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Biomedical subjects

J A Simoneau

Publications and source records attributed to J A Simoneau.

At least 73 records · Page 4Linked to original sources
PubMed1988

Specific effects of low-frequency stimulation upon energy metabolism in tibialis anterior muscles of mouse, rat, guinea pig and rabbit.

Tibialis anterior (TA) muscles of four small mammals were subjected to chronic nerve stimulation for 28 days (10 Hz, 10 hours per day). Total cellular activities of phosphofructokinase (PFK), hexokinase (HK), citrate synthase (CS), 3-hydroxy-acyl-CoA dehydrogenase (HADH) and 3-hydroxybutyrate dehydrogenase (HBDH) were measured in the stimulated and unstimulated contralateral muscles. Normal TA muscles displayed ranges of oxidative and glycolytic capacities with rabbit TA showing the lowest and mouse TA the highest oxidative capacity. Chronic stimulation was almost without effect in mouse TA. In all other species, glycolytic capacity was decreased and reference enzymes of aerobic-oxidative pathways were increased. Rabbit TA displayed the highest increment in oxidative capacity with approximately three-fold increases in CS and HADH and eleven-fold increases in HBDH. Different responses were also observed for HK. In some cases, the extent of adaptation appeared to be independent of the initial enzyme activity levels, while in other cases it appeared to follow an order which corresponded to the size of the animals. Thus, there exist species-specific ranges of adaptation and adaptive alterations in one species may not necessarily reflect the adaptive response of another species.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1988

Isokinetic strength training protocols: do they induce skeletal muscle fiber hypertrophy?

Sedentary subjects were submitted to repeated concentric isokinetic strength training protocols separated by a 50-day detraining period. Peak torque output of the quadriceps muscle group increased by 54% after the first ten-week training protocol. No significant changes in mean skeletal muscle fiber area were observed while a significant increase in percent fiber type and percent fiber area was noticed for type IIa fibers. The activities of the enzymes hexokinase, malate dehydrogenase, 3-hydroxyacyl CoA dehydrogenase, and oxoglutarate dehydrogenase were also increased significantly. Fifty days without training induced a significant decline in peak torque output. All the enzymes that responded to the first training protocol maintained their elevated activities over the detraining period except for the enzyme oxoglutarate dehydrogenase. A second training protocol administered to the same subjects following the 50-day inactivity period did not result in any significant increase in maximum torque output and fiber area. It is concluded that the isokinetic strength training protocol used can increase the functional capacity of skeletal muscle, but this effect does not appear to be related to skeletal muscle fiber hypertrophy.

Adult↗
PubMed1987

Effects of two high-intensity intermittent training programs interspaced by detraining on human skeletal muscle and performance.

The purpose of this study was to investigate the effects of repeated high-intensity intermittent training programs interspaced by detraining on human skeletal muscle and performances. First, nineteen subjects were submitted to a 15-week cycle ergometer training program which involved both continuous and high-intensity interval work patterns. Among these 19 subjects, six participated in a second 15-week training program after 7 weeks of detraining. Subjects were tested before and after each training program for maximal aerobic power and maximal short-term ergocycle performances of 10 and 90s. Muscle biopsy from the vastus lateralis before and after both training programs served for the determination of creatine kinase (CK), hexokinase, phosphofructokinase (PFK), lactate dehydrogenase (LDH), malate dehydrogenase, 3-hydroxyacyl-CoA dehydrogenase (HADH) and oxoglutarate dehydrogenase (OGDH) activities. The first training program induced significant increases in all performances and enzyme activities but not in CK. Seven weeks of detraining provoked significant decreases in maximal aerobic power and maximal 90s ergocycle performance. While the interruption of training had no effect on glycolytic enzyme markers (PFK and LDH), oxidative enzyme activities (HADH and OGDH) declined. These results suggest that a fairly long interruption in training has negligeable effects on glycolytic enzymes while a persistent training stimulus is required to maintain high oxidative enzyme levels in human skeletal muscle. The degree of adaptation observed after the second training program confirms that the magnitude of the adaptive response to exercise-training is limited.

