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Biomedical subjects

C Bouchard

Publications and source records attributed to C Bouchard.

At least 91 records · Page 5Linked to original sources
PubMed1999

Evidence of a major locus for lipoprotein lipase (LPL) activity in addition to a pleiotropic locus for both LPL and fasting insulin: results from the HERITAGE Family Study.

A major gene hypothesis for heparin releasable plasma lipoprotein lipase (PH-LPL) activity was assessed using segregation analyses of data on 495 members in 98 normolipidemic sedentary families of Caucasian descent who participated in the HERITAGE Family Study. Segregation analyses were performed on PH-LPL adjusted for age, and on PH-LPL activity adjusted for age and fasting insulin. Prior to adjustment for insulin, neither a major gene effect nor a multifactorial component could be rejected, and support for a major gene was equivocal i.e. neither the Mendelian transmission nor the no transmission (equal tau s) models were rejected. However, after adjusting for the effects of insulin, a major gene effect on PH-LPL activity was unambiguous. The putative locus accounted for 60% of the total phenotypic variance, and the homozygous recessive form affected 10% (q2) of the sample (i.e. gene frequency (q) = 0.31), and led to a low PH-LPL value. The lack of a significant multifactorial effect suggested that the familial etiology of PH-LPL activity adjusted for insulin was likely to be primarily a function of the major locus. In conclusion, the present study is the first to report segregation analyses on PH-LPL activity prior to and after adjusting for insulin, and suggests that there is an indication of a pleiotropic genetic effect on PH-LPL activity and insulin, in addition to a major gene effect on PH-LPL activity alone.

Adolescent↗
PubMed1999

Plasma adrenal, gonadal, and conjugated steroids following long-term exercise-induced negative energy balance in identical twins.

There are few reports of the change in sex hormone levels accompanying a weight change in men, although an excessive decline in testosterone (TESTO) has been described as an associate of stress-induced weight loss. Plasma levels of cortisol, TESTO, dihydrotestosterone (DHT), dehydroepiandrosterone sulfate (DHEA-S), androsterone glucuronide (ADT-G), and androstane-3alpha, 17beta-diol glucuronide (3alphaDIOL-G) were measured in seven pairs of sedentary male monozygotic twins (age, 21.0 +/- 0.8 years; body mass index [BMI], 26.2 +/- 5.5 kg/m2) before and after 93 days of standardized submaximal (50% to 55% maximum oxygen consumption) cycle-ergometer exercise. A total energy deficit of 244 +/- 9.7 MJ induced significant changes (P < .0001) in body weight ([BW] -5.0 +/- 2.2 kg) and body fatness measures. Plasma TESTO and DHEA-S increased and 3alphaDIOL-G decreased. The increase in TESTO was a significant inverse correlate of loss in all measures of body fat, particularly central adiposity (r = -.58 to -.86, P < .001, fat loss-adjusted). Lower postexercise levels of 3alphaDIOL-G correlated positively with decreased body composition measures (r = .65 to .68, P < .01). The increase in plasma TESTO accompanying the loss of abdominal visceral fat (AVF) was greater in men with lower fasting insulin levels (P < .0001). The baseline within-twin-pair resemblance in TESTO and 3alphaDIOL-G (intraclass correlation coefficients [ICC] = .83 and .78, respectively, P < .01) was lost with intervention. Cortisol, DHEA-S, and ADT-G developed within-twin-pair similarity (ICC adjusted for fat loss: cortisol, .72; ADT-G, .62, P < .05; DHEA-S, .85, P < .002). We conclude that a steroid profile characterized by high TESTO and low androgen metabolite levels accompanied the changes in body composition and body fat distribution generated by the exercise-induced negative energy balance. Furthermore, these changes were characterized by a significant resemblance within identical-twin pairs.

Adult↗
PubMed1999

Total body fat and abdominal visceral fat response to exercise training in the HERITAGE Family Study: evidence for major locus but no multifactorial effects.

