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Biomedical subjects

M Bourdin

Publications and source records attributed to M Bourdin.

At least 19 recordsLinked to original sources
PubMed2005

Rowing performance and estimated training load.

We related the rowing performance and the associated physiological parameters to the training load as estimated by a questionnaire addressing the mean habitual weekly energy expenditure (MHWEE) of twenty-one international and national level oarsmen. The questionnaire also addressed the energy expenditure during training (EET) sessions classified as low- (EE1), moderate- (EE2), and high-intensity (EE3). To evaluate the physiological capability of the oarsmen, they performed incremental exercise to determine their maximal oxygen uptake (V.O(2max)) and the V.O(2) relative to V.O(2max) corresponding to the 4 mmol.l(-1) blood lactate concentration (V.O(2)4 %). The mean work rate sustained during a 2000-m all-out event on a rowing ergometer was considered as the rowing performance. On average, the rowers spent 16.4 +/- 1.0 h.wk(-1) in training with 56 +/- 3 % of the time spent on the water. EET represented 43.5 +/- 1.7 % of MHWEE. Rowing performance and V.O(2max) were both related to MHWEE and EET. Also, rowing performance was related to EE1, EE2, and EE3. In contrast, V.O(2)4 % was not related to the estimated energy expenditures. These results suggest that rowing performance and V.O(2max) are related to training load while V.O(2)4 % was not in the present group of highly trained oarsmen.

Adult↗
PubMed2005

Torque and power-velocity relationships in cycling: relevance to track sprint performance in world-class cyclists.

The aims of the present study were both to describe anthropometrics and cycling power-velocity characteristics in top-level track sprinters, and to test the hypothesis that these variables would represent interesting predictors of the 200 m track sprint cycling performance. Twelve elite cyclists volunteered to perform a torque-velocity test on a calibrated cycle ergometer, after the measurement of their lean leg volume (LLV) and frontal surface area (A(p)), in order to draw torque- and power-velocity relationships, and to evaluate the maximal power (P(max)), and both the optimal pedalling rate (f(opt)) and torque (T(opt)) at which P (max) is reached. The 200 m performances--i.e. velocity (V200) and pedalling rate (f 200)--were measured during international events (REC) and in the 2002 French Track Cycling Championships (NAT). P(max), f(opt), and T(opt) were respectively 1600 +/- 116 W, 129.8 +/- 4.7 rpm and 118.5 +/- 9.8 N . m. P(max) was strongly correlated with T(opt) (p < 0.001), which was correlated with LLV (p < 0.01). V200 was related to P(max) normalized by A(p) (p < or = 0.05) and also to f(opt) (p < 0.01) for REC and NAT. f 200 (155.2 +/- 3, REC; 149 +/- 4.3, NAT) were significantly higher than f(opt) (p < 0.001). These findings demonstrated that, in this population of world-class track cyclists, the optimization of the ratio between P(max) and A(p) represents a key factor of 200 m performance. Concerning the major role also played by f(opt), it is assumed that, considering high values of f 200, sprinters with a high value of optimal pedalling rate (i.e. lower f200-f(opt) difference) could be theoretically in better conditions to maximize their power output during the race and hence performance.

Adult↗
PubMed2004

A simple method for field measurements of leg stiffness in hopping.

A new method to measure the leg stiffness in hopping and bouncing, with simple technical equipment and under field conditions, is introduced and validated. The leg stiffness (K (N)) was calculated from only contact and flight times measured by a contact mat. It was compared to the reference stiffness (K (R)) obtained from force platform measurements. Eight subjects performed, first, submaximal hopping movements at different frequencies (1.8 to 4 Hz, by step 0.2 Hz) and, second, maximal hopping. In sub maximal hopping K (N) was significantly correlated with K (R) (r = 0.94; p < 0.001) and the difference between K (N) and K (R) ranged from -7.2 % to 6.9 % (at 1.8 and 3.6 Hz respectively) with a limit of agreement of -1.5 kN x m (-1). In maximal hopping K (N) was also related to K (R) (r = 0.98, p < 0.001) and the inter individual rank order was respected (R = 0.87). It was concluded that the new method could be applied to study extensively intra individual and inter individual variations of leg stiffness in respectively sub maximal and maximal hopping and thus to simplify further investigations in field conditions of the role of stiffness regulation in the optimization of human locomotion.

Adult↗
PubMed2004

Peak power output predicts rowing ergometer performance in elite male rowers.

