Sprinting Form Kinetics

Transcription

1 Kelly Penfold HMST4314 Practicum Project Sprinting Form Kinetics A review of programming techniques used to enhance sprinting technique 2013 Practicum Location: Acceleration Brisbane Central

2 Table of Contents EXECUTIVE SUMMARY INTRODUCTION LITERATURE REVIEW METHODS AND PROCEDURES 10 SEARCH STRATEGY 10 INCLUSION CRITERIA 10 REVIEW AND ANALYSIS DISCUSSION CONCLUSION 14 LIST OF REFERENCES 15

3 Executive Summary This research has been developed to attempt to understand the role that various training methods have on sprinting technique and speed. The areas of interest include sprinting biomechanics, technique drills, strength and power/plyometric training. An exploratory study has taken place whereby various techniques used by Acceleration ESP (AESP) are used as a case study to identify how theory and practice compare and contrast. This document has been developed as a learning tool, an informative document for those associated with AESP and a review of programming techniques used by AESP. Literature was collected from a range of scholarly articles, collated and compared with one another and with information collected from AESP over a period of time. Specific collection criteria were used to locate appropriate and reliable information for this report. It was determined that a combination of form drills, resistance sprinting, strength and plyometric training will result in enhanced sprinting form technique and therefore sprint performance. 1

4 1.0 Introduction In highly competitive sport, it is becoming more difficult to find the competitive advantage which will differentiate one athlete from the rest. Sprinting has developed from being a sport unto itself to being the key performance indicator for many court and field based athletes. The importance of well-trained sprinters in any sport cannot be underestimated, as speed may be what differentiates one athlete from the next. It is therefore necessary to undertake analysis of the many areas of sprint training, as well as analysis of the individual s maximum force production capability. There are a variety of acceptable training methods used to improve sprint technique and in turn increase speed, and it is the ability to program the correct combination for each individual athlete is what sets a good coach apart from the rest. Maximum velocity will result from adjusting kinematics such as speed, gait cycle- stride frequency and stride length (Behrens & Simonson, 2011). Sprinting kinetics should also be considered, which are the mechanics and anatomy behind sprinting (mainly muscle moment patterns about the ankle, knee, hip, shoulder, and elbow). In addition the athlete must have the ability to accelerate quickly to reach their maximum speed for the required distance, which in most sports will be 0-20m (Jacobs, et al., 1996). In order to train an athlete to full potential, they must work on each phase of sprinting, implementing neurological patterns to become autonomous during competition. Through isolation of each phase, these drills will improve the runner s kinaesthetic sense and complement strength development (Cronin, Hansen, Kawamori, & Mcnarr, 2008). Although there has been much research on the topic of strength and plyometric training on sprint times, there has been little investigation into the combination of strength, power and form drills and the cross-over between each method. There has also been little investigation into sprinting form drills and the responses they elicit in field versus court sport athletes, or their time to acceleration from a compromised position, as opposed to a standard track start. Starting positions 2

5 will vary with each sport, with rugby forwards often coming up from the ground, versus netballers jumping straight into a sprint, or a soccer player from sprinting backwards. Although this review will not cover the difference in the starting positions in detail, it should be noted that this is a consideration during training mechanisms and perhaps an avenue for future investigation. The company under investigation is Acceleration ESP (AESP), a Brisbane based company focused on the development of athletes through a combination of speed, strength and power. The purpose of this report is to compare the methods used at AESP with that suggested in theory, in order to justify techniques, and to find avenues of potential research. The methods under investigation may vary from those used at Acceleration, and will be compared and contrasted with information found in the recent literature. Suggestions will be made as to how speed training can be further developed, as well as avenues for further investigation. Definitions Velocity is defined as the rate at which a body moves from one location to another (Hay,1993, in Danion, 2003, p73) and linear acceleration is defined as the rate of change in velocity for this report (Hall, 2003). In sprinting, factors including step length and step frequency play a major role and previous research has found that world class sprinters have a longer step length and higher step frequency than non-elite sprinters (Kunz and Kaufmann, 1981). The term speed is used in terms of the change in velocity or time over distances ranging from 5 to 20 metres (Cronin, Ogden, Lawton, & Brughelli, 2007). In the context of this report, sprinting will be applied to straight line sprinting as opposed to agility, and speed will be referred to as peak speed for a 15-20m sprint, as opposed to peak maximum speed which occurs between m (Hrysomallis, 2012). 3