The familial etiology of the response in total fat mass (FM) and abdominal visceral fat (AVF) to 20 weeks of exercise training was investigated in families participating in the HERITAGE Family Study. AVF (measured by computed tomographic scanning) and FM (measured by underwater weighing techniques) were assessed at baseline (in a sedentary state) and after 20 weeks of exercise training. The response AVF (AVFdelta) and response FM (FMdelta) were computed as the simple delta values (posttraining - baseline) and adjusted for the effects of sex, generation, and a polynomial in age using multiple regression analysis. To index the AVF response independently of the response in FM and the initial level of visceral fat, the AVFdelta was also adjusted for age and baseline AVF (AVFB) and FMdelta. Familial correlation analysis was used to investigate the multifactorial familial effects (polygenic and/or familial environmental), and segregation analysis was used to search for major gene effects. For the age-adjusted AVFdelta, a putative recessive locus accounting for 18% of the variance (q2 = 1%) was detected. Adjusting AVFdelta for AVFB and FMdelta slightly increased the percentage of variance accounted for (to 26%, q2 = 3%) but did not radically alter the pattern of the parameter estimates. For FMdelta, a putative dominant locus accounting for 31% of the variance (q2 = 49%) was noted. In conclusion, the results were consistent across methods in suggesting that there is little evidence of a multifactorial heritability for either AVFdelta or FMdelta. Rather, the familial etiology of the response to exercise training appears to be primarily due to putative major genes (a recessive locus for AVFdelta and a dominant locus for FMdelta). In addition, a pleiotropic/oligogenic system underlying these variables was inferred. That is, the putative loci for FMdelta and/or AVFB also may impact the AVFdelta, with an additional independent major locus effect on AVFdelta after the former influences have been removed.

Abdomen↗
PubMed1999

Visceral adipose tissue and low-density lipoprotein particle size in middle-aged versus young men.

Age is associated with increased deposition of visceral adipose tissue. We examined whether this age-related change in regional adipose tissue distribution had an impact on low-density lipoprotein (LDL) particle size. For this purpose, the plasma lipoprotein-lipid profile, including LDL peak particle diameter as determined by gradient gel electrophoresis, was assessed in 38 young men (aged 26.4 +/- 4.2 years, mean +/- SD) and compared with 40 middle-aged men (55.9 +/- 6.2 years). Middle-aged men had higher values for total body fat and visceral adipose tissue area as measured by computed tomography than young men (P < .001). Although significant differences were noted between the two age groups for plasma cholesterol, triglyceride (TG), apolipoprotein B (apo B), LDL cholesterol, and LDL apo B, as well as the cholesterol to high-density lipoprotein (HDL) cholesterol ratio (P < .001), no difference was found for LDL peak particle size between young and middle-aged men. While visceral adipose tissue was a significant correlate of plasma lipoprotein levels, the fasting TG concentration was the best predictor of LDL particle size, and the regression of TG levels on LDL peak particle diameter was not different between the two age groups. These results suggest that middle-aged men are characterized by an increased concentration of LDL particles (reflected by increased LDL apo B levels) but not by a reduced LDL peak particle size compared with young men. It is therefore proposed that in the absence of an important age-related change in TG levels, age per se is associated with an increased concentration of atherogenic LDL particles rather than a reduction of LDL particle diameter.

Abdomen↗
PubMed1999

[Spinal cord compression due to tophaceous vertebral gout: a case report and literature review].

INTRODUCTION: Acute gout arthritis and tophaceous gout of the spine is rare. EXEGESIS: We report the case of a 54-year-old man with chronic low back pain. Physical examination and myelography showing neurological compression on L4 laminectomy evidenced tophaceous gout. CONCLUSION: Gout arthritis should always be suspected and investigated in patients with either chronic low back pain or non-specific spinal cord compression.

Arthritis, Gouty↗
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

Linkages and associations between the leptin receptor (LEPR) gene and human body composition in the Québec Family Study.

