Biomedical subjects

Paul Delamarche

Publications and source records attributed to Paul Delamarche.

13 recordsLinked to original sources

PubMed2006

Force-plate based computation of ankle and hip strategies from double-inverted pendulum model.

BACKGROUND: Using statistical characteristics of the centre of pressure displacement or of the ground reaction forces, it is difficult to have quantitative evaluation of the equilibrium strategy employed (ankle or hip). The purpose of this study is to validate a new force-plate based approach that allows to evaluate postural strategies employed through a method based on a double-inverted pendulum model. METHODS: This method allows to compute ankle and hip joint motion only from force plate data and relies on inverse kinematics with the centre of mass considered as the end effector. Furthermore, an index, depending on the covariance between hip and ankle angles, is proposed to quantify the strategy used. To validate the method and the strategy index, we compare the results of our computation to an optical stereophotogrammetry measurement of the angles considered as reference value. FINDINGS: The experiments demonstrate that our method provides acceptable results. The root mean square error between computed and measured hip and ankle angles stands between 4.5 x 10(-3)degrees for ankle angle in static condition and 1.1 x 10(-1) degrees for hip angle in hip forced condition. INTERPRETATION: The main interest of our method for clinicians is that it allows to retrieve the ankle and hip angles only using a simple and widespread device, the force-plate. Moreover, it proposes a new postural index that can be also be computed without videographic systems.

Adult↗

PubMed2006

[Influence of menstrual cycle phase on catecholamine response to sprint exercise in the woman].

The aim of the present study was to verify the menstrual cycle phase influence on catecholamine concentrations (adrenaline (A) and noradrenaline (NA)), peak power (P(pic)), and peak lactatemia (La(pic)) in response to a 6 s sprint exercise on a cycle ergometer in eight untrained women (19.1 +/- 0.9 years, 167.7 +/- 5.4 cm, 59.5 +/- 4.7 kg). All women realize the 6 s sprint test in the morning, within the same menstrual cycle, in the follicular (PF) and the luteal phase (PL). Plasma catecholamine concentrations were determined at rest (A0 and NA0), immediately at the end of the sprint exercise (AEX and NAEX), and after 5 min of recovery (A5 and NA5). P(pic) and La(pic) were not significantly affected by the menstrual cycle phase. Catecholamine concentrations measured at rest, in response to the 6 s sprint test and after 5 min of recovery were not significantly different in PF and PL. Significant relationships were observed between AEX and La(pic) (r = 0.53, p < 0.01) and between AEX and P(pic) (r = 0.70, p < 0.01). In conclusion, this study demonstrated that the menstrual cycle phase did not alter performance, lactatemia, and sympatho-adrenergic responses to a short sprint exercise in untrained women.

Adult↗

PubMed2005

[Average height of adolescents in the Dinaric Alps].

This study contributes to an update of average heights among European populations. Our investigation covering 2705 boys and 2842 girls aged 17 years, shows that, contrary to the general belief, adolescents of the Dinaric Alps are, on average, the tallest in Europe. With an average height of 185,6 cm, they are taller than Dutch adolescents (184 cm on average). Above all, the density of very tall subjects appears to be characteristic of the Dinaric Alps, since 28% measure 190 cm or more in height, as opposed to only 20% in Holland and 1.5% in France. Although our information is not complete, adolescent girls in the Dinaric Alps, with an average height of 171 cm come a close second to girls in Holland.

Adolescent↗

PubMed2005

Normal physical working capacity in prepubertal children with type 1 diabetes compared with healthy controls.

BACKGROUND: Exercise testing has become a valuable help for the physician to examine the influence of recommended exercise training on physical fitness. However, the question as to how diabetic prepubertal children differ from their non-diabetic peers in their performance capacity has only partial and sometimes conflicting answers in the literature. AIM AND METHODS: The aim of the current study was thus to evaluate aerobic fitness during an incremental submaximal test (measure of the Physical Working Capacity 170 (PWC170)) in 17 well-controlled prepubertal insulin-dependent diabetic boys aged 8.5-13 y. Eighteen healthy prepubertal boys matched for age, body size and physical activity served as controls. Part of the method was to check capillary blood glucose level in the diabetic patients and in nine of the healthy subjects throughout the exercise. RESULTS: From this experiment it appeared that the level of physical fitness was similar in diabetic and healthy boys (PWC170 2.28+/-0.09 vs 2.37+/-0.13 W x kg(-1)). While glucose homeostasis was well maintained in the healthy group, diabetic children showed a marked fall in blood glucose during the exercise. In addition, the PWC170 level correlated significantly with the estimate of energy expenditure attributed to vigorous activities in the diabetic boys. CONCLUSION: By studying the responses to incremental exercise there is growing evidence that normal physical fitness is preserved in diabetic prepubertal boys given appropriate involvement in physical activity.

