Biomedical subjects

V Billat

Publications and source records attributed to V Billat.

36 records · Page 2Linked to original sources

PubMed2000

Maximal endurance time at VO2max.

INTRODUCTION: There has been significant recent interest in the minimal running velocity which elicits VO2max. There also exists a maximal velocity, beyond which the subject becomes exhausted before VO2max is reached. Between these limits, there must be some velocity that permits maximum endurance at VO2max, and this parameter has also been of recent interest. This study was undertaken to model the system and investigate these parameters. METHODS: We model the bioenergetic process based on a two-component (aerobic and anaerobic) energy system, a two-component (fast and slow) oxygen uptake system, and a linear control system for maximal attainable velocity resulting from declining anaerobic reserves as exercise proceeds. Ten male subjects each undertook four trials in random order, running until exhaustion at velocities corresponding to 90, 100, 120, and 140% of the minimum velocity estimated as being required to elicit their individual VO2max. RESULTS: The model development produces a skewed curve for endurance time at VO2max, with a single maximum. This curve has been successfully fitted to endurance data collected from all 10 subjects (R2 = 0.821, P < 0.001). For this group of subjects, the maximal endurance time at VO2max can be achieved running at a pace corresponding to 88% of the minimal velocity, which elicits VO2max as measured in an incremental running test. Average maximal endurance at VO2max is predicted to be 603 s in a total endurance time of 1024 s at this velocity. CONCLUSION: Endurance time at VO2max can be realistically modeled by a curve, which permits estimation of several parameters of interest; such as the minimal running velocity sufficient to elicit VO2max, and that velocity for which endurance at VO2max is the longest.

Adult↗

PubMed2000

Time limit and time at VO2max' during a continuous and an intermittent run.

BACKGROUND: The purpose of this study was to verify, by track field tests, whether sub-elite runners (n=15) could (i) reach their VO2max while running at v50%delta, i.e. midway between the speed associated with lactate threshold (vLAT) and that associated with maximal aerobic power (vVO2max), and (ii) if an intermittent exercise provokes a maximal and/or supra maximal oxygen consumption longer than a continuous one. METHODS: Within three days, subjects underwent a multistage incremental test during which their vVO2max and vLAT were determined; they then performed two additional testing sessions, where continuous and intermittent running exercises at v50%delta were performed up to exhaustion. Subject's gas exchange and heart rate were continuously recorded by means of a telemetric apparatus. Blood samples were taken from fingertip and analysed for blood lactate concentration. RESULTS: In the continuous and the intermittent tests peak VO2 exceeded VO2max values, as determined during the incremental test. However in the intermittent exercise, peak VO2, time to exhaustion and time at VO2max reached significantly higher values, while blood lactate accumulation showed significantly lower values than in the continuous one. CONCLUSIONS: The v50%delta is sufficient to stimulate VO2max in both intermittent and continuous running. The intermittent exercise results better than the continuous one in increasing maximal aerobic power, allowing longer time at VO2max and obtaining higher peak VO2 with lower lactate accumulation.

Adult↗

PubMed1999

Oxygen deficit is related to the exercise time to exhaustion at maximal aerobic speed in middle distance runners.

The purpose of this study was to show the relationship between oxygen deficit and the time to exhaustion (tlim) at maximal aerobic speed (MAS). The minimum speed that elicits VO(2max) was assumed to be the maximal aerobic speed (MAS). Fourteen subelite male runners (mean (SD: age = 27 +/- 5 yrs: VO(2max) = 68.9 +/- 4.6 ml kg (-1). min ( -1); MAS = 21.5 +/- 1 km h (-1) ) participated in the study. Each subject performed an incremental test to determine and MAS. The subjects ran to exhaustion at velocities corresponding to 100 and 120 % MAS. Oxygen deficit was measured during the period exercise to exhaustion at 120% of MAS and was calculated from the difference between O(2) demand and the accumulated O 2 uptake. The tlim values at 100% MAS were correlated with the values of tlim at 120% MAS (r = 0.52). The results reveal that the oxygen deficit was related to the time to exhaustion at MAS and indicate that the greater the oxygen deficit, the greater the time to exhaustion at MAS. It was also noted that the adjustment of oxygen consumption is related to the oxygen deficit. In other words, the subjects who have an important anaerobic capacity are the most efficient during an exercise time to exhaustion at MAS. The time limit values can be expressed by a linear regression making intervene MAS and anaerobic capacity. This conclusion could be of great interest in the training of middle distance runners.

