although the distribution of coronary disease was similar, revascularization without recurrent angina (19 vs. 4%, p < 0.001), or following recurrent angina (8 vs. 3%), was significantly more frequent in the US. Combined primary end points (recurrent angina, myocardial infarction, or death) did not differ between US (29%) and UK (25%) patients. CONCLUSION: Therefore, international studies of acute coronary disease need to account for different treatments in different countries. These differences, in the small ATACS study, did not have a major impact on the composite primary outcome variables.

Adult↗

PubMed1998

Limits to maximal performance in individuals with spinal cord injury.

The purpose of this study was to examine the effect of four conditions that might improve oxygen transport and/or utilization during maximal exercise performance in individuals with spinal cord injury (SCI). Five males with tetraplegia (TP) and four males with paraplegia (PR) performed maximal arm cranking exercise in the following positions: 1) sitting; 2) supine; and 3) sitting with the addition of a) anti-gravity suit (anit-G), b) elastic stockings and abdominal binder, and c) functional electrical stimulation (FES) of the paralysed leg muscles. Peak power output (PO peak), peak oxygen uptake (VO2peak), peak heart rate (HR peak) and maximal systolic blood pressure were significantly lower in TP compared to PR for all conditions. A significant decrease in HR peak for PR, and a significant increase in VO2peak/kg for TP was seen during the supine compared to sitting condition. Respiratory exchange ratio (R) decreased significantly during the FES compared to the sitting condition in TP. No other changes were observed for any of the other conditions in either group. Improvements in central circulation previously reported during submaximal exercise for these four conditions did not result in a concomitant rise in maximal exercise performance. The results of this study suggest that the limitation in VO2peak for individuals with SCI is located peripherally (small active muscle mass) rather than centrally (heart or lungs).

Abdomen↗

PubMed1998

Blood redistribution and circulatory responses to submaximal arm exercise in persons with spinal cord injury.

The purpose of this study was to evaluate responses to submaximal arm exercise (20%, 40%, and 60% of peak power output) using four conditions to support the circulatory redistribution in persons with spinal cord injury (SCI). Five males with tetraplegia (TP) and four males with paraplegia (PR) exercised 1) sitting, 2) supine, and 3) sitting with the addition of a) an anti-gravity suit (anti-G), b) elastic stockings and abdominal binder, and c) functional electrical stimulation of the leg muscles. Compared to sitting, the following significant changes were observed: in the supine position, heart rate (HR) decreased (PR: 104 vs 118 b/min, TP: 76 vs 92 b/min) and stroke volume (SV) increased (PR: 132 vs 116 ml, TP: 96 vs 83 ml). The anti-G suit induced a decrease in heart rate (PR: 104 vs 118 b/min, TP: 87 vs 92 b/min) and a decrease in oxygen uptake (VO2) in PR. Stockings only affected TP, i.e. a decrease in heart rate with 5 b/min and an increase in stroke volume with 13 ml/beat. Functional electrical stimulation produced an increase in VO2 (PR: 1.00 vs 0.95 l/min, TP: 0.68 vs 0.53 l/min) and a rise in stroke volume in TP. Results indicate that the methods employed to support the circulatory redistribution have different working mechanisms and, in addition, that the effects are different for TP and PR probably because of differences in active muscle mass, sympathetic impairment and blood pressure values.

Adult↗

PubMed1998

Alterations in resting metabolic rate as a consequence of 20 wk of endurance training: the HERITAGE Family Study.

This study determined the effects of endurance exercise training on the resting metabolic rate (RMR). It was hypothesized that the RMR would be increased posttraining, but that this increase would reflect the influence of the last exercise bout, not a chronic adaptation to exercise training. Seventy-four subjects (40 men and 37 women) aged 17-63 y participated in a 20-wk endurance training program. RMR and maximal oxygen uptake (VO2max) were each measured on 2 separate days both pre- and posttraining; the posttraining RMR measurements were taken 24 and 72 h after the last exercise bout. There were small but significant changes posttraining in relative body fat (-1.0%), fat mass (-0.6 kg), and fat-free mass (0.7 kg) and a 17.9% increase in VO2max. The RMR remained unchanged posttraining, both 24 and 72 h after the last exercise bout, even when the data were adjusted to account for the potential confounding effects of age, sex, body composition, and VO2max. In conclusion, 20 wk of endurance exercise training had no effect on the RMR even in the presence of small changes in body composition and a large increase in VO2max.

