advantages of the 20m sprint testadvantages of the 20m sprint test

Although the CV% at 10, 20, 30, and 40 m demonstrates good reliability, the test was unable to detect the SWC at any of the split distances, as the TE was consistently greater than the calculated SWC giving the test a usefulness of marginal. Young WB, Newton RU, Doyle TL, Chapman D, Cormack S, Stewart G, Dawson B. Physiological and anthropometric characteristics of starters and non-starters and playing positions in elite Australian rules football: A case study. By choosing to simply read up on The 20m Spring Test and ignore the sea of other crucial Performance Testing topics, you run the risk of being detrimental to your athletes success and not realising your full potential. (4). 4. Subjects started each sprint from a 2-point start, precisely 50 cm behind the first timing gate, with players instructed to set off in their own time and run maximally through the final 40-m timing gate. Thus it can be speculated that the 20m sprint does measure acceleration in team sport athlete. McGee KJ, Burkett LN. + " " + md.getFullYear()); The 20m sprint test is part of the SPARQ rating system for. Glaister M. Multiple sprint work: Physiological responses, mechanisms of fatigue and the influence of aerobic fitness. The black circle change is greater than both the typical error (TE) (3.05%) and the SWC combined, therefore, represents a 75% probability that the change is greater than the SWC. equipment required: measuring tape or marked track, stopwatch or timing gates, cone markers, flat and clear surface of at least 40 meters. (2013). (17), using 10 6-second sprints with 30-second rest periods, found that the first sprint produced ATP using 50% PCr and 44% glycolysis, whereas the tenth used 80% PCr and 16% glycolysis; this was accompanied by a 27% loss in power output, an 11.3 mmol/L increase in lactate, and a significant drop in ATP production rate (Table 1). The authors show that the 20mSRT is an acceptable, feasible, and scalable measure of CRF and functional/exercise capacity, and that it has moderate criterion validity and high to very high reliability. Breakdown and resynthesis of phosphorylcreatine and adenosine triphosphate in connection with muscular work in man. During brief maximal sprints, the rapid drop in PCr is offset by increased activation of glycolysis. However, the significance of such loading may only become apparent as sprint frequency increases and rest periods become long enough to again fully engage anaerobic glycolysis. References CHU, D.A. This could be a two, three, or four-point stance. Moir G, Button C, Glaister M, Stone MH. However, as with ATP, because of the contribution made by the other pathways, PCr is not normally depleted. In summary, maximal effort sprints rely on a fast and constant turnover of ATP, powered by the PCr system and anaerobic glycolysis (17). Sports Med 35: 757777, 2005. If the test administrators are using a stopwatch, then the timekeeper must stand at the finish line and perform the countdown and time the sprint. Before founding Science for Sport, he was formerly the Head of Academy Sports Science and Strength & Conditioning at Cardiff City Football Club, and an interim Sports Scientist for the Welsh FA. Perform an appropriate warm up. Repeat sprint ability (RSA) describes the ability of an athlete to recover and maintain maximal effort during subsequent sprints, an attribute considered important to team sports. Mechanical determinants of acceleration and maximal sprinting speed in highly trained young soccer players. Furthermore, it has been suggested, that because of time constraints within professional sport, that it is acceptable to use the TE and SWC generated from a similar population to determine changes in athletic performance (7,25). eg dashes of 40, 50, or 60 m take approximately 4 to 15 seconds and can be used as an indication of alactic . Required Equipment Repeat sprint ability (RSA) describes the ability of an athlete to recover and maintain maximal effort during subsequent sprints, an attribute considered important to team sports. The best of the 3 times for each split was taken for analysis with times measured to the nearest 0.01 seconds on each occasion. 25. This is likely to have a significant effect, as changes in direction, especially those involving large eccentric contractions and the need to stop, will affect energy expenditure. 