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Biomedical subjects

A Tremblay

Publications and source records attributed to A Tremblay.

At least 325 records · Page 18Linked to original sources
PubMed1985

Evidence for a regional component of body fatness in the association with serum lipids in men and women.

Four hundred and seventy-two subjects (234 women and 238 men), 18 to 50 years of age, participated in percent body fat determination from underwater weighing, assessment of 6 subcutaneous skinfold thicknesses, and a 12-hour fast blood sampling for measurement of serum triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), total cholesterol (CHOL), and HDL-C/CHOL ratio. Even though women were significantly fatter than men, they had lower TG, CHOL, and higher values of HDL-C/CHOL ratio. Correlational and variance analyses showed that body fatness seemed to be more closely associated with serum lipids in men than in women. Moreover, the relationship between each skinfold and serum lipids indicated that subscapular and abdominal fat depots are more closely associated with serum lipids than other fat depots in men. In women, correlations were lower and regional differences attenuated. Furthermore, the regional trend observed in men remained significant after correction for concomitant variables such as age, cigarette smoking, habitual energy intake and energy expenditure, maximal aerobic power, and alcohol consumption. However, no effect of increasing body fatness was noted on HDL-C levels in women. Results of this study suggest that measurement of subscapular and abdominal fat should be considered when interpreting the blood lipid profile, particularly in males. A higher percentage of fat must be present in women than in men to observe alterations in serum lipids.

Adipose Tissue↗
PubMed1985

Resting metabolic rate in monozygotic and dizygotic twins.

In order to study the influence of heredity on resting metabolic rate (RMR), 20 monozygotic and 19 dizygotic male twins pairs aged 20.6 (SD 2.9) and 21.4 (SD 3.1) years, gave their consent to participate in the experiment. Fat free weight (FFW) was estimated from underwater weighing. RMR was measured by indirect calorimetry using an open circuit system. RMR was expressed as kJ X min-1, kJ/m2 X h-1, kJ/kg X h-1 and kJ/kgFFW X h-1. Significant intraclass coefficients were observed in MZ twins for the different expressions of RMR. The values ranged from r = 0.45 (P less than 0.05) to r = 0.81 (P less than 0.01). However, DZ twins demonstrated lower intraclass coefficients for RMR, with a range from r = 0.21 to r = 0.44. Significant (P less than 0.05) DZ resemblance was revealed only when RMR was expressed as kJ X min-1 and kJ/kg X h-1. Results of the present study suggest that variations in RMR may have a genetic component. Implications for human energy balance and body fat are discussed.

Adipose Tissue↗
PubMed1985

Contribution of postexercise increment in glucose storage to variations in glucose-induced thermogenesis in endurance athletes.

The present study was undertaken to evaluate the contribution of an increment in glucose storage to the reduced glucose-induced thermogenesis (GIT) characterizing endurance-trained individuals. For that purpose, glucose storage and GIT were determined during an oral glucose tolerance test (OGTT) in eight elite endurance athletes exercising between 6 and 16 h/week. Their values were compared with those obtained in five nontrained subjects submitted to two OGTT, i.e., before and 16 h after they had performed a 90-min vigorous exercise. As expected, endurance athletes exhibited a reduced GIT and a greater glucose storage during the OGTT in comparison to the preexercise values of nontrained subjects. Once the latter subjects had performed the 90-min exercise, their glucose storage during the OGTT was similar to the level found in athletes. This adaptation was accompanied by a significant reduction in GIT, which corresponded to 47% of the difference observed between trained and nontrained subjects when both groups maintained their usual life habits. Unlike GIT, resting metabolic rate (RMR) was found to be higher in athletes than in nontrained individuals. When subdividing the athletes into two subgroups on the basis of the duration of their weekly training, it was found that RMR was mainly elevated in those performing the higher amount of exercise. These results demonstrate that the reduced GIT characterizing endurance-trained individuals is partly explained by an increase in glucose storage during an OGTT. As further discussed, this reduced GIT is likely an indirect consequence of modifications of other energy-requiring energy processes rather than a direct result of the postexercise increment in glucose storage.

