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Biomedical subjects

V L Billat

Publications and source records attributed to V L Billat.

At least 19 recordsLinked to original sources
PubMed2003

Influence of acute moderate hypoxia on time to exhaustion at vVO2max in unacclimatized runners.

Eight unacclimatized long-distance runners performed, on a level treadmill, an incremental test to determine the maximal oxygen uptake (VO2max) and the minimal velocity eliciting VO2max (vVO2max) in normoxia (N) and acute moderate hypoxia (H) corresponding to an altitude of 2,400 m (PIO 2 of 109 mmHg). Afterwards, on separate days, they performed two all-out constant velocity runs at vO2 max in a random order (one in N and the other in H). The decrease in VO2max between N and H showed a great degree of variability amongst subjects as VO2max decreased by 8.9 +/- 4 ml x min(-1) x kg)(-1) in H vs. N conditions (-15.3 +/- 6.3 % with a range from -7.9 % to -23.8 %). This decrease in VO2max was proportional to the value of VO2max (VO2max vs. delta VO2max N-H, r = 0.75, p = 0.03). The time run at vVO2max was not affected by hypoxia (483 +/- 122 vs. 506 +/- 148 s, in N and H, respectively, p = 0.37). However, the greater the decrease in vVO2max during hypoxia, the greater the runners increased their time to exhaustion at vVO2max (vVO2max N-H vs. tlim @vVO2max N-H, r = -0.75, p = 0.03). In conclusion, this study showed that there was a positive association between the extent of decrease in vVO2max, and the increase in run time at vVO2max in hypoxia.

Acclimatization↗
PubMed2003

Whichever the initial training status, any increase in velocity at lactate threshold appears as a major factor in improved time to exhaustion at the same severe velocity after training.

The first purpose of this study was to assess the eventual training adaptations in the time to exhaustion at the same severe velocity occurring after severe interval-training programs in few- and well-trained subjects. In the event of such training adaptations, the second purpose was to identify the discriminant factors of performance improvement according to the initial training status. Seven few- and six well-trained subjects performed: firstly, an incremental test to determine the maximal oxygen consumption (VO2max), the energy cost of running (ECR), the velocity associated with the achievement of VO2max (vVO2max) and the lactate threshold (LT expressed in VO2, km x h(-1), % vVO2max); secondly, an all-out test at the velocity corresponding to the midway between vLT and vVO2max (vdelta50) to determine the time to exhaustion (tmax); such tests were carried out before and after 4- and 8-week severe interval-training programs. In the few-trained subjects, all factors of performance (i.e., VO2max, ECR, vVO2max, LT expressed in VO2, km x h(-1), % vVO2max) and tmax at the pre-training vdelta50 were improved after training (+8, -8, +7, +9, +14, +6% and +79%, respectively); only the increase in vLT was related to the one in tmax (r = 0.714, p < or = 0.05, n = 7). In the well-trained subjects, only vVO2max was improved (+3%) due to the decrease in ECR (-3%), tmax at the pre-training vdelta50 did not vary after training; only the three subjects (over six) who improved their vLT (+0.5, +0.5, +0.8 km x h(-1), respectively) improved their tmax (+10, +24, +101%, respectively) (r = 0.895, p < or = 0.01, n = 6). So, whichever the initial training status, any training-induced adaptation in vLT appeared as a major factor of performance improvement especially at supra-LT velocities.

Adaptation, Physiological↗
PubMed2003

The effects of interval training on oxygen pulse and performance in supra-threshold runs.

