Australia, Crawley, Western Australia Published online: 06 Jan 2014

This article was downloaded by: [University of Western Australia] On: 13 January 2014, At: 19:54 Publisher: Taylor & Francis Informa Ltd Registered in...
Author: Allan Rodgers
0 downloads 1 Views 156KB Size
This article was downloaded by: [University of Western Australia] On: 13 January 2014, At: 19:54 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK

Research in Sports Medicine: An International Journal Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/gspm20

Effect of Warm-Up on Intermittent Sprint Performance a

a

P. Anderson , G. Landers & K. Wallman

a

a

School of Sport Science, Exercise & Health, University of Western Australia, Crawley, Western Australia Published online: 06 Jan 2014.

To cite this article: P. Anderson, G. Landers & K. Wallman (2014) Effect of Warm-Up on Intermittent Sprint Performance, Research in Sports Medicine: An International Journal, 22:1, 88-99, DOI: 10.1080/15438627.2013.852091 To link to this article: http://dx.doi.org/10.1080/15438627.2013.852091

PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/termsand-conditions

Research in Sports Medicine, 22:88–99, 2014 Copyright © Taylor & Francis Group, LLC ISSN: 1543-8627 print/1543-8635 online DOI: 10.1080/15438627.2013.852091

Effect of Warm-Up on Intermittent Sprint Performance P. ANDERSON, G. LANDERS, and K. WALLMAN Downloaded by [University of Western Australia] at 19:54 13 January 2014

School of Sport Science, Exercise & Health, University of Western Australia, Crawley, Western Australia

We aimed to investigate the effects of different warm-up (WUP) intensities on 10 min of subsequent intermittent-sprint running performance. Eleven male, team-sport players performed four trials in a randomized, cross-over design, consisting of an intermittent-sprint protocol (15 × 20-m sprints) that followed either no-WUP or one of three 10-min WUP trials that varied in intensity. Warm-up intensities were performed at either (1) half the difference between anaerobic threshold (AT) and lactate threshold (LT) [(AT-LT)/2] below the LT = WUP 1; (2) midway between LT and AT level = WUP 2; (3) [(AT-LT)/2] above AT = WUP 3. Sprint times were fastest following WUP 3, compared with all other trials, for sprints 1–9 and 14, as well as for total accumulated sprints, with these results supported by moderate to large effect size (ES; range: d = −0.50 to −1.06) and “possible” to “almost certain” benefits. Warm-up 3 resulted in faster intermittent-sprint running performance compared with lower intensity WUPs and no WUP for the first 6 min of sprinting, with accumulated sprints for the entire 10 min protocol also being faster after WUP 3. This information may be pertinent to coaches of team-sport games with respect to player substitutions. KEYWORDS lactate threshold, anaerobic threshold, team sports

Received 10 September 2012; accepted 19 January 2013. Address correspondence to K. Wallman, University of Western Australia, School of Sport Science, Exercise & Health, 35 Stirling Highway, Crawley, Perth, Western Australia, 6009. E-mail: [email protected] 88

