Showing papers by "Claude Bouchard published in 1984"
TL;DR: The results suggest that there are considerable individual differences in the adaptive capacity to short-term endurance training, and sensitivity of maximal aerobic power to such training is largely genotype-dependent.
Abstract: Ten pairs of monozygotic twins of both sexes were submitted to a 20-wk endurance-training program, four and five times per week, 40 min per session, at an average of 80% of the maximal heart rate reserve Testing and training were performed on cycle ergometers Maximal aerobic power (MAP in ml O2 X min-1 X kg-1) and ventilatory aerobic (VAT) and anaerobic (VANT) thresholds (ml O2 X min-1 X kg-1) were measured before and after the training program, as well as during the 7th and 14th week to adjust training to changes in maximal heart rate Considering the 20 individuals as a group, training significantly (P less than or equal to 001) increased MAP (from 44 +/- 6 to 50 +/- 6), VAT (25 +/- 3 to 30 +/- 4), and VANT (36 +/- 5 to 42 +/- 6) Thus, MAP improved by 12% of the pre-test value, while mean changes in VAT and VANT reached 20% and 17%, respectively There were, however, considerable interindividual differences in training gains as exemplified by a range of about 0% to 41% for MAP Differences in the MAP response to training were not distributed randomly among the twin pairs Thus, intraclass correlations computed with the amount of improvement in MAP (ml O2 X min-1 X kg-1) reached 074 (P less than 001) indicating that members of the same twin-pair yielded approximately the same response to training The same coefficient reached 043 and 024 for VAT and VANT, respectively (P greater than 005) These results suggest that there are considerable individual differences in the adaptive capacity to short-term endurance training Moreover, sensitivity of maximal aerobic power to such training is largely genotype-dependent
183 citations
TL;DR: The exercise program significantly lowered the adiposity of men and increased adipocyte epinephrine maximal stimulated lipolysis in women and men, respectively, and in both sexes, a significant increase in ESL was observed after training.
Abstract: 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)
166 citations
TL;DR: There is a sex difference in the trainability of aerobic capacity, but not of maximal aerobic power, under the same 20-week aerobic training program, suggesting that certain genotypes are more sensitive to training than others.
Abstract: The purpose of this experiment was to investigate the individual differences and the specificity in the response of maximal aerobic power (MAP) and capacity (MAC) to a 20-week aerobic training program. Twenty-four subjects (25 +/- 4 years), ascertained as sedentary, including 13 women and 11 men, participated in this study. MAP was determined with a progressive maximal ergocycle test, while MAC was computed as the total work output accomplished during a 90-min maximal ergocycle test. A modified bicycle ergometer allowed the exact measurement of the distance and the load for the computation of the work performed during MAC. The aerobic training program enhanced mean MAP/kg and MAC/kg by 33% and 51%, respectively. Although MAP/kg response to training was similar in both sexes, there was a sex difference in the response of MAC/kg, men improving 50% more than women. Individual differences in the response to the standardized training program were considerable with training gains ranging from 5% to 88% for MAP/kg and from 16% to 97% for MAC/kg. Correlations between training increments in MAP/kg with those in MAC/kg were rather low ranging from 0.28 to 0.44. These results indicate that there is a sex difference in the trainability of aerobic capacity, but not of maximal aerobic power, under the same 20-week aerobic training program. Moreover, large individual differences in the response to similar aerobic training are observed in sedentary persons, suggesting that certain genotypes are more sensitive to training than others. Finally, there is a high level of specificity in the response to training of the power and of the capacity of the aerobic energy metabolism.
140 citations
TL;DR: There are considerable interindividual differences in the level of endowment for endurance performance and this genetic effect remains, however, quite modest when compared with other phenotypes, such as the skeletal dimensions of the body.