OBJECTIVE: To investigate linkage and association between the leptin receptor (LEPR) gene and body composition variables in the Quebec Family Study (QFS). DESIGN: Single-point linkage analysis using families, and covariance and chi-square analyses using normal weight and obese unrelated subjects from QFS. SUBJECTS: 169 nuclear families were used for linkage study. 308 unrelated subjects (146 males; 162 females) from these families were used for chi-square testing of genotype and allele distributions between subjects with body mass index (BMI) < 27 kg/m2 (n = 167) and those with BMI > or = 27 kg/m2 (n = 141), and for a series of covariance analyses using age, plus height for fat mass (FM) and fat free mass (FFM), as covariates. A corrected P value (P*) for multiple tests has been calculated according to P* = 1-(1-P)(number of phenotypes). MEASUREMENTS: Variables were BMI (in kg/m2), sum of six skinfolds (SF6 in mm), FM (in kg), percent body fat (%FAT) and FFM (in kg). Polymerase chain react restricted fragment length polymorphisms PCR-RFLP) was used to identified a K109R substitution in exon 4, a Q223R in exon 6, a K656N in exon 14 and an automatic DNA sequencer for a CA microsatellite repeat in intron 3, and heteroduplex pattern on non-denaturing gel for a CTTT repeat in intron 16. RESULTS: Good evidence of linkage was observed for Q223R with FM (P = 0.005; P* = 0.02), and for the CTTT repeat with FFM (P = 0.007; P* = 0.03). Weaker linkages (0.02 < or = P < or = 0.05) were also observed between Q223R and BMI, SF6 and FFM, between the CA repeat and BMI, SF6 and FM, and between the CTTT repeat and FM. Moreover, FFM values were found to be different among genotypes for the CTTT repeat polymorphism with heavier females, carriers of the 123* allele at the CTTT repeat, showing 4 kg less of FFM (43.6 +/- 1.0, n = 21 vs 47.7 +/- 0.8, n = 30; P = 0.005; P* = 0.02) than non-carriers. Also, at the Q223R polymorphism, in lower BMI males, carriers of the Q223 allele were 4 kg lighter in FFM (53.4 +/- 0.6, n = 47 vs 56.6 +/- 0.9, n = 18; P = 0.005; P* = 0.02) than non-carriers. No significant differences were observed between lower and higher BMI subjects in genotype and allele frequency distributions for any of the polymorphisms. CONCLUSIONS: These results indicate that the LEPR gene is involved in the regulation of the body composition in human particularly of FFM in the QFS.

Adipose Tissue↗
PubMed1999

Gender difference in the effect of body composition on energy metabolism.

OBJECTIVE: The aim of this study was to investigate the relationship between energy expenditure (EE) and fat mass (FM) by using a cross-sectional approach to study the linear relationship between body composition variables and EE phenotypes as well as an intervention design to investigate the effect of body weight loss on energy metabolism in both genders. METHODS: The correlations and linear relationships between body weight, FM, fat-free mass (FFM) and abdominal fat vs 24 h EE (EE 24) and sleeping metabolic rate (SMR) were compared between 65 men and 35 women, and before and after weight loss in 10 men and 10 women. RESULTS: Our results showed that for a given FM, men displayed a higher EE than women, independently of FFM. Furthermore, regression analysis revealed that after body weight loss, men displayed a lower SMR for a given FM or FM adjusted for FFM compared to before the treatment, but this was not so in women. However, when FM was adjusted for abdominal fat deposition, the difference between the conditions was no longer observed. CONCLUSIONS: FM has a significant impact on EE only in men. We suggest that abdominal adipose tissue may exert a potent regulatory effect on energy metabolism which would be more detectable in men who generally store more fat in this compartment than women.

Abdomen↗
PubMed1999

Physique, subcutaneous fat, adipose tissue distribution, and risk factors in the Québec Family Study.