Warm-Up and Sprint Performance

89

Downloaded by [University of Western Australia] at 19:54 13 January 2014

INTRODUCTION Warm-up (WUP) is a well-accepted practice that is performed by many athletes prior to athletic performance (Bishop, 2003; Bishop & Maxwell, 2009). Physiologically, an active WUP increases body and muscle temperatures, which are proposed to improve exercise performance via decreased muscle and joint viscous resistance (Asmussen & Boje, 1945), greater unloading of oxygen from hemoglobin and myoglobin (McCutcheon, Geor, & Hinchcliff, 1999), the speeding of oxygen kinetics (Koga, Shiojiri, & Kondo, 1997), increased anaerobic metabolism (Febbraio, Carey, & Snow, 1996), and by increased nerve conduction rates (Stewart, Macaluso, & De Vito, 2003). An active WUP has also been proposed to impart non-temperature-related benefits on subsequent exercise performance, such as increased blood flow and oxygen delivery to the working muscles (McComas, 1996); elevation of baseline oxygen consumption (McCutcheon et al., 1999); postactivation potentiation (Vandervoort, Quinlan, & McComas, 1983); and reduced muscle stiffness (Proske, Morgan, & Gregory, 1993). While a number of studies have investigated the effect of WUP on continuous exercise or single-sprint performance and reported benefits (Grodjinovsky & Magel, 1970; Sargeant & Dolan, 1987, Stewart & Sleivert, 1998), few studies have assessed the impact of WUP, compared with no WUP, on intermittent-sprint performance (Bishop & Claudius, 2004; Bishop & Maxwell, 2009; Mohr, Krustrup, Nybo, Nielsen, & Bangsbo, 2004; Yaicharoen, Wallman, Morton, & Bishop, 2012a). Minimal research in this area is surprising, as in many countries the most popular sports and those with the highest participation levels are team-game sports such as soccer, rugby, field hockey, and basketball, which require athletes to sprint intermittently throughout the match (Spencer et al., 2004). To date, studies that have assessed the effects of WUP on prolonged intermittent-sprint cycling performance (36–80 min) have reported no benefit of WUP compared with no WUP (Bishop & Claudius, 2004; Bishop & Maxwell, 2009; Yaicharoen et al., 2012a). The failure of WUP to improve prolonged intermittent-sprint performance was proposed to be a result of participants adopting a pacing strategy due to the long duration of the protocol (Bishop & Claudius, 2004; Yaicharoen et al., 2012a). Conversely, Mohr et al. (2004) reported that a WUP performed immediatley prior to the second half of a soccer game (7 min of running and other exercises performed at an average heart rate [HR] of ∼ 135 bpm or ∼70% HRpeak ) resulted in improved short-term (∼65 s) intermittent-sprint running performance (3 × 30 m sprints separated by 25-s), compared with a no WUP/resting control trial. It is possible that the short duration of the protocol used by Mohr et al. (2004) meant that particpants did not employ a pacing strategy, thus allowing the proposed benefits of the prior WUP to become evident. Improved sprint performance is important during a team game where teams strive to score first in the early stages of a match

Downloaded by [University of Western Australia] at 19:54 13 January 2014

90

P. Anderson et al.

(Armatas, Yiannakos, Zaggelidis, Papadopoulou, & Fragkos, 2009), as well as during the latter stages of a game, particularly if scores are close. Of interest to coaches of team-sport games is whether WUP could provide benefit to sprint performance that is longer than 65 s, but not so long as to induce participants to pace (i.e., ≥ 36 min). Moreover, this information could assist team-sport coaches that use player substitution, such as basketball, Australian football, American football, field hockey, rugby union, and rugby league, in determining the timing of substitutions during a game. Another consideration when determining the most appropriate WUP relates to the exercise intensity of the WUP. To date, many studies have ˙ 2 max ) as a guide for WUP intensity used percent maximal oxygen uptake (VO (De Bruyn-Prevost & Lefebvre, 1980; Genovely & Stamford, 1982; Sargeant & Dolan, 1987; Steward & Sleivert, 1998). It has previously been shown however, that HR and blood lactate concentrations differed between participants of varying fitness levels when exercise was performed at a percent ˙ 2 max , but were similar during exercise performed at a percentage of VO of the anaerobic threshold (AT, depicted as a rapid rise in blood lactate concentrations during incremental exercise; Baldwin, Snow, & Febbraio, 2000). To date, the only studies that assessed the effects of WUP on subsequent exercise, where WUP intensities were based on lactate accumulation, involved either kayak (Bishop, Bonetti, & Dawson, 2001) or cycling performance (Yaicharoen et al., 2012a, Yaicharoen, Wallman, Morton and Bishop, 2012b; Yaicharoen, Wallman, Morton, Bishop, & Grove, 2012). Further studies are needed to determine the optimal WUP intensity, where WUP is based on lactate thresholds for subsequent intermittent-sprint running performance. Therefore, the aim of this study was to investigate the effect of varying WUP intensities, based on lactate accumulation, on 10 min of intermittentsprint running performance, so as to determine which WUP intensity resulted in better subsequent exercise performance. Based on the premise that benefits of WUP are in part temperature related, a second aim of this study was to investigate whether core temperature (Tc ) induced by the various WUP strategies was positively correlated with exercise performance.