Adolescent↗

PubMed2005

Overnight urinary cortisol and cortisone add new insights into adaptation to training.

PURPOSE: To examine the effects of training on the HPA axis using two new noninvasive tools: salivary cortisol response to awakening and overnight urinary cortisol and cortisone excretion, and on the sympathoadrenal system using overnight catecholamines excretion. To dissociate the effects of training to those of seasonal hormonal variations, endurance-trained men were compared with sedentary men. METHODS: Nine untrained (UT) men and 10 triathletes were followed during a 10-month season. Clinical (total score of fatigue, total training load, and performances during the competition period) and hormonal parameters (overnight excretion of glucocorticoids and catecholamines, increment of saliva cortisol response to awakening) were measured. RESULTS: Significant seasonal variations in overnight urinary glucocorticoids (decreased in June) and catecholamines (increased in June) concentrations and in saliva cortisol response to awakening were depicted in the two groups. Whereas urinary cortisol excretion was similar between both groups, overnight urinary cortisone excretion was significantly higher in triathletes compared with UT men (ANOVA: training effect: F(2,45) = 9.50, P = 0.0003), suggesting that during a resting day there is a higher inactivation of cortisol into cortisone in highly trained men. Two triathletes developed an overtraining syndrome and presented an increased urinary cortisol/cortisone ratio (>1) due to lower cortisone inactivation compared with the triathlete group. CONCLUSION: : When not taken into account, seasonal variations may induce errors in the interpretation of hormonal variations with training. The increased intracellular inactivation of cortisol during the night in endurance-trained men uncovers subtle changes in HPA function during training. We show in this study the interest of noninvasive biological markers of the activity of the neuroendocrine system to monitor the repercussion of training load during longitudinal follow-up of athletes.

Adaptation, Physiological↗

PubMed2004

Using virtual reality to analyze links between handball thrower kinematics and goalkeeper's reactions.

This work investigates the design of a new method to evaluate the importance of visual elements taken into account by a handball goalkeeper facing a thrower. Virtual reality was used to design and reproduce standardised situations in a controlled environment. Under such conditions, it was possible to isolate for investigation one visual element in the thrower's gestures. The goalkeeper's movements were recorded in order to compare his reactions to two separate throws where only one visual element was modified. Our systems allowed us to measure and record the effects of small changes in the thrower's movements. With the numerical values we obtained from our results we were able to come up with a scale of significance for each isolated element. These preliminary results look promising for neuroscience, allowing us to better understand the strategies used in duel situations.

Biomechanical Phenomena↗

PubMed2004

Do handball throws always exhibit a proximal-to-distal segmental sequence?

Previous studies on overarm throwing have described a proximal-to-distal segmental sequence. The proximal segments reached their maximal linear velocities before the distal ones. In handball, no study has demonstrated this sequence from the upper torso to the wrist, although a recent study did present a different organization. The aim of this study was to analyse the throwing arm segmental organization during handball throwing. We found that the maximal linear velocity of the shoulder occurred after the maximal linear velocity of the elbow. Moreover, the maximal angular velocity of the upper torso occurred later than that of the elbow. Hence, contrary to other disciplines, the rotation of the upper torso was not suddenly stopped just after the forward arm motion was initiated. These results may apply to handball in general or be specific to the population of handball players studied. It may be advisable in future studies to include international players.

Adolescent↗

PubMed2004

Effect of training on beta1 beta2 beta3 adrenergic and M2 muscarinic receptors in rat heart.