32. To keep up with the latest in sport science and this website, subscribe to our newsletter. Cronin, J.B., & Templeton, R.L. Brooks GA, Fahey TD, Baldwin KM. The contribution of each energy system is determined by exercise intensity and duration of rest period (18). For the 5m sprint test, we recommended a distance of 0.3m. Keywords: In addition, sufficient recovery (e.g. The 5m sprint test is a simple and popular test used to measure an athletes accelerative abilities. The athlete must place one foot on or beyond the 20m marker at the end of each shuttle. Please try again soon. 11. For the purposes of this article, the term sprint refers to efforts of 6 seconds, whereby peak power/velocity could be maintained throughout the repetition. The athlete warms up for 10 minutes. The data provided demonstrate a small effect (ES = 0.52 0.65), suggesting that 50-cm start position improves sprint time compared with the 30-cm start position, although the confidence interval (CI) associated with the ES for initial error (ES = 0.43 0.65) suggests that the differences are unclear (20). Data is temporarily unavailable. Gabbett TJ. J Strength Cond Res 28: 26892696, 2014. Scand J Med Sci Sports 7: 206213, 1997. 26. The 10m sprint test is a simple and popular test used to measure an athletes ability to accelerate. On the other hand, the average sprint distance in team sport athletes has been reported to be between 15-21m (4, 5, 6) and rarely last more than 3-seconds (7, 8, 9). J Appl Physiol 97: 21322138, 2004. J Gen Physiol 59: 2232, 1972. Though the 20m sprint test is commonly used to measure acceleration in both track and team sport athletes, there is currently uncertainties to what this test actually measures. Signorile JF, Tremblay LM, Ingalls C. The effects of active and passive. J Strength Cond Res 21: 11721176, 2007. Here are results for the 20m sprint tests from a variety of sports. The 20m sprint (with split timing at 5m and 10m) has a high reliability and, because most tennis nations use it, has adequate normative data for the various age groups. Unable to load your collection due to an error, Unable to load your delegates due to an error. 7. Surprisingly, values as high as 40 mmol/kg dry muscle (16) and 4 mmol/kg dry muscle (23) have been recorded after just 6-second sprint cycling and 1.28 seconds of electrical stimulation, respectively. This, coupled with how to report results, will be the topic of this review. Yquel RJ, Arsac LM, Thiaudiere E, Canioni P, Manier G. Effect of creatine supplementation on phosphocreatine resynthesis, inorganic phosphate accumulation and pH during intermittent maximal exercise. Track sprinters have been shown to accelerate continuously through at least 50m during a 100m sprint event (1, 2, 3). However, when expressed as a CV%, the TE generally decreases with sprint distance, suggesting that sprinting over longer distances (>20 m) is more reliable in adolescent rugby players. Performance Testing entails many, many topics. 14. (2011). In addition, the study provides an example of how practitioners can interpret their data using the TE and SWC to determine when a change is real. gates are used. About usContact usJoin our teamOfficial partnersPrivacy policyTerms of useTerms and conditionsDisclaimer, 2023 Science for Sport | Catapult Sports. 10m Sprint Test. Validity: Precisely measures acceleration and speed.Jun 29, 2014 Advertisement What exercises help sprint speed? 40. These distances were chosen to enable assessment of initial and maximal sprint capabilities as used by Barr et al. Sahlin K, Ren JM. The 20-m shuttle run test (20mSRT)-a progressive aerobic exercise test involving continuous running between 2 lines 20 m apart in time to audio signals-is probably the most widely used field test of CRF. With the current reliability data in mind, it is now possible for researchers to plot individual changes for participants in studies involving adolescent rugby union and league players to determine whether players improved both beyond the TE and practically (>SWC). 26. From a metabolic perspective, power is dictated by the rate at which adenosine triphosphate (ATP) is used to fuel muscle contractions. Pyne DB. International Journal of Sports Science and Coaching, 10(1), 39-50. Reliability of a repeated sprint test for field-hockey. As ATP stores are broken down, various metabolic pathways (energy systems) collaborate to resynthesize ATP and maintain peak rates of turnover. 13. The method proposed can be used to demonstrate individual responses to training interventions alongside group mean data to improve the dissemination of research findings. 7. Effects of sprint training with or without Ball carry in elite Rugby players. 35. Therefore, the RST protocol using CODs could offer some advantages compared to RST-SS, however, future studies should verify these findings. 