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Biomedical subjects

J C Chatard

Publications and source records attributed to J C Chatard.

At least 37 records · Page 2Linked to original sources
PubMed1996

Blood lactate recovery measurements, training, and performance during a 23-week period of competitive swimming.

The purpose of this study was to relate measurements of blood lactate concentration, performance during a maximal anaerobic lactic test (MANLT) and training loads during a 23-week swimming season. Six elite 200-m freestyle male swimmers [mean age 19.5 (SD 1.6) years, height 184 (SD 5) cm and body mass 77.7 (SD 9.0) kg], participated in the study. The MANLT consisted of four all-out 50-m swims interspersed with 10-s recovery periods. Blood lactate concentrations were determined at 3 and 12-min post-exercise and were performed on weeks 2,6,10,14,18 and 21. Swimmers participated in 200-m freestyle competitions on weeks 1,7,13 and 23 (national championships). During weeks 1-10, training mostly involved aerobic exercise, while during weeks, 11-23, it involved anaerobic exercise. At 3-min and 12-min post-MANLT lactate concentrations varied throughout the season [range from 14.9 (SD 1.2) to 18.7 (SD 1.0) mmol.l-1] but demonstrated non-systematic variations. In contrast, the percentage of mean blood lactate decrease (% [La-]recovery) between min 3 and min 12 of the passive recovery post-MANLT increased from week 2 to 10 with aerobic training and decreased from week 10 to 21 with anaerobic training. The MANLT performance improved continuously throughout the season, while competition performance improved during the first three competitions but declined in the final championships, coinciding with the lowest % [La-]recovery and signs of overtraining, such as bad temper and increased sleeping heart rate. The results of this study indicated that % [La-]recovery could be an efficient marker for monitoring the impact of aerobic and anaerobic training and avoiding overtraining in elite 200-m swimmers.

Adolescent↗
PubMed1996

Hormonal responses to training and its tapering off in competitive swimmers: relationships with performance.

During a winter training season, the effects of 12 weeks of intense training and 4 weeks of tapering off (taper) on plasma hormone concentrations and competition performance were investigated in a group of highly trained swimmers (n = 8). Blood samples were collected and the swimmers performed their speciality in competition at weeks 10 (mid-season), 22 (pre-taper) and 26 (post-taper). No statistically significant changes were observed in the concentrations of total testosterone (TT), non-sex hormone binding globulin-bound-testosterone (NSBT), cortisol (C), luteinising hormone, thyroid stimulating hormone, triiodothyronine, thyroxine plasma catecholamines, creatine kinase and ammonia during training and taper. Mid-season NSBT: C ratio and the amount of training were statistically related (r = 0.82, P < 0.05). Competition performance slightly declined during intense training [0.52 (SD 2.51)%, NS] and improved during taper [2.32 (SD 1.69)%, P < 0.01]. Changes in performance during training and taper correlated with changes in ratios TT: C (r = 0.86, P < 0.01 and r = 0.81, P < 0.05, respectively) and NSBT: C (r = 0.77, P < 0.05 and r = 0.76, P < 0.05, respectively). In summary, these results showed that the monitored plasma hormones and metabolic indices were unaltered by 12 weeks of intense training and 4 weeks of taper. The TT: C and NSBT: C ratios, however, appeared to be effective markers of the swimmers' performance capacities throughout the training season.

Adult↗
PubMed1996

Effects of training and taper on blood leucocyte populations in competitive swimmers: relationships with cortisol and performance.

The effects of 12 weeks of training and 4 weeks of taper on blood leucocyte populations and cortisol were investigated in 8 well-trained competition swimmers. Blood samples were taken at rest in the mid-season (week 10), before taper (week 22) and after taper (week 26). Swimmers improving by more than 2% with taper (N = 4), efficient (GE), were compared with swimmers improving by less than 2% (N = 4), less efficient (GLE). No significant changes were observed in leucocyte subpopulations or cortisol during training. The percentage of neutrophils decreased during taper (p < 0.05). Basophils and the percentage of granulocytes tended to decrease, while lymphocytes tended to increase. The increment in lymphocytes was positively related with the reduction in training volume during taper (r = 0.86, p < 0.05). Cortisol levels did not change with taper and were not related with leucocyte status and kinetics. GE swimmers had higher pre- and post-taper eosinophil counts than GLE swimmers (p < 0.05). Lymphocyte counts in GE tended to be higher, too. Cortisol decreased with taper in GE, while it increased in GLE. In conclusion, taper appeared to have an influence on leucocyte populations, which did not seem to be related with blood cortisol.