6 2.0 Literature Review BIOMECHANICAL ANALYSIS Biomechanical analysis is used at AESP in order to assess the athletes sprint technique as discussed above. The purpose of biomechanical analysis is to address where the athlete may possess a weakness, such as over or under-active tissues; it is also used to determine the athlete s current sprinting habits and natural striking patterns. The following explains how the ideal striking pattern occurs according to the literature. According to research, the biomechanics of sprinting relates to the structure and function of the lower limbs and the kinetic chain which results in sprinting by human beings (Nicola & Lewison, 2012). The gait cycle involves a stance phase (contact with the ground), through swing phase (time in the air), through to the next stance phase. According to Nicola & Lewison, (2012), this is important when analysing sprint biomechanics because the best sprinters have limited time in stance phase, meaning they need to ensure that contact time with the ground is kept to a minimum (Altman & Davis, 2012). The ball of the foot should be the only point of contact during foot strike, at a point underneath the hips, for sprinting to be most efficient, as opposed to heel strike out in front (Altman & Davis, 2012). During the sprinting gait cycle, the foot will absorb up to 3 times body weight when striking the ground (Rudakov, Podgaets, Podgaets, Razumov, & Yakovleva, 2006). The ankle-knee-hip complex requires further assessment, as minor differences in each joint can attribute to loss of speed and efficiency. At AESP there is a large focus on the concept of triple-extension, whereby the ankle, knee and hip joints are fully extended which allows for more length to be gained out of each step. This is supported by Chumanov, Heiderscheit, & Thelen (2007), who measured three-dimensional kinematics and electromyography (EMG) activities of 19 4

7 athletes sprinting on a treadmill at speeds ranging from 80% to 100% of maximum speed, in order to determine lower extremity joint angles and muscular contribution of the quadriceps, hamstrings and gastrocnemius. The use of the arms in sprinting is the final detail in the breakdown of sprint movement. The AESP performance cue is cheek to cheek, which is justified by Arellano & Kram, (2011), who found that arm swing reduces energetic cost and improves lateral balance. This has supported Egbuonu, Cavanagh, & Miller, (1990) who found a 4% increase in the energetic cost of sprinting with no arm swing; whereas a recent report by Pontzer, Holloway, Raichlen, & Lieberman, (2009) concluded that sprinting without arm swing did not affect energetic cost or lateral balance. The biomechanics of sprinting form is of importance, as the following sprinting form drills and resistance training methods are designated in a program according to what the biomechanical analysis shows. SPRINTING FORM DRILLS There are a number of factors which determine sprinting ability (height, weight, structure, base strength, mental toughness), the purpose of this review is to focus on the different training methods used to enhance technique. There is a multitude of sprinting form drills used in the sprinting arena to work on the various phases of the gait cycle. The form drills chosen for the purpose of this report include high knee skip, rip skip, wall march, spring march and run, hurdle run; a description is provided for each method, and evidence is provided for each of these. High Knee March The high knee march is used to achieve a high knee for sprinting, whilst controlling the movement with the hips. It is also aims to teach the athlete extension of the leg in stance phase, and control of arm movement depending on variation. 5

8 The athlete mimics the sprinting action, slowly taking one step at a time, bringing the knee up to approximately 90 each step and keeping the ankle at dorsiflexion.at approximately 90. The variation of the skip adds ground reaction force to the movement, as the athlete hops forward on the stance leg each time it strikes. The next variations teach the athlete to make fast contact with the ground and produce a movement closer to sprinting, and eventually sprinting with high knee s (high knee run) is commenced. Newton s law of motion describes that each action has an equal and opposite direction (Murgia, 2008). This means that if the athlete exerts a force on the ground with that foot, whatever ground reaction force they place in the ground will be equal to the amount of force behind their forward movement. Arm swing is essential to maintain balance during leg motion, making the energy use during sprinting more efficient. Rip March This is similar to the high knee march, however it teaches more horizontal force on foot strike than the high knee march. This exercise also promotes keeping the knee high and toe upward whilst sprinting and a quick recovery phase from foot strike though swing phase. This exercise has a variation of rip skip and rip double skip- which more closely mirrors actual sprinting; there is also a rip run, which teaches the quick rip on the ground to propel the athlete forward. The rip march action is often described as the toe grab and push off, or clawing and requires optimal force production of the foot and ankle plantar flexion muscles (Murgia, 2008; Nicola & Lewison, 2012). Many athletes, particularly rugby players, have a habit of decelerating as they accelerate, by placing their foot in a position such that the ground absorbs the force of the step (Sayers, 1998). This can be minimised if the athlete ensures their foot is already moving backward at foot strike, reducing the shock on the hamstrings and increasing the use of the gluteal muscles. 6