19. There is a discussion over how many timing gates use to accurately calculate the sprint mechanical output. Morin and Samozino study says that there must be no less than 5 timing gates. Search for Similar Articles 9. Bethesda, MD 20894, Web Policies J Sports Sci Med 13: 476482, 2014. Alongside between-day reliability, standardization of tests is necessary, with recent research reporting differences in 5-m sprint times with varying start positions 30, 50, and 100 cm behind the start (1). Interpreting the Results of Fitness Testing. (30) report seasonal improvement of 0.03 seconds (1.82 0.06 seconds to 1.79 0.07 seconds; p 0.05) and 0.04 seconds (1.83 0.09 seconds to 1.79 0.11 seconds; p 0.05) over 10 m, and 0.05 seconds (3.14 0.10 seconds to 3.09 0.11 seconds; p < 0.01) and 0.06 seconds (3.15 0.21 seconds to 3.09 0.20 seconds; p 0.05) over 20 m in under 18 and under 20 annual age categories, respectively, in rugby league players. var months = new Array ("January","February","March","April","May","June","July", Buchheit M, Rabbani A, Beigi HT. If any between-code differences were identified for a split time, it was removed from reliability analysis, as it would not accurately reflect the TE and SWC for a specific rugby code. 1Research Institute Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, West Yorkshire, United Kingdom; 2Yorkshire Carnegie Rugby Football Club, Kirkstall Training Ground, Leeds Rugby Academy, Leeds, West Yorkshire, United Kingdom. Although mean values for W:R are available, they do not suggest the typical movement patterns. Try out our Academy and access our growing library of sports science courses. B., & Zushi, K. (2014b). The natural assumption is that aerobic endurance training, by virtue of increasing V[Combining Dot Above]O2max, will increase recovery rates and thus improve RSA; this is discussed later. Distances were measured out using a 50-m tape measure. Review of criterion-referenced standards for cardiorespiratory fitness: what percentage of 1142026 international children and youth are apparently healthy? The maximal turnover rate of ATP production via glycolysis is around 59 mmol/kg dry muscle per second (17,23,24,28). Glaister (18) summarizes that fatigue may also be a consequence of a lack of ATP for actin-myosin coupling, NA+/K+ pumping, and Ca2+ uptake by the sarcoplasmic reticulum (SR). Glaister (18) concludes that the key role of the aerobic system during repeated sprints is the return to homeostasis during rest. Int J Sports Physiol Perform 10: 761766, 2014. This will be followed by suggestions for reporting results from RSA testing protocols and the requirements for future research within this area. 2023 Jan 24:1-32. doi: 10.1007/s10639-023-11584-0. What is a good time for 20m sprint? However, present findings show valid and reliable outputs are obtained with fewer checkpoints. 20. var months = new Array ("January","February","March","April","May","June","July","August","September","October","November","December") 16. Another significant issue with the validity of RSA testing is the fact that the players from most sports are expected to maintain RSA over many more sprints than the number used in many of the current protocols. 3). (29) (using 6 30-m sprints with 20-second rest) found that the strongest predictor of RSA was anaerobic power, that is, the fastest individual sprint time, and this explained 78% of the variance and had a relationship (r) of 0.66, respectively. Use this article to get your knowledge up to speed surrounding the 20m Sprint Test. Aziz AR, Mukherjee S, Chia M, Teh KC. reliability: Reliability is greatly improved if timing gates are used. You may search for similar articles that contain these same keywords or you may Sprinting Activities and Distance Covered by Top Level Europa League Soccer Players. 2004. Stone MH, Stone M, Sands W. Principles and Practice of Resistance Training. Sport Med 33: 406426, 2003. to determine acceleration, and also a reliable indicator of speed, agility and quickness. If three sprints were completed, all the scores are normally then generated into a mean score which provides an overall 20m sprint time. Acta Physiol Scand 152: 279285, 1994. Players refrained from physical activity for 48 hours before each testing sessions and maintained their normal dietary habits. Thebault N, Leger LA, Passelergue P. Repeated-sprint ability and aerobic fitness. However, there is no current research which identifies an optimal height for testing. In summary, the 20m sprint test has been shown to be a reliable predictor of linear speed, but its validity is determined by the knowledge of the test administrator. Sayers and Killip suggest that 5-0-5 agility test lacks validity for two primary reasons: 1) it is actually more a measure of CODs and not true agility (previously discussed), and 2) the 5m sprint distance should be reduced to 1m to minimise the influence of linear running ability. 3. . modify the keyword list to augment your search. 2022 Dec 8;9(12):1926. doi: 10.3390/children9121926. Keywords: sprint, speed, linear, acceleration, sports science. Mujika I, Padilla S, Adilla S, Ibanez J, Izquierdo I, Gorostiaga E. Creatine supplementation and sprint performance in soccer players. 