Adipose Tissue↗
PubMed1985

Influence of caffeine on the resting metabolic rate of exercise-trained and inactive subjects.

The effect of caffeine on the resting metabolic rate (RMR) was investigated in endurance exercise-trained (N = 14) and inactive (N = 10) male individuals. Subjects were also classified into regular and non-regular consumers of caffeine. After an overnight fast, RMR was measured using an indirect calorimetry open circuit system. Thereafter, subjects orally consumed 300 mg of caffeine, after which RMR was measured for 90 min. Five of the exercise-trained subjects were also studied after the administration of a placebo. Plasma concentrations of glycerol and free fatty acid and respiratory exchange ratio (R) were measured at each 15-min interval. Before caffeine ingestion, no significant differences were observed in RMR, R, glycerol, free fatty acid and blood pressure levels between exercise-trained and inactive groups. Following caffeine consumption, a three-way analysis of variance revealed that inactive subjects exhibited a greater increase (P less than 0.05) in RMR than did exercise-trained subjects. No significant differences were observed in RMR response between regular or nonregular consumers of caffeine. Moreover, no differences were observed in glycerol, free fatty acid, heart rate, and blood pressure response between exercise-trained and inactive subjects and between regular and non-regular consumers of caffeine. These results suggest that endurance training results in a reduced thermogenic response to a caffeine challenge.

Adult↗
PubMed1985

HLA system, body fat and fat distribution in children and adults.

The association between the genotypes and the alleles at the A, B or C locus of the HLA system and body fat was studied in a total of 1578 individuals subdivided in four cohorts: adult males (n greater than or equal to 204), adult females (n greater than or equal to 184), boys and male adolescents (n greater than or equal to 282), and girls and female adolescents (n greater than or equal to 257). None of these subjects were grossly obese or had known metabolic disorders. Percent body fat from underwater weighing, subcutaneous fat from 6 skinfold measurements, trunk fat (3 skinfolds) and extremity fat (3 skinfolds) were considered in the analysis. Although a few significant associations were encountered, the lack of consistency across samples suggested that they were probably random and biologically not meaningful. The same negative findings were found for the ratio of trunk subcutaneous fat to extremity subcutaneous fat and the ratio of subcutaneous fat (6 skinfolds) to total fat mass. Earlier reports indicating a significant association between high body fat content and antigens B18, Bw35 or Cw4 were not supported by the results of this study. It was concluded that no consistent pattern of association emerged between genotypes or alleles of the HLA system and percent body fat, subcutaneous fat or fat distribution in children and adults of both sexes.

ABO Blood-Group System↗
PubMed1985

Effects of aerobic training on fat distribution in male subjects.

To investigate the effects of aerobic training on adipose tissue morphology and fat distribution, several indicators of body fatness (percent body fat, seven subcutaneous skinfolds, fat cell weight) were assessed in 13 sedentary male subjects (SS) submitted to a 20-wk aerobic training program and in 20 male long-distance runners (LDR). The LDR subjects had a mean +/- SD VO2max of 65.9 +/- 6.5 ml . min-1 . kg-1 and averaged 120 km . wk-1. Training increased the VO2max values of the SS group significantly (pre: 41.9 +/- 7.0 vs post: 53.4 +/- 6.4 ml . kg-1 . min-1; P less than 0.001) and decreased significantly percent body fat (P less than 0.01), sum of skinfolds (P less than 0.01), and fat cell weight (P less than 0.05). Trunk skinfolds were more altered by training than extremity skinfolds, with reductions of 22 and 12.5%, respectively. Significant correlations were found between fat cell weight and percent body fat in SS before and after training (r = 0.75; P less than 0.01), while no significant relationship was noted in the LDR group. Moreover, using the sum of skinfolds divided by percent fat or by fat mass to reflect the proportion of subcutaneous fat to total fat, the LDR subjects exhibited less subcutaneous fat than the SS group (P less than 0.01) and training did not alter these ratios in the SS group. These results suggest that 20 wk of aerobic training can alter body fatness in men but that the induced fat loss does not seem to deplete preferentially subcutaneous fat.

