ARTICLE IN PRESS. Available online at Journal of Science and Medicine in Sport xxx (2008) xxx xxx.

Transcription

1 Available online at Journal of Science and Medicine in Sport xxx (2008) xxx xxx Original paper Yo-Yo intermittent recovery test versus the Université de Montréal Track Test: Relation with a high-intensity intermittent exercise Gregory Dupont a,b,, Mathieu Defontaine a, Laurent Bosquet a,c, Nicolas Blondel a, Wassim Moalla d, Serge Berthoin a a Laboratory of Human Movement Studies, Faculty of Sports Sciences and Physical Education, Artois and Lille 2 Universities, France b Celtic Lab, Sport Science Department, Celtic FC, Glasgow, Scotland, United Kingdom c Department of Kinesiology, University of Montreal, Montreal, Canada d Research Unit Evaluation, Sport and Health, Medicine and Sport Science National Centre, Tunis, Tunisia Received 7 March 2008; received in revised form 8 October 2008; accepted 10 October 2008 Abstract The first purpose of this study was to determine whether the peak velocity (V Yo-Yo ) achieved during the Yo-Yo intermittent recovery test (Yo-Yo) and the maximal aerobic velocity (MAV) determined from the Université de Montréal Track Test (UMTT) could be used interchangeably. The second purpose was to check that the V Yo-Yo is related to the intermittent exercise performance, which consisted of repeated 90 m distance runs in 15 s performed until exhaustion, alternated with 15 s of passive recovery (15/15). Fourteen amateur soccer players performed, in a random order, the 15/15 and two incremental field-tests: the Yo-Yo and the UMTT. The results of this study showed that MAV was significantly correlated to the V Yo-Yo (r = 0.79, p < 0.01). However, the error was not constant, when the V Yo-Yo and the MAV values were higher than 16.3 km h 1, the MAV values tends to be higher than the V Yo-Yo, while when the V Yo-Yo and the MAV values were lower than 16.3 km h 1, the MAV values tends to be lower than the V Yo-Yo. MAV and V Yo-Yo were significantly correlated to the time to exhaustion of the 15/15 (r = 0.74 and r = 0.72, respectively) and show that both tests are similarly related to the high-intensity intermittent exercise performance Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. Keywords: Intermittent exercise; Soccer; Field test; Performance 1. Introduction High-intensity intermittent exercises, such as 15-s runs alternated with 15-s of recovery (15/15), are often planned in training programs to improve both aerobic and anaerobic qualities. 9 According to the distance covered in 15-s (from 80 to 90 m), this kind of exercise presents the advantages of being fast to perform and easily implemented on a soccer pitch with many players. However, in order to optimise the improvements, the individualisation of the intensity is a key factor. The 15/15 is usually individualised from the maximal aerobic velocity 8,9 determined during a field-test, the Université de Montréal Track Test 14 in order to reduce the variability Corresponding author. address: gregory.dupont@univ-lille2.fr (G. Dupont). of the time to exhaustion (TTE). MAV has been found reliable to predict the maximal oxygen uptake 14 and can be considered as the velocity associated with VO 2 max. 4 However, the UMTT is a progressive continuous run, while intermittent runs such as 15/15 require to accelerate, to decelerate, to stop and to recover quickly during the short pause. The Yo- Yo intermittent recovery test 2 includes these acceleration, deceleration and recovery abilities. Although the estimation of VO 2 max from the Yo-Yo results is not accurate, 3,5 this test is used to evaluate an athletes ability to repeatedly perform intense exercise and his potential to recover from intense exercise. 12 However, the performance criterion for this test is the distance covered, which is efficient to class a population or to analyse the effects of a training program, but not to individualise the intensity. Using the peak velocity reached during the Yo-Yo (V Yo-Yo ), it would become /$ see front matter 2008 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. doi: /j.jsams