Adult↗
PubMed1996

Effect of a 6-week endurance training programme and branched-chain amino acid supplementation on histomorphometric characteristics of aged human muscle.

The effects of a 6-week endurance training programme and a branched-chain amino acid (BCAA) supplementation were investigated on skeletal muscle histomorphometric characteristics of elderly men. Seventeen elderly men, age (63 +/- 5 years), height (173 +/- 5 cm) and weight (75 +/- 8 kg) were included in the study. One group (n = 9) received an oral BCAA supplementation for 6 weeks (16, 2 and 2 g per day of leucine, isoleucine and valine, respectively), while another group (n = 8) received a placebo. During these 6 weeks, subjects trained on a Monark cycle ergometer at 75 +/- 9% of their maximal heart rate for 1 h/day, 4 days/week. Muscle biopsy samples taken at rest before and after endurance training were analyzed for capillarization, fibre type distribution and fibre area. As a result of endurance training, maximal oxygen uptake was significantly increased by about 5% in control and BCAA supplemented groups (P < 0.01). The number of capillaries per fibre and in contact with type I fibres was significantly increased (P < 0.05), this effect being similar in control and BCAA supplemented groups. The percentage distribution and area of type I, type IIa and type IIb fibres did not differ between the two groups and remained unchanged with endurance training. It is concluded that skeletal muscle of elderly men can adapt to a 6-week endurance training programme and that a BCAA supplementation does not further enhance the induced histomorphometric changes.

Aged↗
PubMed1996

Modeled responses to training and taper in competitive swimmers.

This study investigated the effect of training on performance and assessed the response to taper in elite swimmers (N = 18), using a mathematical model that links training with performance and estimates the negative and positive influences of training, NI and PI. Variations in training, performance, NI, and PI were studied during 3-, 4-, and 6-wk tapers. The fit between modeled and actual performance was significant for 17 subjects; r2 ranged from 0.45 to 0.85, P < 0.05. Training was progressively reduced during tapers. Performance improved during the first two tapers: 2.90 +/- 1.50% (P < 0.01) and 3.20 +/- 1.70% (P < 0.01). Performance improvement in the third taper was not significant (1.81 +/- 1.73%). NI was reduced during the first two tapers (P < 0.01 and P < 0.05, respectively), but not during the third. PI did not change significantly during tapers. Thus, the present results show that the model used is a valuable method to describe the effects of training on performance. Performance improvement during taper was attributed to a reduction in NI. PI did not improve with taper, but it was not compromised by the reduced training periods.

Adult↗
PubMed1996

Creatine supplementation does not improve sprint performance in competitive swimmers.

This study was conducted to examine the effects of creatine (Cr) supplementation on sprint swimming performance and energy metabolism. Twenty highly trained swimmers (9 female, 11 male) were tested for blood ammonia and for blood lactate after the 25-, 50-, and 100-m performance in their best stroke on two occasions 7 d apart. After the first trial, subjects were evenly and randomly assigned to either a creatine (5 g creatine monohydrate 4 times per day for 5 d) or a placebo group (same dosage of a lactose placebo) in a double-blind research design. No significant differences in performance times were observed between trials. Post-exercise blood ammonia concentration decreased in the 50- and 100-m trials in the creatine group and in the 50-m trial in the placebo group. The supplementation period had no effect on post-exercise blood lactate. Therefore, creatine supplementation cannot be considered as an ergogenic aid for sprint performance in highly trained swimmers although adenine nucleotide degradation may be reduced during sprint exercise after 5 d of creatine ingestion.

Adult↗
PubMed1995

The relations between physical ability and bone mass in women aged over 65 years.

In this cross-sectional study of 55 women (mean age 73.54 +/- 5.87), the magnitude of the relation between different indices of physical ability and confounding factors to bone density were determined. Physical fitness was assessed by direct measurement of maximal oxygen consumption (VO2 max), isokinetic muscle strength, and quadriceps and psoas muscle surfaces and densities using computed tomography. Anthropometry, chronological and gynecological ages, and dietary calcium intake were also recorded. The bone mineral density (BMD) was evaluated at the axial level (lumbar spine and proximal femur) and at the peripheral level (radius and tibia, cancellous and cortical compartments). Parameters related to physical ability proved to be the best predictors of BMD in radial and tibial cancellous compartments, spine, femoral neck, and trochanter, accounting for 15-27.5% of the total variance. The VO2 max was a major determinant of the femoral mineral density and one of the predictors of radial and tibial cancellous compartments. Psoas parameters were strongly related to spine mineral density and also constituted a predictor of radius (cancellous) and tibia mineral densities. The arm muscle strength could predict, though weakly, the BMD of axial skeleton, whereas thigh muscle strength only predicted the BMD of inferior limbs. No correlation was observed between current dietary calcium intake and BMD. Age-postmenopause and fertile life remained predictive of BMD at mostly cancellous sites, whereas anthropometry exerted important effects on radial and tibial cortices. The study suggests distinct sets of relations between physical ability and the BMD variables. Subjects with greater and denser psoas muscles had greater spine BMD, and those with higher VO2 max had greater proximal femur BMD.

