Biomedical subjects

L Messonnier

Publications and source records attributed to L Messonnier.

9 recordsLinked to original sources

PubMed2006

Effects of training on lactate kinetics parameters and their influence on short high-intensity exercise performance.

The purpose of the present study was to relate the training-induced alterations in lactate kinetics parameters to the concomitant changes in time to exhaustion (T(lim)) at a work rate corresponding to maximal oxygen uptake (Pa(peak)). Eight subjects performed before and after training i) an incremental exercise up to exhaustion to determine Pa(peak), ii) a 5-min 90 % Pa(peak) exercise followed by a 90-min passive recovery to determine an individual blood lactate recovery curve fitted to the bi-exponential time function: La(t) = La(0) + A1(1 - e -gamma1 x t) + A2(1 - e -gamma2 x t), and iii) a time to exhaustion at Pa peak to determine T lim. A biopsy of the vastus lateralis muscle was made before and after training. The training programme consisted in pedalling on a cycle ergometer 2 h a day, 6 days a week, for 4 weeks. Training-induced increases (p < 0.05) in Pa(peak), muscle capillary density, citrate synthase activity, gamma2 that denotes the lactate removal ability (from 0.0547 +/- 0.0038 to 0.0822 +/- 0.0071 min (-1)) and T(lim) (from 299 +/- 23 to 486 +/- 63 s), decreases (p < 0.05) in activities of lactate dehydrogenase (LDH) and muscle type of LDH, the phosphofructokinase/citrate synthase activities ratio and the estimated net amount of lactate released (NALR) during exercise recovery (from 66.5 +/- 8.6 to 47.2 +/- 11.1 mmol) were also observed. The improvement of T (lim) with training was related to the increase in gamma2 (r = 0.74, p = 0.0367) and to the decrease in NALR (r = 0.77, p = 0.0250). These results suggest that the post-training greater ability to remove lactate from the organism and reduced muscle lactate accumulation during exercise account for the concomitant improvement of the time to exhaustion during high-intensity exercise performed at the same relative work rate.

Adult↗

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↗

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↗

PubMed2003

Differences in lactate exchange and removal abilities in athletes specialised in different track running events (100 to 1500 m).

The purpose of this study was to investigate whether track running specialisation could be associated with differences in the ability to exchange and remove lactate. Thirty-four male high-level runners were divided into two groups according to their specialty (100 - 400 m/800 - 1500 m). All performed a 1-min 25.2 km x h -1 event, followed by a 90-min passive recovery to obtain individual blood lactate recovery curves which were fitted to a bi-exponential time function: [La](t) = [La](0) + A 1 (1-e -gamma1t) + A 2 (1-e -gamma2t). The velocity constant gamma 1 which denotes the ability to exchange lactate between the previously worked muscles and blood was higher (p < 0.001) in middle-distance runners than in sprint runners. The velocity constant gamma 2 which reflects the overall ability to remove lactate did not differ significantly between the two groups. gamma 1 was positively correlated with the best performance over 800 m achieved by 16 athletes during the outdoor track season following the protocol (r = 0.55, p < 0.05). In conclusion, the lactate exchange ability seems to play a role on the athlete's capacity to sustain exercise close to 2-min-duration and specifically to run 800 m.

Adaptation, Physiological↗

PubMed2002

Time to exhaustion at VO(2)max is related to the lactate exchange and removal abilities.

The aim of the present study was to investigate the relationships between lactate exchange and removal abilities and the capacity to prolong exercise, as assessed by the time to exhaustion (Tlim) at a work rate corresponding to VO(2)max (Pa max ). The individual blood lactate recovery curves obtained for 13 untrained subjects after 5 min 90 % Pa max exercise were fitted to the biexponential time function: La(t) = La(0) + A(1) (1-e (-gamma(1) x t) + A(2) (1-e (-gamma(2) x t), where t is time into the recovery, La(0) is the arterialized lactate concentration measured at the end of the exercise, gamma(1) and gamma(2) are velocity constants denoting the lactate exchange and removal abilities, respectively. Tlim was positively related to gamma(1) and gamma(2) (r = 0.60, p < 0.05 and r = 0.56, p < 0.05, respectively) but was negatively related to La(0) (r = 0.75, p < 0.01). gamma()1 was positively related to the capillary density (r = 0.69, p < 0.01) and to the number of capillaries per type I fiber area (r = 0.62, p < 0.05). It was concluded that 1) high lactate exchange and removal abilities would allow continuing a high-intensity exercise for a longer duration, and 2) a high capillary density may explain the associated high lactate exchange ability.