2 2 G. Dupont et al. / Journal of Science and Medicine in Sport xxx (2008) xxx xxx possible to use it to individualise the intermittent exercises intensities. Therefore, the first purpose of this study was to determine whether the V Yo-Yo and the MAV could be used interchangeably. The second purpose was to check that the V Yo-Yo is related to the intermittent exercise performance such as the 15/15. We hypothesise that the relationships between the V Yo-Yo and the 15/15 performance will be stronger than the relationships between the MAV and the 15/15 performance. 2. Methods Fourteen amateurs male soccer players, who performed 3 5 sessions (from 70 to 120 min) and one match per week participated to this study. Age, height and body mass of the participants were 23.2 ± 3.5 yr (range: yr), ± 6.4 cm (range: cm) and 70.8 ± 6.5 kg (range: kg), respectively. Their percentage body fat, estimated from a bioelectrical impedance balance with 4 electrodes (Tanita TBF 543, Tokyo, Japan), was 12.3 ± 2.8% (range: %). All subjects were fully informed of the protocol, benefits and risks before giving their written informed consent. This investigation was lead with the accordance of the local Ethics Committee in Biomedical Research. All subjects completed three tests on a 200-m indoor tartan track in a random order: the UMTT, the Yo-Yo intermittent recovery test, and an intermittent exercise (15/15). Before the tests, all subjects were fully familiarised with the exercise procedures. Sessions were carried out at the same time of day and were separated by at least 48 h, but all were completed within 2 weeks. For this test, the initial speed was set at 10 km h 1 and was increased by 1 km h 1 every 2 min. Cones were set at 25-m intervals along the 200-m track (inside the first lane). The running pace was dictated by audio signals and the participants had to be within 2-m of the cones at each signal. When subjects were behind a cone for three consecutive times, the test was terminated. The velocity at the last completed stage was increased by 0.5 km h 1 if the subject was able to run a half stage, and was assumed to represent the MAV. Léger and Boucher (1980) found that this test is valid to estimate the VO 2 max of trained and untrained young and middle-age females and males (r = 0.96, SEE = 2.81 ml kg 1 min 1 ) and reliable (r = 0.97, SEE = 1.92 ml kg 1 min 1 ). The protocol used for the Yo-Yo intermittent recovery test (level 1) was the same as that described by Krustrup et al. 12 It consists of repeated 2 20-m runs back and forth between the starting, turning, and finishing line at a progressively increased speed controlled by audio bleeps from a computer. 2 Between each running bout, the subjects have a 10-s active rest period, consisting of 2 5-m of jogging. Red cones were set at 20-m intervals to set the running distance, while a green cone was set 5-m behind the red cone representing the finishing line to set the recovery distance. This test version was characterised by 4 running bouts at km h 1 (0 160 m) and another 7 runs at km h 1 ( m), thereafter it continues with stepwise 0.5 km h 1 speed increments after every 8 running bouts until exhaustion. The test ended when the subjects had twice failed to reach the finishing line in time. The V Yo-Yo was calculated from the following equation developed by Kuipers et al., 13 where V Yo-Yo = V (n/8). In this equation, V represents the velocity during the next to last stage; the 0.5 represents the increment in velocity after each stage (in km h 1 ); n represents the number of runs completed in the last stage and 8 represents the number of runs in each stage from 14.5 km h 1. Intermittent exercise consisted of repeating 90-m distance runs in 15-s until exhaustion, alternating with 15-s of passive recovery, which corresponded to a constant velocity of 21.6 km h 1 (6ms 1 ). This running distance was chosen since each subject could achieve a few repetitions that led to exhaustion. 