Adult↗
PubMed1986

Inheritance of human skeletal muscle and anaerobic capacity adaptation to high-intensity intermittent training.

The role of heredity in the response of maximal anaerobic capacities and skeletal muscle histochemical and biochemical characteristics to a 15-week cycle ergometer training program involving both continuous and interval work patterns was investigated in 14 pairs of monozygotic twins. The training program consisted mainly of series of ergocycle supramaximal exercises lasting from 15 s to 90 s and performed 4 and 5 times a week. The subjects were submitted to 10 s and 90 s all-out ergocycle tests to estimate maximal anaerobic alactacid (AAC) and lactacid (ALC) capacities, respectively. Muscle fiber types and creatine kinase (CK), hexokinase (HK), phosphofructokinase (PFK), lactate dehydrogenase (LDH), malate dehydrogenase (MDH), 3-hydroxyacyl CoA dehydrogenase (HADH), and oxoglutarate dehydrogenase (OGDH) activities were determined in a biopsy from the vastus lateralis. Training increased AAC, ALC, fiber type I proportion, MDH, HADH, and OGDH (P less than 0.05) and decreased fiber type IIb proportion and the PFK/OGDH ratio. No significant change was observed for CK, HK, PFK, and LDH. Large interindividual differences in the response to training were observed for all variables. However, intraclass correlations indicated that the extent of the response of ALC and CK, HK, LDH, MDH, and OGDH activities and of the PFK/OGDH activity ratio to training were significantly similar within pairs of twins. Although the role of heredity appeared absent for the changes in fiber type proportions and in anaerobic alactacid capacity, the present results suggest that the response of anaerobic lactacid capacity and most enzyme activities to high-intensity intermittent training is significantly determined by the genotype.

Adaptation, Physiological↗
PubMed1986

Repeatability of fibre type and enzyme activity measurements in human skeletal muscle.

In order to assess the variability in repeated determination of human muscle fibre type distribution, fibre area and enzyme activity measurements, two biopsies were taken within 10 days in the same vastus lateralis for 12 females and 13 males, and in the right and in the left muscles for 25 other subjects (13 females and 12 males). Within muscle, intraclass reliability coefficients were 0.88, 0.82 and 0.56 for type I, IIa and IIb per cent fibres, respectively, and ranged from 0.74 to 0.82 for fibre areas and from 0.71 to 0.90 for enzyme markers of different metabolic pathways. Correlations between right and left muscle measurements were also high for fibre areas (from 0.85 to 0.91) and enzyme activities (from 0.71 to 0.87), except for phosphofructokinase (r = 0.63). In contrast, the right and left thigh muscle correlation reached 0.67, 0.40 and 0.64 for type I, IIa and IIb fibre distribution, respectively. Thus, the variation in muscle sampling and technical procedures reached about 15% of the total variation (i.e. total differences between subjects) for the proportion of fibre type I and IIa and about 20-25% for fibre areas and enzyme activities. On the other hand, the technical error for the proportion of fibre type I and IIa is about 6-7%. This implies that differences brought about by any experimental treatment on these skeletal muscle characteristics in human studies have to be of a relatively large magnitude before being detectable. On the other hand, fibre areas and enzyme activities measured in single needle biopsy sample, from one of the vastus lateralis muscles, are quite representative of the other vastus lateralis. Similarity in fibre type proportion between right and left vastus lateralis cannot be postulated, however, without investigating both muscles.

Adult↗
PubMed1986

Genetic effects in human skeletal muscle fiber type distribution and enzyme activities.

