(active vs. passive) on performance during a short

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Effects of recovery mode (active vs. passive) on performance during a short highintensity interval training program: a longitudinal study Abderraouf Ben Abderrahman, Hassane Zouhal, Karim Chamari, Delphine Thevenet, Pierre-Yves de Mullenheim, Steven Gastinger, et al. European Journal of Applied Physiology ISSN 1439-6319 Eur J Appl Physiol DOI 10.1007/s00421-012-2556-9

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Author's personal copy Eur J Appl Physiol DOI 10.1007/s00421-012-2556-9

ORIGINAL ARTICLE

Effects of recovery mode (active vs. passive) on performance during a short high-intensity interval training program: a longitudinal study Abderraouf Ben Abderrahman • Hassane Zouhal • Karim Chamari Delphine Thevenet • Pierre-Yves de Mullenheim • Steven Gastinger Zouhair Tabka • Jacques Prioux

• •

Received: 19 June 2012 / Accepted: 17 November 2012 Ó Springer-Verlag Berlin Heidelberg 2012

Abstract The aim of this longitudinal study was to compare two recovery modes (active vs. passive) during a seven-week high-intensity interval training program (SWHITP) aimed to improve maximal oxygen uptake _ 2max ), maximal aerobic velocity (MAV), time to (VO exhaustion (tlim) and time spent at a high percentage of _ 2max , i.e., above 90 % (t90 VO _ 2max ) and 95 % (t95 VO _ _ VO2max ) of VO2max . Twenty-four adults were randomly assigned to a control group that did not train (CG, n = 6) and two training groups: intermittent exercise (30 s

Communicated by David C. Poole. A. Ben Abderrahman  H. Zouhal  D. Thevenet  P.-Y. de Mullenheim  S. Gastinger  J. Prioux Movement, Sport and Heath Sciences Laboratory (M2S), Rennes 2 University, ENS Cachan - Brittany branch, Cachan, France A. Ben Abderrahman  Z. Tabka Faculte´ de me´decine Ibn El Jazzar, Laboratoire des adaptations cardio-circulatoires, respiratoires, me´taboliques et hormonales a` l’exercice musculaire, 4002 Sousse, Tunisia A. Ben Abderrahman  K. Chamari Institut Supe´rieur du Sport et de l’Education Physique de Tunis, University of Manouba, Ksar-Saıˆd, 2010 La Manouba, Tunisia A. Ben Abderrahman (&) UFR STAPS, Ksar-Saıˆd, 2010 La Manouba, Tunisia e-mail: [email protected] K. Chamari Research Laboratory ‘‘Sport Performance Optimisation’’, National Center of Medicine and Science in Sport (CNMSS), Tunis, Tunisia D. Thevenet  P.-Y. de Mullenheim  J. Prioux ENS Cachan - Brittany branch, Antenne de Bretagne, Campus de Ker-Lann, 35170 Bruz, France

exercise/30 s recovery) with active (IEA, n = 9) or passive recovery (IEP, n = 9). Before and after seven weeks with (IEA and IEP) or without (CG) high-intensity interval training (HIT) program, all subjects performed a maximal _ 2max and MAV. Subsegraded test to determine their VO quently only the subjects of IEA and IEP groups carried out an intermittent exercise test consisting of repeating as long as possible 30 s intensive runs at 105 % of MAV alternating with 30 s active recovery at 50 % of MAV (IEA) or 30 s passive recovery (IEP). Within IEA and IEP, mean tlim and MAV significantly increased between the onset and the end of the SWHITP and no significant difference was found in t90 VO2max and t95 VO2max. Furthermore, before and after the SWHITP, passive recovery allowed a longer tlim for a similar time spent at a high percentage of VO2max. Finally, within IEA, but not in IEP, mean VO2max increased significantly between the onset and the end of the SWHITP both in absolute (p \ 0.01) and relative values (p \ 0.05). In conclusion, our results showed a significant increase in VO2max after a SWHITP with active recovery in spite of the fact that tlim was significantly longer (more than twice longer) with respect to passive recovery. Keywords Longitudinal study  Recovery mode  Maximal oxygen uptake  Time spent at maximal oxygen uptake  Time to exhaustion Introduction _ 2max ) is considered an Maximal oxygen uptake (VO important physiological determinant of middle- and longdistance running performance (Pollock et al. 1980; Brandon 1995; Midgley et al. 2006). Although effective training methods have not been clearly defined to enhance the

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_ 2max of well-trained distance runners, it is recognized VO _ 2max may be an optimal stimulus that training at or near VO in that regard (Midgley et al. 2006; Wenger and Bell 1986). In this context, it can be assumed that the percentage of _ 2max reached during exercise and the time for which it is VO _ 2max ) or 95 % (t95 VO _ 2max ) sustained above 90 % (t90 VO _ 2max may be relevant parameters to characterize and of VO to analyze the effectiveness of a given training exercise on _ 2max . Among the different types of training methods, VO intermittent exercises (IE), consisting of intensive exercise alternated with recovery, are well known to improve aerobic fitness (Eddy et al. 1977; Gorostiaga et al. 1991; Tabata et al. 1996; Franch et al. 1998; Billat et al. 1999). It has been suggested that active recovery with light exercise or just stretching allows for better performance during the next periods of high-intensity exercise than does passive recovery (Dorado et al. 2004). However, experimental data are not conclusive (Dorado et al. 2004). While some researchers have reported greater exercise capacity with active recovery (Thiriet et al. 1993; Weltman et al. 1977), others have not confirmed these results (Bangsbo et al. 1994; Dupont et al. 2003a; Thiriet et al. 1993). The 30/30 s intermittent exercise (30sIE), consisting of 30 s highintensity exercise alternated with 30 s active or passive recovery, is commonly practiced by endurance athletes during training. Astrand et al. (1960) (30 s at 2.160 km h-1 alternated with 30 s with passive recovery; Total exercise time: 60 min) and Gorostiaga et al. (1991) (30 s at 100 % _ 2max alternated with 30 s with passive recovery; Total of VO exercise time: 30 min) have shown that a 30sIE performed _ 2max with a passive recovery, does not at 100 % of VO _ 2max . More recent studies allow a subject to elicit VO (Millet et al. 2003a; Tardieu-Berger et al. 2004) have investigated the 30sIE performed at supra maximal inten_ 2max ) with active recovery (50 % sity (105 or 110 % of VO _ of VO2max ) showing that adequate combination between exercise and recovery intensities during 30sIE exercises _ 2 max not only to be reached but also this may allow VO intensity to be sustained (Millet et al. 2003b; TardieuBerger et al. 2004). Our group has analyzed the effects of the recovery mode (active vs. passive) on time spent at _ 2 max during an intermittent session in young and VO endurance-trained athletes (Thevenet et al. 2007a). The results demonstrated no influence of recovery mode on _ 2 max or t95 VO _ 2 max mean values despite absolute t90 VO significantly longer time to exhaustion (tlim) values for 30sIE with passive recovery than for 30sIE with active recovery. More recently, we examined the effects of three _ 2 max during a short interrecovery intensities on t90 VO mittent session in eight endurance-trained male adolescents (Thevenet et al. 2008). Each subject performed three