Adipose Tissue↗
PubMed1984

Effects of exercise-training and detraining on fat cell lipolysis in men and women.

The effects of training and detraining on adipose tissue lipolysis were studied in 19 healthy subjects (7 women and 12 men) who were submitted to a 20-week aerobic training program. Thereafter, subjects refrained from exercise for a period of 50 days. Suprailiac fat biopsies were performed before training, after training, and at the end of the detraining period. Mean fat cell diameter and epinephrine stimulated lipolysis (ESL) were assessed on collagenase isolated fat cells. Body density through underwater weighing and skinfolds at seven different sites were also obtained. Training significantly increased ESL (P less than 0.05) in men but not in women. However, ESL values in men returned to pretraining values after the exercise restriction period. No significant changes in women lipolysis were observed under any conditions. Changes in lipolysis were not correlated with changes in body fatness. However, a significant correlation was observed between the increase in ESL produced by training and the subsequent decrease caused by detraining (r = -0.53; P less than 0.05). The present results suggest that lipolysis in fat cells from the female subjects seems to be insensitive to changes in energy expenditure. Moreover, the present study demonstrates that there are high and low responders in adipocytes ESL to variations in habitual energy expenditure.

Adipose Tissue↗
PubMed1984

The effect of a 20-week endurance training program on adipose-tissue morphology and lipolysis in men and women.

In order to assess the effect of endurance training on adipose-tissue morphology and lipolysis, 22 adult subjects (11 men and 11 women) took part in a 20-week ergocycle training program, four to five days a week, 40 minutes a day, at 80% of their maximal heart rate. Before and after training, they were submitted to an adipose-tissue biopsy in the suprailiac region. Fat cell weight (FCW), and lipolytic activity were determined on isolated fat cells. For the whole sample, training significantly reduced FCW (pre: 0.40 +/- 0.13 (mean +/- SD) versus post: 0.36 +/- 0.13 micrograms; P less than 0.05), percentage of fat (pre: 22.0 +/- 8.3 versus post: 19.7 +/- 8.1%; P less than 0.05), and increased adipocyte epinephrine maximal stimulated lipolysis (ESL) (pre: 1.08 +/- 0.49 versus post: 1.69 +/- 0.67 mumol glycerol/30 min/10(6) cells; P less than 0.001). No changes were observed in fat cell number. In women, however, training induced no changes in the fatness indicators (% fat, sum of skinfolds, FCW). The exercise program significantly lowered the adiposity of men (% fat: P less than 0.001; sum of skinfolds: P less than 0.01; FCW: P less than 0.05). In both sexes, a significant increase in ESL was observed after training. ESL of men, however, responded better than that of women to training (ESL of women: 1.36 +/- 0.67 versus ESL of men: 2.02 +/- 0.50 mumol glycerol/30 min/10(6) cells; P less than 0.05), with increases over pre-training values of 46% and 66% in women and men, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1984

Level of physical fitness and adipocyte lipolysis in humans.

The present experiment was conducted to study the influence of exercise training on adipose tissue lipolytic activity and to identify the amount of training required to induce maximal adaptation in humans. Fifty-one male subjects were divided into three groups according to their training regimen: 1) sedentary subjects (SS) (n = 21); 2) trained subjects (TS) (n = 15) who had exercised during a period of 20 wk, 5 days/wk, 45 min/session; and 3) experienced marathon runners (MR) (n = 15) who ran an average of 120 km/wk for many years. Biopsies of fat were performed in the suprailiac region after an overnight fast. Adipocyte diameter (AD) and epinephrine-stimulated lipolysis ( ESL ) were assessed on collagenase-isolated fat cells. A lower AD was noted in the MR group compared with the two other groups. Basal lipolysis (BL) and ESL were significantly higher in TS and MR than in controls. Moreover, BL values were comparable in the two trained groups, whereas ESL in the TS group was higher than in the MR group. These results indicate that training increases suprailiac fat cell lipolysis, which seems to adapt maximally within about 4 mo.