Adolescent↗

PubMed1998

Lower daily energy expenditure as measured by a respiratory chamber in subjects with spinal cord injury compared with control subjects.

BACKGROUND: This study was designed to determine the effect of chronic spinal cord injury on daily energy expenditure. OBJECTIVE: We hypothesized that both resting and total energy expenditure would be lower in spinal cord-injured (SCI) subjects than in control subjects because of lower sympathetic nervous system activity and reduced levels of physical activity in SCI subjects. DESIGN: Twenty-four-hour energy expenditure (24-h EE), resting metabolic rate (RMR), sleeping metabolic rate, spontaneous physical activity, the thermic effect of food (TEF), and 24-h respiratory quotient were measured by using a respiratory chamber in 10 male SCI subjects (injury ranged from level C6 to L3) and 59 age-matched, noninjured, male control subjects. RESULTS: The 24-h EE was lower in SCI than in control subjects (7824 +/- 305 compared with 9941 +/- 188 kJ, P < 0.01). After adjustment for fat-free mass, fat mass, and age, 24-h EE was still lower (-753 kJ/d, P < 0.01) in SCI than in control subjects. Spontaneous physical activity measured by a radar system was also significantly lower (4.6 +/- 0.6% compared with 6.5 +/- 0.3% of time, P < 0.01) in SCI than in control subjects. In absolute value (7347 +/- 268 compared with 9251 +/- 1326 kJ/d, P < 0.01) or after adjustment for fat-free mass, fat mass, and age (-678 kJ/d, P < 0.01), RMR was also lower in SCI than in control subjects. TEF was significantly lower in SCI than in control subjects (987 +/- 142 compared with 1544 +/- 213 kJ/d, representing 12.9% and 15.9% of total energy intake, respectively, P < 0.05). The sleeping metabolic rate and 24-h respiratory quotient did not differ significantly between groups. CONCLUSIONS: The 24-h EE was significantly lower in SCI than in control subjects. This difference can be explained by the lower levels of physical activity, and lower RMR and TEF values, in SCI subjects.

Adult↗

PubMed1998

Loblolly pine (Pinus taeda L.) contains multiple expressed genes encoding light-dependent NADPH:protochlorophyllide oxidoreductase (POR).

NADPH:protochlorophyllide oxidoreductase (POR) catalyzes the light-dependent reduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide), a key regulatory step in chlorophyll biosynthesis. In most angiosperms, POR is encoded by a small nuclear gene family, containing at least two differentially-expressed genes designated porA and porB. We have demonstrated that the PORs of loblolly pine (Pinus taeda L.), a gymnosperm, are encoded by a large multigene family, composed of two distinct subfamilies encoding porA and porB genes similar to those previously described in angiosperms. DNA gel blot analysis of genomic DNA showed that the two por subfamilies of loblolly pine have duplicated at different rates, with the porA subfamily containing two members, and the porB subfamily containing at least 11 potential members. DNA sequence analysis and gel blot hybridization studies also showed that a subset of the por genes present in the loblolly pine genome are pseudogenes. Based on the results of 5'- and 3'-RACE analysis, it appears that multiple porA and porB genes are expressed in loblolly pine cotyledons and stems during development. Using gene specific probes, no difference was observed in the steady-state levels of the different porA and porB transcripts in cotyledons of dark-grown seedlings before and following illumination. However, the steady state levels of the porA and porB transcripts were found to increase at different rates in the stems of dark-grown seedlings following illumination. The phylogenetic relationship between the por gene family members in P. taeda and other pine species and the potential significance of the two por subfamilies to the evolution of por gene function are discussed.

Amino Acid Sequence↗

PubMed1998

Familial resemblance for VO2max in the sedentary state: the HERITAGE family study.