Abstract: Performance in endurance sports is affected by a variety of factors, including exercise-training habits, nutrition and other lifestyle components. Endurance performance can also be seen as a multifactorial phenotype influenced by genetic and non-genetic factors. Current models in quantitative genetics and experimental data available in the sport sciences literature suggest that the effects of genetic variation on endurance performance can be observed as (a) the consequence of a character highly determined by the genotype which is correlated with endurance performance, (b) inherited differences in endurance performance exhibited by individuals of a sample or population, and (c) genotype-dependent individual differences in the response to endurance training. This review considers the evidence for genetic effects in several determinants of endurance performance, namely: body measurements and physique, body fat, pulmonary functions, cardiac and circulatory functions, muscle characteristics, substrate utilisation, maximal aerobic power and others. Moreover, the response to aerobic training of indicators of aerobic work metabolism and endurance performance is reviewed, with emphasis on the specificity of the response and the individual differences observed in trainability. It is concluded that there are considerable interindividual differences in the level of endowment for endurance performance. This genetic effect remains, however, quite modest when compared with other phenotypes, such as the skeletal dimensions of the body. Moreover, while trainability of the capacity for endurance performance is quite high on the average, there are important individual differences in the sensitivity to endurance training. Recent data suggest that this sensitivity to aerobic training is largely genotype-dependent.
87 citations
TL;DR: It is concluded that submaximal power output is only moderately affected by the genotypes of free-living children, adolescents and young adults.
Abstract: SummarySubmaximal power output was determined in relative steady state on a bicycle ergometer at a heart rate of 150 beats per minute (PWC150). PWC150 was measured in 880 individuals, 9 to 26 years of age, belonging to 46 sibships of adopted sibs, 66 sibships of unrelated individuals including adoptees, 33 sibships of first-degree cousins, 225 sibships of biological sibs, 56 sibships of DZ twins and 54 sibships of MZ twins. PWC150, PWC150/kg of body weight, PWC150/kg lean body mass, PWC150/cm of height and PWC150/m2 of body surface area were submitted to analysis of variance and correlation analysis after statistical control over age and sex of subjects. Few significant resemblances were found in PWC measurements for adoptive siblings, unrelated sibs and cousins. Sibling resemblance was, however, significant for the sibships of biological sibs, and of DZ and MZ twins. Interclass correlations reached significance only in pairs of biological brothers and sisters, and in pairs of DZ and MZ twins. Estimates o...
50 citations
TL;DR: The reproducibility of the assessment of ventilatory thresholds was investigated in two test-retest experiments, one performed on a cycle ergometer with 21 moderately active male subjects and the other on a treadmill with 20 well trained male subjects as discussed by the authors.
Abstract: The reproducibility of the assessment of ventilatory thresholds was investigated in two test‐retest experiments, one performed on a cycle ergometer with 21 moderately active male subjects and the other on a treadmill with 20 well‐trained male subjects. The first (VT‐1) and the second (VT‐2) nonlinear increases in ventilation (V E) relative to O2 consumption were determined (a) by three independent evaluators coding separately (OIE), (b) as the mean of three independent evaluators (TIE) and (c) by two dependent evaluators (TDE). One of the evaluators repeated the assessment four months later (SELF). The VT‐1 and VT‐2 were also assessed from the graph of V E /VO2 relative to VO2 . Under the SELF condition VT‐1 and VT‐2 in ml O2 per kg min‐1 proved to be reliable measurements with intraclass correlations of 0.84 and 0.91 respectively. Independent evaluators were individually reliable assessors of VT‐1 and VT‐2, with the exception of VT‐1 in the treadmill group in terms of ml O2 per kg min‐1 with coe...
47 citations
TL;DR: The present results suggest that lipolysis in fat cells from the female subjects seems to be insensitive to changes in energy expenditure, and demonstrates that there are high and low responders in adipocytes ESL to variations in habitual energy expenditure.
Abstract: 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<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<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.
45 citations
Journal Article•
TL;DR: The results show that training per se has an effect on adipose tissue lipolysis beyond variation in fatness, and sensitivity of stimulatedlipolysis to training appears to have a genetic basis.