Adult↗

PubMed1998

High level runners are able to maintain a VO2 steady-state below VO2max in an all-out run over their critical velocity.

During prolonged and intense running exercises beyond the critical power level, a VO2 slow component elevates VO2 above predicted VO2-work rates calculated from exercise performed at intensities below the lactate threshold. In such cases, the actual VO2 value will increase over time until it reaches VO2max. The aims of the present study were to examine whether the VO2 slow component is a major determinant of VO2 over time when running at a speed beyond critical velocity, and whether the exhaustion latency period at such intensity correlates with the magnitude of the VO2 slow component. Fourteen highly trained long-distance runners performed four exhaustive runs, each separated by one week of light training. VO2 and the velocity at VO2max (vVO2max) were determined for each by a graded treadmill exercise. The critical velocity (86.1 +/- 1.5% vVO2max) of each runner was calculated from exhaustive treadmill runs at 90, 100 and 105% of vVO2max. During supra-critical velocity runs at 90% of vVO2max, there was no significant rise in VO2max (20.9 +/- 2.1 ml min-1 kg-1 between the third and last min of tlim 90), such that the runners reached a VO2 steady-state, but did not reach their vVO2max level over time (69.5 +/- 5.0 vs 74.9 +/- 3.0 ml min-1 kg-1). Thus, subjects' time to exhaustion at 90% of vVO2max was not correlated with the VO2max slow component (r = 0.11, P = 0.69), but significantly correlated with the lactate threshold (r = 0.54, P = 0.04) and the critical velocity (% vVO2max; r = 0.65, P = 0.01). In conclusion, the present study demonstrates that for highly trained long-distance runners performing exhaustive, supra-critical velocity runs at 90% of vVO2max, there was not a VO2 slow component tardily completing the rise of VO2. Instead, runners will maintain a VO2 steady-state below VO2max, such that the time to exhaustion at 90% of vVO2max for these runners is positively correlated with the critical velocity expressed as % of vVO2max.

Adult↗

PubMed1997

Anaerobic contribution to the time to exhaustion at the minimal exercise intensity at which maximal oxygen uptake occurs in elite cyclists, kayakists and swimmers.

Using 23 elite male athletes (8 cyclists, 7 kayakists, and 8 swimmers), the contribution of the anaerobic energy system to the time to exhaustion (t(lim)) at the minimal exercise intensity (speed or power) at which maximal oxygen uptake (VO2max) occurs (IVO2max) was assessed by analysing the relationship between the t(lim) and the accumulated oxygen deficit (AOD). After 10-min warming up at 60% of VO2max, the exercise intensity was increased so that each subject reached his IVO2max in 30 s and then continued at that level until he was exhausted. Pre-tests included a continuous incremental test with 2 min steps for determining the IVO2max and a series of 5-min submaximal intensities to collect the data that would allow the estimation of the energy expenditure at IVO2max. The AOD for the t(lim) exercise was calculated as the difference between the above estimation and the accumulated oxygen uptake. The mean percentage value of energy expenditure covered by anaerobic metabolism was 15.2 [(SD 6)%, range 8.9-24.1] with significant differences between swimmers and kayakists (16.8% vs 11.5%, P < or = 0.05) and cyclists and kayakists (16.4% vs 11.5%, P < or = 0.05). Absolute AOD values ranged from 26.4 ml.kg-1 to 83.6 ml.kg-1 with a mean value of 45.9 (SD 18) ml.kg-1. Considering all the subjects, the t(lim) was found to have a positive and significant correlation with AOD (r = 0.62, P < or = 0.05), and a negative and significant correlation with VO2max (r = -0.46, P < or = 0.05). The data would suggest that the contribution of anaerobic processes during exercise performed at IVO2max should not be ignored when t(lim) is used as a supplementary parameter to evaluate specific adaptation of athletes.