The purpose of the study was to estimate the genetic effect for skeletal muscle characteristics using pairs of nontwin brothers (n = 32), dizygotic (DZ) twins (n = 26), and monozygotic (MZ) twins (n = 35). They were submitted to a needle biopsy of the vastus lateralis for the determination of fiber type distribution (I, IIa, IIb) and the following enzymes were assayed for maximal activity: creatine kinase, hexokinase, phosphofructokinase (PFK), lactate dehydrogenase, malate dehydrogenase, 3-hydroxyacyl CoA dehydrogenase, and oxoglutarate dehydrogenase (OGDH). For the percentage of type I fibers, intraclass correlations were 0.33 (p less than 0.05), 0.52 (p less than 0.01), and 0.55 (p less than 0.01) in brothers and DZ and MZ twins, respectively. MZ twins exhibited significant within-pair resemblance for all enzyme activities (0.30 less than or equal to r less than or equal to 0.68). In spite of these correlations, genetic analyses performed with the twin data alone indicated that there was no significant genetic effect for muscle fiber type I, IIa, and IIb distribution and fiber areas. Although there were significant correlations in MZ twins for all muscle enzyme activities, the often nonsignificant intraclass coefficients found in brothers and DZ twins suggest that variations in enzyme activities are highly related to common environmental conditions and nongenetic factors. However, genetic factors appear to be involved in the variation of regulatory enzymes of the glycolytic (PFK) and citric acid cycle (OGDH) pathways and in the variation of the oxidative to glycolytic activity ratio (PFK/OGDH ratio). Data show that these genetic effects reach only about 25-50% of the total phenotypic variation when data are adjusted for age and sex differences.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1986

Skeletal muscle characteristics in sedentary black and Caucasian males.

Twenty-three male Black African and 23 male Caucasian subjects, ascertained as sedentary, participated in this study designed to determine whether there were differences in skeletal muscle histochemical and biochemical characteristics between racial groups. Muscle fiber type proportions (I, IIa, and IIb), fiber areas and activities of several enzyme markers of different energy metabolic pathways were determined from a biopsy of the vastus lateralis. Results indicated that Caucasians had a higher percent type I (8%, P less than 0.01) and a lower percent type IIa (6.7%, P less than 0.05) fiber proportions than Africans. No significant differences were observed between the two racial groups in the type IIb fiber proportion or in the three fiber type areas. Enzymes catalyzing reactions in phosphagenic [creatine kinase (CK)] and glycolytic [hexokinase (HK), phosphofructokinase (PFK), and lactate dehydrogenase (LDH)] metabolic pathways had significantly higher activities (about 30-40%) in the Black African group than in the Caucasian group (P less than 0.01). No significant difference was noted in the activities of oxidative enzymes [malate dehydrogenase (MDH), oxoglutarate dehydrogenase (OGDH), and 3-hydroxyacyl-CoA dehydrogenase (HADH)]. Consequently, the PFK/OGDH ratio was significantly elevated in Africans (P less than 0.05). The racial differences observed between Africans and Caucasians in fiber type proportion and enzyme activities of the phosphagenic and glycolytic metabolic pathways may well result from inherited variation. These data suggest that sedentary male Black individuals are, in terms of skeletal muscle characteristics, well endowed for sport events of short duration.

Adult↗
PubMed1986

Inheritance of human muscle enzyme adaptation to isokinetic strength training.

Five monozygotic twin pairs were submitted to a 10-week isokinetic strength training program and biochemical characteristics measured before and after training to determine the role of heredity in skeletal muscle adaptation, while 5 unrelated sedentary subjects served as control group. Experimental subjects performed twice 3 series of 5 bilateral reciprocal alternating knee flexions and extensions at a velocity of 90 degrees/s 5 times per week. Before and after the training period, for each subject, the peak muscular torque output was measured at the same velocity and the vastus lateralis muscle was biopsied for biochemical determinations. No significant change was observed in the control group. Training increased peak muscular torque output by 24%. The activities of hexokinase, malate dehydrogenase and 3-hydroxyacyl CoA dehydrogenase also increased significantly by 28, 26 and 38%, respectively. Interindividual variations in the response of these variables to training were noted but these were shown to be independent of the genotype. No overall effect of training was observed for oxoglutarate dehydrogenase activity (OGDH). However, changes were seen in individual pairs of twins and these were in opposite directions in some pairs compared to others, thus explaining the absence of a general training effect. Significant intrapair resemblance in the training response was present for OGDH (r = 0.76), indicating that the sensitivity to isokinetic strength training for OGDH was highly variable, not random and probably genetically determined.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1986

Fat distribution and adipose tissue metabolism in non-obese male black African and Caucasian subjects.