OBJECTIVE: To investigate the relationships among subcutaneous fatness, subcutaneous adipose tissue (SAT) distribution, somatotype and risk factors for coronary heart disease (CHD). SUBJECTS: The sample included 1410 (715 male and 695 female) youths and adults from the Quebec Family Study. MEASUREMENTS: Six skinfolds and the dimensions necessary for the derivation of the Heath-Carter anthropometric somatotype (endomorphy, mesomorphy, ectomorphy) were measured. The six skinfolds were summed to provide an index of subcutaneous adiposity (SUM). In addition, the trunk-to-extremity skinfold ratio, adjusted for SUM using regression procedures (TER), and the first principal component (PC1) of skinfold residuals (also adjusted for SUM) were used to indicate SAT distribution, independent of the overall level of fatness. Risk factors for CHD included systolic and diastolic blood pressures, and fasting glycaemia, triglycerides (TGs), plasma cholesterol, high and low density lipoprotein (HDL-C and LDL-C) cholesterol, and the HDL-C/total cholesterol (CHOL) ratio. RESULTS: In general, SUM was positively correlated with endomorphy and mesomorphy, and negatively correlated with ectomorphy. On the other hand, SAT distribution was not associated with somatotype, except in females where TER and PC1 were negatively correlated with mesomorphy. Results of forward stepwise regression analyses to predict CHD risk factors, indicated that a significant proportion of the variance in the risk factors could be accounted for by SUM, SAT distribution and somatotype (up to 16%). SUM is the best predictor, entering the regressions first (most important) in six of 15 significant regressions in males and 14 of 16 significant regressions in females. Somatotype components enter as predictors 10 times in males, and six times in females. Similarly, TER and PC1 enter as predictors nine times in males and five times in females. CONCLUSIONS: Somatotype is related to SUM, while somatotype and SAT distribution are largely independent of one another. Furthermore, SUM, somatotype and SAT distribution are significant predictors of biological risk factors for CHD.

Adipose Tissue↗
PubMed1999

A mitochondrial DNA D-loop polymorphism and obesity in three cohorts of women.

OBJECTIVE: To examine the hypothesis of an association between a mtDNA D-loop Kpn I restriction site polymorphism (RSP) at base pair (bp) 16,133 (morph-1) and obesity in women. DESIGN: Comparisons of carriers and noncarriers of the mutation for BMI (Body Mass Index) levels and of the frequency of the mutation in obese and normal weight women. SUBJECTS: 567 unrelated adult Caucasian non-diabetic women from the HERITAGE Family Study (n = 63; BMI: 15-47 kg/m2), Quebec Family Study (QFS; 77 controls, BMI: 19-26 kg/m2 and 38 obese, BMI: 27-56 kg/m2) and Swedish Obese Subjects (SOS) Study (81 controls, BMI: 18-26 kg/m2 and 308 obese, BMI: 33-58 kg/m2). MEASUREMENTS: BMI was calculated from weight and height (kg/m2). mtDNA was amplified between base pair 15,928 and 16,500 by polymerase chain reaction (PCR) and digested with the restriction endonuclease Kpn I. RESULTS: No significant differences in the age-adjusted BMI for the mtDNA D-loop Kpn I RSP at base pair (bp) 16,133 (morph-1) between carriers and non-carriers in the HERITAGE cohort. No significant association was found between BMI and the Kpn I RSP carrier status in the SOS and QFS cohorts. The observed frequencies for the Kpn I RSP were not significantly (P > 0.05) different between the SOS controls and SOS obese irrespective of the degree of severity of obesity (BMI > 40, > 45 or > 50 kg/m2). CONCLUSION: We conclude that the mtDNA D-loop Kpn I RSP at bp 16,133 (morph-1) is not a determinant of human obesity.

Adult↗
PubMed1999

The prediction of abdominal visceral fat level from body composition and anthropometry: ROC analysis.