Adult↗

PubMed1997

Biomechanical events in the time to exhaustion at maximum aerobic speed.

Recent studies reported good intra-individual reproducibility, but great inter-individual variation in a sample of elite athletes, in time to exhaustion (tlim) at the maximal aerobic speed (MAS: the lowest speed that elicits VO2max in an incremental treadmill test). The purpose of the present study was, on the one hand, to detect modifications of kinematic variables at the end of the tlim of the VO2max test and, on the other hand, to evaluate the possibility that such modifications were factors responsible for the inter-individual variability in tlim. Eleven sub-elite male runners (Age = 24 +/- 6 years; VO2max = 69.2 +/- 6.8 ml kg-1 min-1; MAS = 19.2 +/- 1.45 km h-1; tlim = 301.9 +/- 82.7 s) performed two exercise tests on a treadmill (0% slope): an incremental test to determine VO2max and MAS, and an exhaustive constant velocity test to determine tlim at MAS. Statistically significant modifications were noted in several kinematic variables. The maximal angular velocity of knee during flexion was the only variable that was both modified through the tlim test and influenced the exercise duration. A multiple correlation analysis showed that tlim was predicted by the modifications of four variables (R = 0.995, P < 0.01). These variables are directly or indirectly in relation with the energic cost of running. It was concluded that runners who demonstrated stable running styles were able to run longer during MAS test because of optimal motor efficiency.

Adaptation, Physiological↗

PubMed1996

Critical velocity of continuous and intermittent running exercise. An example of the limits of the critical power concept.

The relationship between exhaustion time (tlim) and distance Dlim for running exercises at constant velocity until exhaustion can be described by a linear relationship (Dlim = a + b tlim) whose slope corresponds to a critical velocity. Seven runners participated to the study which compared the critical velocity of continuous versus intermittent running exercises. The critical velocity for continuous running (Vcritc) was calculated from the results (tlimc and Dlimc) of running exercises performed at 95 and 105% of the final velocity of the Montreal Track Test (vMTT). The intermittent running consisted of repetitions of running exercises performed at 95 and 105% vMTT during a time equal to half the value of the corresponding tlimc. The subjects recovered during a time equal to running time while jogging at a slow pace. The critical velocity for intermittent running (Vcriti) was calculated from the cumulated running distance (Dlimi) and cumulated running time (tlimi) corresponding to 95 and 105% vMTT. Vcriti was equal to Vcritc (4.56 +/- 0.444 m.s-1 vs 4.60 +/- 0.416 m.s-1). Nevertheless, in some subjects, the repetition numbers were very different for the intermittent running exercises at 95 and 105% vMTT. This paradoxical result could be explained by the fact that the value of Vcrit should be theoretically little sensitive to a large error in the value of tlim corresponding to a velocity slightly higher than critical velocity, for intermittent exercises as well as continuous exercises.

Adult↗

PubMed1996

A comparison of time to exhaustion at VO2 max in élite cyclists, kayak paddlers, swimmers and runners.

A recent study has shown the reproducibility of time to exhaustion (time limit: tlim) at the lowest velocity that elicits the maximal oxygen consumption (vVO2 max). The same study found an inverse relationship between this time to exhaustion at vVO2 max and vVO2 max among 38 élite long-distance runners (Billat et al. 1994b). The purpose of the present study was to compare the time to exhaustion at the power output (or velocity) at VO2 max for different values of VO2 max, depending on the type of exercise and not only on the aerobic capacity. The time of exhaustion at vVO2 max (tlim) has been measured among 41 élite (national level) sportsmen: 9 cyclists, 9 kayak paddlers, 9 swimmers and 14 runners using specific ergometers. Velocity or power at VO2 max (vVO2 max) was determined by continuous incremental testing. This protocol had steps of 2 min and increments of 50 W, 30 W, 0.05 m s-1 and 2 km-1 for cyclists, kayak paddlers, swimmers and runners, respectively. One week later, tlim was determined under the same conditions. After a warm-up of 10 min at 60% of their vVO2 max, subjects were concluded (in less than 45 s) to their vVO2 max and then had to sustain it as long as possible until exhaustion. Mean values of vVO2 max and tlim were respectively equal to 419 +/- 49 W (tlim = 222 +/- 91 s), 239 +/- 56 W (tlim = 376 +/- 134 s), 1.46 +/- 0.09 m s-1 (tlim = 287 +/- 160 s) and 22.4 +/- 0.8 km h-1 (tlim = 321 +/- 84 s), for cyclists, kayak paddlers, swimmers and runners. Time to exhaustion at vVO2 max was only significantly different between cycling and kayaking (ANOVA test, p < 0.05). Otherwise, VO2 max (expressed in ml min-1 kg-1) was significantly different between all sports except between cycling and running (p < 0.05). In this study, time to exhaustion at vVO2 max was also inversely related to VO2 max for the entire group of élite sportsmen (r = -0.320, p < 0.05, n = 41). The inverse relationship between VO2 max and tlim at vVO2 max has to be explained, it seems that tlim depends on VO2 max regardless of the type of exercise undertaken.