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intermittent exercises consisting of repeating 30 s exercise sessions runs at 105 % of maximal aerobic velocity (MAV) alternated with 30 s active recovery runs at 50 % (IE50), _ 2 max in 67 % (IE67), or 84 % (IE84) of MAV. t90 VO absolute values and tlim were significantly shorter during IE84 than during IE67 and IE50 and there were no significant _ 2 max in absolute values during IE67 differences in t90 VO and IE50 even though tlim was significantly longer during IE50 compared with IE67. These results were in line with earlier studies (Dupont and Berthoin 2004; Thevenet et al. 2007a), which showed that passive recovery induced a longer tlim with a similar time spent at a high percentage of _ 2 max and with the very recent study of Chidnok et al. VO (2012) whose results showed that tlim was inversely proportional to the intensity of recovery. However, it is unclear how our initial findings would apply in a longitudinal training intervention. Consequently, the aim of this study was to compare before and after seven weeks of a high-intensity interval-training program (SWHITP), the effects of the recovery mode (active vs. passive), during a _ 2 max , maximal aerobic velocity (MAV), tlim, 30sIE, on VO _ 2 max and t95 VO _ 2 max . It was hypothesized that a t90 VO SWHITP with passive recovery during 30sIE would allow _ 2 max compared with a a higher increase in tlim and VO SWHITP with active recovery.

Materials and methods Subjects Thirty male physical education students volunteered to participate in this study but only 24 were included for data analysis at the end of the study. Indeed, after the first measurement, two of the subjects enrolled did not want to go further in the study and four of the remaining subjects were excluded for technical reasons (data loss, incorrect data, technical problems etc.). The remaining subjects were assigned in randomized order to a control group (CG, n = 6), and two high-intensity interval-training groups: intermittent exercise (30sIE) with active (IEA, n = 9) or passive recovery (IEP, n = 9). All subjects were well trained but none were specialized in middle- and/or long-distance running and had never practiced 30sIE before this study. Their age and physical characteristics were measured before and after the SWHITP and are displayed in Table 1. This study had been approved by the University of Rennes 2 Research Ethics Committee. Prior to participation, the participants underwent a medical examination and were fully informed about the experimental procedures and a signed consent was obtained from the participants.

Author's personal copy Eur J Appl Physiol Table 1 Mean (±SD) data measured for the age and anthropometric data Age (Years) Pre-test

Body mass (kg)

BMI (kg m-2)

Post-test

Pre-test

Posttest

Pretest

Height (cm) Posttest

Pre-test

Fat mass (%) Posttest

Pretest

Posttest

IEA (n = 9)

20.9 (0.8)

NS

21.0 (0.9)

179.2 (3.3)

NS

178.9 (3.0)

76.8 (8.3)

NS

77.3 (7.9)

24.0 (2.9)

NS

24.2 (2.7)

10.7 (2.8)

NS

10.8 (2.8)

IEP (n = 9)

20.4 (0.6)

NS

20.4 (0.6)

181.3 (3.5)

NS

180.4 (2.5)

74.1 (8.8)

NS

73.6 (8.1)

22.5 (2.5)

NS

22.6 (2.5)

12.2 (3.2)

NS

12.8 (3.7)

CG (n = 6)

20.5 (0.5)

NS

20.5 (0.5)

176.8 (3.8)

NS

176.7 (3.7)

66.5 (4.4)

NS

67.2 (4.7)

21.3 (1.5)

NS

21.5 (1.6)

10.5 (1.3)

NS

10.9 (1.6)

IEA trained group with active recovery, IEP trained group with passive recovery, CG control group without SWHITP, BMI body mass index, NS no significant difference within each group between the pre- and post-tests

Overview

Maximal graded test

All subjects visited the laboratory for a familiarization session with all the material of the experiment. During this session the anthropometric measurements (height, body mass and percentage of fat mass) were taken. All subjects first performed a maximal graded test (Leger and Boucher 1980) to determine their maximal oxygen _ 2 max ) and maximal aerobic velocity (MAV) uptake (VO before and after the SWHITP. Then, in a random order and before and after the SWHITP, subjects of IEA and IEP groups carried out an intermittent exercise test consisting of repeating as long as possible 30 s intensive runs at 105 % of MAV alternating with 30 s active recovery at 50 % of MAV (IEA) or 30 s passive recovery (IEP), respectively (Fig. 1). The CG subjects only performed two maximal graded tests and did not participate to any physical training program. The subjects of the IEA and IEP groups performed another maximal graded test (without expired gas measurement) at the mid of the SWHITP (on the Wednesday of the fourth week) in order to assess MAV and to update the training speeds for the remaining of the training program. All tests were carried out under similar environmental conditions (temperature ranging from 14 to 18 °C, wind speed \2 m s-1 and humidity ranging from 50 to 70 %). The maximal graded test took place in the morning after a standardized breakfast. All the tests were performed until exhaustion on a 200 m outdoor tartan track (of which 60 m indoors) calibrated with cones, at the same time of the day, with 48 h of rest between each test. For each test, the subjects were verbally encouraged to run for as long as possible. Tests were stopped when subjects could not maintain the required speed or when they stopped the exercise, judging themselves exhausted. Before and after the SWHITP, all tests (maximal graded tests and intermittent exercise tests) were completed within 2 weeks (Fig. 1).