OBJECTIVE: To evaluate the merit of body mass index (BMI), % body fat, waist circumference and waist-to-hip ratio as predictors of abdominal visceral fat (AVF) level. DESIGN: Cross-sectional measurements obtained from 458 female and 331 male subjects of French Canadian descent with an age range from 18-72 y. MEASUREMENTS: AVF level was assessed by computed tomography. BMI was calculated as weight (in kg) divided by stature2 (in m), body density was derived from underwater weighing and % body fat was computed from the estimate of body density with the Siri equation. Waist-to-hip ratio was calculated as waist circumference divided by hip circumference. Receiver operating characteristic (ROC) curves were used to identify the optimal cut-off points. RESULTS: In younger women (< 40 y, n = 258), waist-to-hip ratio was the poorest predictor of AVF level with areas under the ROC curves (Az) ranging from 0.684-0.716, sensitivity (Sen) from 63.3-68.8% and specificity (Spe) from 64.0-67.5%, whereas the Az, Sen and Spe for other predictors ranged from 0.924-0.983, 87.0-96.8, and 83.4-92.7, respectively. The same trend was observed in older (> or = 40 y, n = 200) women, although differences between waist-to-hip ratio and other predictors were less pronounced. In older men, waist circumference was the best overall predictor (Az from 0.88-0.92), whereas BMI showed the lowest Az values (0.831-0.875, P < or = 0.001 vs waist circumference). In younger men, BMI had the smallest Az (P < 0.007 vs others) with the lowest AVF cut-off point (100 cm2). However, with higher AVF cut-offs the differences were not significant. CONCLUSION: Waist circumference is the best overall predictor of abdominal visceral obesity, whereas in women waist-to-hip ratio is a poor indicator of AVF and its use as a surrogate measure of visceral fat should be avoided.

Adipose Tissue↗
PubMed1999

Contribution of the cholesteryl ester transfer protein gene TaqIB polymorphism to the reduced plasma HDL-cholesterol levels found in abdominal obese men with the features of the insulin resistance syndrome.

OBJECTIVE: The aim of this study was to examine the relation between the CETP-TaqIB polymorphism and reduced plasma HDL-cholesterol levels commonly observed among men characterized by abdominal obesity and features of the insulin resistance syndrome. SUBJECTS: A total of 187 sedentary men, non-smokers and free from metabolic disorders were classified on the basis of their CETP-TaqIB genotype. RESULTS: Plasma HDL and HDL3-cholesterol concentrations as well as the CETP activity were significantly different between the three genotypes, B1B1 men having significantly lower HDL and HDL3-cholesterol levels and higher CETP activity than B2B2 homozygotes. A 2x3 ANOVA was used to determine the source of variation of plasma HDL and HDL2-cholesterol levels among the three genotypic groups of men divided on the basis of either a high (>/=27 kg/m2) or a low (<27 kg/m2) BMI, a high (>/=130 cm2) or a low (<130 cm2) accumulation of visceral adipose tissue assessed by computed tomography, or a low versus a high fasting plasma insulin concentration (using the median value as a cut-off point). The effect of the CETP genotype observed on plasma HDL-cholesterol concentrations was attenuated among men with features of the insulin resistance syndrome. It seems that the expected raising effect of the B2 allele on plasma HDL-cholesterol concentrations was blunted in the presence of a BMI>/=27 kg/m2, a high accumulation of visceral adipose tissue or hyperinsulinaemia. CONCLUSION: Our data indicate that the CETP gene TaqIB polymorphism influences plasma CETP activity on one hand and plasma HDL-cholesterol concentrations on the other hand among men. The association between the TaqIB polymorphism and plasma HDL-cholesterol concentrations is altered by the presence of abdominal obesity and some features of the insulin resistance syndrome.

Abdomen↗
PubMed1999

Association and linkage between an insulin-like growth factor-1 gene polymorphism and fat free mass in the HERITAGE Family Study.