The aim of the present study was to test the hypothesis that peak power output (Ppeak) sustained during maximal incremental testing would be an overall index of rowing ergometer performance over 2000 m (P2000), and to study the influence of selected physiological variables on Ppeak. A group of 54 highly trained rowers (31 heavyweight [HW] and 23 lightweight [LW] rowers) was studied. Body mass, maximal oxygen uptake ((.-)VO(2max)), oxygen consumption corresponding to a blood lactate of 4 mmol. l (-1) expressed in percentage of (.-)VO(2max) (V.O (2)La4 %), and rowing gross efficiency (RGE) were also determined during the incremental test. In the whole group Ppeak was the best predictor of P2000 (r = 0.92, p < 0.0001). Body mass (r = 0.65, p < 0.0001), V.O (2max) (r = 0.84, p < 0.0001), (.-)VO 2)La4 % (r = 0.49, p < 0.0001) and RGE (r = 0.35, p < 0.01) were significantly correlated with P2000 as well. To take the influence of body mass into account, (.-)VO(2max) was related to kg (0.57). Ppeak was significantly related to body mass (r = 0.56, p < 0.0001), (.-)VO(2max) x kg (-0.57) (r = 0.63, p < 0.0001), (.-)VO(2)La4 % (r = 0.45, p < 0.001) and RGE (r = 0.34, p < 0.05). Multiple regression analysis indicated that the above parameters taken together explained 82.8 % of Ppeak variation in the whole group. It was also demonstrated that Ppeak was the best predictor of P2000 when LW and HW groups were considered separately. It was concluded that, by integrating the main physiological factors of performance, Ppeak is an overall index of physiological rowing capacity and rowing efficiency in heterogeneous as well as in homogeneous groups. It presents the further advantage of being easily measured in the field.

Adult↗
PubMed2004

Laboratory blood lactate profile is suited to on water training monitoring in highly trained rowers.

AIM: This study validated the laboratory testing used to monitor on water training. The purpose was to test that reference heart rates (HR) determined during an incremental test elicit comparable blood lactate levels ([La](b)) during a 30 min on water rowing. METHODS: Blood lactate profile were determined during incremental graded exercise in 14 national and international level oarsmen. The HR corresponding to [La](b) of 2 and 3 mmol x l(-1) were determined (HRLa2 and HRLa3 respectively). The rowers then performed a 30 min training session in a boat. Training intensity, as assessed by HR monitors, had to range between HRLa2 and HRLa3. Field [La](b) (Laf) and HR (HRf) were measured at the end of the training session. RESULTS: Laf was 2.13+/-0.49 mmol x l(-1) (range: 1.43-3.07) and did not differ significantly from 2 mmol x l(-1). HRf (162+/-7.4 beats x min(-1)) ranged from HRLa2 (159+/-9.5 beats x min(-1)) to HRLa3 (171+/-9 beats x min(-1)). HRf was not significantly different from HRLa2. CONCLUSIONS: It was concluded that the HR determined during the laboratory testing are valid for monitoring on water training in highly trained rowers.

Adult↗
PubMed2002

Influence of changes in nasal ventilation on estimated workload during submaximal field running.

BACKGROUND: Breathe Right (BR) external nasal dilator have become increasingly popular over the past few years, however, the physiological basis for using BR remains unclear. We have examined whether alteration in nasal ventilation would influence the metabolic cost of submaximal running. METHODS: Metabolic cost was estimated in 10 male endurance triathletes by measuring heart rate (HR) and exercise perception by measuring the rate of perceived exertion (RPE) during submaximal field running. The protocol consisted of 5 min of running at 80% of their maximal aerobic velocity (MAV(f), previously determined under field conditions) for three randomised experimental conditions, separated by a 10 min rest. The conditions were normal nasal ventilation (N), no nasal ventilation (using a nose clip) (NC) and with a BR. RESULTS: Running with the BR or with NC did not significantly influence HR (N: 173+/-7, BR: 173+/-8, NC: 172+/-7 beat x min(-1); F=0.01, p=0.99) or RPE (N: 12.1+/-1.7, BR: 11.8+/-1.9, NC: 13.2+/-0.8; F=1.88, p=0.18). We conclude that alteration in nasal ventilation produced by using BR or NC do not influence HR or RPE in a group of triathletes running 5 min at 80% of MAV(f). CONCLUSIONS: The present study tended to demonstrate that both nasal ventilation would not influence the total metabolic cost, and that the BR device is not advantageous during high intensity exercise.