Blue cones were set at 50 m intervals along the track (inside the first line) while red cones were set 2 m behind the blue cones. The running pace was set by an examiner, equipped with a whistle and a chronometer, emitting short sound when the subject had to pass by a cone to be able to maintain a constant speed for each test-stage. At each sound, the subject had to be within 2 m of the blue cones. When subjects were behind a red cone three consecutive times or when the subjects stopped the exercise, judging themselves exhausted, the test ended. The initial intensity was set at the stage 9, corresponding to 9 METS or 7.6 km h-1 (one MET corresponds to resting oxygen uptake value). Thereafter, the velocity was increased by 2 METS every 2 min. The velocity at the last completed stage was considered as MAV. If for example, the velocity at exhaustion was only maintained for 1 min (half of the stage duration), then MAV was considered to be equal to the velocity during the previous stage plus 0.5 km h-1 (Kuipers et al. 1985). During the test, the subjects were verbally encouraged to run for as long as possible. Intermittent exercise test These tests were carried out on the same track as the maximal graded test. Before each test we calculated, as a function of the MAV of each subject, the required distance to be covered during the 30 s intensive runs at 105 % of MAV and the 30 s active recovery at 50 % of MAV. These distances were indicated by blue cones on the track. Red cones were positioned 1 m behind each blue cones. A sound was emitted at the beginning and at the end of each period of 30 s. At the end of each period of 30 s of running, the subject had to be necessarily between the red cone and the blue one. If this was not achieved the test was stopped and time corresponding was registered as time limit (tlim) of the subject. When the recovery was active, we calculated

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Author's personal copy Eur J Appl Physiol Fig. 1 Experimental protocol for IEA trained group with active recovery during 30sIE, IEP trained group with passive recovery during 30sIE, CG control group without SWHITP. Both tests were preceded by the same warm-up. MAV maximal aerobic velocity measured during maximal graded tests. _ 2 max maximal oxygen uptake VO measured during maximal graded tests. tlim total exercise duration measured during intermittent exercise tests. Pretest and post-test tests realized before and after the SWHITP, respectively

the required distance to be covered in 15 s. These distances were indicated by green cones on the track. Red cones were positioned 1 m behind each green cone. At the mid of the recovery period (15 s) and at the first sound signal the subject had to be between the red cone and the green one and make a U-turn. At the second sound signal (30 s) he should be back to the blue cone and begin a new period of 30 s intensive run at 105 % of MAV. When the recovery was passive athletes were asked to walk around the starting area. The intermittent exercise tests were preceded by a standardized warm-up consisting of 10 min continuous jogging, followed by 5 min of the participant’s usual stretching routine, five short bursts of accelerations on the track and 2 min rest. Respiratory gas exchange and heart rate measurements During the maximal graded tests and intermittent exercise tests, respiratory gas exchange was measured breath-bybreath using a portable telemetric system (Cosmed K4b2, Rome, Italy; McLaughlin et al. 2001). Before each test, the O2 and CO2 analysis systems were calibrated using ambient air and a gas of known O2 and CO2 concentrations (16 and 5 %, respectively). The calibration of the K4b2 turbine flow-meter was performed using a 3–1 syringe (Quinton

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Instruments, Seattle, WA, USA). Heart rate was recorded by the device from a chest belt transmitter and continuously monitored (Polar Electro, Kempele, Finland). The cardiorespiratory values were averaged over a 5 s period during the maximal graded tests and during the intermittent exercise tests. _ 2 max Determination of VO _ 2 max was measured during the maximal graded test. The VO _ 2 max (in absolute and relative values) corresponded to VO _ 2 attained in two successive 5 s periods. It the highest VO _ 2 max when was judged that subjects had reached their VO _ 2 the following criteria were met: (1) a steady state of VO _ 2 despite increasing running speed. This steady state in VO _ was defined as being when the change in VO2 was less than 150 ml min-1 or 2.1 ml kg-1 min-1 between successive stages (Taylor et al. 1955); (2) a final respiratory exchange ratio (Rmax) higher than 1.1; (3) a heart rate at the end of exercise within 10 beats min-1 of age-predicted maximum ([210-(0.65 9 age)]—Spiro 1977). When these criteria were not met, the test was not considered maximal. In the present experiment, all subjects met the above-mentioned criteria and none was re-tested for unsatisfying criteria.

Author's personal copy Eur J Appl Physiol Table 2 Seven-week intermittent training program (SWHITP) for the trained groups (IEA and IEP) Week 1

Week 2

Week 3

Week 4

Week 5

Week 6

Week 7

29

29

29

29

29

29

29

(8 9 30sIE)

(10 9 30sIE)

(8 9 30sIE)

(10 9 30sIE)

(10 9 30sIE)

(10 9 30sIE)

(10 9 30sIE)

100/50 % MAV R = 5 min.

110/50 % MAV R = 5 min.

110/50 % MAV R = 5 min.

110/50 % MAV R = 5 min.

110/50 % MAV R = 5 min.

100/50 % MAV R = 5 min.

100/50 % MAV R = 5 min.

Training sessions IEA (n = 9)

IEP (n = 9)

TL: 600 ATU

TL: 800 ATU

TL: 640 ATU

TL: 800 ATU

TL: 800 ATU

TL: 750 ATU

TL: 750 ATU

29

29

29

29

29

29

29

(12 9 30sIE) 100/0 % MAV R = 5 min.

(15 9 30sIE) 110/0 % MAV R = 5 min.

(12 9 30sIE) 110/0 % MAV R = 5 min.

(15 9 30sIE) 110/0 % MAV R = 5 min.

(15 9 30sIE) 110/0 % MAV R = 5 min.

(15 9 30sIE) 100/0 % MAV R = 5 min.

(15 9 30sIE) 100/0 % MAV R = 5 min.