9 Resisted Sprints There is a vast range of research on resisted sprint mechanisms; however some of it presents conflicting data. Resisted sprints are those used to apply resistance to the athlete and force them to run whilst pulling extra weight. The mode of training utilised most often by AESP is resistance runs with a harness, and sled towing. There has been more empirical evidence to support the use of the sled instead of the harness due to the resistance being applied by a human which varies substantially according to who holds the harness. A study by Linthorne (2013) showed that resisted sprinting kinetics ultimately overloaded the neuromuscular system, resulting in greater recruitment of muscle fibres viua neural activation, and therefore more strength when sprinting. A study by Cronin, et al., (2008) determined that the kinematics during the acceleration phase (0-20m), not the peak speed phase (20-50m), will alter using resistance sprinting. However, at AESP the sled is only used to train acceleration over 0-20m, and therefore it is an appropriate method to train with. The sled will place the body in a position of increased trunk lean, increasing the angle of the knee, forcing the athlete to work harder to extend, which forces them to put more force into the ground and increase their step length (Cronin, et al., 2008). STRENGTH TRAINING Many investigations have looked at the relationship between resistance training and sprint ability, given the correlation between the relationship between a strong ground reaction force and strength (McBride, et al., 2009). This provides a solid foundation of reasoning as to why strength training is so integral to an athlete s ability to perform at their peak. The purpose of strength training is to increase the size of the muscle fibres and therefore strength of the athlete, which then improves the ability to train power (Behrens & Simonson, 2011, & McBride, et al., 2009). According to Behrens & Simonson (2011) it is important to consider the training principle of specificity when programming strength for different sports. It is suggested that coaches need to 7

10 understand the biomechanics of each movement most often performed on the field, and then program for that movement (Behrens & Simonson, 2011). The squat as an exercise may not be as applicable for sprinting given the low velocity at which a squat is performed (Haff, 2012); however a study by Cronin et al., (2007), found that the combination of low velocity high resistance, and high velocity low resistance (power exercises) are most effective. According to McBride, et al. (2009), who completed a study on 1RM squats and their effect on a 10 and 40 yard sprint, there will be significant increases in strength and power, and therefore ground reaction force, when using a 1RM squat for training. However at AESP, and in Haff (2012), it is suggested that a 1RM for training produces too much DOMS, as well as prevents the athlete achieving the ideal volume for their training, and therefore loads of 4-6RM are used over multiple sets. In comparison, de Villarreal, Requena, Izquierdo, & Gonzalez-Badillo, (2013) found that performing a squat variation showed small but insignificant changes in sprint time, but notable changes in technique. They suggested the combination of strength and power exercises would be optimal, and given that the subjects were not competing at the time, their program lacked specificity to a particular sport. Sprinting is mostly a unilateral and horizontal movement, given that at contact one foot is planted on the ground and the other in swing phase (Chumanov, Heiderscheit, & Thelen, 2007). This suggests the need to program not only the standard back squat, but also more unilateral single leg exercises (Behrens & Simonson, 2011; de Villarreal et al., 2013). The musculature around the hips needs to be strong, particularly the hip flexors for driving the leg upwards fast, as well as the hamstrings and gluteals for achieving triple extension. This improves power and sprinting technique as increased step frequency and step length can occur through strengthened hip and knee extensors. POWER AND PLYOMETRIC TRAINING Sprinting is a power exercise (de Villarreal, et al., 2013), and as such requires power 8

11 training in order to obtain, improve and mainatin speed. These exercises emphasize a more forceful and rapid execution of the stretch shortening cycle, enhancing maximal power output and strength performance. Given that many strength exercises have such a low velocity, power exercises are a way of ensuring movements are the same velocity required in sprinting (de Villarreal, et al., 2013). According to (Chelly, et al., 2010), activities which target a specific movement in sprinting include hurdle hops, depth jumps and hurdle jumps. This is supported by Hori, et al.,( 2008) who stated that training exercises should include rapid acceleration through the whole range of motion to improve power, and Olympic lifts are commonly included for this purpose. These exercises exert high ground forces against at a rapid pace, exhibiting power output. Body weight power exercises are a specific example of high velocity low resistance exercises which have been found to increase sprinting ability; these include: box jumps, counter movement box jumps and bounding (de Villarreal, et al., 2013). Past studies have shown that velocity over distances of 0 30, 10 20, and m is increased significantly (p, 0.05) after 10 weeks of plyometric training, which included a combination of Olympic lifts and body weight movement exercises (Behrens & Simonson, 2011). 9