8 During a pilot study with 10 subjects, we checked the reliability of this exercise with a group of 10 subjects on 2 occasions, 1 week apart. The reliability of the 15/15 was good (15.8 ± 10.8 versus 16.0 ± 9.1 repetitions), as the typical error of measurement was 1.49% (95% confidence limits: %). For this exercise, running paces were given by a manual timer producing a sound every 15-s from the start to the end of the exercise. During the 15-s exercise period, subjects had to cover a 90-m distance. Subjects were allowed to stop running within the 3-m distance between the inner and the outer cone. After a 15-s rest, they started to run again in the opposite direction for 15-s. Times to exhaustion (TTE) were measured. Recovery periods were included in the TTE. During UMTT and Yo-Yo, heart rate (HR) and respiratory gas exchange values were measured breath-by-breath using a portable system (Cosmed K4b 2, Rome, Italy) in order to determine ventilation (VE), oxygen uptake (VO 2 ) and carbon dioxide output (VCO 2 ). This device has previously been validated for measuring these parameters over a wide range of exercise intensities. 15 Heart rate was recorded by the K4b 2 from a chest belt transmitter (Polar Electro, Kempele, Finland). Respiratory gas exchanges and HR values were averaged every 15 s. Before each test, the O 2 and CO 2 analysis systems were calibrated using ambient air with a gas mix of known O 2 and CO 2 concentrations. Partial oxygen and carbon dioxide in ambient air were assumed to be 20.93% and 0.03%, respectively. The reference gas concentrations of O 2 and CO 2 were 16.00% and 5.00%, respectively. The turbine flowmeter of the K4b 2 was calibrated using a 3-L syringe (Quinton Instruments, Seattle, USA). Maximal values corresponded to values obtained from the UMTT, while peak values corresponded to values obtained from the Yo-Yo. The VO 2 max was calculated from the UMTT. The primary criterion used was a plateau in VO 2 characterised by an increase of less than 2.1 ml 1 kg 1 min 1 despite increasing running speed. When the primary criterion was not met, the

3 G. Dupont et al. / Journal of Science and Medicine in Sport xxx (2008) xxx xxx 3 secondary criteria were used and corresponded to: (1) a final respiratory exchange ratio (RER) higher than 1.10 and (2) a post-exercise blood lactate concentration ([La] b ) higher than 8 mmol l 1. 7 Three minutes after the two incremental tests (UMTT and Yo-Yo), fingertip blood samples (10 l) were collected in order to measure capillary [La] b by a spectro-photometer technique (Dr. Lange, miniphotometer + LP20, type LPG 344). This device has been previously validated. 10 The accuracy of the analyser was checked before each test with standard solutions in lactate concentration (2, 4, 10, 15 and 30 mmol l 1 ). The [La] b were corrected from results found with standard solutions. Data are reported as means ± standard deviations. Normal Gaussian distribution of the data was verified by the Shapiro Wilk test, and homoscedasticity by a modified Levene test. As data were normally distributed and homoscedastic, parametric tests were used. Comparisons were performed using the paired Student s t-test. Pearson product moment correlations and confidence intervals (95% CI) were used to assess the relationships between variables. The correlation coefficients were interpreted in accordance with the scale of magnitude proposed by Hopkins 18 : r < 0.1 is trivial; 0.1 r < 0.3 is small; 0.3 r < 0.5 is moderate; 0.5 r < 0.7 is large; 0.7 r < 0.9 is very large; 0.9 r <1 is nearly perfect. Bland and Altman plots were used to determine the bias and limits of agreement between the MAV and the V Yo-Yo. Significance was accepted at p < Results For the UMTT, the MAV was 16.8 ± 1.1 km h 1 (range: km h 1 ). For the Yo-Yo, the V Yo-Yo was 16.5 ± 0.6 km h 1 (range: km h 1 ). The distance performed during the Yo-Yo was 2034 ± 367 m. The VO 2 max, HRmax, VEmax, RER, [La] b obtained for the UMTT were 60.1 ± 6.5 ml kg 1 min 1, ± 8.0 beats min 1, ± 14.2 l min 1, 1.13 ± 0.04 and 12.8 ± 3.3 