Adipose Tissue↗
PubMed1984

Adipose tissue characteristics of ex-obese long-distance runners.

Mean fat cell diameter and lipolytic activities of adipose tissue were determined in five ex-obese runners (EOR) who had experienced a mean weight loss of 39.5 kg during the course of a long-distance running program. At the time of investigation, their mean weekly running distance was 95 km in which no diet manipulation was needed to maintain their body weight. Body fat was estimated to be 14.3 percent of their body weight. Despite the high amount of exercise, subjects were not able to reduce body weight any further. Their values were compared with those obtained in the two following groups (1): six elite long-distance runners (ER) having a lower percent body fat (percent fat = 9.5); (2) five sedentary controls (SC) who were paired for adiposity with EOR (percent fat = 14.4). All subjects were submitted to a biopsy of subcutaneous fat in the suprailiac region, in which mean fat cell diameter was 57.5, 74.5, and 86 microns in EOR, ER and SC respectively. Basal and epinephrine-stimulated lipolysis were similar in EOR and SC, while ER exhibited higher values. These results indicate that exercise-training can produce important weight losses when subjects are capable of tolerating high levels of energy expenditure for extended periods of time. Moreover, the reduced fat cell diameter for a higher adiposity in EOR as compared to ER suggests that resistance to further fat loss may occur when the fat cell size is markedly reduced. No deficit in maximal epinephrine stimulated lipolysis of isolated fat cells was found in EOR in comparison to SC subjects, but they failed to adapt like lean ER subjects.

Adipose Tissue↗
PubMed1983

The influence of high carbohydrate diet on plasma glucose and insulin of trained subjects.

In previous studies we have shown that when endurance athletes refrain from daily exercise for three days, they rapidly loose their enhanced insulin sensitivity. This finding suggests that a precompetitive high carbohydrate diet with reduced training might alter plasma glucose and insulin regulation. To test this hypothesis, six long distance runners were recruited to participate in a five-day experiment. During the first two days, the subjects fasted while running 16 km d-1. Thereafter, they consumed 16.3 MJ (3900 kcal) and 539 g carbohydrate per day for three days while remaining inactive. Before and after each portion of this experiment, an intravenous glucose tolerance test (IVGTT) was performed in fasting state. As expected, fasting with exercise induced a considerable deterioration of glucose tolerance, as reflected by lower K value and higher total area glucose during IVGTT. The high carbohydrate refeeding restored glucose tolerance to a level comparable to that observed when subjects maintain their usual life habits. However, while a decrease in insulin sensitivity is observed in subjects inactive for three days, the insulin sparing effect of exercise training is retained if this period of inactivity is preceded by two days of fast accompanied by exercise. These results show that glucose disposal and insulin response to glucose injection are not adversely modified by the precompetitive "glycogen loading" procedure.

Blood Glucose↗
PubMed1983

Diminished dietary thermogenesis in exercise-trained human subjects.

The influence of exercise-training on dietary-induced thermogenesis (DIT) was investigated in humans. The resting metabolic rate was identical in trained and non-trained subjects, but the response to a meal containing 1,636 kcal (6.9 MJ) was markedly lower in trained subjects. Mean dorsal skin temperature, as measured by thermography, was not influenced by training. A significant correlation was observed between postprandial RQ and DIT, which indicates that the reduced energy expenditure noted in trained subjects is related to a greater lipid oxidation. This sparing effect of exercise-training on energy utilization in the form of carbohydrate, is interpreted as adaptive in the sense that energy is preserved for the purpose of producing work.

Adult↗
PubMed1983

Daily variations of plasma glucose and insulin in physically-trained and sedentary subjects.