10. Despite this, a CV <5% was set as the criterion to declare that a variable was reliable as previously reported (6,9). To this end, it is used in the physical testing battery designed to distinguish the best American football prospects in the draft (23). As the distance from the start-line, starting position, and the height of the timing gates have all been shown to affect the test results, it is advised that these are all mandated and kept consistent to avoid testing error. The 20-meter sprint is a standard timed event for measuring speed. J Strength Cond Res 29: 23612366, 2015. The https:// ensures that you are connecting to the results: Two trials are allowed, and the best time is recorded to the nearest 2 decimal places. Although gas-analyzed peak oxygen uptake is the criterion physiological measure of children's CRF, it is not practical for population-based testing. (35) found that field-based team sports are consistent in mean sprint time and distance, 23 seconds and 1020 m, respectively. Balsom P, Ekblom B, Sjdin B. Hillsdale, NJ: Lawrence Erlbaum Associates; 1998. A thorough warm up should be given, including some practice starts and accelerations. National Library of Medicine The distance between the start-line and the first timing gate (cones A Figure 1) has been shown to affect short-distance sprint times (14). Brad Harvey ran 2.78 the same year, and Jonathon Marsh also ran 2.78 seconds in 2013. Glycolysis describes the breakdown of glycogen in the muscle or glucose in the blood to resynthesize ATP. Rugby league players were faster at 5 m than rugby union players, with further difference unclear. Learn about the fundamentals of Agility and even get a practical coaching guide to help you to develop engaging sessions. var md = new Date(document.lastModified) Put simply, the greater the distance, the faster the sprint time as it allows the athlete to generate more speed before crossing the first timing gate. Between-day reliability for consecutive trials was determined, alongside the SWC and test rating. FOIA To appreciate RSA, we must first look at the biochemical production of power. Between-code and consecutive trial differences were measured to assess if split times were lower, similar, or greater than the SWC or smallest practical difference (SPD). Search for Similar Articles Before the start of the test, it is important to ensure you have the following items: Test Configuration However, although V[Combining Dot Above]O2 uptake may increase with successive sprints, the supply of ATP made by the aerobic system is significantly less than required for repeated sprints (17) and uses a lower ATP turnover rate. 1m) and stick to it. Kinematics of transition during human accelerated sprinting. Res. Pyne DB, Saunders PU, Montgomery PG, Hewitt AJ, Sheehan K. Relationships between repeated sprint testing, speed, and endurance. Frost. advantages: very sensitive to training disadvantages: an exhaustive effort for valid results When To Test? If possible, set up the track with a crosswind to minimize the effect of wind. A common distance for the sprint test is the 20 meters speed test. . Because the majority of field-based team sports involve active recovery, its athletes may indirectly be employing this method (35). The anaerobic conversion of pyruvate yields lactate and H+, not always lactic acid (the lactic acid molecule cannot exist at the physiological pH of 7); thus, despite the high correlation, lactate is not the cause of fatigue (12). This research was part funded by Leeds Rugby as part of the Carnegie Adolescent Rugby Research (CARR) project. Though the test has been deemed valid and reliable, it is important to understand what it is actually valid for. Progressive statistics for studies in sports medicine and exercise science. Learn about the fundamentals of Agility and even get a practical coaching guide to help you to develop engaging sessions. 8. Secular trends of cardiorespiratory fitness in children and adolescents over a 35-year period: Chronicle of a predicted foretold. Physical testing is implemented in professional sports worldwide to assist in the prescription and evaluation of training interventions (21,26). 6. 8. Darrall-Jones, JD, Jones, B, Roe, G, and Till, K. Reliability and usefulness of linear sprint testing in adolescent rugby union and league players. Despite the importance placed on sprint time, between-day reliability is rarely reported, suggesting that both researchers and practitioners are unaware when a change is real (25). To keep up with the latest in sport science and this website, subscribe to our newsletter. 1. The 10m sprint test is a simple and popular test used to measure an athlete's ability to accelerate. J Strength Cond Res 5: 144149, 1991. Analysis of sprinting activities of professional soccer players. 31. Data are percentage change (coefficient of variation [CV] as error bars) with the gray area representing the smallest worthwhile change (SWC). (1996) Explosive Power and Strength. 