TL: 600 ATU

TL: 825 ATU

TL: 660 ATU

TL: 825 ATU

TL: 825 ATU

TL: 750 V

TL: 750 ATU

MAV maximal aerobic velocity, R passive recovery between series, IEA trained group with active recovery, IEP trained group with passive recovery, TL training load, ATU arbitrary training units Example: [2 x (8 9 30sIE) 100/50 % MAV. R = 5 min.] it means that the subject had to run two series of eight times 30sIE composed of 30 s running at 100 % of MAV and 30 s active recovery at 50 % of MAV. The subject recovers passively 5 min between each series. Each session is repeated 3 times a week Example of training load calculation for IEA during the first week: [[(100 ? 50)/2] 9 4 9 2] = 600 ATU

Seven-week high-intensity interval training program (SWHITP) IEA and IEP groups participated in the SWHITP three times per week (on Monday, Wednesday and Friday) for 7 weeks (21 HIT sessions in total) (Table 2). The HIT sessions were separated by at least 48 h to allow adequate recovery. During each session, temperature, humidity and wind speed were continuously measured with an anemometer (USA, Kestrel 3500). The HIT sessions were exclusively composed of intermittent exercises with active recoveries for IEA or passive recoveries for IEP. All sessions included three different periods: the sessions were preceded by a standardized warm-up, which consisted of 15 min continuous jogging, followed by 5 min stretching exercises and 5 short bursts of accelerations on the track. During every HIT session on the track there was one subject per lane. All different distances for each athlete (running and recovery intervals) were fixed by the examiner before every session. The subjects start from a standing position, behind a cone. Then, they performed their HIT session. For these training sessions, the subjects’ pace was given by an examiner emitting sounds at regular intervals up to the end of the exercise. During the 30 s active recovery, subjects of IEA had to cover a distance determined according to their own MAV. Subjects of IEP did not run and were standing waiting for the next effort. During the recovery period (IEP and IEA), a longer sound was made at mid period (15 s) to inform the subjects of the remaining time for the end of recovery. At the end of the HIT session subjects cooled down for about 15 min, running at low intensity and performing static stretching. Two members of our laboratory supervised all HIT

sessions. At the mid of the SWHITP (on the Wednesday of the fourth week), IEA and IEP groups performed a maximal graded test (without respiratory gas exchange measurements) to asses MAV in order to update the training speed of each subject. During this experimental period the control group (CG) did not participate to any physical training program. Time to exhaustion, time spent above 90 or 95 % _ 2 max of VO Time to exhaustion (tlim) corresponded to the delay between the onset and the end of the intermittent exercise test. Before and after the SWHITP, time spent above 90 % _ 2 max ) or 95 % of VO _ 2 max (t95 VO _ 2 max ) were (t90 VO _ determined from the VO2 values higher or equal to 90 or _ 2 max and were calculated according to the 95 % of VO _ 2 max values measured before and after the SWHITP. VO Determination of mean intensity (Imean) and mean _ 2mean ) during the intermittent oxygen uptake (VO exercise tests For each intermittent exercise tests, the mean intensity corresponded to the sum of exercise and recovery intensities, expressed in absolute values, which was then divided by two (example in IEA for a subject with a MAV of 16 km h-1. (Imean = [(16 ? 8)/2] = 12 km h-1). For each intermittent exercise test, the mean oxygen uptake, expressed in relative value, corresponded to the average values of oxygen uptake averaged over a 5 s period during these tests.

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Percentage of fat mass and fat free mass calculations

20

**

Statistical analysis

NS

** 18

MAV (km.h-1)

Percentage of fat mass was estimated from four skin folds thickness (biceps, triceps, sub-scapular, and supra-iliac) according to the method of Durnin and Rahaman (1967). Fat free mass (FFM) was estimated as the difference between measured body mass and estimated body fat.

IEA IEP

NS

NS

16

NS

NS

14

*

Data were expressed as mean values ± standard deviation (SD). On the basis of a power analysis (desired power = 0.80 and an alpha error = 0.05), we determined that a sample size of n = 6 per group would be sufficient to detect a significant increase in our parameters. After testing for normal distribution (Kolmogorov–Smirnov test), differences between the groups were analysed using a twoway analysis of variance (ANOVA) (time 9 group). After confirming significant group differences over time, post hoc Newman–Keuls tests were performed. A value of p \ 0.05 was accepted as the minimal level of statistical significance. Statistical analyses were carried out with the SigmaStat 1.0 program (Jandel Scientific, San Rafael, US).

Results Maximal graded test For IEA and IEP, mean MAV significantly increased (p \ 0.001 and p \ 0.001, respectively) between the onset (16.1 ± 1.2 and 15.5 ± 1.0 km h-1, respectively) and the mid (17.1 ± 0.9 and 16.1 ± 1.5 km h-1, respectively) and between the onset and the end (17.0 ± 1.0 and 16.5 ± 1.1 km h-1, respectively) of the SWHITP (Fig. 2; Table 3) with a statistically significant interaction between group and time (p \ 0.001). No significant difference was observed, in any group, in mean MAV between the mid and the end of the SWHITP and no significant difference was observed between IEA and IEP at the onset, at the mid and at the end of the SWHITP (Fig. 2). Finally, no significant difference was observed in mean MAV for CG between the onset (16.1 ± 0.3 km h-1) and the end (15.8 ± 0.5 km h-1) of the SWHITP (Table 3). _ 2 max significantly increased between For IEA, mean VO the onset and the end of the SWHITP when expressed in absolute (4.5 ± 0.6 l min-1 vs. 4.8 ± 0.6 l min-1, p \ 0.001) or relative values (p \ 0.01) and no significant difference was observed for IEP and CG (Table 3). For IEA and IEP, our results also show a statistically significant interaction between group and time (p \ 0.05) but only _ 2 max was expressed in absolute values. when VO

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* 12 Pré

Int

Post

Fig. 2 Mean (±SD) maximal aerobic velocity (MAV) measured during a maximal graded test completed before (Pre), at the mid (Int) and after (Post) the SWHITP. The maximal graded test realized at the mid of the SWHITP only assess MAV and was used to update the training speed. IEA trained group with active recovery (n = 9). IEP trained group with passive recovery (n = 9). NS no significant difference. Significant difference *p \ 0.05 and **p \ 0.01

_ 2 max expressed in relative values Concerning mean VO no significant difference was observed between IEA, IEP and CG at the onset (59.37 ± 7.5 vs. 58.66 ± 4.2 vs. 60.41 ± 2.0 ml min-1 kg-1, respectively) and at the end (62.85 ± 7.9 vs. 60.35 ± 4.7 vs. 59.96 ± 3.0 ml min-1 kg-1, respectively) of the SWHITP (Table 3). After the _ 2 max expressed in absolute values was SWHITP, mean VO _ 2 max for significantly (p \ 0.05) higher for IEA than mean VO CG (Table 3). Intermittent exercise test For IEA (p \ 0.05) and IEP (p \ 0.001) mean tlim significantly increased between the onset (923 ± 188 and 1,883 ± 788 s, respectively) and the end (1,163 ± 188 and 3,015 ± 1,095 s, respectively) of the SWHITP (Table 4) with a statistically significant interaction between group and time (p \ 0.01). No other significant difference was observed _ 2 max and t95 VO _ 2 max expressed in relative or for t90 VO absolute values (Table 4). Imean significantly increased for IEA (p \ 0.01) and IEP (p \ 0.05) between the onset (12.01 ± 0.90 and 8.01 ± 0.61 km h-1, respectively) and the end (12.72 ± 0.60 and 8.40 ± 0.53 km h-1, respectively) of the SWHITP (Fig. 3a), with no statistically significant interaction between group and time (p = 0.174). Moreover, before and after the SWHITP, Imean was significantly higher for IEA (p \ 0.01) compared to IEP. _ 2 max significantly increased (p \ 0.05) for IEA and Lastly,VO IEP between the onset (51.6 ± 2.9 and 42.4 ± 2.9 ml.min-1 kg-1, respectively) and the end (53.8 ± 2.2 and 43.4 ± 2.2 ml.min-1 kg-1, respectively) of the