This study investigates the familial resemblance of maximal oxygen uptake (VO2max) based on data from 86 nuclear families of Caucasian descent participating in the HERITAGE Family Study. In the current study, VO2max was measured twice on a cycle ergometer in 429 sedentary individuals (170 parents and 259 of their offspring), aged between 16 and 65 yr. The VO2max was adjusted by regression procedures for the effects of 1) age and sex; 2) age, sex, and body mass; and 3) age, sex, body mass, fat mass, and fat-free mass, as determined by underwater weighing. Evidence for significant familial resemblance was observed for each of the three VO2max phenotypes. Spouse, sibling, and parent-offspring correlations were significant, suggesting that both genetic and environmental factors contribute to the familial resemblance for VO2max. Maximal heritability estimates were at least 50%, a value inflated to an undetermined degree by nongenetic factors. The hypothesis of maternal inheritance, with the father's contribution being environmental, was also found to fit the data with estimates of maternal heritability, potentially associated in part with mitochondrial inheritance, reaching about 30%. These results suggest that genetic and nongenetic factors as well as maternal influences contribute to the familial aggregation of VO2max in sedentary individuals.

Adolescent↗

PubMed1998

Reproducibility of cardiovascular, respiratory, and metabolic responses to submaximal exercise: the HERITAGE Family Study.

This study determined the reproducibility of cardiovascular, respiratory, and metabolic responses to submaximal cycle ergometer exercise at two power outputs (50 W and 60% VO2max) on each of two separate days in a sample of 390 subjects (198 men and 192 women) participating in the HERITAGE Family Study. The same protocol was conducted across 3 d in an intracenter quality control substudy which included an additional 55 subjects. Reproducibility estimates included technical error, coefficient of variation, and intraclass correlation for each of the selected variables for both subject populations. Further, since the data were collected across four clinical centers, intraclass correlations were also computed separately by clinical center. Most variables were highly reproducible, with coefficients of variation below 9% and intraclass correlations over 0.80. These results were consistent for both subject populations and across all four clinical centers. Reproducibility indicators were generally better at the higher power output. It is concluded that within-subject day-to-day variation and measurement unreliabilities are generally small compared with the between-subject variance in the response to submaximal exercise at each of the clinical centers of the HERITAGE Family Study.

Adolescent↗

PubMed1998

Three mitochondrial DNA restriction polymorphisms in elite endurance athletes and sedentary controls.

This study examined the associations between elite endurance athlete (EEA) status and three mitochondrial DNA (mtDNA) restriction fragment length polymorphisms (RFLPs) in the subunit 5 of the NADH dehydrogenase (MTND5) locus and one in the D-loop region. A group of 125 Caucasian male EEA well endowed with the phenotypic expression of VO2max (78.9 +/- 3.8 mL x kg(-1) x min(-1), mean +/- SD) and 65 sedentary controls (SCON: VO2max = 39.8 +/- 8.2 mL x kg(-1) x min(-1)) participated in the study. VO2max was determined during an incremental exercise test on a cycle ergometer or a motor-driven treadmill. mtDNA was extracted from white blood cells or lymphoblastoid cell lines and specific regions were amplified by the polymerase chain reaction. The Pearson Chi-square statistic test and Fisher exact test revealed no significant association (P > 0.05) between any of the three mtDNA RFLPs and EEA status. The MTND5-BamHI RFLP at bp 13,470 (morph 3) was found in 12.8% of the EEA and 12.3% of the SCON (chi2 = 0.009, P = 0.92). The prevalence of the MTND5-Ncil RFLP at bp 13,364 (morph 2) was 12.9% and 14% for the EEA and SCON, respectively (chi2 = 0.043, P = 0.83). The D-loop-KpnI RFLP at bp 16,133 (morph 1) was found in 5.8% of the EEA and in 1.6% of the SCON (Fisher exact test = 1.80, P = 0.18). The MTND5-HincII RFLP at bp 12,406 (morph 1) was not present in this study sample. These results indicate no evidence for a difference in the frequency of two polymorphic restriction sites in the subunit 5 of the NADH dehydrogenase gene of mtDNA and one in the D-loop region between elite endurance athletes and sedentary controls.