mmol l 1, respectively. The VO 2 peak, HRpeak, VEpeak and [La] b obtained for the Yo-Yo were 58.7 ± 7.2 ml kg 1 min 1, ± 7.8 beats min 1, ± 18.3 l min 1, 12.0 ± 3.7 mmol l 1, respectively. No significant differences were found between VO 2 max and VO 2 peak, HRmax and HRpeak, VEmax and VEpeak, and between [La] b collected after the two incremental tests. The VO 2 max calculated during the UMTT was significantly correlated with the VO 2 peak during the Yo-Yo (r = 0.92, CI 95%: , p < 0.001). The HRmax reached during the UMTT was significantly correlated with the HRpeak (r = 0.88, CI 95%: , p < 0.001) collected during the Yo-Yo. The VO 2 max was significantly correlated with MAV (r = 0.79, CI 95%: , p < 0.001), and with the V Yo-Yo (r = 0.59, CI 95%: , p < 0.05). Fig. 1. (A) Relationships between the V YO-YO and MAV. (B) Relationships between the difference between MAV and V YO-YO and MAV. No significant relation was found between [La] b obtained after the UMTT and after the Yo-Yo (r = 0.48, CI 95%: 0.07 to 0.81, p > 0.05). The MAV was not significantly different from the V Yo-Yo. Relationships between the V Yo-Yo and MAV (A) and those concerning the difference between means and MAV (B) are presented in Fig. 1. The velocity, where the two values (MAV and V Yo-Yo ) are equal, corresponded to 16.3 km h 1. Fig. 2 presents the Bland and Altman plot of MAV versus the V Yo-Yo. Fig. 2. Bland and Altman plot of MAV versus the peak velocity achieved during the Yo-Yo intermittent recovery test. 95% CI: 1.70 to 1.42.

4 4 G. Dupont et al. / Journal of Science and Medicine in Sport xxx (2008) xxx xxx Fig. 3. Relationships between performance for intermittent exercise (TTE) and MAV. Fig. 4. Relationships between performance for intermittent exercise (TTE) and V YO-YO. During 15/15, subjects performed 14 ± 9 (range: 6 35) repetitions, which corresponded to a TTE of 405 ± 267 s (range: s). The constant velocity for 15/15 (21.6 km h 1 ) represented ± 8.6% (range: %) of MAV, ± 4.5% (range: %) of the V Yo-Yo. Significant relationships were found between performance for 15/15 (TTE) and both MAV (Fig. 3) and the V Yo-Yo (Fig. 4). 4. Discussion The first purpose of this study was to check that the V Yo-Yo and the MAV could be used interchangeably. According to the results, MAV was significantly correlated to the V Yo-Yo (r = 0.79, p < 0.01). Although this correlation coefficient was considered as very large, the error was not constant since it increased linearly with the speed increments (Fig. 1B). When the V Yo-Yo values and the MAV values were higher than 16.3 km h 1, the MAV values tend to be higher than the V Yo-Yo values, while when the V Yo-Yo and the MAV values were lower than 16.3 km h 1, the MAV values tends to be lower than the V Yo-Yo. For example, the subject with the highest MAV value (19 km h 1 ) reached a V Yo-Yo of 17.4 km h 1, while the subject with the lowest MAV values (15 km h 1 ) reached a V Yo-Yo value of 15.7 km h 1. Consequently, the MAV appears to be more sensitive than the V Yo-Yo for subjects with the highest values, while the V Yo-Yo appears to be more sensitive than the MAV for subjects with the lowest values. In spite of a significant relationship between MAV and the V Yo-Yo, it does not appear appropriate to estimate MAV from the V Yo-Yo, as the standard errors of the estimate (Sy.x) appears too high (0.72 km h 1 ; Fig. 1B). This result means that within 95% of the cases, the errors would be ±1.41 km h 1. These errors appear to be too high (about 8.6% in average within 95% of the cases), since improvements induced by the training programs are often lower than these errors range, especially with the high initial level. In a previous study, Krustrup et al. 12 found that the HRpeak reached during the Yo-Yo was 99 ± 1% of the HRpeak reached during a graded treadmill test. In the present study, HRpeak obtained during the Yo-Yo was not significantly different from HRmax obtained during the UMTT and these values were significantly related (r = 0.88, p < 0.001). This very large correlation