Adult↗

PubMed2002

Leg strength and stiffness as ability factors in 100 m sprint running.

BACKGROUND: The purpose of this study was to determine the importance of leg strength and stiffness relative to i) 100 m sprint performance, ii) mean speed on the three phases of the 100 m race (30-60-100 m) and iii) the speed differences between these phases. METHODS: Nineteen regional to national level male sprinters competed in a 100 m race. Video analysis was used to determine mean velocity parameters. Two subgroups were created since some of the runners decreased their velocity during the third phase (G1), whereas others maintained or accelerated it (G2). Leg strength (concentric half-squats - counter movement jump) and stiffness (hopping) were determined. Simple (r) and multiple regressions (R) were used. RESULTS: The mean performance over 100 m was 11.43 sec (10.72-12.87 sec). The concentric half-squats were related to 100 m (r=0.74, p<0.001) and to the mean speed of each phase (R=0.75, p<0.01). The counter movement jump was related to 100 m (r=0.57, p<0.05) and was the predictor of the first phase (r=0.66, p<0.01). The hopping test was the predictor of the two last phases (R=0.66, p<0.05). Athletes who had the greatest leg stiffness (G1) produced the highest acceleration between the first and the second phases, and presented a deceleration between the second and the third ones. CONCLUSIONS: The concentric half-squats test was the best predictor in the 100 m sprint. Leg stiffness plays a major role in the second phase.

Adult↗

PubMed2001

Blood lactate exchange and removal abilities after relative high-intensity exercise: effects of training in normoxia and hypoxia.

The effects of 4 weeks of endurance training in conditions of normoxia or hypoxia on muscle characteristics and blood lactate responses after a 5-min constant-load exercise (CLE) at 90% of the power corresponding to the maximal oxygen uptake were examined at sea-level in 13 sedentary subjects. Five subjects trained in normobaric hypoxia (HT group, fraction of oxygen in inspired gas = 13.2%), and eight subjects trained in normoxia at the same relative work rates (NT group). The blood lactate recovery curves from the CLE were fitted to a biexponential time function: La(t) = La(0) + A1(1 - e- gamma 1.t) + A2(1 - e- gamma 2.t), where the velocity constants gamma 1 and gamma 2 denote the lactate exchange and removal abilities, respectively, A1 and A2 are concentration parameters that describe the amplitudes of concentration variations in the space represented by the arterial blood, La(t) is the lactate concentration at time t, and La(0) is the lactate concentration at the beginning of recovery from CLE. Before training, the two groups displayed the same muscle characteristics, blood lactate kinetics after CLE, and gamma 1 and gamma 2 values. Training modified their muscle characteristics, blood lactate kinetics and the parameters of the fits in the same direction, and proportions among the HT and the NT subjects. Endurance training increased significantly the capillary density (by 31%), citrate synthase activity (by 48%) and H isozyme proportion of lactate dehydrogenase (by 24%), and gamma 1 (by 68%) and gamma 2 (by 47%) values. It was concluded that (1) endurance training improves the lactate exchange and removal abilities estimated during recovery from exercises performed at the same relative work rate, and (2) training in normobaric hypoxia results in similar effects on lactate exchange and removal abilities to training in normoxia performed at the same relative work rates. These results, which were obtained non-invasively in vivo in humans during recovery from CLE, are comparable to those obtained in vitro or by invasive methods during exercise and subsequent recovery.

Adult↗

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↗