Adolescent↗

PubMed1998

Familial clustering of insulin and abdominal visceral fat: the HERITAGE Family Study.

Abdominal visceral fat (AVF) is an obesity-related phenotype thought to be associated with insulin resistance, diabetes mellitus, and atherosclerosis. Significant genetic influences on both AVF and insulin levels have been reported. However, information is lacking as to whether common genetic influences on AVF and insulin levels exist. AVF was assessed by computed tomography scan, and fasting insulin was measured by RIA in 512 members of 98 sedentary Caucasian families participating in the HERITAGE Family Study. Baseline data, collected before exercise training, were used in the present investigation. A bivariate familial correlation model was applied to evaluate whether there are familial influences that are common to insulin and AVF before and after adjustment for total fat mass (FM), and to assess the overall heritability of insulin and AVF. The maximal heritability for AVF, before and after adjustment for total FM, was 42% and 50%, respectively; and for insulin, it was 21%. Interestingly, 29% of the familial influences on insulin were also common to AVF, whereas 14% of the familial influences on AVF were shared by insulin. Furthermore, after AVF was adjusted for total FM, these common familial influences were increased to 48% and 20%. Genes and/or familial nongenetic factors with pleiotropic effects seem to influence both AVF and plasma insulin levels to a certain degree. Genes involved in the regulation of lipid storage and mobilization in the abdominal fat depot are potential candidates for these genetic pleiotropic effects.

Adipose Tissue↗

PubMed1998

Familial resemblance for resting blood pressure with particular reference to racial differences: preliminary analyses from the HERITAGE Family Study.

Resting blood pressure in both white and black families participating in the HERITAGE Family Study was analyzed using a simple familial correlation model to assess familial influences. The two samples of black and white families were analyzed separately and together, providing an opportunity to test for heterogeneity in the familial resemblance. Maximal heritability was 46% for systolic blood pressure (SBP) and 31% for diastolic blood pressure (DBP) in the pooled sample. Noticeably higher heritabilities were found in the black sample (68% for SBP and 56% for DBP) than in the white sample (43% for SBP and 24% for DBP). The patterns of familial correlations were similar in blacks and whites, with the exception that spouse resemblance was significant in white families but not in black families. These results along with the finding that the magnitude of the familial correlations was higher in the black sample than in the white sample suggest that the effects of host and familial environmental factors differ between the races.

Adolescent↗

PubMed1997

Segregation analysis of abdominal visceral fat: the HERITAGE Family Study.

A major gene hypothesis for abdominal visceral fat (AVF) level, both before and after adjustment for total body fat mass, was investigated in 86 white families who participated in the HERITAGE Family Study. In this study, sedentary families were tested for a battery of measures (baseline), endurance exercise trained for 20 weeks, and then remeasured again. The baseline measures reported here are unique in that the variance due to a potentially important environmental factor (activity level) was limited. AVF area was assessed at L4 to L5 by the use of computerized tomography scan, and total body fat mass was assessed with underwater weighing. For fat mass, a putative locus accounted for 64% of the variance, but there was no evidence of a multifactorial component (i.e., no polygenic and/or common familial environmental effects). For AVF area, both a major gene effect accounting for 54% of the variance and a multifactorial component accounting for 17% of the variance were significant. However, after AVF area was adjusted for the effects of total level of body fat, the support for a major gene was reduced. In particular, there was a major effect for fat mass-adjusted AVF area, but it was not transmitted from parents to offspring (i.e., the three transmission probabilities were equal). The importance of this study is twofold. First, these results confirm a previous study that suggested that there is a putative major locus for AVF and for total body fat mass. Second, the findings from the HERITAGE Family Study suggest that the factors underlying AVF area in sedentary families may be similar to those in the population at large, which includes both sedentary and active families. Whether the gene(s) responsible for the high levels of AVF area is the same as that which influences total body fat content remains to be further investigated.