The aim of this study was to examine (i) the effects of a severe interval training period on oxygen pulse kinetics (O2-p, the ratio between VO2 and heart rate), and (ii) to study the consequences of these effects on the variation of performance (time to exhaustion) during severe runs. Seven athletes were tested before and after an eight-weeks period of a specific intermittent training at v Delta 50, i.e., the intermediate velocity between the lactate threshold (vLT) and the velocity associated with VO2max (vVO2max ). During the test sessions, athletes performed an incremental test and an all-out test at the pretraining v Delta 50. After the training period they also completed an additional all-out test at the posttraining v Delta 50 (v Delta 50bis). Results showed that after training there was i) an increase in the O2-p maximal value during the incremental test (22.7 +/- 1.5 mlO2.b-1 vs. 20.6 +/- 1.5 mlO2.b-1; p < 0.04), ii) a decrease in the time to reach the O2-p steady state (TRO2-p ) at the same absolute v Delta 50 (33 +/- 7 s vs. 60 +/- 27 s; p < 0.04) and iii) an increase in the O2-p steady state duration (TSSO2-p) at the same absolute v Delta 50 (552 +/- 201 s vs. 407 +/- 106 s; p < 0.04). However, there was no relationship between the improvement of these two O 2 -p kinetics parameters (TRO2-p and TSS O2-p) and those of the performance. This study found that after an individualised interval-training program conducted at the same absolute velocity, the O2-p kinetics reached a steady state quicker and for a longer duration than before training. This is however not related with the improvement of performance.

Adult↗
PubMed2002

Effect of training in humans on off- and on-transient oxygen uptake kinetics after severe exhausting intensity runs.

The purpose of this study was to examine the effect of 4 weeks of intense interval-training on the pulmonary off-transient oxygen uptake (V*O2) after running until exhaustion at the same absolute speed. Seven physical education students ran as follows in three maximal tests on a synthetic track (400 m) whilst breathing through a portable, telemetric metabolic analyser: firstly, in an incremental test which determined maximal oxygen uptake (V*O2max), the minimal speed associated with V*O2max (vV*O2max) and the speed at the lactate threshold ( v(LT)). Secondly, in two continuous severe intensity runs at 90% (R90) and 95% (R95) of vV*O2max. After training, the times to exhaustion ( t(lim)) at these two speeds (i.e. the time limits t(lim90) and t(lim95), respectively), were significantly increased at both speeds (+37% and +66% for t(lim90) and t(lim95), P=0.04 and 0.01, respectively) and v(LT) and vV*O2max were increased by 8% and 5%, respectively ( P<0.02). The time constants of the cardio-dynamic added to the metabolic phase (phases I+II) and of the slow phase (phase III) of oxygen kinetics in the on-transient phase decreased significantly after training ( P=0.05). However, the decrease in the time constants of oxygen kinetics in the on-transient phases II and III were not correlated with the improvement in performance (i.e. increase in t(lim)). After training the V*O2 off-transient phase was significantly faster [off-time constant (tau(off)) decreased significantly both after R90 and R95, P=0.03]. This decrease in tau(off) was correlated with the increase in t(lim90) ( r=0.795, P=0.03). The physiological factors best correlated with the increased performance after training were v(LT) for t(lim90) and vV*O2max for t(lim95).

Adult↗
PubMed2002

The influence of exercise duration at VO2 max on the off-transient pulmonary oxygen uptake phase during high intensity running activity.

The purpose of this study was to examine the influence of time run at maximal oxygen uptake (VO2 max) on the off-transient pulmonary oxygen uptake phase after supra-lactate threshold runs. We hypothesised: 1) that among the velocities eliciting VO2 max there is a velocity threshold from which there is a slow component in the VO2-off transient, and 2) that at this velocity the longer the duration of this time at VO2 max (associated with an accumulated oxygen kinetics since VO2 can not overlap VO2 max), the longer is the off-transient phase of oxygen uptake kinetics. Nine long-distance runners performed five maximal tests on a synthetic track (400 m) while breathing through the COSMED K4b2 portable, telemetric metabolic analyser: i) an incremental test which determined VO2 max, the minimal velocity associated with VO2 max (vVO2 max) and the velocity at the lactate threshold (vLT), ii) and in a random order, four supra-lactate threshold runs performed until exhaustion at vLT + 25, 50, 75 and 100% of the difference between vLT and vVO2 max (vdelta25, vdelta50, vdelta75, vdelta100). At vdelta25, vdelta50 (= 91.0 +/- 0.9% vVO2 max) and vdelta75, an asymmetry was found between the VO2 on (double exponential) and off-transient (mono exponential) phases. Only at vdelta75 there was at positive relationship between the time run at VO2 max (%tlimtot) and the VO2 recovery time constant (Z = 1.8, P = 0.05). In conclusion, this study showed that among the velocities eliciting VO2 max, vdelta75 is the velocity at which the longer the duration of the time at VO2 max, the longer is the off-transient phase of oxygen uptake kinetics. It may be possible that at vdelta50 there is not an accumulated oxygen deficit during the plateau of VO2 at VO2 max and that the duration of the time at VO2 max during the exhaustive runs at vdelta100, could be too short to induce an accumulating oxygen deficit affecting the oxygen recovery.