Author's personal copy Eur J Appl Physiol Table 3 Mean (±SD) data measured during the maximal graded test for the trained groups (IEA and IEP) and the control group (CG) and before and after the SWHITP MAV (km h-1)

_ 2 max (l min-1) VO

Pre-test

Post-test

Pre-test

_ 2 max (ml min-1 kg-1) VO Post-test

Pre-test

Post-test

IEA (n = 9)

16.1 (1.2)

***

17.0 (1.0)

4.5 (0.6)

***

4.8a9 (0.6)

59.37 (7.5)

**

62.85 (7.9)

IEP (n = 9)

15.5 (1.0)

***

16.5 (1.1)

4.3 (0.3)

NS

4.4 (0.4)

58.66 (4.2)

NS

60.35 (4.7)

CG (n = 6)

16.1 (0.3)

NS

15.8 (0.5)

4.0 (0.3)

NS

4.0 (0.3)

60.41 (2.0)

NS

59.96 (3.0)

IEA trained group with active recovery, IEP trained group with passive recovery, CG control group without SWHITP, MAV maximal aerobic _ 2 max maximal oxygen uptake, NS no significant difference between the onset (pre-test) and the end (post-test) of the SWHITP velocity, VO * Significant difference between the onset (pre-test) and the end (post-test) of the SWHITP: ** P \ 0.01, *** P \ 0.001 a9

Significant difference from CG: a9P \ 0.05,

a9a9

P \ 0.1,

a9a9a9

P \ 0.001

Table 4 Mean (±SD) data measured during the intermittent exercise tests for IEA and IEP before and after the SWHITP _ 2 max (% tlim) t90 VO

_ 2 max (s) t95 VO

Posttest

Pre-test

Post-test

Pretest

_ 2 max (s) t90 VO

tlim (s) Pre-test

Post-test

Pretest

_ 2 max (% tlim) t95 VO Posttest

Pre´-test

Post-test

IEA (n = 9)

923a9 (188)

*

1163a9a9a9 (188)

543 (293)

NS

635 (428)

50.5a9 (23.2)

NS

52.2a9 (20.5)

335 (313)

NS

497 (365)

29.5a9 (15.1)

NS

40.9a9 (20.0)

IEP (n = 9)

1883 (788)

** *

3015 (1095)

338 (317)

NS

477 (442)

13.3 (12.2)

NS

13.4 (11.3)

161 (158)

NS

231 (243)

6.1 (6.0)

NS

6.2 (5.7)

_ 2 max time above 90 % of IEA trained group with active recovery, IEP trained group with passive recovery, tlim total exercise duration, t90 VO _ 2 max in absolute (s) and relative (% tlim) values, t95 VO _ 2 max time spent above 95 % of VO _ 2 max expressed in absolute (s) and relative (% tlim) VO values, NS no significant difference between the onset (pre-test) and the end (post-test) of the SWHITP * Significant difference between the onset (pre-test) and the end (post-test) of the SWHITP: * P \ 0.05, ** P \ 0.1, *** P \ 0.001 a9

Significant difference between IEA and IEP: a9P \ 0.05,

a9a9

P \ 0.01,

a9a9a9

P \ 0.001

_ 2mean ) (b) during intermittent exercise tests with active (IEA) and passive (IEP) Fig. 3 Mean intensity (Imean) (a) and mean oxygen uptake (VO recovery. Significant difference *P \ 0.05 and **P \ 0.01

SWHITP (Fig. 3b), with no statistically significant interaction between group and time (p = 0.508). Before and after _ 2mean was significantly higher (p \ 0.05) for the SWHITP, VO IEA compared to IEP.

Mean tlim both at the onset (p \ 0.05) and at the end (p \ 0.01) of the SWHITP were significantly longer for IEP compared with IEA (Table 4). At the onset and at the end of _ 2 max and mean t95 VO _ 2 max the SWHITP mean t90 VO

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expressed in relative values were significantly higher _ 2 max (p \ 0.05) for IEA compared to IEP. For mean t90 VO _ and mean t95 VO2 max , both expressed in absolute values, no significant differences were observed between IEA and IEP at the onset and at the end of the SWHITP (Table 4). Before the SWHITP three subjects from IEP group failed to reach 95 % _ 2 max and one subject failed to reach 90 % of VO _ 2 max of VO and all subjects from IEA group reached 95 and 90 % of _ 2 max . After the SWHITP, one subject from IEP group VO _ 2 max and all subjects from failed to reach 95 and 90 % of VO _ 2 max . IEA group reached 95 and 90 % of VO