22. SPRINT SPEED IS RELATED TO THE ABILITY TO DEPLETE LARGE AMOUNTS OF HIGH-ENERGY PHOSPHATES AT A FAST RATE. 21. Oliver JL. The assistant measures out a 20-metre section and marks each end with marker cones. and transmitted securely. Most strength and conditioning coaches agree that for validity and dynamic correspondence, the RSA training session or testing protocol should resemble the work to rest ratio (W:R) and movement mechanics of the sport in question. J Sci Med Sport 8: 333345, 2005. 4. As the 10m sprint is a measure of acceleration, it is recommended that the start-line is position 0.3m behind the first timing gate in accordance with Altmann and colleagues (14). Participant should be counted down 3 2 1 GO . References CHU, D.A. 24. Reliability and accuracy of handheld stopwatches compared with electronic timing in measuring sprint performance. J Strength Cond Res 26: 12451248, 2012. (2008). The split stance (one leg forward, and one back) is most recommended. Participants started their About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright . 37. This system involves multiple enzymatic reactions, so it is not as fast as the PCr system, but the 2 combine to maintain an ATP turnover rate of 1114 mmol/kg dry muscle per second (11,17). Sprinting patterns of national rugby league competition. Each participant MUST complete a MINIMUM OF THREE SPRINTS, each separated by a 2-3 minute rest if reliable results are desired. 23. Fulco CS, Lewis SF, Frykman PN, Boushel R, Smith S, Harman EA, Cymerman A, Pandolf KB. The authors would like to thank Andrew Rock (Academy director) and the players who were involved in the project. Spencer M, Fitzsimons M, Dawson B. Hultman E, Sjholm H. Energy metabolism and contraction force of human skeletal muscle in situ during electrical stimulation. 20m Sprint Test. Heres why theyre wrong Circadian rhythms in exercise performance: Implications for hormonal and muscular adaptation. Sprint time at each split interval is shown in Table 2, with Table 3 displaying the TE and CV%. J Physiol 345: 525532, 1983. Your message has been successfully sent to your colleague. Clipboard, Search History, and several other advanced features are temporarily unavailable. Furthermore, the study aimed to identify the ability of the test to detect a practically important change and to report reference TE and SWC values for adolescent rugby players. PMC "August","September","October","November","December") Stone. See, AFL recruiters are looking for talented local league players who can reach a benchmark of three seconds for the 20-meter sprint, among other characteristics (from an article in the Geelong Advertiser online, July 2010). Both the CV (0.6%) and 10-m sprint time (1.75 seconds) are then used to calculate a between-subject SD (1.75 0.6%) and multiplied by 0.2 to give the SWC. There are around 80 mmol/kg dry muscle of PCr stored in the muscle (17) and with a turnover rate of around 9 mmol ATP/kg dry muscle per second (23); stores are largely depleted within 10 seconds of sprinting (18). It is assumed that distances of 510 m can be used to assess an individual's ability to accelerate, whereas maximal velocities are considered to manifest between 20 and 40 m (3,4,31). purpose: The aim of this test is Therefore, to improve RSA, it appears prudent to target the development of vOBLA. Data are presented as either mean SD or mean values with 90% CI where specified. Is a fatigue index a worthwhile measure of repeated sprint ability? Balsom P, Gaitanos D, Ekblom B, Sjdin B. The test may be good for ten to sixty meters, recorded by a stopwatch or timing gates. Relationship of contraction capacity to metabolic changes during. See more. facility) so that it is protected from varying weather types, and with a dependable surface that is not affected by wet or slippery conditions. 29. As it is suggested that both TE and SWC are population specific (25), it would seem that for a true understanding of the relationship between the TE and SWC in a 10-m sprint, the authors should have calculated the SWC within their own population to then give recommendations applicable to professional rugby union players. Conflicts of Interest and Source of Funding: The authors report no conflicts of interest and no source of funding. Some coaches believe that reading one article will make them an expert on Performance Testing. Based on the above, RSA (as tested by the studies presented) can be improved via anaerobic qualities such as strength, power, and speed, along with the athlete's vOBLA; this is regardless of the between-sport variability in RSA demands. For example, Gaitanos et al. Results suggest that in addition to training targeting the improvement of vOBLA, it should also focus on improving sprint speed, strength, and power. The moderating role of physical fitness in the relationship between sugar-sweetened beverage consumption and adiposity in schoolchildren. J Strength Cond Res 28: 27242731, 2014. J Strength Cond Res 17: 611, 2003. Though the 20m