Twenty-four male black African (25.5 +/- 3.0, mean +/- s.d., years of age) and 24 male Caucasian (21.5 +/- 3.6) subjects, ascertained as sedentary individuals, participated in this study designed to determine whether there were racial differences in fat distribution and adipose tissue metabolism while controlling the differences in body fat. An adipose tissue biopsy was obtained from the suprailiac region for the determination of basal (BL), epinephrine submaximal 10(-4) M (ESML) and maximal 10(-3) M (EML) stimulated lipolysis, basal (BLG) and maximal insulin 9 microU/ml (ILG) stimulated lipogenesis and heparin releasable lipoprotein lipase (LPL) activity. Body density was determined through underwater weighing procedures and body fat derived with the Siri equation. The following skinfolds were also measured: triceps, biceps, subscapular, abdomen, suprailiac, front thigh and medial calf. Caucasians were matched with the black Africans for age, body weight and body density. Results indicated that when Caucasians and black Africans of similar percentage body fat were compared, no significant differences were observed in the total amount of subcutaneous fat, fat distribution and suprailiac mean fat cell size. Moreover, no significant differences were observed between the two groups for BL, BLG, and ILG of adipose tissue. However, black Africans had higher (P less than 0.01) epinephrine stimulated lipolytic values (ESML and EML) and LPL activity (P less than 0.01) than the Caucasian subjects. These results suggest that for a comparable level of fatness and similar fat morphology and distribution, there are racial differences in adipose tissue metabolism.

Adipose Tissue↗
PubMed1986

Aerobic performance in brothers, dizygotic and monozygotic twins.

Forty-two brothers, 66 dizygotic twins of both sexes and 106 monozygotic twins of both sexes, 16 to 34 yr of age, took part in this study that was designed to investigate the effect of heredity in aerobic performance. Maximal oxygen uptake (VO2 max), maximal heart rate (HR max), maximal ventilation, and maximal oxygen pulse were obtained from a progressive ergocycle test to exhaustion. Total work output in a 90-min maximal ergocycle test was also determined in the twins. Fat-free weight was estimated from body density measurements obtained through underwater weighing. Aerobic performance scores were adjusted for age (brothers), and age and sex (dizygotic and monozygotic twins) by regression procedures. Dizygotic twins and brothers of same sibship exhibited about the same level of resemblance for all variables or were only slightly different, with the exception of HR max. Monozygotic pairs were generally more alike than the other sibs, as suggested by the intra-class coefficients. Twin data were used to compute the genetic effects. The within-pair estimate of genetic variance revealed that it was significant (P less than or equal to 0.05) for all variables except VO2 max X kg-1 fat-free weight X min-1. In the case of HR max, the among-pairs component estimate had to be used, and it also proved significant (P less than or equal to 0.01). The size of the genetic effect was computed from three different methods, and it reached about 40% for VO2 max X kg-1 X min-1, 50% for HR max, 60% for maximal oxygen pulse and maximal ventilation, and 70% for 90-min work output X kg-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Heredity and muscle adaptation to endurance training.