METHODS Participants Eleven healthy, team-sport, male athletes, aged between 18 and 25 y ˙ 2peak : 51.9 ± (mean ± SD age: 21.6 ± 2.5 y, body mass: 78.9 ± 7.5 kg, VO 5.4 mL·kg−1 ·min−1 ), who were currently playing soccer, hockey, or Australian rules football, were recruited to this study. This study was approved by the Research Ethics Committee (the University of Western Australia) and all participants provided written informed consent. Participants visited the exercise physiology laboratory on five occasions in order to complete a familiarization session and four experimental trials.

Warm-Up and Sprint Performance

91

Downloaded by [University of Western Australia] at 19:54 13 January 2014

Experimental Design During the familiarization session, participants had their height measured (stadiometer), and their body-mass assessed (Sauter, model ED3300, Ebingen, West Germany) and then performed a graded exercise test in order to determine lactate and anaerobic thresholds. Participants then participated in four experimental trials in a randomized manner (Latin square design), with trials held at the same time of day, one week apart. The four trials consisted of a no-WUP trial (10-min of seated rest) and three 10-min WUP trials, with each WUP trial performed at a different intensity. The no-WUP and WUP trials were followed by a 5-min active rest period (walking) and then the intermittent-sprint running protocol. The running protocol was performed on a nonslip wooden floor of an indoor gym. Participants were asked to consume no food or beverages, other than water, during the 2-h period prior to testing. Participants were requested to keep a diary of their food and drink intake during the 48-h period prior to exercise and to replicate this intake prior to each exercise trial. Additionally, participants were asked not to consume alcohol or to perform vigorous exercise in the 24-h prior to testing. ˙ 2peak test was performed on a motorized treadmill (Nury Tec The VO VR3000, Germany) and consisted of 3-min intervals, starting at a speed of 9 km.h−1 , with each progressive stage increasing by 1 km·h−1 . One minute of passive rest was undertaken between each exercise stage in order to take blood samples. Expired air was continuously analyzed for O2 and CO2 concentrations using calibrated Ametek gas analysers (Applied Electrochemistry, SOV S-3 A/1 and COV CD-3A, Pittsburgh, PA, USA), while ventilation was recorded every 15-s using a turbine ventilometer (Morgan, 225A, Kent, United Kingdom). Anaerobic threshold was determined during this test using the modified Dmax method as outlined by Bishop, Jenkins, and Mackinnon (1998). All WUP trials were performed on the same treadmill as the graded exercise test. The intensity of each WUP was performed as follows: WUP 1 = half the difference between AT and LT, [(AT-LT)/2], below LT level; WUP 2 = midway between LT and AT level; WUP 3 = half the difference between LT and AT, [(AT-LT)/2], above AT level; and no WUP. The intermittent-sprint running protocol involved 15 × 20 m sprints. The second sprint departed 30 s after the start of the first sprint, while the third sprint departed 60 s after the start of the second sprint. From then on, the next two sprints departed 30 s apart with the subsequent sprint departing 60 s later, with this pattern (30 s, 30 s, 60 s) being repeated until all 15 sprints were performed. At the start of each sprint, the participant took up a two-point starting position, 50 cm behind the first electronic timing gate. On the verbal command, “3, 2, 1, GO,” the participant ran as fast as possible for 20 m. Sprints were timed using electronic timing gates (Fitness Technology, Info Tech, Victoria, Australia), while percent performance decrement for each trial