confirms that the Yo-Yo can be used to determine the HRmax. Although VO 2 analyses have been performed directly during the Yo-Yo intermittent endurance test, 1,6,16 no study, to our knowledge, has directly analysed the VO 2 during the other test version, the Yo-Yo intermittent recovery test. According to Krustrup et al., 12 the VO 2 peak estimated from the relationship between HR and VO 2 during a graded treadmill test corresponded to 97 ± 1% of VO 2 max. In the present study, no significant difference was found between VO 2 peak collected during the Yo-Yo and VO 2 max determined during the UMTT and these values were significantly related (r = 0.92 considered as nearly perfect, p < 0.001). A significant relationship was found between VO 2 max and the peak velocity achieved during the Yo-Yo (r = 0.61 considered as large, p < 0.05). As the originality of this study was to choose the velocity instead of the distance covered to analyse the relationships with VO 2 max, it could have been expected to estimate VO 2 max from the V Yo-Yo. However, in spite of a significant relationship between the V Yo-Yo and the VO 2 max (r = 0.59; p < 0.05), large inter-individual differences were found (Sy.x = 5.5 ml kg 1 min 1 ). For example, two players with the same V Yo-Yo (16.3 km h 1 ) had very different VO 2 max (from 53.6 to 64.3 ml kg 1 min 1 ). According to this result, it appears that for the same speed during the Yo-Yo, the interval for the VO 2 values, and consequently energetic cost, is larger than during the UMTT. This heterogeneity in energetic cost values is probably linked to the specific coordination and agility required by the Yo-Yo (acceleration, deceleration, stop, u-turn). These results confirm those found by Krustrup et al. 12 who observed large inter-individual differences for the relationship between distance covered during the Yo-Yo and the VO 2 max measured during a graded treadmill test. Krustrup and Bangsbo 11 also found that the effects of intense intermittent training was significant for the Yo-Yo

5 G. Dupont et al. / Journal of Science and Medicine in Sport xxx (2008) xxx xxx 5 distance (+31%), but not for the VO 2 max (+3%). The distance improvements on the Yo-Yo may be linked to the other factors such as anaerobic capacity, the ability to recover between the runs and the technical ability to do the test: reaction time at the sound signal, acceleration, stop and shift of direction. According to these latter results, it does not appear consistent to estimate VO 2 max from the distance covered during the Yo- Yo or from the V Yo-Yo even if this criterion is less sensitive than the distance. The second purpose was to check that the V Yo-Yo is related to the intermittent exercise performance such as the 15/15. Results of this study showed that TTE for the 15/15 was significantly related with the V Yo-Yo (r = 0.72 considered as large, p < 0.01). It confirms that the Yo-Yo is related with the ability to repeatedly perform aerobic high-intensity work, 3 as previously shown by Krustrup et al. 12 where the Yo-Yo test performance was significantly correlated (r = 0.71) with the high-intensity running covered by the players during games. In the present study, MAV was also significantly related to the TTE for the 15/15 (r = 0.74 considered as large, p < 0.01). This result confirms that the MAV is also related to the high-intensity intermittent exercise performance. Rampini et al. 17 found also significant correlations between the peak speed in a modified shorter version of the UMTT and the high intensity running (higher than 14.4 km h 1, r = 0.65) and very high intensity running (higher than 19.8 km h 1, r = 0.64) during official football matches. So, contrary to our hypothesis, the relationship between the V Yo-Yo and the 15/15 performance (r = 0.72 considered as large, p < 0.01) was not stronger than the relationships between the MAV and the 15/15 performance (r = 0.74 considered as large, p < 0.01). In summary, the results of this study showed that MAV was significantly correlated to