Adult↗
PubMed2001

Very short (15s-15s) interval-training around the critical velocity allows middle-aged runners to maintain VO2 max for 14 minutes.

The purpose of this study was to compare the effectiveness of three very short interval training sessions (15-15 s of hard and easier runs) run at an average velocity equal to the critical velocity to elicit VO2 max for more than 10 minutes. We hypothesized that the interval with the smallest amplitude (defined as the ratio between the difference in velocity between the hard and the easy run divided by the average velocity and multiplied by 100) would be the most efficient to elicit VO2 max for the longer time. The subjects were middle-aged runners (52 +/- 5 yr, VO2 max of 52.1 +/- 6 mL x min(-1) x kg(-1), vVO2 max of 15.9 +/- 1.8 km x h(-1), critical velocity of 85.6 +/- 1.2% vVO2 max) who were used to long slow distance-training rather than interval training. They performed three interval-training (IT) sessions on a synthetic track (400 m) whilst breathing through the COSMED K4b2 portable metabolic analyser. These three IT sessions were: A) 90-80% vVO2 max (for hard bouts and active recovery periods, respectively), the amplitude= (90-80/85) 100=11%, B) 100-70% vVO2 max amplitude=35%, and C) 60 x 110% vVO2 max amplitude = 59%. Interval training A and B allowed the athlete to spend twice the time at VO2 max (14 min vs. 7 min) compared to interval training C. Moreover, at the end of interval training A and B the runners had a lower blood lactate than after the procedure C (9 vs. 11 mmol x l(-1)). In conclusion, short interval-training of 15s-15s at 90-80 and 100-70% of vVO2 max proved to be the most efficient in stimulating the oxygen consumption to its highest level in healthy middle-aged long-distance runners used to doing only long slow distance-training.

Heart Rate↗
PubMed2001

Effect of free versus constant pace on performance and oxygen kinetics in running.

PURPOSE: This study tested the hypothesis that free versus constant pace enhanced the performance (i.e., distance run) in suprathreshold runs between 90 and 105% of the velocity associated with the maximal oxygen consumption determined in an incremental test (v.VO(2max)). Moreover, we hypothesized that variable pace could decrease the slow phase of oxygen kinetics by small spontaneous recoveries during the same distance run at an average velocity. METHOD: Eleven long-distance runners performed nine track runs performed until exhaustion. Following an incremental test to determine v.VO(2max), the runners performed, in a random order, four constant-velocity runs at 90, 95, 100, and 105% of v.VO(2max) to determine the time to exhaustion (tlim90, tlim95, tlim100, and tlim105) and the distance limit at 90, 95, 100 and 105% of v.VO(2max) (dlim90, dlim95, dlim100, and dlim105). Finally, they performed the distance limit determined in the constant velocity runs but at variable velocity according to their spontaneous choice. RESULTS: The coefficient of variation of velocity (in percent of the average velocity) was small and not significantly different between the four free pace dlim (4.2 +/- 1.3%, 4.8 +/- 2.4%, 3.6 +/- 1.1%, and 4.6 +/- 1.9% for dlim90, dlim95, dlim100, and dlim105, respectively; P = 0.40). Performances were not improved by a variable pace excepted for the dlim at 105% v.VO(2max) (4.96 +/- 0.6 m.s-1 vs 4.86 +/- 0.5 m.s-1, P = 0.04). Oxygen kinetics and the volume of oxygen consumed were not modified by this (low) variation in velocity. CONCLUSION: These results indicate that for long-distance runners, variable pace modifies neither performance nor the oxygen kinetics in all-out suprathreshold runs.

Adult↗
PubMed2001

Physical and training characteristics of top-class marathon runners.