Adolescent↗

PubMed1996

Gender effect on the relationship of time limit at 100% VO2max with other bioenergetic characteristics.

The aim of this study was to investigate the influence of gender on the possible contribution of tlim at Va max (minimal speed that elicits VO2max) in performance speeds. The male and female elite middle-distance runners had similar performance (IAAF scores). Fourteen female and fifteen male (25.2 +/- 3.6 and 25.1 +/- 4.2 yr old; VO2max = 63.2 +/- 4.2 and 77.7 +/- 6.4 ml.kg-1 min-1; Va max = 17.3 +/- 0.7 and 20.8 +/- 1.1 km.h-1, respectively) performed three exercise tests on a treadmill (3 degrees slope) within a 2-wk period: an incremental test to determine VO2max, Va max and the velocity at the onset of blood lactate accumulation (VOBLA); an exhaustive constant velocity test to determine tlim at Va max; and an exhaustive constant velocity test at 110% Va max to determine the accumulated oxygen deficit (AOD). There were no effects of gender, i.e., no significant differences were observed between female and male for tlim at Va max (421 +/- 129 vs 367 +/- 118 s respectively; P = 0.24), VOBLA as % Va max (88.4 +/- 2.7 vs 90.4 3% of Va max; P = 0.07), AOD (40.1 +/- 14.9 vs 48.9 +/- 21.3 ml.O2.kg-1; P = 0.22), running economy at the same absolute speed, i.e., 14 km.h-1 (53.4 +/- 2.6 vs 52.7 +/- 4.1 ml.O2.min-1.kg-1; P = 0.64) nor for gross oxygen cost of running (CR) at the same relative velocity (75% Va max) (0.214 +/- 0.001 vs 0.214 +/- 0.002 ml.O2.kg-1.m-1; P = 0.94). However, an effect of gender was found on the relationship between the bioenergetic parameters and performance. For male, v1500 was predicted by Va max, VOBLA, tlim at 110% of Va max, and CR (R2 = 0.96). For female, no bioenergetic parameters were strongly correlated with v1500 m. The inverse relationship found between Va max and tlim at Va max in previous literature was confirmed by the 29 runners in this study and for the subset of male only.

Adult↗

PubMed1995

[Hypoxemia and exhaustion time to maximal aerobic speed in long-distance runners].

A recent paper (Billat et al., 1994a) has shown the reproducibility but also the great variability between subelite long-distance runners in their time to exhaustion at the velocity which elicits VO2max, called the maximal aerobic speed (MAS). The present study delved further into the reasons for this large difference between runners having the same VO2max. The question addressed was whether the exercise-induced hypoxemia (EIH) was more important for athletes having the longest time to exhaustion at 90 (Tlim 90), 100 (Tlim 100), or 105% (Tlim 105) of MAS. The study was conducted on 16 elite male runners. EIH was observed, that is, arterial oxyhemoglobin saturation and arterial partial pressure of oxygen dropped significantly after all the Tlim tests. However, EIH was only correlated with Tlim 90 (r = -0.757; -0.531, respectively).