The variations in plasma glucose and insulin levels were measured at 30-minute intervals throughout the day in physically trained and in sedentary subjects. The subjects exercised for 75 minutes at 65% of VO2max in the first experiment and refrained from heavy exercise in the second experiment. In all situations the physically trained subjects overall had lower plasma glucose and insulin levels than the nontrained subjects. In addition, the positive correlation between plasma glucose and plasma insulin levels observed in the physically trained subjects was significantly smaller than that note in the nontrained subjects, indicating reduced insulin requirements in physically-trained persons. During the period of exercise, glucose levels increased significantly in the trained subjects only. In the period that followed exercise, that is between 1:30 PM and 9:00 PM, the physically trained subjects had plasma glucose levels that were higher than those noted during the comparable hours not preceded by exercise; no comparable difference were found with insulin. Calculation of the total area for insulin indicated a reduction of insulin requirement of about 40% associated with physical training.

Adult↗
PubMed1983

A method to assess energy expenditure in children and adults.

A variety of studies has a need to estimate the amount and pattern of daily energy expenditure. To this end, a 3-day activity record was developed and is described. Every 15-min period over 3 days, including a weekend day, was qualified in terms of energy cost on a 1 to 9 scale corresponding to a range of 1.0 MET to 7.8 METs and higher. A reliability study of 61 subjects indicated a highly reproducible procedure as shown by an intraclass correlation of 0.96 for mean kcal of energy expenditure over 3 days. Repeatability was unchanged whether or not the hours of sleep were included in the record. Samples of 150 children and 150 adults were also drawn to investigate the relationship between energy expenditure, physical working capacity, and body fatness. Results support the hypothesis that mean energy expenditure per kg of body weight is significantly correlated with physical working capacity expressed per kg of body weight (r = 0.31; p less than 0.01). Mean energy expenditure per kg of body weight is negatively related to body fat (-0.08 less than or equal to r less than or equal to -0.13). It is concluded that the 3-day activity record is a procedure suitable to estimate energy expenditure in population studies.

Activities of Daily Living↗
PubMed1982

Variations in plasma glucose, insulin, growth hormone and catecholamines in response to insulin in trained and non-trained subjects.

Previous studies have shown a reduced insulin secretion in trained subjects challenged by a glucose load. In the present study the response to insulin of 8 athletes was compared to that of 8 non-trained subjects. The disappearance of plasma insulin was not different between the two groups, but the level of hypoglycemia was greater in the trained subjects. The injection of insulin increased the plasma levels of epinephrine (E) and norepinephrine (NE) in both groups of subjects, but the raise in E was greater in the trained subjects. Similarly, the increase of growth hormone (GH) was greater in the trained subjects. These findings substantiate previous results showing a decreased insulinic index and an increased insulin binding to monocytes in trained subjects. It is also suggested that the enhanced E and GH secretion found in trained subjects injected with insulin, is possibly related to the greater fall in plasma glucose in the trained subjects compared to the non-trained subjects.

Adult↗
PubMed1982

Role of exercise-training in the prevention of hyperinsulinemia caused by high energy diet.

The present study was undertaken to determine whether exercise-training done in combination with feeding a high energy diet could modulate carbohydrate metabolism. Male rats were divided into exercise-trained or sedentary groups that received either a palatable high energy diet or merely standard laboratory diet. After 10 weeks of training, the animals were subjected to an intravenous glucose tolerance test. Body weight, epididymal fat pads, and adipocyte volume were reduced following training. The results also showed that exercise-training protects against deterioration of glucose tolerance produced by high energy diet. Training prevented the elevation of basal as well as glucose challenged insulin levels induced by the high energy diet in spite of a high fat as well as high overall energy intake. A highly significant coefficient of correlation (r = 0.78, P less than 0.01) was observed between the size of adipocytes and the insulin response to glucose load and suggests that the prevention of hyperinsulinemia in rats fed high energy foods while training could be associated with the ability to prevent obesity.

Adipose Tissue↗