Abstract: In order to study the effects of heredity and of physical training on adipose tissue morphology and metabolism, 15 pairs of monozygotic twins (MZ) (six males and nine females), aged from 16 to 24 years, weighing 56.2 +/- 9.1 kg and with 13.9 +/- 8.2 percent body fat, were submitted to a biopsy of adipose tissue in the suprailiac region. In addition, eight pairs of twins (four male and four female) took part in a 20-week ergocycle training program, five days a week, 40 min a day, at 80 percent of their maximal heart rate. Adipocyte diameter (AD) was assessed on collagenase isolated fat cells. Basal (BL), epinephrine submaximal (10(-5) M) (ESML) and epinephrine maximal stimulated lipolysis (10(-4) M) (EML) were determined on isolated fat cells. Intraclass correlation coefficients indicated significant intrapair resemblance before training for all fat morphological and metabolic indicators (0.78 less than or equal to ri less than or equal to 0.93). Training significantly increased VO2 max (pre: 44.7 +/- 7.6 (ml/kg) vs post: 50.8 +/- 5.0; P less than or equal to 0.001). No training effect was found in percent body fat and AD. Training significantly increased BL, ESML, and EML (P less than or equal to 0.01). Moreover, twins of the same MZ pair yielded identical responses in ESML and EML with training. Intraclass coefficients for the magnitude of change in activity over pretraining values reached 0.84 and 0.90 respectively. Apparently a genetically determined response to training could not be found for BL. These results show that training per se has an effect on adipose tissue lipolysis beyond variation in fatness. Furthermore, sensitivity of stimulated lipolysis to training appears to have a genetic basis.
40 citations
TL;DR: Results indicate that training increases suprailiac fat cell lipolysis, which seems to adapt maximally within about 4 mo, and the amount of training required to induce maximal adaptation in humans is identified.
Abstract: 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.
36 citations
TL;DR: Fat cell weight, basal and insulin-stimulated lipogenesis and lipoprotein lipase activity per gram showed high reliability of measurement, interclass and intraclass coefficients being 0.83 and over, while no significant correlation was observed between basallipogenesis and fat cell weight.
Abstract: Lipogenesis from glucose and lipoprotein lipase activity were investigated in humans. The reliability of measurements was quantified and correlations with fat cell weight were assessed. Twenty-four subjects (7 women, 17 men) were studied twice within a 2-week period, along with 17 additional male subjects who were studied once and used only in the correlation analyses. All subjects were not regularly involved in an exercise-training program and were between 18 and 30 years of age. Following an overnight fast, adipose tissue specimens were obtained by suprailiac biopsy and fat cells were collagenase isolated. Mean fat cell weight was obtained from 400 to 500 cell diameter determinations per subject. Basal and insulin-stimulated fat cell lipogenesis from glucose were determined using D-[U-14C]glucose and were reported in nanomoles of glucose per hour per 106 cells. Adipose tissue heparin-releasable lipoprotein lipase activity was also determined and expressed in micromoles of free fatty acids per hour per g...
27 citations
TL;DR: The search for genetic variants associated with endurance performance should continue for other genetic systems, particularly in skeletal muscle and other tissues related even to endurance performance, according to appropriate reference populations.
Abstract: In an attempt to associate genetic variation with endurance performance, red cell antigens ABO, MNSs, Rhesus, Duffy, Kell, P and red cell enzymes lactate dehydrogenase (EC: 11127), malate dehydrogenase (EC: 11137), phosphoglucomutasej (EC: 2751) and phosphogluconate dehydrogenase (EC: 11144) genetic systems were studied in 79 Caucasian athletes who participated in endurance sports during the 1976 Montreal Olympic Games Gene frequencies were reported and phenotype frequencies were compared to appropriate reference populations No significant differences were observed between the athletes and the nonathletic populations of reference Comparisons of three genetic systems could be made with a sample of athletes from the 1968 Mexico Olympic Games Phenotype frequencies were identical in the two samples of athletes The search for genetic variants associated with endurance performance should continue for other genetic systems, particularly in skeletal muscle and other tissues related even
01 Jul 1984
TL;DR: The observations suggest that submaximal power output is less related to energy intakes and that the association tends to be slightly more important in adults than in children, and that physical fitness is determined by the genotype and the habitual energy expenditure and to a lesser degree by the nutritional habits.