Discussion The aim of this study was to compare before and after a SWHITP, the effects of recovery mode (active vs. passive), _ 2 max , maximal aerobic velocity during a 30sIE, on VO _ _ 2 max . Indeed, many (MAV), tlim, t90 VO2 max and t95 VO studies have described the acute physiological effects of short intermittent exercise as 15 s/15 s intermittent exercise (15sIE) (Dupont et al. 2002, 2003a, b; Dupont and Berthoin 2004; Billat et al. 2001), 30sIE (Billat et al. 2000a, b; Thevenet et al. 2007a, b, 2008) or the chronic physiological effects of HIT program such as 20 s/10 s (Tabata et al. 1996). To our knowledge only one study has described the chronic physiological effects of 30sIE in which only passive recovery was used (Burke et al. 1994) and no study has described the chronic physiological effects of 30sIE with variations in recovery mode (active vs. passive). In our study, the choice of exercise (105 % of MAV) and recovery (50 % of MAV or passive) intensities during the intermittent exercise tests and the experimental protocol used during these tests were then based on our previous study (Thevenet et al. 2007a). High-intensity interval training can be broadly defined as repeated bouts of short to moderate duration exercise (i.e. 10 s–5 min) completed at an intensity that is greater than the anaerobic threshold (Laursen and Jenkins 2002) or _ 2peak (i.e, C90 % of VO _ 2peak ) close to that which elicits VO (Gibala and McGee 2008). During HIT, exercise bouts are separated by brief periods of low-intensity work or inactivity that allow a partial but often not a full recovery (Laursen and Jenkins 2002). During the present study SWHITP, the durations of the exercise bouts and recoveries were of 30 s, the recovery bouts were either run at an intensity of 50 % of MAV (IEA) or were passive (IEP). The intensity of the exercise bouts ranged from 100 to 110 % of MAV. This training program matches the previous HIT definition. Lastly, the training load (TL), calculated by week and over the SWHITP, was obtained by the product of the mean intensity of the HIT sessions with this duration (expressed in min) and the number of series (Calvert et al.

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1976). This training load was practically similar for IEA and IEP over the SWHITP (Table 2). _ 2 max Effects of recovery mode on MAV and VO The purpose of HIT was to repeatedly stress the physiological systems that will be used during a specific endurance-type exercise (Daniels and Scardina 1984) to a greater extent than that which is actually required during the activity. In this respect, MAV appears useful for prescribing HIT (Laursen and Jenkins 2002). In the present study, the SWHITP induced a significant improvement in MAV for IEA and IEP between the onset and the mid of the SWHITP and between the onset and the end of the SWHITP (Fig. 2). It is difficult to compare our results with others, because to our knowledge no studies have described the chronic physiological effects of short intermittent exercise as 30sIE and their variations with recovery mode. However, this significant improvement of MAV, regardless of the recovery mode and after only 3.5 weeks of HIT, was consistent with that of Billat et al. (1999), Smith et al. (1999) and Denadai et al. (2006) in highly trained runners and with that of Billat et al. (2002) and Heubert et al. (2003) in physical education students, who observed a significant increase in MAV after only 4 weeks of HIT. In the present study, the maximal graded test performed at the mid of the SWHITP was used to assess MAV and then to update the training speed. In spite of that no significant changes were observed between the mid and the end of the SWHITP in both IEA and IEP. Sports training is a very complex process because the possibilities for structuring training according to its frequency, intensity and duration are almost endless (Wenger and Bell 1986; Berg 2003). However, in the present study the higher intensity of the exercise bouts (i.e.,110 % MAV) during the SWHITP were located between the second and the fifth weeks (Table 2). Thereafter, the exercise bouts intensity remained at 100 % of MAV until the seventh weeks. Both intensity and volume are stimuli for improving aerobic fitness and performance. Furthermore, the volume of work is normally greater when intensity is in the lower portion of a training program (Berg 2003). Then, the present study results about MAV improvements between the mid and the end of the SWHITP could be explained by either an exercise intensity that resulted too low during the two last weeks of the SWHITP and/or by a too low training volume and/or this parameter had attained a threshold value. To effectively answer the question regarding optimum training intensity and training volume during a SWHITP, more longitudinal studies are needed. Finally, considering that no significant difference was observed in MAV for CG over the SWHITP (Table 3) and that the SWHITP induced a significant improvement in MAV for IEA and IEP, it may be

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reasonable to assume that the significant improvement in MAV during a SWHITP does not depend on the recovery mode (active or passive) used during 30sIE. Our results also suggest that, regardless of the recovery mode used during 30sIE, a high-intensity interval training program of 7 weeks duration is sufficient to significantly increase MAV. One of the main findings from this study was that during SWHITP the significant increase in MAV for IEA and IEP was associated with a significant increase in absolute and relative _ 2 max but only for IEA. Very few studies have to body mass VO _ 2 max after a described the improvement in both MAV and VO SWHITP. Most often, studies described (1) only improve_ 2 max (Carter et al. 1999; Tabata et al. 1996; Burke ments in VO et al. 1994) after 6 or 7 weeks of training or (2) improvements _ 2 max but after only 4 weeks of training in both MAV and VO (Billat et al. 1999, Denadai et al. 2006). However, the results _ 2 max , seem to obtained from IEA and IEP, about MAV and VO be in agreement with previous results reported in the literature confirming that either a 6 weeks of aerobic training improved _ 2 max in moderately trained sports students significantly VO (Tabata et al. 1996; Carter et al. 1999) or that a 4-week training program in trained athletes caused a significant _ 2 max (Denadai improvement in MAV with no change in VO et al. 2006; Billat et al. 1999). Nevertheless, the data for the IEP group in this study is not in agreement with the results of Burke et al. (1994) who revealed in ten female physical _ 2 max significantly improved after education students that VO 7 weeks of 30sIE with passive recovery. The comparison with the present study is difficult because in the study of Burke et al. (1994) the subjects trained to exhaustion four times per week and the training program, performed on _ 2 max and bicycle ergometer, began at an intensity of 85 % VO _ 2 max ). increased 5 % every 2 weeks (to reach 90 and 95 % VO _ 2 max (Table 3) and the In the present study the initial VO frequency, exercise duration, program length and then the training load were identical for IEA and IEP (Table 2) but the mean intensities during SWHITP were always higher for IEA because of the active recovery. Wenger and Bell (1986) concluded in their review of the training literature that at any level of exercise duration, frequency, program length or initial fitness level, intensity was the most important factor in producing improvements in aerobic power. Then perhaps the conflicting findings described above may be due to the fact that the present study training program failed to provide the necessary training stimulus to promote a significant change in _ 2 max for IEP. VO Effects of recovery mode on time to exhaustion In accordance with the study of Noakes (1991), the benefits of training do not only depend on the level of the stress