OBJECTIVE: To investigate the relationship between a DNA microsatellite marker in the insulin-like growth factor-1 (IGF-1) gene and body composition phenotypes before and following exposure to 20 weeks of aerobic exercise training in the HERITAGE Family Study. DESIGN: A controlled intervention study: fat mass (FM), percentage body fat (%FAT), fat free mass (FFM), body mass index (BMI) and abdominal visceral fat (AVF) at baseline (B) and in response to training (delta=post minus pre-training value) were measured. Association and sib-pair linkage studies were undertaken. SUBJECTS: A maximum of 502 Caucasian individuals (99 families; 190 parents and 312 adult offspring). MEASUREMENTS: The polymorphism was typed by polymerase chain reaction and DNA sequencer. The body composition phenotypes were determined from the underwater weighing method, and AVF was assessed by computerized tomography scan. RESULTS: 11 alleles were found: the lengths ranged from 189 to 209 base pairs (bp), and the frequency of the most common allele, 189 bp, reached 0.71. In association studies, significant differences for B-FM, B-FFM and B-%FAT among the three genotypes (189 bp homozygotes, heterozygotes and non-carriers) were detected. The B-FM for 189 bp homozygotes was 19.7+/-0.6 kg, but 21.6+/-0.7 and 21.3+/-1.5 kg for the 189 bp heterozygotes and the non-189 bp carriers respectively (P=0.03 after adjustment for age, sex and generation). Differences among the three genotypes were also observed for B-%FAT (25.9+/-0.5 versus 27.4+/-0.6 and 26.6+/-1.2 kg; P<0.05) and B-FFM (53.7+/-0.4 versus 54.9+/-0.5 kg and 54.4+/-1.0 kg; P<0.05). No significant difference for B-AVF was found among the three genotypes. Following 20 weeks of endurance exercise, the 189 bp homozygotes gained only about half the amount of FFM compared with the other two IGF-1 genotypes (0.3+/-0.1 vs 0.7+/-0.1 and 0.5+/-0.2 kg; P=0.005). A strong linkage was observed between the IGF-1 marker and the changes in FFM (308 pairs of full sibs, P=0.0002) but only a suggestive linkage with B-AVF (352 pairs of full sibs, P<0.02) CONCLUSION: Associations were detected between the IGF-1 gene marker and FM, %FAT and FFM at baseline, and a strong association with the changes in FFM in response to training. Moreover, the IGF-1 gene marker was found to be strongly linked to the changes in FFM in response to 20 weeks of endurance exercise and weakly linked to abdominal visceral fat in the sedentary state.

Adolescent↗
PubMed1999

Seven-year stability of indicators of obesity and adipose tissue distribution in the Canadian population.

BACKGROUND: The prevention of obesity appears to be a better approach than treatment; thus, the prediction of future obesity from current status is important. OBJECTIVE: The aim of the study was to examine the stability of adiposity and adipose tissue distribution (ATD) in the Canadian population. DESIGN: The sample included 1048 males and 1063 females aged 7-69 y at baseline from the Campbell's Survey, a 7-y follow-up of the Canada Fitness Survey. Indicators of adiposity included body mass index (BMI), sum of 5 skinfold thicknesses (SF5), and waist circumference (Waist), whereas indicators of ATD included the ratio of trunk to extremity skinfold thicknesses adjusted for SF5 (TER(adj)), and Waist adjusted for BMI (Waist(adj)). RESULTS: Interage correlations ranged from 0.53 to 0.91 for BMI, from -0.09 to 0.72 for SF5, from 0.24 to 0.89 for Waist, from 0.23 to 0.73 for TER(adj), and from 0.18 to 0.77 for Waist(adj). Correlations for BMI were higher than for SF5, suggesting that fat-free mass may contribute to the stability of BMI. Although lower than those for BMI, correlations for indicators of ATD were significant, indicating a propensity to retain an android or gynoid pattern. Furthermore, the average percentage of participants remaining in the lower or upper quintiles for the various indicators ranged from 37.8% to 66.7% in males and from 47.0% to 65.3% in females, indicating that those in the lower and upper portions of the distribution tend to remain there. CONCLUSION: Obesity and ATD showed significant stability over 7 y in the Canadian population.