Abdomen↗

PubMed1997

Effect of electrical stimulation of leg muscles on physiological responses during arm-cranking exercise in healthy men.

The purpose of this study was to investigate the hypothesis that changes in physiological responses during arm-cranking exercise using electrical stimulation of the leg muscles (ACE-ES) compared to arm-cranking exercise alone (ACE) in able-bodied subjects (ABS) are based on an increase in active muscle mass rather than the enhancing effect of the leg muscle pump. In ABS the sympathetic nervous system induced vasoconstriction and activity of the leg muscle pump are intact, therefore, a normal redistribution of blood takes place during exercise. Consequently, ES should have no additional effect on the redistribution of blood in these ABS during exercise and, thus, changes in physiological responses will be based on an increase in active muscle mass. A group of 11 ABS performed three maximal arm-cranking tests. In the first test peak power output (POpeak) was determined. The other tests were both submaximal and maximal ACE, once with ACE-ES and once with ACE. The POpeak was not significantly different between ACE-ES and ACE. Oxygen uptake (VO2) increased significantly during ACE-ES compared to ACE. Cardiac output (Qc), stroke volume (SV), heart rate and ventilation were not significantly different during ACE-ES compared to ACE. Respiratory exchange ratios were significantly lower during ACE-ES compared to ACE at 60% POpeak and at maximal exercise. In conclusion, ACE-ES caused significant increases in VO2 with a lack of elevation in Qc and SV during submaximal and maximal exercise in ABS. The results of this study suggest that changes in physiological responses during ACE-ES are based on an increase in the active muscle mass rather than stimulation of the leg muscle pump.

Adult↗

PubMed1997

Reproducibility of the HERITAGE Family Study intervention protocol: drift over time.

PURPOSE: The primary goal of the HERITAGE Family Study was to document the role of the genotype in the response to aerobic exercise training. Toward this end, nuclear families were enrolled in a 20-week exercise training program, with a large variety of tests performed before and after the training. Since study drift has the potential to adversely affect the results, reproducibility and potential bias over six consecutive 4-month periods were examined for selected test. METHODS: Intraclass correlations (ICC), technical errors (TE), coefficients of variation within subject (CV), and means were calculated with use of the pretraining test results for each of the six time periods. To check for homogeneity, hypothesis tests were performed on the intraclass correlations and means. If homogeneity was not found across all six periods, further tests were performed to assess differences between pairs of time periods. RESULTS: There was little evidence for real drifts in reproducibility, with most tests having ICCs of 0.8 or better. Only a few tests showed any change over time, and in no case was there evidence of a systematic drift in mean values. CONCLUSIONS: Overall, the reproducibility of the HERITAGE Family Study tests and assays considered in this paper was found to be very good, with no evidence of any systematic drift over time.

Adolescent↗

PubMed1997

Reproducibility of anthropometric and body composition measurements: the HERITAGE Family Study.

OBJECTIVE: To determine the reproducibility of anthropometric and body composition measures using the HERITAGE Family Study protocol. DESIGN: Anthropometric and body composition measures were obtained on three separate days within a 3-wk period at each of the four HERITAGE Clinical Centers. SUBJECTS: Sixty men and women representative of the HERITAGE subject population, 15 from each of four Clinical Centers. MEASUREMENTS: Anthropometric measures included eight skinfolds, three girths and one length; and body composition measures included stature, mass, hydrostatic weight, residual volume, and body density, from which relative fat, fat mass and fat-free mass were estimated. RESULTS: Reproducibility as determined by technical error, coefficient of variation, and intraclass correlations was very high for the total sample. For example, intraclass correlations for the total sample generally ranged from 0.95-0.99 for the anthropometric measures, and from 0.97-1.00 for the body composition measures. The results across Clinical Centers were in close agreement with each other and with the pooled data. CONCLUSIONS: The reproducibility of anthropometric and body composition measures using the HERITAGE Family Study protocol is sufficiently high that it should be possible to detect small changes in any of these measures and to determine the genetic basis of these changes consequent to a 20 wk endurance training program.

Adult↗