Downloaded by [University of Western Australia] at 19:54 13 January 2014

92

P. Anderson et al.

was calculated using the method described by Fitzsimons, Dawson, Ward, and Wilkinson (1993), (100-[(total time/[best time × 15]) × 100]). Test–retest reliability (n = 9) performed prior to the study resulted in a typical error (TE) of 0.08 s and a coefficient of variation (CV) of 2.2% for the first sprint, and a TE of 0.72 s and CV of 1.5% for total sprint time. Blood lactate was taken from the fingertip (Lactate Pro, Kyoto, Japan), with measurements made prior to and immediately after every stage of the graded exercise test, as well as prior to and immediately after each WUP trial. Heart rate (HR; Polar Electro Oy, Kempele, Finland) and ratings of perceived exertion (RPE: Borg, 1982) were recorded 10-s before the end of each stage of the graded exercise test, as well as prior to and immediately post-WUP and immediately after the intermittent-sprint running protocol. Core temperature (Tc ) was measured using a silicon-coated core temperature pill (CorTemp, HQ Inc., Palmetto, Florida, USA). The ingestible pill was swallowed ∼6-h prior to intermittent-sprint running performance to ensure that it was past the stomach, in the small intestine, and insensible to the drinking of cold fluids. Temperature readings by CorTemp have been found to be highly correlated to rectal temperature (r = 0.98, p < 0.01: Easton, Fudge, and Pitsiladis, 2007). Due to financial constraints, six participants were randomly selected for the collection of Tc readings. These participants had their Tc assessed for each of the four experimental trials.

STATISTICAL ANALYSES Individual sprint times, blood lactate, HR, and RPE were assessed using a repeated-measures, two-way ANOVA. Post-hoc tests (LSD) were applied whenever significance was found, with statistical significance set at p ≤ 0.05. Performance variables were also compared between WUP intensities using Cohen’s d effect sizes (ES) and thresholds (≤0.49, small; 0.5–0.79 = moderate; ≥0.8, large; Cohen, 1988). Only moderate to large ES (≥0.5) are reported. Further analysis was conducted to identify the smallest worthwhile change in sprint scores between trials (Batterham & Hopkins, 2005). The smallest worthwhile value of change was set at 0.8%, representing the hypothetical, smallest change in 20-m sprint time that would benefit the athlete (Paton, Hopkins, & Vollebregt, 2001). Where the chance of benefit and harm were both calculated to be ≥5%, the true effect was deemed unclear (Batterham & Hopkins, 2005). When clear interpretation was definitively possible, a qualitative descriptor was assigned to the following quantitative chances of benefit: 25–75%, benefit possible; 75–95%, benefit likely; 95–99%, benefit very likely; > 99%, benefit almost certain (Batterham & Hopkins, 2005). Pearson correlation coefficients were used to assess the relationship between Tc and performance variables. All data was analyzed using SPSS (Version 13.0 for Windows; SPSS Inc., Chicago, IL, USA).

93

Warm-Up and Sprint Performance

All WUP sessions were performed in an air-conditioned laboratory (24.9 ± 1.8◦ C; relative humidity 39 ± 10%), while all sprint sessions were performed in an indoor gym (18.5 ± 1.9◦ C; relative humidity: 59.1 ± 9.1%). While analyses of individual sprint times (sprints 1–15; Figure 1) resulted in no significant interaction effect (p = 0.85), or main effect for trial (p = 0.434), there was a significant main effect for sprints (p = 0.001). Post-hoc analyses demonstrated a significant difference between sprints 3 to 4, with sprints being faster for sprint 4 in all trials (p = 0.045). Furthermore, there were significant differences between sprints 4 and 12 (p = 0.019), 5 and 12 (p = 0.018), 7 and 12 (p = 0.002), and 10 and 12 (p