12 3.0 Methods and Procedures In order to collect detailed data for this report, a number of articles were collated and analysed. Each Journal has been determined either eligible or not according to its status as a Peer Reviewed journal, analysed, and interpreted. Search Strategy Strategies for locating quality primary and secondary studies included using systematic broad search terms on UQ library Summon and across other computerised Journals (e.g., MEDLINE, PubMed, ScienceDirect, HUMAN KINETICS, SPORTDiscus, Google Scholar). The following search terms were most often used in multiple combinations: sprint; sprinting form; speed; assisted; resisted; biomechanics; strength; step time; stride length; contact time; force capability. Inclusion Criteria In order to gain the most accurate current methods of training sprint form, primary and secondary studies that were reported in English between 2003 and 2013 were included. Studies that focused on athletes in sports whereby sprinting speed is not integral were excluded. Although small-sample studies often lack statistical power, studies with smaller sample sizes were included, as they can be used as support for similar articles. There were no exclusion criteria for study design; however studies based on clinical populations were not included. This review contains studies published in journals that have presented original research data on healthy human subjects. No age, gender, or language restrictions were used during the research stage. There was no statistical analysis incorporated into this review, given the varied nature of the studies performed. Sprinting technique was observed- in person and from video analysis, which was then used to compare sprinting technique cues in practice as compared to theory. 10

13 Review and Analysis A literature review was performed in order to obtain information on what sprinting form, strength and power techniques have been used previously to improve speed; these were then compared with a sample of techniques used at AESP for improved sprinting technique and ultimately speed. 11

14 4.0 Discussion Through examination of the literature, it is possible to see that most studies correlate with each other regards to writing speed programs. There was some variation in the literature support that these studies drew upon. The results have shown that to improve sprinting form there are two main components- stride length and frequency. It is important to aim at improving one of these components when training better sprinting technique. It was found that by driving more force through the ground, step length and therefore stride length was improved. Through teaching extension through the ankle, knee and hip joints, the optimum amount of power can be transferred as kinetic energy, with minimal loss as a result of heat, sound or absorbed energy (Linthorne, 2013; Nicola & Lewison, 2012; Rudakov, et al., 2006). With regards to sprinting form drills it is evident that there are certain form points which require close attention. Research has shown that a strong arm drive will not only reduce energy expenditure during sprinting, but also allows for an increased stride length (Altman & Davis, 2012). There is limited research on the topic of sprinting form drills and their effect on speed performance, and therefore the methods employed by AESP could be further experimented with. Most sports are played on a level playing field, therefore resisted training drills such as sled sprints may be considered a very applicable exercise. The research has shown that resisted sprints have benefits for increased speed and better technique, however it is suggested this is most efficient when incorporated into a program with strength and power training. An avenue for further research would be the impact of assisted sprints on sprinting ability, such as treadmill, uphill and downhill sprinting (Cronin, et al., 2008). These techniques result in a change in kinematics and kinetics, in comparison to game surface; this would need to be a consideration when deciding on suitability of these exercises. 12

15 Practical Implications and Avenues for Future Research There is a large space in the literature with regards to the kinematics of agility speed versus straight line sprinting, and the responses elicited from certain Cue words in coaching. Limitations of this report included the ability to collect information on children aged 18 years and younger, due to ethical standards in the literature. Another interesting field of research is how sprinting shoes affect biomechanics of sprinting, given the new fascination with barefoot sprinting. Sprinting shoes were originally designed to cushion the foot and allow for neutralization of certain biomechanical differences in runners that were thought to predispose them to injury. This leads into the concept that different field surfaces require different shoes, however athletes will mostly train in a different shoe on a hard court surface compared to their natural competition surface- eg football boots for rugby, and therefore should they be training in those? 13

16 5.0 Conclusion This report was conducted by reviewing various programming techniques used at Acceleration ESP, and comparing and contrasting them to those considered in literature. It was found that there is a large amount of evidence supporting these techniques, however there are many other avenues of research for strength and conditioning coaches to utilise. This report was also created as a support tool for those athletes and others associated with AESP, to assist with understanding the mechanics behind sprinting form programming. This report was created as a review of straight line sprinting form techniques, although there are many other aspects that could have been considered, such as agility training for speed. It was determined that the combination of sprinting form exercises, resisted speed training, strength and plyometric exercises allow for the greatest improvements to be made. Suggestions have been made as to avenues for future research. 14