PURPOSE: This study compares the physical and training characteristics of top-class marathon runners (TC), i.e., runners having a personal best of less than 2 h 11 min for males and 2 h 32 min for females, respectively, versus high-level (HL) (< 2 h 16 min and < 2 h 38 min). METHODS: Twenty marathon runners (five TC and HL in each gender) ran 10 km at their best marathon performance velocity (vMarathon) on a level road. This velocity was the target velocity for the Olympic trials they performed 8 wk later. After a rest of 6 min, they ran an all-out 1000-m run to determine the peak oxygen consumption on flat road (.VO(2peak)). RESULTS: Marathon performance time (MPT) was inversely correlated with .VO(2peak). (r = -0.73, P < 0.01) and predicted 59% of the variance of MPT. Moreover, TC male marathon runners were less economical because their energy cost of running (Cr) at marathon velocity was significantly higher than that of their counterparts (212 +/- 17 vs 195 +/- 14 mL.km(-1).kg(-1), P = 0.03). For females, no difference was observed for the energetic characteristics between TC and HL marathon runners. However, the velocity reached during the 1000-m run performed after the 10-km run at vMarathon was highly correlated with MPT (r = -0.85, P < 0.001). Concerning training differences, independent of the gender, TC marathon runners trained for more total kilometers per week and at a higher velocity (velocity over 3000 m and 10,000 m). CONCLUSION: The high energy output seems to be the discriminating factor for top-class male marathon runners who trained at higher relative intensities.

Body Weight↗
PubMed2001

Decrease of O(2) deficit is a potential factor in increased time to exhaustion after specific endurance training.

The main purpose of this study was to investigate the effects of an 8-wk severe interval training program on the parameters of oxygen uptake kinetics, such as the oxygen deficit and the slow component, and their potential consequences on the time until exhaustion in a severe run performed at the same absolute velocity before and after training. Six endurance-trained runners performed, on a 400-m synthetic track, an incremental test and an all-out test, at 93% of the velocity at maximal oxygen consumption, to assess the time until exhaustion. These tests were carried out before and after 8 wk of a severe interval training program, which was composed of two sessions of interval training at 93% of the velocity at maximal oxygen consumption and three recovery sessions of continuous training at 60--70% of the velocity at maximal oxygen consumption per week. Neither the oxygen deficit nor the slow component were correlated with the time until exhaustion (r = -0.300, P = 0.24, n = 18 vs. r = -0.420, P = 0.09, n = 18, respectively). After training, the oxygen deficit significantly decreased (P = 0.02), and the slow component did not change (P = 0.44). Only three subjects greatly improved their time until exhaustion (by 10, 24, and 101%). The changes of oxygen deficit were significantly correlated with the changes of time until exhaustion (r = -0.911, P = 0.01, n = 6). It was concluded that the decrease of oxygen deficit was a potential factor for the increase of time until exhaustion in a severe run performed after a specific endurance-training program.

Adult↗
PubMed2000

Intermittent runs at the velocity associated with maximal oxygen uptake enables subjects to remain at maximal oxygen uptake for a longer time than intense but submaximal runs.

Interval training consisting of brief high intensity repetitive runs (30 s) alternating with periods of complete rest (30 s) has been reported to be efficient in improving maximal oxygen uptake (VO2max) and to be tolerated well even by untrained persons. However, these studies have not investigated the effects of the time spent at VO2max which could be an indicator of the benefit of training. It has been reported that periods of continuous running at a velocity intermediate between that of the lactate threshold (vLT) and that associated with VO2max (vVO2max) can allow subjects to reach VO2max due to an additional slow component of oxygen uptake. Therefore, the purpose of this study was to compare the times spent at VO2max during an interval training programme and during continuous strenuous runs. Eight long-distance runners took part in three maximal tests on a synthetic track (400 m) whilst breathing through a portable, telemetric metabolic analyser: they comprised firstly, an incremental test which determined vLT, VO2max [59.8 (SD 5.4) ml.min-1; kg-1], vVO2max [18.5 (SD 1.2) km.h-1], secondly, an interval training protocol consisting of alternately running at 100% and at 50% of vVO2max (30 s each); and thirdly, a continuous high intensity run at vLT + 50% of the difference between vLT and vVO2max [i.e. v delta 50: 16.9 (SD 1.00) km.h-1 and 91.3 (SD 1.6)% vVO2max]. The first and third tests were performed in random order and at 2-day intervals. In each case the subjects warmed-up for 15 min at 50% of vVO2max. The results showed that in more than half of the cases the v delta 50 run allowed the subjects to reach VO2max, but the time spent specifically at VO2max was much less than that during the alternating low/high intensity exercise protocol [2 min 42 s (SD 3 min 09 s) for v delta 50 run vs 7 min 51 s (SD 6 min 38 s) in 19 (SD 5) interval runs]. The blood lactate responses were less pronounced in the interval runs than for the v delta 50 runs, but not significantly so [6.8 (SD 2.2) mmol.l-1 vs 7.5 (SD 2.1) mmol.l-1]. These results do not allow us to speculate as to the chronic effects of these two types of training at VO2max.