OBJECTIVE: Physical training is known to alter several cardiovascular parameters. These adaptations are for a great part linked to an alteration of the myocardial responses to its autonomic nervous regulation. To further explain the parasympathetic and catecholamine effects, we hypothesized that endurance training could modify rat myocardial beta1, beta2, beta3 adrenoreceptors (AR) and M2 muscarinic cholinergic receptor (AchR) densities. METHODS: Two groups of adults female Wistar rats were studied: controls (C) (N = 7) and trained (T) (N = 9). An 8-wk treadmill training protocol was performed, 5 d x wk and of 1 h x d. At the end of the training session, left ventricle and atria muscle were isolated and weighed. Then, quantification of beta1, beta2, beta3 AR and M2 AchR was performed using Western blot analysis. RESULTS: M2 AchR densities were not modified in left ventricle or in atria by training (respectively, 100 +/- 22%, C vs 101 +/- 14%, T and 100 +/- 23%, C vs 119 +/- 30%, T). Concerning the left ventricle beta AR isoforms, beta1AR density was decreased in T (80 +/- 10% T vs 100 +/- 14% C, P = 0.01), beta2AR was unaltered (102 +/- 12%, T vs 100 +/- 17%, C), and beta3 AR density was increased in T (139 +/- 38% T vs 100 +/- 15% C; P < 0.05). CONCLUSIONS: Our results show for the first time that in female rats an 8-wk treadmill training protocol alters specifically the left ventricle beta AR isoforms densities but not the M2 AchR one. These results could explain some of the beneficial cardiovascular adaptations of the physically trained heart.

Animals↗

PubMed2003

Effect of the intensity of training on catecholamine responses to supramaximal exercise in endurance-trained men.

In this study we investigated whether plasma catecholamine responses to the Wingate test are affected by the intensity of training in endurance-trained subjects. To do this we compared plasma adrenaline (A) and noradrenaline (NA) concentrations in response to a Wingate test in three different groups: specialist middle-distance runners (MDR) in 800-m and 1,500-m races, specialist long-distance runners (LDR) 5,000-m and 10,000-m races, and untrained subjects (UT). The maximal power ( W(max)) and the mean power ( W) were determined from the Wingate test. Blood lactate (La), plasma A and NA concentrations were analysed at rest (La(0), A(0) and NA(0)), immediately at the end of the exercise (A(max )and NA(max)) and after 5 min recovery (La(max), A(5) and NA(5)). The ratio A(max)/NA(max )was considered as an index of the adrenal medulla responsiveness to the sympathetic nervous activity. At the end of the test, W(max) and W were similar in the three groups but La(max) was significantly greater in MDR compared to LDR and UT [15.2 (2.2) mmol l(-1), 11.7 (3.1) mmol l(-1), 11.6 (1.6) mmol l(-1), respectively, for MDR, LDR and UT; mean (SD)]. Concerning the plasma catecholamine concentrations in response to exercise, MDR and LDR A(max) values [3.73 (1.53) nmol l(-1), 3.47 (0.74) nmol l(-1), respectively, for MDR and LDR] were significantly greater than those of UT [1.48 (0.32) nmol l(-1)] who also exhibited the lowest NA(max) values [11.09 (6.58) nmol l(-1)] compared to MDR and LDR [20.43 (3.51) nmol l(-1); 15.85 (4.88) nmol l(-1), respectively, for MDR and LDR]. However, no significant differences were observed between the two trained groups either for A(max) or NA(max.) These results suggest that long-term endurance training can enhance plasma catecholamine concentrations in response to supramaximal exercise. However, as there were no significant differences between MDR and LDR A(max) and NA(max) values, the effect of the intensity of training remains to be clarified.

Adolescent↗

PubMed2003

Does training have consequences for the walk-run transition speed?

A number of authors when studying the walk-run transition phenomenon focused either on the mechanical or energy expenditure whilst only a few used both parameters concurrently. Moreover the literature demonstrates that the contribution of these variables changes along with the level and method of training. Consequently the purpose of this study is to find, by analyzing concurrently these two variables, if the walk-run transition speed is linked to the type of training. To this end we calculated two theoretical transition speeds: one based on the metabolic energy expenditure St(1) and the second one based on the internal work St(2). Subjects were divided into three groups (untrained, sprint and endurance-trained men) who were required to walk and run on a treadmill at increasing speeds. Firstly we show that the relationship between St(1) and St(2) differs depending on the groups. Sprinters have a significantly lower St(2) than St(1) whereas the opposite is found for untrained subjects. We also show that the transition speed is linked to the subject's type of training. To conclude it seems that acquiring running techniques through specific training has consequences for the walk-run transition phenomenon.