Absorptiometry, Photon↗
PubMed1995

Mitochondrial ATP production rate in 55 to 73-year-old men: effect of endurance training.

The effect of 6-week endurance training on mitochondrial ATP production rate was investigated in 14 elderly men. Mean age, body weight and height were 63 +/- 6 yr, 75.6 +/- 9.2 kg and 174 +/- 4 cm, respectively. Subjects trained on a Monark cycle ergometer at 79 +/- 8% of their maximal heart rate for 1 h day-1, 4 days week-1. Muscle samples were obtained at rest, before and after endurance training, by a needle biopsy technique and used for determination of mitochondrial ATP production rate in isolated mitochondria and enzyme assays. Endurance training resulted in a significant increase in maximal oxygen uptake (L min-1) (P < 0.01). Citrate synthase activity, a mitochondrial marker enzyme, and hexokinase activity increased significantly (both P < 0.01) in response to training while 3-hydroxyacyl-CoA dehydrogenase and carnitine palmitoyltransferase I activities remained statistically unchanged. A higher mitochondrial ATP production rate was observed after endurance training with the substrate combinations pyruvate+palmitoyl-L-carnitine+L-glutamate+malate (P < 0.01), L-glutamate (P < 0.001), pyruvate+malate (P < 0.05) and palmitoyl-L-carnitine+malate (P < 0.01). The largest increase was obtained with L-glutamate (170%). Significant correlations were observed between the percent increase in citrate synthase activity and those of mitochondrial ATP production rates. It was concluded that the increased mitochondrial ATP production rate of aged human skeletal muscle with training seems mainly to occur through an increased mitochondrial content, and in a way similar to those observed in young men.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1995

Effects of training on performance in competitive swimming.

The relationships between the mean intensity of a training season, training volume and frequency, and the variations in performance were studied in a group of 18 elite swimmers. Additionally, differences between the swimmers who improved their personal record of the previous year during the follow-up training season (GIR, n = 8) and those who did not (GNI, n = 10) were investigated. The improvement in performance during the follow-up season was significantly correlated with the mean intensity of the training season (r = 0.69, p < 0.01), but not with training volume or frequency. The performance improvement during the follow-up season was negatively related to the initial performance level (r = 0.90, p < 0.01). The decline in performance during detraining from the previous year was less for the GIR than for the GNI (6.21 +/- 2.30% vs. 9.79 +/- 2.18%, p < 0.01). The present findings suggest that training intensity is the key factor in performance improvement in a group of elite swimmers. Factors such as previous detraining and initial performance level could jeopardize success in spite of a good adaptation to training.

Adaptation, Physiological↗
PubMed1995

Wet suit effect: a comparison between competitive swimmers and triathletes.

The purpose of the present investigation was to examine the wet suit effect on 8 swimmers and 8 triathletes. For swimmers, the performances of a 400-m swim with and without wet suit were not statistically different (4 min 12.5 +/- 8 s vs 4 min 13.9 +/- 4 s) while for triathletes the swim times were reduced by 19 s (4 min 45.8 +/- 34 s vs 5 min 04.7 +/- 30 s, P < 0.01). For swimmers, VO2max and blood lactate measured with the wet suit were lower than without (P < 0.01), while for triathletes stroke rate was significantly higher with the wet suit (P < 0.01). For the whole group, the individual differences of performance were related to the blood lactate differences (r = -0.68; P < 0.01) and to the hydrostatic lift (r = 0.63; P < 0.01). For swimmers, the energy cost of swimming and the gliding ability were not statistically different with or without wet suit, while for triathletes they were significantly lower and decreased with velocity. It is concluded that the wet suit effect improves performance more in inefficient swimmers with low buoyancy, swimming at low speeds.

Adolescent↗
PubMed1995

Electrical stimulation and swimming performance.