Adult↗

PubMed1995

Times to exhaustion at 90, 100 and 105% of velocity at VO2 max (maximal aerobic speed) and critical speed in elite long-distance runners.

Previous studies had concluded that the treadmill velocity-endurance time hyperbolic relationship for runs could be accuratly approached with a regression at condition that bouts of exercise duration were included between 2 and 12 min. This regression allows to calculate the critical speed (CS) defined as the slope of the regression of work (distance) on time to exhaustion, the anaerobic running capacity (ARC) being the intercept of this line (Monod & Scherrer, 1965). The purpose of this investigation was to give practical indication concerning the choice of the velocities in reference to the maximal aerobic speed (MAS i.e. the minimum speed which elicits VO2max). Subjects were fourteen elite male long-distance runners (27 +/- 3 years old; VO2max = 74.9 +/- 2.9 ml.kg-1.min-1, MAS = 22.4 +/- 0.8 km.h-1, CS = 19.3 +/- 0.7 km.h-1 and 86.2 +/- 1.5% MAS). tlim 100 values (321 +/- 83 s) were negatively correlated with MAS (r = -0.538, p < 0.05) and with CS (km.h-1) (r = -0.644, p < 0.01). tlim 90 (1015 +/- 266 s) was positively correlated with CS when expressed in % MAS (r = 0.645, p < 0.01) and not when expressed in km.h-1 (r = -0.095, P > 0.05). tlim 105 (176 +/- 40 s) only was correlated with ARC (r = 0.526, p < 0.05). These data demonstrate that running time to exhaustion at 100 and 105% of MAS in a homogeneous elite male long-distance runners group is inversely related to MAS. Moreover, tlim 90 is positively correlated with CS (%MAS) but neither with tlim 100 and 105 nor with maximal aerobic speed. So from a practical point of view, the velocities chosen to determine the critical speed, would be closed to the maximal aerobic speed (time to exhaustion around 6 min), taking into account that the tlim 105 is correlated with the anaerobic capacity, whereas tlim 90 is correlated with the critical speed.

Adult↗

PubMed1995

A test to approach maximal lactate steady-state in 12-year old boys and girls.

The purpose of this study was to measure the running velocity corresponding to the individual maximal lactate steady-state of a group of 12-year old boys and girls on a treadmill. This running velocity (v MLST) was compared with the maximal aerobic running velocity (v a max) at which maximal oxygen uptake (VO2 max) occurs. Thirteen pupils of the same school whose puberal maturation corresponded to the end of stage 2 and the beginning of stage 3 of Tanner: 6 boys (12.2 years old +/- 0.5, 38.4 +/- 2 kg, 150 +/- 4.8 cm: group 1) and 7 girls (12.3 years old +/- 0.5, 37.6 +/- 6 kg, 151.4 +/- 5.6 cm: group 2) carried out two tests at one week interval. The first test was a maximal incremental test for the determination of VO2 max with Douglas's bag method and v a max. The purpose of the second test was the determination of maximal lactate steadystate velocity (v MLST) With two stages of ten minutes at 60 +/- 5% and 74 +/- 4.5% v a max separated by 40 minutes of complete rest (Billat, 1992); VO2max and v a max were significantly different, equal to 49.4 +/- 7 ml.min-1.kg-1, 40.4 +/- 4.7 ml.min-1.kg-1 and 12.6 +/- 0.2 km.h-1, 11.2 +/- 1.2 km.h-1 for group 1 and 2 respectively (P < 0.05). Moreover, maximal lactate steady state velocity (v MLST) was respectively equal to 64.8 +/- 12.5% and 64.6% +/- 12.5% VO2 max respectively, representing 67.8 +/- 6.2% and 68.8% +/- 8.3% v a max and was not significantly different for group 1 and 2. In conclusion, this study shows that maximal lactate steady-state velocity is not significantly different between young boys and girls of 12 years old, when expressed in fraction of VO2 max or v a max. However, VO2 max and v a max were significantly higher in boys: +27.2 and +11.6% higher respectively.

Child↗

PubMed1995

Energy specificity of rock climbing and aerobic capacity in competitive sport rock climbers.