Acceleration↗

PubMed2003

Effect of active and passive recovery on blood lactate and performance during simulated competition in high level gymnasts.

The purpose of this study was to investigate the effect of two recovery strategies between men's gymnastics events on blood lactate removal (BL) and performance as rated by expert "blind" judges. Twelve male gymnasts (21.8 +/- 2.4 years) participated. The sessions were composed of routine performances in the six Olympic events, which were separated by 10 min of recovery. All gymnasts performed two recovery protocols between events on separate days: Rest protocol, 10 min rest in a sitting position; Combined protocol, 5 min rest and 5 min self-selected active recovery. Three blood samples were taken at 2, 5, and 10 min following each event. Gymnasts produced moderate values of BL following each of the six events (2.2 to 11.6 mmol.L-1). There was moderate variability in BL values between events that could not be accounted for by the athlete's event performance. Gymnasts showed higher BL concentration (p > .05) and significantly (p < .05) higher scoring performances (as rated by a panel of certified judges) when they used a combined recovery between gymnastics events rather than a passive recovery (delta BL = 40.51% vs. 28.76% of maximal BL, p < .05, and total score = 47.28 +/- 6.82 vs. 38.39 +/- 7.55, p < .05, respectively).

Adult↗

PubMed2003

[Catecholamine response to the Wingate test in untrained women].

Supramaximal exercises are well known to induce a severe stress on the adrenal medulla and nervous sympathetic system. This stress induces increased plasma catecholamines concentrations. The responses of catecholamines to supramaximal exercises in women are still not well characterized and have been studied mostly in trained subjects. Hence the aim of the present study was to evaluate plasma catecholamine responses to a Wingate test in young and untrained women (n = 6) and men (n = 7). Venous plasma catecholamine concentrations were determined by HPLC, at rest, at the end of the warm-up and of the exercise, and during recovery (5, 10, 20, and 30 mn). Our results failed to show any significant difference in resting catecholamine concentrations ([A]p: 0.41 +/- 0.05 vs. 0.45 +/- 0.05 nmol. L-1; [NA]p: 3.28 +/- 0.68 vs. 2.58 +/- 0.26 nmol.L-1), kinetics, and maximal plasma catecholamine concentrations (Amax: 4.47 +/- 1.08 vs. 3.31 +/- 0.63 nmol.L-1; NAmax: 18.05 +/- 1.11 vs. 14.01 +/- 2.02 nmol.L-1) in response to the Wingate test between women and men, respectively. The Amax/NAmax ratio used as an index of adrenal medulla sensitivity to sympathetic input was also similar between genders. In conclusion, this study was able to demonstrate, in untrained subjects, that gender did not alder the sympatho-adrenergic response induced by a severe stress.

Adolescent↗

PubMed2003

Estrogen receptor alpha mRNA in human skeletal muscles.

INTRODUCTION/PURPOSE: To explain the effect of estrogen on skeletal muscle, the presence of estrogen receptor alpha mRNA (ERalpha mRNA) was investigated in human skeletal muscle. METHODS: The highly sensitive technique of nested reverse transcriptase-polymerase chain reaction (nested RT-PCR) was applied on a variety of tissue samples of both sexes: women (deltoid, pectoral, and uterus muscles) (N= 3) and men (deltoid muscle) (N= 3). The total ribonucleic acid was isolated from each tissue sample, reverse transcribed in a thermocycler, and nested PCR was then performed with specific primers. The by-products were analyzed by agarose gel electrophoresis. Internal standard 28S was simultaneously amplified. The ERalpha mRNA level was quantitated by using the ERalpha mRNA/28S mRNA ratio. RESULTS: The expected 204-bp product corresponding to ERalpha was amplified in all tested tissue samples, i.e., deltoid, pectoral, and uterine muscles from women and deltoid muscle from men. The ERalpha mRNA/28S mRNA ratios indicating the receptor expression levels in deltoid muscle from men and women were 0.945 +/- 0.393 (mean +/- SD) (N= 3) and 0.973 +/- 0.136 (mean +/- SD) (N= 2), respectively. CONCLUSIONS: In conclusion, the nested RT-PCR technique identified the presence of transcript encoding ERalpha mRNA in human skeletal muscles. Semi-quantification did not reveal gender difference.

Adult↗