The purpose of the study was to examine the influence of a 3-wk period of electrostimulation training on the strength of the latissimus dorsi m. and the swimming performances of 14 competitive swimmers divided into 7 electrostimulated (EG) and 7 control swimmers (CG). The peak torques registered during the flexion-extension of the arm was determined with the help of an isokinetic dynamometer at different velocities (from -60 degrees.s(-1) to 360 degrees.s(-1)). Performances were measured over a 25-m pull buoy and a 50-m freestyle swim. For EG, a significant increase of the peak torques was measured in isometric, eccentric, and concentric conditions (P < 0.5). The swimming times declined significantly (P < 0.01) by 0.19 +/- 0.14 s, for the 25-m pull-buoy, and by 0.38 +/- 0.24 s, for the 50-m freestyle. For CG, no significant difference was found for any of the tests. For the whole group, the variations of the peak torques, measured in eccentric condition (-60 degrees.s(-1)) were related to the variations of the performances (r = 0.77; P < 0.01). These results showed that an electrostimulation program of the latissimus dorsi increased the strength and swimming performances of a group of competitive swimmers.

Adult↗
PubMed1993

Possible nonlinear effects of exercise on bone in male subjects over age 60 years.

We investigated the relationships among bone mass, bone cell activities, and exercise level in 20 healthy 61-77 year old male volunteers divided into three groups according to the time they physically trained per week: nine subjects training less than 3 hr/week, five subjects between 3 and 6 hr/week and six subjects more than 6 hr/week. Physical performance was evaluated by VO2 max (ml min-1 kg-1). After tetracycline double labeling, iliac crest biopsy was obtained from each subject. The longer the physical activity, the higher the VO2 max. Subjects exercising between 3 and 6 hr/week revealed higher adjusted appositional and bone formation rates than all the others; mass and structural parameters also showed higher (nonsignificant) values. For the whole population VO2 max appeared negatively related to cortical thickness, cancellous bone volume, and trabecular thickness. These alterations were accompanied by increased cancellous bone turnover; this was evidenced by an increase in activation frequency and in resorption and formation rates as VO2 max increased. The bone remodeling periods tended to decrease also. Whatever the bone turnover rate, subjects were in steady state as far as their bone balance was concerned. Relationships between VO2 max and mineral apposition rate on the one hand and VO2 max and resorption surface on the other hand were best fitted by a quadratic model, suggesting a possible nonlinear effect of physical training on bone mass. We hypothesize that there is a threshold (6 hr/week) determining different effects. Adjustment of bone mass and trabecular arrangement were completed at time of biopsy and reflected probably past and transient bone imbalance.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

A new tool for evaluating energy expenditure: the "QAPSE" development and validation.

The objective of this study was to design and validate a working tool for the objective evaluation of daily energy expenditure (DEE) by means of a simple, noninvasive method: the QAPSE (Saint-Etienne Physical Activity Questionnaire), a questionnaire about physical activity (PA) over a period of 7 d (168 h). This eight-page questionnaire is designed to provide a complete picture of the subject's habitual PA without any restriction concerning the activities investigated, nor any specialization in relation to health components. It investigates the five areas of PA during daily life: work or way of keeping occupied, leisure activity (sports and nonsports activities), housework, basic everyday activity, moving about from place to place. Assessment of physical activity was conducted in 115 healthy volunteer subjects of both sexes aged 20-88. The values of mean habitual daily energy expenditure (MHDEE) obtained varied between 6,510 and 24,331 kJ.d-1. The MHDEE were in agreement with the data reported in the literature for various groups differing in respect to level of activity, sex, and age. The study demonstrated the reproducibility of the QAPSE (r = 0.997; N = 20; P < 0.0001). Its validity was tested in a comparative study between MHDEE and caloric intake (r = 0.576; N = 20; P < 0.01).

Activities of Daily Living↗
PubMed1992

Benefits of caffeine ingestion on sprint performance in trained and untrained swimmers.

The influence of specific training on benefits from caffeine (Caf) ingestion was examined during a sprint test in a group of highly trained swimmers (T) and compared with the response of a group of untrained occasional swimmers (UT). Seven T and seven UT subjects swam freestyle two randomly assigned 2 x 100 m distances, at maximal speed and separated by 20 min of passive recovery, once after Caf (250 mg) and once after placebo (Pla) ingestion. Anaerobic capacity was assessed by the mean velocity (meters per second) during each 100 m and blood was sampled from the fingertip just before and 1, 3, 5, 7, and 9 min after each 100 m for resting and maximal blood lactate concentration ([la-]b,max) determination. The [la-]bmax was significantly enhanced by Caf in both T and UT subjects (P less than 0.01). However, only T subjects exhibited significant improvement in their swimming velocity (P less than 0.01) after Caf or any significant impairment during the second 100 m. In light of these results, it appears that specific training is necessary to benefit from the metabolic adaptations induced by Caf during supramaximal exercise requiring a high anaerobic capacity.