Over the past few years, competitive rock climbing has experienced increased popularity world wide. In 1989, the first six-event World Cup competition was held with all events contested on artificial modular walls. The aim of this study was to determine the extent to which oxidative metabolism is utilized in competitive rock climbing with regard to the climber's maximal O2 consumption (VO2max). VO2max--was measured with two direct triangular protocols: the first from running ("running" VO2max) and the second from pull offs performed with arms and before arms ("pulling" VO2). Moreover, VO2 was also before measured during two competitive climbing routes difficulty quantified 7b on the European numerical scale ranging from 5 to 9. However these routes had different profiles: route 1 was more complex from the informational aspect, holds being smaller and more difficult to see even though the second route was presumed harder from the physical point of view, the holds being bigger but the profile being steeper. The first and the second route involved only 45.6% and 37.7% of the "running" VO2max but 111.6% and 92.3% of the "pulling" VO2max. Heart rates (HR) were equal to 176 bpm and 159 bpm i.e. 85.5% and 77% of maximal HR respectively. Blood lactate collected three minutes after the end of the two ascents were 5.7 mmol.1(-1) and 4.3 mmol.1(-1). The paired "t" test indicated no significant differences in heart rates for the two exercises condition i.e. climbing route. These results suggest that the competitive rock climbing elicit particularly arms since heart rate is high for a relatively low value of VO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

A method for determining the maximal steady state of blood lactate concentration from two levels of submaximal exercise.

The aim of this study was to estimate the characteristic exercise intensity (WCL) which produces the maximal steady state of blood lactate concentration (MLSS) from submaximal intensities of 20 min carried out on the same day and separated by 40 min. Ten fit male adults [maximal oxygen uptake (VO2max) 62 (SD 7) ml.min-1.kg-1] exercised for two 30-min periods on a cycle ergometer at 67% (test 1.1) and 82% of VO2max (test 1.2) separated by 40 min. They exercised 4 days later for 30 min at 82% of VO2max without prior exercise (test 2). Blood lactate was collected for determination of lactic acid concentration every 5 min and heart rate and O2 uptake (VO2) were measured every 30 s. There were no significant differences at the 5th, 10th, 15th, 20th, 25th, or 30th min between VO2, lactacidaemia, and heart rate during tests 1.2 and 2. Moreover, we compared the exercise intensities (WCL) which produced the MLSS obtained during tests 1.1 and 1.2 or during tests 1.1 and 2 calculated from differential values of lactic acid blood concentration ([la-]b) between the 30th and the 5th min or between the 20th and the 5th min. There was no significant difference between the different values of WCL [68 (SD 9), 71 (SD 7, 73 (SD 6), 71 (SD 11)% of VO2max] (ANOVA test, P < 0.05). Four subjects ran for 60 min at their WCL determined from periods performed on the same day (test 1.1 and 1.2) and the difference between the [la-]b at 5 min and at 20 min (delta ([la-]b)) was computed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Times to exhaustion at 100% of velocity at VO2max and modelling of the time-limit/velocity relationship in elite long-distance runners.

The aim of this study was to measure running times to exhaustion (Tlim) on a treadmill at 100% of the minimum velocity which elicits VO2max (vVO2max in 38 elite male long-distance runners (VO2max = 71.4 +/- 5.5 ml.kg-1.min-1 and vVO2max = 21.8 +/- 1.2 km.h-1). The lactate threshold (LT) was defined as a starting point of accelerated lactate accumulation around 4 mM and was expressed in %VO2max. Tlim value was negatively correlated with vVO2max (r = -0.362, p < 0.05) and VO2max (r = -0.347, p < 0.05) but positively with LT (% vVO2max) (r = 0.378, p < 0.05). These data demonstrate that running time to exhaustion at vVO2max in a homogeneous group of elite male long-distance runners was inversely related to vVO2max and experimentally illustrates the model of Monod and Scherrer regarding the time limit-velocity relationship adapted from local exercise for running by Hughson et al. (1984).

Adult↗

PubMed1994

Reproducibility of running time to exhaustion at VO2max in subelite runners.