sprint test is commonly used to measure acceleration in both track and team sport athletes, there is currently uncertainties to what this test actually measures. If sprints are repeated, the V[Combining Dot Above]O2 of successive sprints will increase (17,35) if recovery periods are not sufficient to resynthesize PCr, oxidize lactate, and remove accumulated intracellular Pi (via adenosine diphosphate phosphorylation). All players were familiar with the testing procedures and trained at the club 23 times per week including resistance training, aerobic conditioning, speed development, and speed technique sessions. For example, during the first 6 seconds of a 30-second maximal sprint (28) or the first 5 seconds of a 3-minute intense bout (>120% V[Combining Dot Above]O2max) (7), an ATP turnover rate of 1.3 mmol ATP/kg dry muscle per second and 0.7 mmol ATP/kg/s, respectively, was hypothesized, both contributing around 10% of total energy produced. *, Linear speed testing split times at 10, 20, 30, and 40 m combined mean (, Measures of reliability for linear speed testing at 10, 20, 30, and 40 m.*. 38. Unlike the FI, the Sdec takes into account all sprints and is less influenced by a good or bad start or finish (35). 30. J Strength Cond Res 20: 246251, 2006. We recommend that practitioners and researchers use the TE alongside the SWC to make an informed decision on whether a change is both real (greater than the noise of the test, i.e., >TE) and of practical significance (>SWC), as proposed by Hopkins (21). The TE at each split in this study ranged from 0.05 to 0.08 seconds, suggesting that the error is consistent across the distance of a sprint. 2001;15(1):7580. Exercise Physiology: Human Bioenergetics and Its Applications (4th ed). Although the issue of whether RSA is affected by a high V[Combining Dot Above]O2max seems dependent on the protocol used, one must consider the validity of the tests to the sport in question (discussed later: see Ecological Validity and Future Research section). Timing light height affects sprint times. The 20m sprint is used in the WHL to assess the athlete's speed and acceleration. It was concluded that 10-m time is a good reflection of acceleration capabilities and either 20 to 40 m in a 40-m sprint test or 20 to 30 m in a 30-m sprint test can be used to estimate. New York, NY: McGraw-Hill Higher Education, 2005. 2022 Jan;52(1):101-122. doi: 10.1007/s40279-021-01537-3. We are also on facebook and twitter. 2. Andrzejewski, M., Chmura, J., Pluta, B., & Konarski, J. M. (2015). The multi-stage fitness test was first described by Luc Lger [6] with the original 1-minute protocol, which starts at a speed of 8.5 km/h, and increases by 0.5 km/h each minute. Significant involvement (>10%) from the aerobic system would reduce ATP production rate and thus sprint speed. Junior rugby union players from a professional regional academy in the United Kingdom and junior rugby league players from a professional Super League club in the United Kingdom were assessed for 5, 10, 20, 30, and 40 m sprint time on 2 occasions at the same time of day, in similar environmental conditions with 3-day rest between sessions. Some error has occurred while processing your request. The site is secure. cardiorespiratory fitness; children; criterion-referenced standards; normative data; reliability; validity. Recent recommendations have been made regarding optimizing acceleration capabilities in elite rugby union and league players with horizontally orientated resistance exercises to maximize horizontal force production, thus improving acceleration ability (11). NOTE: it is important for reliability that the participant always uses the same starting stance. Of note, in field-based team sports, glycogen-loading strategies are important in minimizing performance decrements (35). J Sports Sci 20: 399405, 2002. J Strength Cond Res. 28. Further findings show that short acceleration (5 m) ability is greater in rugby league than rugby union players, and that code-specific TE and SWC need to be generated for this distance. Would you like email updates of new search results? Advances in electronic timing systems: Considerations for selecting an appropriate timing system. This review aims to clarify the international utility of the 20mSRT by synthesizing the evidence describing measurement variability, validity . Champaign, IL: Human Kinetics, 2009. Data is temporarily unavailable. Sant'Ana Pereira JA, Sargeant AJ, Rademaker AC, de Haan A, van Mechelen W. Myosin heavy chain isoform expression and high energy phosphate content in human muscle fibres at rest and post-exercise. This has been addressed in rugby union (14) over a distance of 10 m using 3 different starting techniques, with the authors concluding that there is only a marginal chance of reliably detecting a worthwhile change due to the TE (0.02 seconds) being greater than the SWC (0.002 seconds).