17 List of References Altman, A. R., & Davis, I. S. (2012). Barefoot Sprinting: Biomechanics and Implications for Sprinting Injuries. Current Sports Medicine Reports, 11(5), Arellano, C. J., & Kram, R. (2011). The effects of step width and arm swing on energetic cost and lateral balance during sprinting. Journal of Biomechanics, 44(7), Behrens, M. J., & Simonson, S. R. (2011). A Comparison of the Various Methods Used To Enhance Sprint Speed. Strength and Conditioning Journal, 33(2), Chelly, M. S., Ghenem, M. A., Abid, K., Hermassi, S., Tabka, Z., & Shephard, R. J. (2010). EFFECTS OF IN- SEASON SHORT- TERM PLYOMETRIC TRAINING PROGRAM ON LEG POWER, JUMP AND SPRINT PERFORMANCE OF SOCCER PLAYERS. Journal of Strength and Conditioning Research, 24(10), Chumanov, E., Heiderscheit, B., & Thelen, D. (2007). The Effects of speed and influence of individual muscles on hamstring mechanics during the swing phase of sprinting. Journal of Biomechanics, 40(16), Cronin, J., Hansen, K., Kawamori, N., & Mcnarr, P. (2008). Effects of weighted vests and sled towing on sprint kinematics. Sports Biomechanics, 7(2), Cronin, J., Ogden, T., Lawton, T., & Brughelli, M. (2007). Does Increasing Maximal Strength Improve Sprint Sprinting Performance? Strength and Conditioning Journal, 29(3), Danion, F., Varraine, E., Bonnard, M., & Pailhous, J. (2003). Stride Variability in human gaiy: the effect of stride frequency and stride length. Gait and Posture, 18(1), de Villarreal, E. S., Requena, B., Izquierdo, M., & Gonzalez- Badillo, J. J. (2013). Enhancing sprint and strength performance: combined versus maximal power, traditional heavy- resistance and plyometric training. Journal of Science and Sport, 16(2), Egbuonu, M. E., Cavanagh, P. R., & Miller, T. A. (1990). Degradation of sprinting economy through changes in sprinting mechanics. Medicine and Science in Sport and Exercise, 22, 17. Haff, G. G. (2012, April). Training for Strength, Power, and Speed. Strength and Conditioning Journal, 34(2), Hori, N., Newton, R. U., Andrews, W. A., Kawamori, N., McGuigan, M. R., & Nosaka, K. (2008). DOES PERFORMANCE OF HANG POWER CLEAN DIFFERENTIATE PERFORMANCE OF JUMPING, SPRINTING AND CHANGING OF DIRECTION? Journal of Strength and Conditioning Research, 22(2), Hrysomallis, C. (2012). The Effectiveness of Resisted Movement Training on Sprinting and Jumping Performance. Journal of Strength and Conditioning Research, 26(1), Jacobs, R., Bobbert, M. F., & van Ingen Schenau, G. J. (1996). Mechanical Output from Individual Muscles During Explosive Leg Extensions: The Role of Biarticular Muscles. Journal of Biomechanics, 29(4),

18 Linthorne, N. P. (2013). A mathematical modelling study of an athlete s sprint time. Sports Engineering, 16, McBride, J. M., Blow, D., Kirby, T. J., Haines, T. L., Dayne, A. M., & Triplett, T. N. (2009). Relationship between maximal squat strength and five, ten, and forty yard sprint times. Journal of Strength and Conditioning Research, 23(6), Murgia, C. (2008). Seperating fact from fiction: Increasing Sprinting Speed. Journal of Physical Education, Recreation & Dance, 79(8), Nicola, T. L., & Lewison, D. J. (2012). The Anatomy and Biomechanics of Sprinting. Clinics in Sport Medicine, 31(2), Pontzer, H., Holloway, J. H., Raichlen, D. A., & Lieberman, D. E. (2009). Control and function of arm swing in human walking and sprinting. The Journal of Experimental Biology, 212, Rudakov, R. N., Podgaets, A. R., Podgaets, R. M., Razumov, A. A., & Yakovleva, Y. V. (2006). Sport Biomechanics of Movements in Resisting Media. Journal of Biomechanics, 39(6), 548. Sayers, M. (1998). Sprinting Techniques for Sprinting Rugby. Applied Sports Knowledge,