Adolescent↗
PubMed1992

Physiological aspects of swimming performance for persons with disabilities.

The purpose of this study was to evaluate the various factors involved in the performances of three groups of swimmers with disabilities. These factors were average VO2max (Av-VO2max) measured during swimming and gliding factors measured by the passive drag. Thirty-four swimmers with disabilities were assigned into three groups ranging from more disabilities to fewer disabilities. The first group (G I) included 13 subjects in wheelchairs, the second group (G II) 10 subjects walking with technical aids, and the third group (G III) 11 swimmers with disabilities walking without any help. For G I, the performances and Av-VO2max were lower (P < 0.05) than for G II and G III while the passive drag was higher than for G III (P < 0.05). The performances, Av-VO2max, and passive drag were not statistically different between G II and G III. Some of the swimmers had a pronounced amyotrophia of the lower extremities (i.e., reduced volume of inactive muscles). The height from the top of the head to the beginning of the bilateral amyotrophia was called "height without amyotrophia" (HWA). In the whole group, passive drag was not related to the mass or the height but to the ratio mass/HWA (r = 0.71, P < 0.01). However, within each group, passive drag was mainly related to the mass (r = 0.63, 0.78, 0.62, P < 0.01, for G I, G II, and G III respectively). Performances of a 100-m and 400-m swim were mainly related to Av-VO2peak (r = 0.81 and 0.79, P < 0.01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Assessment of running velocity at maximal oxygen uptake.

To investigate the different ways of assessing the running velocity at which maximal oxygen uptake (VO2max) occurs, or maximal aerobic velocity (vamax), 32 well-trained runners (8 female and 24 male) were studied. The vamax and the running velocity corresponding to a blood lactate concentration of 4 mmol.l-1 (vla4) were measured during a progressive treadmill session. Within the week preceding or following the treadmill measurement the subjects completed a Université de Montreal Track-Test (UMTT). The velocity corresponding to the last stage of this test (vUMTT) was slightly higher than vamax: 6.08 m.s-1, SD 0.41, vs 6.01 m.s-1, SD 0.44 (P less than 0.03) but these two velocities were strongly correlated (r = 0.92, P less than 0.001). The heart rate values corresponding to these velocities were similar and well correlated (r = 0.79, P less than 0.01); the corresponding blood lactate values had similar mean values: 10.5 mmol.l-1, SD 2.7 vs 11.8 mmol.l-1, SD 2.5, but were not correlated. Both vamax and vUMTT correlated well with the best performance sustained over 1500 m during the season. These results suggest that the UMTT provides a value of vamax as accurately as a treadmill measurement and that either could be used to measure the running velocity corresponding to VO2max. The v1a4 was 86.6%, SD 2.6 of vamax; these two velocities correlated strongly. Thus, in well trained runners, v1a4, when measured with a well-defined procedure, corresponds to a constant fraction of vamax and depends then on VO2max and the energy cost of running.

Adult↗
PubMed1991

Energy cost of front-crawl swimming in women.

The purpose of this study was to examine the relationship between the energy cost of swimming per unit distance (Cs) at different velocities (v) and performance level, body size and swimming technique in women. A total of 58 females swimmers were studied. Three performance levels (A, B, C) were determined, ranging from the slower (A) to the faster (B, C). At level C and at 1.1 m.s-1, Cs,1.1 was reduced by 7% when directly compared to level B. The Cs,1.1 was reduced by 10% when calculated per unit of height (h) and by 37% when calculated per unit of h and hydrostatic lift (HL). For the whole group of swimmers, the equation regression was Cs,1.1 = 0.27 h-2.38 HL - 7.5 (r = 0.53, P less than 0.01). To evaluate the specific influence of arm length two groups of long- and short-armed swimmers were selected among swimmers of similar h and performance. The Cs was significantly higher (P less than 0.05) by 12%, SD 2.2%, for short-armed than for long-armed swimmers. To evaluate the influence of different types of swimming technique, two other groups of similar performance and anthropometric characteristics were selected. The Cs was significantly higher (P less than 0.05) by 12%, SD 4.5% for swimmers using for preference their legs rather than their arms. The Cs of the sprinters was 15.7%, SD 2% higher than that of the long-distance swimmers. For all groups, Cs increased with v on average by 8% to 11% every 0.1 m.s-1. These findings showed that Cs variations of these women were close to those previously demonstrated for men. The Cs depends on performance level, body size, buoyancy, swimming technique and v.

Adolescent↗