Adult↗
PubMed1998

The spring-mass model and the energy cost of treadmill running.

During running, the behaviour of the support leg was studied by modelling the runner using an oscillating system composed of a spring (the leg) and of a mass (the body mass). This model was applied to eight middle-distance runners running on a level treadmill at a velocity corresponding to 90% of their maximal aerobic velocity [mean 5.10 (SD 0.33) m x s(-1)]. Their energy cost of running (Cr). was determined from the measurement of O2 consumption. The work, the stiffness and the resonant frequency of both legs were computed from measurements performed with a kinematic arm. The Cr was significantly related to the stiffness (P < 0.05, r=-0.80) and the absolute difference between the resonant frequency and the step frequency (P < 0.05, r=0.79) computed for the leg producing the highest positive work. Neither of these significant relationships were obtained when analysing data from the other leg probably because of the work asymmetry observed between legs. It was concluded that the spring-mass model is a good approach further to understand mechanisms underlying the interindividual differences in Cr.

Biomechanical Phenomena↗
PubMed1997

Lactate exchange and removal abilities in rowing performance.

The relationships between individual performance and lactate exchange and removal abilities were studies in 12 male rowers all subjected to three measurements on a rowing ergometer. An incremental exercise carried out to determine the maximal oxygen uptake (VO2max) and the corresponding maximal aerobic power (Pamax), a 2500-m all-out test where the mean work rate (P2500) represented the individual performance, and a 6-min 90% Pamax exercise designed to assess the lactate kinetics during the following 90 min passive recovery were performed. The lactate recovery curves were fitted to the bi-exponential time function: La(t) = La(O) + A1(1-e-gamma 1.t) + A2(1-e-gamma 2.t). The velocity constants gamma 1 and gamma 2 denote the lactate exchange and removal abilities, respectively. The mean value of P2500 sustained by the rowers was 376 +/- 41W (106 +/- 5% of Pamax (P2500%). P2500 was positively correlated with gamma 2 (P < 0.05). gamma 1 and gamma 2 explained 67% of the P2500 variance. P2500% was also correlated with gamma 2 (P < 0.01). These results suggest that a better performance on the rowing ergometer is associated with improved lactate exchange and removal abilities. Furthermore, the ability to row at high relative work rates was correlated with an increased lactate removal ability. Training-induced adaptations could explain the high gamma 1 and gamma 2 displayed by the present rowers.

Adaptation, Physiological↗
PubMed1995

Effect of vertical loading on energy cost and kinematics of running in trained male subjects.

This investigation examined, in a group of 10 trained male runners, the effect of vertical loading during level treadmill running at a velocity of 5 m/s. The net energy cost of running (Cr), the external work of the center of mass of the body (Wext; both expressed in J.kg-1.m-1), and the eccentric-to-concentric ratio (Ecc/Con) of integrated electromyographic activity for the vastus lateralis (VL) and gastrocnemius lateralis muscles were measured. It was observed that Wext and Ecc/Con for the VL could explain a large part of the interindividual variations in Cr. This result reinforces the hypothesis that Ecc/Con could be a good index of effectiveness in the stretch-shortening cycle. When the subjects ran with a vertical load of 9.3% of their body mass, Cr and Wext were significantly reduced (P < 0.01 and P < 0.05, respectively), whereas Ecc/Con for the VL and gastrocnemius lateralis remained unchanged. The variations in Cr and Wext due to vertical loading were significantly correlated (r = 0.75; P < 0.01). It was then concluded that the significant improvement of Cr observed with the added load was mainly due to the fact that Wext was significantly decreased.

Adult↗
PubMed1995

[Bone anchored hearing aid: the Bordeaux experience].

Bone anchored hearing aids (BAHA) based on the concept of osseointegration offer the possibility of restoring hearing in cases of conduction or mixed deafness. The authors report on their experience with 42 implants in 35 patients, dived into two major groups, with bilateral agenesia on the one hand (15 cases) and problems of chronic otitis media (20 cases) on the other hand. The functional results are excellent, with 30 patients fitted with 32 HC200 or HC300 prostheses. The authors stress the necessity of strictly observing the audiometric criteria and the determinant factors of osseointegration, essentially the surgical technique.

Adolescent↗
PubMed1993

Influence of training, sex, age and body mass on the energy cost of running.