To determine whether sensitivity of muscle characteristics and aerobic performances to endurance training was genotype-dependent, 6 pairs of monozygotic (MZ) twins, 21 +/- 4 yr of age (mean +/- SD), took part in a 15-wk ergocycle endurance training program. Tests were performed before and after 7 and 15 weeks of training. A biopsy of the vastus lateralis muscle was obtained for the determination of fiber type composition and activities of creatine kinase, hexokinase, phosphofructokinase, lactate dehydrogenase, malate dehydrogenase, 3-hydroxyacyl CoA dehydrogenase, and oxoglutarate dehydrogenase. Maximal oxygen uptake was measured with a progressive maximal ergocycle test, while endurance performance was determined as the total work output during a 90-min maximal ergocycle test. Results indicated that maximal oxygen uptake X kg-1 and endurance performance X kg-1 increased significantly (14 and 31%, respectively) with training, and intra-pair resemblance (intra-class) in response to 15 wk of training ranged from 0.65 to 0.83. Hexokinase (31%), phosphofructokinase (37%), lactate dehydrogenase (21%), malate dehydrogenase (31%), and 3-hydroxyacyl CoA dehydrogenase (60%) were significantly increased with training whereas no mean change in fiber-type proportions, oxoglutarate dehydrogenase and creatine kinase activities and the phosphofructokinase/oxoglutarate dehydrogenase ratio was observed. Similarity within twin pairs in the response to enzyme activities was mainly detected in the second half of the training program. The present results confirm, therefore, that both maximal oxygen uptake and endurance performance responses to training are largely genotype-dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1985

Relationships between skeletal muscle characteristics and aerobic performance in sedentary and active subjects.

Forty-eight sedentary and 39 quite active or well-trained men participated in this study. Muscle biopsy samples were taken from the vastus lateralis for the determination of fiber type composition (I, IIa, IIb), fiber type area, and assay of the following enzymes: malate dehydrogenase (MDH), 3-hydroxyacyl CoA dehydrogenase (HADH) and oxoglutarate dehydrogenase (OGDH). Maximal oxygen uptake (VO2max) was determined with a progressive cycle ergometer test, while endurance performance or maximal aerobic capacity (MAC) was defined as the total work output during a 90-min cycle ergometer test. Correlation analysis revealed no evidence of association between fiber type composition and VO2max kg-1 or MAC kg-1 in sedentary subjects, while active men exhibited significant correlation between % type I (r = 0.52), % type IIb (r = 0.31) and VO2max kg-1. Enzyme activities were not significantly correlated with MAC kg-1 and VO2max kg-1 in sedentary men while active men exhibited significant correlation for the three enzymes (0.37 less than or equal to r less than or equal to 0.51) with VO2max kg-1. These results show that the contribution of muscle fiber type and enzyme activities to aerobic performance may be inflated from a statistical point of view by the training status heterogeneity of subjects. They also suggest that variation in these muscle characteristics does not account for the individual differences in aerobic performance of subjects who have never trained before. Therefore, the assessment of muscle characteristics is not as useful as originally thought for the detection of individuals with a high potential for endurance performance among untrained subjects.

Adolescent↗
PubMed1985

Human skeletal muscle fiber type alteration with high-intensity intermittent training.

The response of muscle fiber type proportions and fiber areas to 15 weeks of strenuous high-intensity intermittent training was investigated in twenty-four carefully ascertained sedentary (14 women and 10 men) and 10 control (4 women and 6 men) subjects. The supervised training program consisted mainly of series of supramaximal exercise lasting 15 s to 90 s on a cycle ergometer. Proportions of muscle fiber type and areas of the fibers were determined from a biopsy of the vastus lateralis before and after the training program. No significant change was observed for any of the histochemical characteristics in the control group. Training significantly increased the proportion of type I and decreased type IIb fibers, the proportion of type IIa remained unchanged. Areas of type I and IIb fibers increased significantly with training. These results suggest that high-intensity intermittent training in humans may alter the proportion of type I and the area of type I and IIb fibers and in consequence that fiber type composition in human vastus lateralis muscle is not determined solely by genetic factors.

Adult↗
PubMed1985

Specificity of aerobic and anaerobic work capacities and powers.