Adult↗
PubMed2000

Oxygen kinetics and modelling of time to exhaustion whilst running at various velocities at maximal oxygen uptake.

The purpose of this study was to characterise the relationship between running velocity and the time for which a subject can run at maximal oxygen uptake (VO2max), (tlimVO2max). Seven physical education students ran in an incremental test (3-min stages) to determine VO2max and the minimal velocity at which it was elicited (vVO2max). They then performed four all-out running tests on a 200-m indoor track every 2 days in random order. The mean times to exhaustion tlim at 90%, 100%, 120% and 140% vVO2max were 13 min 22 s (SD 4 min 30 s), 5 min 47 s (SD 1 min 50 s), 2 min 11 s (SD 38 s) and 1 min 12 s (SD 18 s), respectively. Five subjects did not reach VO2max in the 90% vVO2max test. All the subjects reached VO2max in the runs at 100% vVO2max. All the subjects, except one, reached VO2max in the runs at 120% vVO2max. Four subjects did not reach VO2max in the 140% vVO2max test. Time to achieve VO2max was always about 50% of the time to exhaustion irrespective of the intensity. The time to exhaustion-velocity relationship was better fitted by a 3- than by a 2-parameter critical power model for running at 90%, 100%, 120%, 140% vVO2max as determined in the previous incremental test. In conclusion, tlimVO2max depended on a balance between the time to attain VO2max and the time to exhaustion tlim. The time to reach VO2max decreased as velocity increased. The tlimVO2max was a bi-phasic function of velocity, with a peak at 100% vVO2max.

Adult↗
PubMed2000

Influence of light additional arm cranking exercise on the kinetics of VO2 in severe cycling exercise.

This study examined the influence of light additional arm cranking exercise on the VO2 slow component observed during severe cycling exercise. During incremental tests, eleven triathletes exercised to exhaustion cycling with leg, cranking with arm and combined arm and leg cranking and cycling (arm work-rates being set at the third of leg work rates) to determine arm, leg and combined arm and leg lactate threshold and VO2max. After these incremental tests subjects performed in random order severe exercises until exhaustion at work-rates corresponding to the lactate threshold + 50% of the difference to the work rate associated with VO2max and the lactate threshold, i.e., delta50: 1) with legs only (leg delta50) 2) leg delta50 plus a very light arm cranking exercise at 25 % of the arm lactate threshold (Ldelta50 + A25). VO2 slow component was the increase of VO2 (in ml x min(-1)) between the third and the sixth minute of exercise (deltaVO2 63 min). Results showed 1) Nine of the eleven triathletes had a VO2 slow component in arm delta50; 2) a light cycle arm exercise (25% of lactate threshold) added to a severe leg cycle exercise did not decrease time to exhaustion in severe exercise (493 +/- 154s vs 418 +/- 84, P=0.4); 3) For the five subjects who had a VO2 slow component in leg cycling, the addition of a light arm exercise (25% of arm LT) decreased the VO2 slow component significantly (from 457 +/- 173 ml x min(-1) for leg delta50 to 111 +/- 150 ml x min(-1) for Ldelta50 + A25, Z = -2.0, P = 0.04). In conclusion, light additional arm cranking decreases the VO2 slow component in severe cycling. Further studies are needed to confirm the hypothesis that extra work due to an increasing handgrip on the handlebars may contribute to the VO2 slow component in cycling.