To highlight the influences of age, sex, body mass (mb) and running training on the energy cost of running (Cr) young basketball players [38 boys (BB) and 14 girls (BG), aged 14.2 (SD 0.3) and 12.2 (SD 1.9) years, respectively] were selected to be compared to middle-distance runners [27 men (MR) and 14 women (FR) aged 23.7 (SD 3.4) and 23.9 (SD 4.1) years, respectively]. The Cr was measured during a maximal treadmill test. In each group Cr and body mass (mb) and body height were negatively and significantly correlated. A stepwise regression showed that among both the body dimensions measured, mb was the most important factor in determining the variations of Cr. For the whole group (n = 93) the correlation coefficient was 0.72 (P < 0.0001). For a given mb, there was no significant difference between the Cr of BG, BB and MR: this result would support the hypothesis that the differences in Cr currently attributed to age, running training or sex differences are mainly related to mb. On the other hand, for a given mb, FR showed a significantly lower Cr than the basketball players (P < 0.01 for BG and BB) and than MR (P < 0.05), thus suggesting that women decrease their Cr as a response to running training more efficiently than do men.

Adolescent↗
PubMed1993

[Comparative enantioselectivity of the disposition of two non-steroidal anti-inflammatory agents, ketoprofen and carprofen, in man and animals].

After the administration of racemic ketoprofen and carprofen to man, both enantiomers of each compound exhibit similar plasma profiles. This contrasts with the rat where the active S(+) enantiomer is predominant. For carprofen, regardless of the route of administration, the R(-) enantiomer is predominant in the plasma of all investigated animal species. The S(+)/R(-) ratio of the "areas under the curves" during the time course of the kinetics, is: 0.60 in dogs, 0.53 in Yucatan micro-pigs, 0.48 in mini-goats, 0.67 in calves and 0.19 in horses. For ketoprofen, the S(+) enantiomer is predominant in dogs, cats and horses, with ratios of 30.3, 5.3 and 1.5, respectively, while R(-) is the predominant enantiomer in sheep. The interpretation of these inter-species differences can be supported by experimental evidence, however some informations are lacking and additional investigation is required. In the case of ketoprofen where S(+) is predominant in rats, dogs and horses, the metabolic chiral inversion from R(-) to S(+), which has been demonstrated in rats, may also take place in the latter two species. In addition, the well documented stereoselective clearance of the glucuronides, possibly in favour of the enantiomer S(+), may explain the lower body clearance of the R(-) enantiomer in sheep. For carprofen, no metabolic chiral inversion was shown in rats and dogs after administration of each enantiomer individually, but for this compound, stereoselective clearance of glucuronides has been demonstrated which may support the idea of a plasma concentration shift of the enantiomeric proportions vs time in favour of the R(-) enantiomer. Regardless of the possible biological mechanisms which are responsible for these inter-species differences, the existence of these differences gives rise to at least two important issues: The choice of animal species which can be used in the research of drugs destined for human therapeutics: the most pertinent animal species will be the one which demonstrates an enantiomeric plasma profile closest to that observed in man. The present data show that the ideal animal species from this respect has still to be identified. For application in veterinary therapeutics, a careful balance must be established between the requirement of favourable bioavailability of the active S(+) enantiomer and the potential of any possible chiral inversion of R(-) to generate hybrid molecules in meat and milk which in turn may lead to residues, the toxicity of which to the human consumer is still unknown.

Animals↗
PubMed1992

Physiological correlates of middle-distance running performance. A comparative study between men and women.

To compare the relative contributions of their functional capacities to performance in relation to sex, two groups of middle-distance runners (24 men and 14 women) were selected on the basis of performances over 1500-m and 3000-m running races. To be selected for the study, the average running velocity (v) in relation to performances had to be superior to a percentage (90% for men and 88% for women) of the best French v achieved during the season by an athlete of the same sex. Maximal O2 consumption (VO2max) and energy cost of running (CR) were measured in the 2 months preceding the track season. This allowed us to calculate the maximal v that could be sustained under aerobic conditions, va,max. A v:va,max ratio derived from 1500-m to 3000-m races was used to calculate the maximal duration of a competitive race for which v = va,max (tva,max). In both groups va,max was correlated to v. The relationships calculated for each distance were similar in both sexes. The CR [0.179 (SD 0.010) ml.kg-1 x m-1 in the women versus 0.177 (SD 0.010) in the men] and tva,max [7.0 (SD 2.0) min versus 8.4 (SD 2.1)] also showed no difference. The relationships between VO2max and body mass (mb) calculated in the men and the women were different. At the same mb the women had a 10% lower CR than the men; their lower mb thus resulted in an identical CR.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