imposed on the cardiovascular system but also on time spent at a high intensity determining the muscular adaptation. In the present study, the fact that a longer tlim was observed with passive than with active recovery could be explained by the resynthesis, during passive recovery, of a higher proportion of the muscle phosphocreatine (PCr) used during the 30 s intensive runs at 105 % of MAV. This hypothesis is supported by the results of the study conducted by Chidnok et al. (2012). Indeed, they showed during intermittent exercise consisting of a series of 60 s severe-intensity work bouts that tlim was a function of the recovery intensity in the recovery bouts. These authors suggested that the fact that a longer tlim was observed with passive recovery than with active recovery intervals during intermittent exercise allowed some of the fatigue-related substrates to be resynthesized (e.g., muscle phosphocreatine concentration ([PCr])) and for fatigue-related metabolites to be cleared from the muscle (e.g., H?), thereby delaying the attainment of a ‘‘limiting’’ intramuscular environment (Jones et al. 2008). Effects of recovery mode on time spent at high _ 2 max percentage of VO In the present study, it was hypothesized that a SWHITP with passive recovery during 30sIE would allow a higher increase in tlim compared with a SWHITP with active recovery without concomitant difference in absolute t90 _ 2 max before and after the SWHITP. The _ 2 max or t95 VO VO _ 2 max or t95 present study results show that when t90 VO _ 2 max were expressed in relative values (%tlim) a sigVO nificantly higher percentage of tlim for IEA than for IEP was observed, both at the onset and at the end of the SWHITP. These results are in agreement with our previous study (Thevenet et al. 2007a) and confirm that the 30sIE active recovery is more efficient than the 30sIE passive recovery when the sole objective of the exercise is to sustain a high _ 2 max since one spends proportionally less percentage of VO _ 2 max or t95 time running for the same value of t90 VO _ 2 max . The present study results also show that there was VO no significant difference in time spent at 90 and 95 % of _ 2 max in absolute values between IEA and IEP even when VO tlim was significantly longer during IEP compared with IEA both at the onset and at the end of the SWHITP. In line with this, our hypothesis is verified. The present results are in line with earlier studies (Dupont and Berthoin 2004; Thevenet et al. 2007a, 2008) which showed that passive recovery induced a longer time to exhaustion with a similar _ 2 max . These results time spent at a high percentage of VO _ 2 throughout the could be explained by a lower level of VO end of exercise performed with a passive recovery and

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corroborated our previous assumption (Thevenet et al. _ 2 appears 2008) that the decrease in the time course of VO with low recovery intensities and thus it may be linked with a long exercise duration (Thevenet et al. 2007a, 2008). _ 2 response profile can be Lastly, the finding that the VO modulated during intermittent exercise is also consistent with the study of Chidnok et al. (2012) which showed a significant reduction in the slope of the relationship _ 2 and time in the conditions where the recovbetween VO ery intensities were lower compared with when recovery intensity was higher. Collectively, the present study results and those of Chidnok et al. (2012) indicate that the tra_ 2 during an exercise reflects the development jectory of VO of muscular fatigue and is an important determinant of exercise tolerance during intermittent exercise (Chidnok et al. 2012). Conclusion This study is the first, to the best of our knowledge, describing the chronic physiological effects of 30sIE and their variations taking into account the recovery mode (active vs. passive). The present study results show that both at the onset and at the end of the SWHITP with passive recovery during 30sIE, there was no significant _ 2 max and a difference in time spent at 90 and 95 % of VO longer tlim compared with the SWHITP with active recovery. We also show that the SWHITP induced a significant improvement in MAV for IEA and IEP between the onset and the end of the SWHITP associated with a sig_ 2 max nificant increase in absolute and relative values of VO but only for IEA. Then, the SWHITP with passive recovery _ 2 max expressed during 30sIE does not seem to affect the VO in absolute and relative values. From a practical point of view if the sole objective of a training session is to improve _ 2 max , it seems that an active recovery (at 50 % of MAV) VO should be chosen. However, others studies should be carried out to confirm our results. Particularly, it would be interesting to assess the exercise performance with the help of a time trial over a set distance on the track. This would reveal how our findings translate to exercise performance and which training mode and training adaptations. Acknowledgments The authors wish to acknowledge all the subjects for their participation in the study. We also wish to honor the memory of Delphine The´venet by dedicating this article to her.

References Astrand I, Astrand PO, Christensen EH, Hedman R (1960) Intermittent muscular work. Acta Physiol Scand 48:448–453

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Bangsbo J, Graham T, Johansen L, Saltin B (1994) Muscle lactate metabolism in recovery from intense exhaustive exercise: impact of light exercise. J Appl Physiol 77:1890–1895 Berg K (2003) Endurance training and performance in runners: research limitations and unanswered questions. Sports Med 33(1):59–73 Billat VL, Bocquet V, Slawinski J, Laffite L, Demarle A, Chassaing P, Koralsztein JP (2000a) Effect of a prior intermittent run at v _ 2max on oxygen kinetics during an all-out severe run in VO humans. J Sports Med Phys Fitness 40(3):185–194 Billat VL, Flechet B, Petit B, Muriaux G, Koralsztein JP (1999) _ 2max effects on aerobic performance and Interval training at VO overtraining markers. Med Sci Sports Exerc 31:156–163 Billat VL, Mille-Hamard L, Demarle A, Koralsztein JP (2002) Effect of training in humans on off- and on-transient oxygen uptake kinetics after severe exhausting intensity runs. Eur J Appl Physiol 87:496–505 Billat VL, Slawinksi J, Bocquet V, Chassaing P, Demarle A, Koralsztein JP (2001) Very Short (15 s–15 s) Interval-Training around the critical velocity allows middle-aged runners to maintain VO2max for 14 minutes. Int J Sports Med 22:201–208 Billat VL, Slawinski J, Bocquet V, Demarle A, Lafitte L, Chassaing P, Koralsztein JP (2000b) 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. Eur J Appl Physiol 81:188–196 Brandon LJ (1995) Physiological factors associated with middle distance running performance. Sports Med 19(4):268–277 Burke J, Thayer R, Belcamino M (1994) Comparison of effects of two interval-training programs on lactate and ventilatory thresholds. Br J Sports Med 28:18–21 Calvert T, Banister EW, Savage M et al (1976) A system model of the effects of training on physical performances. IEE Trans Syst Man Cybern smc 6:94–102 Carter H, Jones AM, Doust JH (1999) Effect of 6 weeks of endurance training on the lactate minimum speed. J Sports Sci 17:957–967 Chidnok W, Dimenna FJ, Bailey SJ, Vanhatalo A, Morton RH, Wilkerson DP, Jones AM (2012) Exercise tolerance in intermittent cycling: application of the critical power concept. Med Sci Sports Exerc 44(5):966–976 Daniels J, Scardina N (1984) Interval training and performance. Sports Med 1:327–334 Denadai BS, Ortiz MJ, Greco CC, de Mello MT (2006) Interval training at 95 % and 100 % of the velocity at VO2max effects on aerobic physiological indexes and running performance. Appl Physiol Nutr Metab 31:737–743 Dorado C, Sanchis-Moysi J, Calbet JA (2004) Effects of recovery mode on performance, O2 uptake, and O2 deficit during high-intensity intermittent exercise. Can J Appl Physiol 29(3):227–244 Dupont G, Berthoin S (2004) Time spent at a high percentage of VO2max for short intermittent runs: active versus passive recovery. Can J Appl Physiol 29(Suppl):S3–S16 Dupont G, Blondet N, Berthoin S (2003a) Performance for short intermittent runs: active recovery vs. passive recovery. Eur J Appl Physiol 89:548–554 Dupont G, Blondel N, Berthoin S (2003b) Time spent at VO2max a methodological issue. Int J Sports Med 24:291–297 Dupont G, Blondel N, Lensel G, Berthoin S (2002) Critical velocity and time spent at a high level of VO2max for short intermittent runs at supramaximal velocities. Can J Appl Physiol 27(2):103–115 Durnin J, Rahaman M (1967) The assessment of the amount of fat in the human body from measurements of skinfold thickness. Brit J Nutr 21:681–689 Eddy DO, Sparks KL, Adelizi DA (1977) The effect of continuous and interval training in women and men. Eur J Appl Physiol 37:83–92