Adult↗
PubMed2000

Effect of a prior intermittent run at vVO2max on oxygen kinetics during an all-out severe run in humans.

BACKGROUND: The purpose of this study was to examine the influence of prior intermittent running at VO2max on oxygen kinetics during a continuous severe intensity run and the time spent at VO2max. METHODS: Eight long-distance runners performed three maximal tests on a synthetic track (400 m) whilst breathing through the COSMED K4 portable telemetric metabolic analyser: i) an incremental test which determined velocity at the lactate threshold (vLT), VO2max and velocity associated with VO2max (vVO2max), ii) a continuous severe intensity run at vLT+50% (vdelta50) of the difference between vLT and vVO2max (91.3+/-1.6% VO2max)preceded by a light continuous 20 minute run at 50% of vVO2max (light warm-up), iii) the same continuous severe intensity run at vdelta50 with a prior interval training exercise (hard warm-up) of repeated hard running bouts performed at 100% of vVO2max and light running at 50% of vVO2max (of 30 seconds each) performed until exhaustion (on average 19+/-5 min with 19+/-5 interval repetitions). This hard warm-up speeded the VO2 kinetics: the time constant was reduced by 45% (28+/-7 sec vs 51+/-37 sec) and the slow component of VO2 (deltaVO2 6-3 min) was deleted (-143+/-271 ml x min(-1) vs 291+/-153 ml x min(-1)). In conclusion, despite a significantly lower total run time at vdelta50 (6 min 19+/-0) min 17 vs 8 min 20+/-1 min 45, p=0.02) after the intermittent warm-up at VO2max, the time spent specifically at VO2max in the severe continuous run at vdelta50 was not significantly different.

Adult↗
PubMed1999

Determination of the velocity associated with the longest time to exhaustion at maximal oxygen uptake.

The so-called velocity associated with VO2max, defined as the minimal velocity which elicits VO2max in an incremental exercise protocol (v(VO2max)), is currently used for training to improve VO2max. However, it is well known that it is not the sole velocity which elicits VO2max and it is possible to achieve VO2max at velocities lower and higher than v(VO2max). The goal of this study was to determine the velocity which allows exercise to be maintained the longest time at v(VO2max). Using the relationship between time to exhaustion at VO2max in the all-out runs at 90%, 100%, 120% and 140% of v(VO2max) and distance run at VO2max, the velocity which elicits the longest time to exhaustion at VO2max (CV') was determined. For the six subjects tested (physical education students), this velocity was not significantly different from v(VO2max) (16.96+/-0.92 km x h(-1) vs 17.22+/-1.12 km x h(-1), P = 0.2 for CV' and v(VO2max), respectively) and these two velocities were correlated (r = 0.88, P = 0.05).

Adult↗
PubMed1999

The role of cadence on the VO2 slow component in cycling and running in triathletes.

The purpose of this study was to compare the effect of two different types of cyclic severe exercise (running and cycling) on the VO2 slow component. Moreover we examined the influence of cadence of exercise (freely chosen [FF] vs. low frequency [LF]) on the hypothesis that: 1) a stride frequency lower than optimal and 2) a pedalling frequency lower than FF one could induce a larger and/or lower VO2 slow component. Eight triathletes ran and cycled to exhaustion at a work-rate corresponding to the lactate threshold + 50% of the difference between the work-rate associated with VO2max and the lactate threshold (delta 50) at a freely chosen (FF) and low frequency (LF: - 10 % of FF). The time to exhaustion was not significantly different for both types of exercises and both cadences (13 min 39 s, 15 min 43 s, 13 min 32 s, 15 min 05 s for running at FF and LF and cycling at FF and LF, respectively). The amplitude of the VO2 slow component (i.e. difference between VO2 at the last and the 3rd min of the exercise) was significantly smaller during running compared with cycling, but there was no effect of cadence. Consequently, there was no relationship between the magnitude of the VO2 slow component and the time to fatigue for a severe exercise (r = 0.20, p = 0.27). However, time to fatigue was inversely correlated with the blood lactate concentration for both modes of exercise and both cadences (r = - 0.42, p = 0.01). In summary, these data demonstrate that: 1) in subjects well trained for both cycling and running, the amplitude of the VO2 slow component at fatigue was larger in cycling and that it was not significantly influenced by cadence; 2) the VO2 slow component was not correlated with the time to fatigue. If the nature of the linkage between the VO2 slow component and the fatigue process remains unclear, the type of contraction regimen depending on exercise biomechanic characteristics seems to be determinant in the VO2 slow component phenomenon for a same level of training.