the V Yo-Yo (r = 0.79, p < 0.01). However, the error was not constant, when the V Yo-Yo and the MAV values were higher than 16.3 km h 1, the MAV values tends to be higher than the V Yo-Yo and vice versa. Both tests (UMTT and Yo-Yo) were significantly correlated to the 15/15 performance (r = 0.74 and r = 0.72, respectively). It would be interesting, for future research, to compare the performance variability during intermittent exercises when they are individualised from the MAV and from the V Yo-Yo. Practical Implications Peak velocity reached during the Yo-Yo and MAV should not be used interchangeably. Below a speed of 16.3 km h 1, V Yo-Yo values tend to be higher than MAV, while above 16.3 km h 1, MAV values tend to be higher than V Yo-Yo. Yo-Yo and UMTT were very largely correlated with a highintensity intermittent exercise (15/15) suggesting that both tests could be used to individualise this exercise. Acknowledgements The authors gratefully acknowledge the subjects for their cooperation, the Stade Régional Couvert de Liévin administration and Alan McCall and Dr Derek McCormack to have checked the English. References 1. Aziz AR, Frankie HY, Teh T, Teh KC. A pilot study comparing two field tests with the treadmill run test in soccer players. J Sports Sci Med 2005;4: Bangsbo J. Fitness training in football: a scientific approach. Bagsværd, Denmark: HO + Storm; p Bangsbo J, Iaia FM, Krustrup P. The Yo-Yo intermittent recovery test: a useful tool for evaluation of physical performance in intermittent sports. Sports Med 2008;38(1): Billat LV, Koralsztein JP. Significance of the velocity at VO 2 max and time to exhaustion at this velocity. Sports Med 1996;22(2): Castagna C, Impellizzeri FM, Chamari K, Carlomagno D, Rampinini E. Aerobic fitness and yo-yo continuous and intermittent tests performances in soccer players: a correlation study. J Strength Cond Res 2006;20(2): Castagna C, Impellizzeri FM, Belardinelli R, Abt G, Coutts A, Chamari K, et al. Cardiorespiratory responses to Yo-yo Intermittent Endurance Test in nonelite youth soccer players. J Strength Cond Res 2006;20(2): Duncan GE, Howley ET, Johnson BN. Applicability of VO 2 max criteria: discontinuous versus continuous protocols. Med Sci Sports Exerc 1997;29(2): Dupont G, Blondel N, Lensel G, Berthoin S. Critical velocity and time spent at a high level of VO 2 for short intermittent runs at supramaximal velocities. Can J Appl Physiol 2002;27(2): Dupont G, Akakpo K, Berthoin S. The effect of in-season, highintensity interval training in soccer players. J Strength Cond Res 2004;18(3): Hopkins WG. A new view of statistics. Internet Society for Sport Science; 2000: Kamber M. Lactate measurements in sports medicine: comparison of measurement methods. Schweiz Ztschr Sportmed 1992;40: Krustrup P, Bangsbo J. Physiological demands of top-class soccer refereeing in relation to physical capacity: effect of intense intermittent exercise training. J Sports Sci 2001;19(11): Krustrup P, Mohr M, Amstrup T, Rysgaard T, Johansen J, Steensberg A, et al. The yo-yo intermittent recovery test: physiological response, reliability, and validity. Med Sci Sports Exerc 2003;35(4): Kuipers H, Verstappen FT, Keizer HA, Geurten P, van Kranenburg G. Variability of aerobic performance in the laboratory and its physiologic correlates. Int J Sports Med 1985;6(4): Léger L, Boucher R. An indirect continuous running multistage field test: the University de Montréal Track Test. Can J Sport Sci 1980;5(2): McLaughlin JE, King GA, Howley ET, Bassett Jr DR, Ainsworth BE. Validation of the COSMED K 4 b 2 portable metabolic system. Int J Sports Med 2001;22(4): Metaxas TI, Koutlianos NA, Kouidi EJ, Deligiannis AP. Comparative study of field and laboratory tests for the evaluation of aerobic capacity in soccer players. J Strength Cond Res 2005;19(1): Rampinini E, Bishop D, Marcora SM, Ferrari Bravo D, Sassi R, Impellizzeri FM. Validity of simple field tests as indicators of match-related physical performance in top-level professional soccer players. Int J Sports Med 2007;28(3):