Adipose Tissue↗
PubMed1999

Alterations in body weight and composition consequent to 20 wk of endurance training: the HERITAGE Family Study.

BACKGROUND: Obesity is a major public health problem in the United States. The role of physical activity and formal exercise in controlling body weight has not been clearly determined. OBJECTIVE: This study determined the magnitude of change in body weight and composition across sex, race, and age in response to 20 wk of endurance training. DESIGN: Men and women (n = 557) of various ages (16-65 y) and 2 races (black and white) exercised on cycle ergometers 3 d/wk for a total of 60 exercise sessions starting at 55% of maximal oxygen consumption (VO(2)max) for 30 min/session and building to 75% of VO(2)max for 50 min/session, where it was maintained during the last 6 wk. Skinfold-thickness measurements, circumferences, body composition (by hydrostatic weighing), and body fat distribution (by computed tomography scan at L4-L5 and the waist-hip ratio) were determined before and after training. RESULTS: All skinfold-thickness and circumference measures, waist-hip ratio, body mass index, total body mass, fat mass, percentage body fat, and computed tomography scan measures of total, subcutaneous, and visceral abdominal fat decreased with training, whereas total body density and fat-free mass increased. These changes were significant, but small. There were several differences in training response by sex and race, but not by age. CONCLUSIONS: A short-term exercise intervention can induce favorable changes in body composition, but the magnitude of these changes is of limited biological significance. Increasing physical activity likely has a major effect on body-composition and fat distribution characteristics only when it is of a greater magnitude and sustained for much longer periods

Adolescent↗
PubMed1999

Linkage of the Na,K-ATPase alpha 2 and beta 1 genes with resting and exercise heart rate and blood pressure: cross-sectional and longitudinal observations from the Quebec Family Study.

OBJECTIVE: To investigate whether genetic variations in the genes encoding the alpha and beta subunits of the Na,K-ATPase are linked with hemodynamic phenotypes. DESIGN AND PARTICIPANTS: Cross-sectional data based on 533 subjects (no antihypertensive medication) were obtained from 150 families of phase 2 of the Quebec Family Study, together with longitudinal data from 338 subjects (105 families) who had been measured 12 years earlier in phase 1 of the Quebec Family Study. MAIN OUTCOME MEASURES: Restriction fragment length polymorphisms were examined at the alpha 2 (exon 1 and exon 21-22 with BglII) and beta 1 (Msp I and Pvu II) loci of Na,K-ATPase. Hemodynamic phenotypes measured included systolic and diastolic blood pressure, heart rate and rate-pressure product at rest and during low-intensity exercise. RESULTS: Sib-pair analysis revealed relatively strong linkages (P = 0.0003-0.002) between the resting heart rate and rate-pressure product and the alpha 2 exon 21-22 marker and alpha 2 haplotype. Moreover, the alpha 2 exon 21-22 marker showed suggestive linkages (P = 0.01 to 0.043) with resting systolic blood pressure and exercise diastolic blood pressure, heart rate and rate-pressure product, and the alpha 2 haplotype with exercise diastolic blood pressure and rate-pressure product and the 12-year change in resting systolic blood pressure (P = 0.03 to 0.05). Both the beta 1 Msp I marker and the beta 1 haplotype were linked with the resting rate-pressure product (P = 0.007 and 0.003, respectively), and all beta 1 markers showed linkage with the change in resting systolic blood pressure (P = 0.00005 to 0.024). In men, there was a significant (P = 0.01) interaction between the alpha 2 exon 21-22 genotype and the postglucose plasma insulin level with regard to resting systolic blood pressure. CONCLUSIONS: These data suggest that the alpha 2 and beta 1 genes of Na,K-ATPase contribute to the regulation of hemodynamic phenotypes in healthy subjects.

Blood Pressure↗
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↗