Author's personal copy Eur J Appl Physiol Franch J, Madsen K, Djurhuus MS, Pedersen PK (1998) Improved running economy following intensified training correlates with reduced ventilatory demands. Med Sci Sports Exerc 30(8):1250– 1256 Gibala MJ, McGee SL (2008) Metabolic adaptations to short-term high-intensity interval training: a little pain for a lot of gain? Exerc Sport Sci Rev 36(2):58–63 Gorostiaga EM, Walter CB, Foster C, Hickson RC (1991) Uniqueness of interval and continuous training at the same maintained exercise intensity. Eur J Appl Physiol 63:101–107 Heubert R, Bocquet V, Koralsztein JP, Billat V (2003) Effet de 4 semaines d’entraıˆnement sur le temps limite a` VO2max. Can J Appl Physiol 28(5):705–724 Jones AM, Wilkerson DP, DiMenna FJ, Fulford J, Poole D (2008) Muscle metabolic responses to exercise above and below the ‘critical power’ assessed using 31P-MRS. Am J Physiol Regul Integr Comp Physiol 294:R585–R593 Kuipers H, Verstappen FT, Keizer HA, Geurten P, van Kranenburg G (1985) Variability of aerobic performance in the laboratory and its physiologic correlates. Int J Sports Med 6(4):197–201 Laursen PB, Jenkins DG (2002) The scientific basis for high-intensity interval training. Optimising training programmes and maximizing performance in highly trained endurance athletes. Sports Med 32(1):53–73 Leger L, Boucher R (1980) An indirect continuous running multistage field test: the Universite´ de Montre´al track test. Can J Appl Sport Sci 5(2):77–84 McLaughlin JE, King GA, Howley ET, Bassett DR Jr, Ainsworth BE (2001) Validation of the COSMED K4 b2 portable metabolic system. Int J Sports Med 22:280–284 Midgley AW, McNaughton LR, Wilkinson M (2006) Is there an optimal training intensity for enhancing the maximal oxygen uptake of distance runners ? Empirical research findings, current opinions, physiological rationale and practical recommendations. Sports Med 36(2):117–132 Millet GP, Candau R, Fattori P, Bignet F, Varray A (2003a) VO2max responses to different intermittent runs at velocity associated with VO2max. Can J Appl Physiol 28(3):410–423 Millet GP, Libicz S, Borrani F, Fattori P, Bignet F, Candau R (2003b) Effects of increased intensity of intermittent training in runners with differing VO2max kinetics. Eur J Appl Physiol 90:50–57 Noakes T (1991) The lore of running. Leisure Press Champaign, IL

Pollock ML, Jackson AS, Pate RR (1980) Discriminant analysis of physiological differences between good and elite distance runners. Res Q Exerc Sport 51(3):521–532 Smith TP, Mc Naughton LR, Marshall KJ (1999) Effects of 4-wk training using Vmax/Tmax on VO2max and performance in athletes. Med Sci Sports Exerc 31:892–896 Spiro SG (1977) Exercise testing in clinical medicine. Br J Dis Chest 71:145–172 Tabata I, Nishimura K, Kouzaki M, Hirai Y, Ogita F, Miyachi M, Yamamoto K (1996) Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max. Med Sci Sports Exerc 28:1327–1330 Tardieu-Berger M, Thevenet D, Zouhal H, Prioux J (2004) Effects of active recovery between series on performance during an intermittent exercise model in young endurance athletes. Eur J Appl Physiol 93(1–2):145–152 Taylor H, Buskirk E, Henschel A (1955) Maximal oxygen intake as an objective measure of cardiorespiratory performance. J Appl Physiol 8:73–80 Thevenet D, Leclair E, Tardieu-Berger M, Berthoin S, Regueme S, Prioux J (2008) Influence of recovery intensity on time spent at maximal oxygen uptake during an intermittent session in young, endurance-trained athletes. J Sports Sci 26(12):1313–1321 Thevenet D, Tardieu-Berger M, Berthoin S, Prioux J (2007a) Influence of recovery mode (passive vs. active) on time spent at maximal oxygen uptake during an intermittent session in young and endurance-trained athletes. Eur J Appl Physiol 99(2):133–142 Thevenet D, Tardieu M, Zouhal H, Jacob C, Abderrahman BA, Prioux J (2007b) Influence of exercise intensity on time spent at high percentage of maximal oxygen uptake during an intermittent session in young endurance-trained athletes. Eur J Appl Physiol 102:19–26 Thiriet P, Gozal D, Wouassi D, Oumarou T, Gelas H, Lacour JR (1993) The effect of various recovery modalities on subsequent performance, in consecutive supramaximal exercise. J Sports Med Phys Fitness 33:118–129 Weltman A, Stamford BA, Moffatt RJ, Katch VL (1977) Exercise recovery, lactate removal, and subsequent high intensity exercise performance. Res Q 48:786–796 Wenger HA, Bell GJ (1986) The interactions of intensity, frequency and duration of exercise training in altering cardiorespiratory fitness. Sports Med 3(5):346–356

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