Adult↗
PubMed1999

Interval training at VO2max: effects on aerobic performance and overtraining markers.

PURPOSE: Between inefficient training and overtraining, an appropriate training stimulus (in terms of intensity and duration) has to be determined in accordance with individual capacities. Interval training at the minimal velocity associated with VO2max (vVO2max) allows an athlete to run for as long as possible at VO2max. Nevertheless, we don't know the influence of a defined increase in training volume at vVO2max on aerobic performance, noradrenaline, and heart rate. METHODS: Eight subjects performed 4 wk of normal training (NT) with one session per week at vVO2max, i.e., five repetitions run at 50% of the time limit at vVO2max, with recovery of the same duration at 60% vVO2max. They then performed 4 wk of overload training (OT) with three interval training sessions at vVO2max. RESULTS: Normal training significantly improved their velocity associated with VO2max (20.5+/-0.7 vs 21.1+/-0.8 km x h(-1), P = 0.02). As a result of improved running economy (50.6+/-3.5 vs 47.5+/-2.4 mL x min(-1) x kg(-1), P = 0.02), VO2max was not significantly different (71.6+/-4.8 vs 72.7+/-4.8 mL x min(-1) x kg(-1)). Time to exhaustion at vVO2max was not significantly different (301+/-56 vs 283+/-41 s) as was performance (i.e., distance limit run at vVO2max: 2052.2+/-331 vs 1986.2+/-252.9 m). Heart rate at 14 km x h(-1) decreased significantly after NT (162+/-16 vs 155+/-18 bpm, P < 0.01). Lactate threshold remained the same after normal training (84.1+/-4.8% vVO2max). Overload training changed neither the performance nor the factors concerning performance. However, the submaximal heart rate measured at 14 km x h(-1) decreased after overload training (155+/-18 vs 150+/-15 bpm). The maximal heart rate was not significantly different after NT and OT (199+/-9.5, 198+/-11, 194+/-10.4, P = 0.1). Resting plasma norepinephrine (veinous blood sample measured by high pressure liquid chromatography), was unchanged (2.6 vs 2.4 nm x L(-1), P = 0.8). However, plasma norepinephrine measured at the end of the vVO2max test increased significantly (11.1 vs 26.0 nm x L(-1), P = 0.002). CONCLUSION: Performance and aerobic factors associated with the performance were not altered by the 4 wk of intensive training at vVO2max despite the increase of plasma noradrenaline.

Adult↗
PubMed1998

The V(O2) slow component for severe exercise depends on type of exercise and is not correlated with time to fatigue.

The purpose of this study was to examine the influence of the type of exercise (running vs. cycling) on the O2 uptake V(O2) slow component. Ten triathletes performed exhaustive exercise on a treadmill and on a cycloergometer at a work rate corresponding to 90% of maximal VO2 (90% work rate maximal V(O2)). The duration of the tests before exhaustion was superimposable for both type of exercises (10 min 37 s +/- 4 min 11 s vs. 10 min 54 s +/- 4 min 47 s for running and cycling, respectively). The V(O2) slow component (difference between V(O2) at the last minute and minute 3 of exercise) was significantly lower during running compared with cycling (20.9 +/- 2 vs. 268.8 +/- 24 ml/min). Consequently, there was no relationship between the magnitude of the V(O2) slow component and the time to fatigue. Finally, because blood lactate levels at the end of the tests were similar for both running (7.2 +/- 1.9 mmol/l) and cycling (7.3 +/- 2.4 mmol/l), there was a clear dissociation between blood lactate and the V(O2) slow component during running. These data demonstrate that 1) the V(O2) slow component depends on the type of exercise in a group of triathletes and 2) the time to fatigue is independent of the magnitude of the V(O2) slow component and blood lactate concentration. It is speculated that the difference in muscular contraction regimen between running and cycling could account for the difference in the V(O2) slow component.

Adult↗