The purpose of this study was to assess the reproducibility of running time to exhaustion (Tlim) at maximal aerobic speed (MAS: the minimum speed that elicits VO2max), on eight subelite male long distance runners (29 +/- 3-yr-old; VO2max = 69.5 +/- 4.2 ml.kg-1.min-1; MAS = 21.25 +/- 1.1 km.h-1). No significant differences were observed between Tlim measured on a treadmill at a 1-wk interval (404 +/- 101 s vs 402 +/- 113 s; r = 0.864); however, observation of individual data indicates a wide within-subjects variability (CV = 25%). In a small and homogenous sample of runners studied, exercise time to exhaustion at MAS was not related to VO2max (r = 0.138), MAS (r = 0.241), running economy (mlO2.kg-1.min-1 at 16 km.h-1) (r = 0.024), or running performance achieved for 3000 m (km.h-1)(r = 0.667). However, Tlim at MAS was significantly related to the lactate threshold determined by the distinctive acceleration point detected in the lactate curve around 3-5 mmol.l-1 expresses in %VO2max (r = 0.745) and to the speed over a 21.1-km race (km.h-1) (r = 0.719). These data demonstrate that running time to exhaustion at MAS in subelite male long distance runners is related to long distance performance and lactate threshold but not to VO2max or MAS.

Adult↗

PubMedDate not supplied

The VO2 slow component in swimming.

All studies on the oxygen uptake (VO2) slow component have been carried out for the sporting disciplines of cycling or running, but never for swimming. Considering that front crawl swimming is a sport discipline that is fundamentally different from both running and cycling, the aim of this study was to verify whether this slow component also appears in swimming. Six elite pentathletes were tested in a swimming flume while front crawl swimming to exhaustion. Swimming velocity for the slow component test was determined as v50% delta = CV + [vVO2peak - CV)/2], where CV is the critical velocity and vVO2peak the lowest velocity at which peak VO2 occurred. To set the subject's CV, expressed as the slope of a straight line that describes the correlation between swimming distance and time, the record times over three swimming distances were recorded in a 50 m swimming pool. The vVO2peak was measured by means of an incremental test in the swimming flume. Gas exchange was measured by means of a telemetric metabolimeter (K4 RQ, Cosmed, Italy) that was connected to a snorkel. The slow component was found in all subjects, with a mean (SD) value of 239 (194) mlO2.min-1. Therefore, although front crawl swimming is fundamentally different from both running and cycling, it appears that it also incurs a VO2 slow component. The origin of this phenomenon, however, is even more uncertain than for the other sport disciplines.

Adolescent↗

PubMedDate not supplied

Time to exhaustion at VO2max and lactate steady state velocity in sub elite long-distance runners.

The aim of the present study was to estimate the importance of lactate steady state velocity (WCL) of the running velocity at maximal oxygen uptake (Va max) and its time to exhaustion (Tlim), in the performance of a half marathon stated by the velocity over 21.1 km sustained by the runners during 1 h 12 min +/- 2 min 27 s. The population consisting of ten sub-elite male long distance runners (32 +/- 4 years old) was homogeneous with regard to their velocities on 21 km (V21 = 17.5 +/- 0.88 km.h-1, coefficient of variation, CV = 5%) and their aerobic maximal speed (Va max) (21.6 +/- 1.2 km.h-1, CV 6%). The fractional utilization of VO2max on 21 km was calculated from their own running economy (oxygen consumed per kilo of body mass and kilometer run (194 +/- 74 ml.kg-1.km-1). V21 represented 83 +/- 5% VO2max (VO2max = 68.1 +/- 4.1 ml.kg-1.min-1) and 81 +/- 3.3% Va max. The velocity corresponding to lactate steady state and called "lactate steady state velocity" (WCL) was measured according to a protocol proposed by CHASSAIN (1986). The subjects ran twenty minutes at a constant velocity representing 70-75% and 85-90% VO2max. Lactatemia was measured at the fifth (Lact 5) and the twentieth minute (Lact 20). Lactate slope was measured for two running velocities in order to determine the velocity (WCL) corresponding to lactate steady state, i.e. the lactate slope is equal to zero.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