Thirty-three untrained subjects of both sexes, 18-31 years of age, performed several tests on cycle ergometers. Maximal aerobic power (MAP) was obtained in a progressive work test. Maximal aerobic capacity (MAC) was measured in a 90-min maximal test and was computed as the total work output during that period. Two all-out cycle ergometer work tests lasting 10 s and 90 s were used to estimate the anaerobic alactic capacity (AAC) and lactic capacity (ALC). Anaerobic alactic power (AAP) was computed as the highest output in 1 s in the AAC test and anaerobic lactic power (ALP) was obtained as the mean output during the last 5 s in an all-out test of 30 s. Correlation coefficients were computed between all measurements of capacity and power expressed per kg of body weight as well as with scores adjusted for sex differences. Common variances (r2 X 100) between measurements of power were either low (MAP-AAP, 40%) or moderate (MAP-ALP, 61%; AAP-ALP, 62%) while common variances between measurements of capacity were sometimes low (MAC-AAC, 49%) or higher (MAC-ALC, 76%; AAC-ALC, 77%). The common variances between tests of power and capacity reached high values when calculated with metabolic criteria of the same class (MAP-MAC, 81%; AAP-AAC, 92%). These results provide quantitative evidence to support the notion of specificity between the aerobic and the anaerobic work performances and support the distinction between capacity and power of the three energy systems.

Adenosine Triphosphate↗
PubMed1985

Skeletal muscle histochemical and biochemical characteristics in sedentary male and female subjects.

The purpose of this study was to assess the relationship between muscle fiber type distribution and enzymatic characteristics in sedentary male and female subjects. Muscle biopsy samples from the vastus lateralis muscle of 38 females and 37 males were analyzed to determine the fiber type composition (I, IIa, and IIb), the fiber size, and maximal activities of enzyme markers of energy metabolic pathways. Significant correlations were found (p less than 0.05) between percent fiber type I area and hexokinase (r = -0.39), phosphofructokinase (r = -0.39), lactate dehydrogenase (r = -0.41), and oxoglutarate dehydrogenase (r = 0.33) activities, whereas such correlations with total phosphorylase (r = -0.02), malate dehydrogenase (r = 0.12), and 3-hydroxyacyl CoA dehydrogenase (r = 0.12) activities were not significant. The results of the present study also suggest the presence of a significant but low covariation of less than 30% between the fiber type distribution and muscle enzyme activities. They confirm the presence of an important metabolic heterogeneity independent of the muscle fiber type distribution in sedentary male and female subjects. Moreover, these results indicate that sedentary males exhibit a lower mean value of percent fiber type I and higher glycolytic enzyme activities than sedentary females.

Adult↗
PubMed1985

Familial resemblance in maximal heart rate, blood lactate and aerobic power.

There are considerable interindividual differences in maximal oxygen uptake per kilogram of body weight (VO2 max/kg), maximal heart rate (max HR) and maximal blood lactate (max blood La) measured during a progressive exercise test. The aim of the study was to quantify the familial relationships for these variables. Parents and children of 38 families of French-Canadian descent were submitted to a modified Balke treadmill test. VO2 max/kg and max HR were the highest values reached during the test for 1 min. Max blood La was obtained from a blood sample taken 2 min after the test. The effects of age and sex were significant for max blood La and VO2 max/kg in each generation. Scores were thus adjusted through multiple regression procedures (age + sex + age X sex + age2), yielding residuals which were submitted to further analysis. Intraclass correlations (ri) were significant in pairs of sibs for max blood La and max HR, i.e. 0.28 (p less than 0.01) and 0.43 (p less than 0.05), respectively. For VO2 max/kg, pairs of spouses and sibs were about similarly correlated (ri = 0.20 and 0.15; p less than 0.05). Data suggested that children were more related to their mother than to their father for VO2 max/kg, VO2 max/kg of fat-free weight, and particularly for max HR. It was concluded that familial resemblance and heritability estimates for maximal aerobic power, max HR and max blood La were quite low and generally nonsignificant. Correlations between biological sibs were, however, consistently significant for max HR and max blood La. The suggestion of a maternal effect in maximal aerobic power should be further investigated.

Adolescent↗
PubMed1984

Responses of maximal aerobic power and capacity to aerobic training.

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.

Adult↗