Theory and Practice of Improving Acceleration in Athletes

Transcription

1 1 Theory and Practice of Improving Acceleration in Athletes Introduction Acceleration ability is defined as the sprint performance of an athlete over short distances (16), with the distance defined as the acceleration phase ranging from anywhere between 0 and 50 meters (3). A general outline of the biomechanical characteristics, relative importance of muscle groups, and exercises to improve acceleration are presented in Figure 1 (3).

2 2 An athlete s ability to accelerate their body mass is dependent upon a number of factors, including technique and the force production capability of the body, in particular the lower limb musculature (3). Mann et al (15) explain that the ability to perform well in sprints over short distances is dependant on the ability to produce large amounts of force at crucial times. Acceleration is integral to successful performance in almost every sport and may be a decisive factor in determining the outcome of a game. Although maximal speed is very important in most field- game situations, acceleration is arguably of relatively greater importance. Generally in these sports players cover only short distances at a maximal effort (18), with an example being that the typical sprint distance of rugby union players during a game is approximately only 20m (4). An example of acceleration s importance can be seen when observing that the ability to accelerate appears to be the most crucial factor in a game of rugby for many positions with a mean duration of sprints being between 3s and 5s for forwards. This short time frame probably precludes the attainment of maximal velocity. (6) (see figure 2)

3 3 Thus, with repeated short sprints being common, the ability to develop velocity in as short a time as possible (acceleration) may be of most importance to playing performance (3) in rugby union but would hold true also in almost every other field based sport (League, AFL, Football etc). While studies have shown that that this high intensity activity occurs relatively infrequently during competition, these bursts of maximal effort tend to be concentrated around crucial actions such as kicking a goal, making a break away from the opposition, or when executing a tackle (16). Figure2.Mean maximal sprinting durations of positional groups during a Super 12 rugby union game (6) Therefore, the development of the acceleration phase of sprinting would seem to be of great benefit to all field sport athletes (and competitors in most sports), with training programs focusing on the adjustment of players stride length (the distance the center of mass (generally the hips) travels during one running stride) and stride frequency (the number of steps taken in a given amount of time or over a given distance being viewed as a vital component of a conditioning program (18).

4 4 Methods used to enhance force output, stride length, and stride frequency for improving acceleration include various forms of weight training, plyometric training, and unassisted, assisted, and resisted sprinting techniques (3). Improved strength levels allow for the production of greater force and decreased ground contact time, leading to possible increases in stride frequency. Take 5 Read the article Does increasing maximal strength improve sprint running performance to learn more about maximal strength and its relation to sprint running performance found in Appendix 1 Increased stride length may be achieved by improved utilization of elastic energy during the support stage of the sprint cycle. Sprint loading techniques may be used in an effort to increase muscular force output, especially at the hip, knee, and ankle, leading to a potential increase in stride frequency (18). Take 5 Read the article Resisted sprint training for the acceleration phase of sprinting for more detail on the methodology and results of resisted sprint training found in Appendix 1 Training for acceleration in a team sport presents a number of additional considerations due to the fact that acceleration often occurs from numerous positions and in a variety of situations other than a standing start. Sprints vary in terms of change of direction, ball carriage, and opponent avoidance (17).

5 5 Young et al (20) explain that in a team sport, a 10-meter sprint may often be initiated from a jogging start, meaning that a relatively high percentage of maximum speed could be reached when shorts sprints are initiated from a moving start. It has also be observed that athletes will be required to accelerate from lying prone or a crouch, from moving sideways or backwards, from landing on one leg and pivoting sideways, from catching a ball, and from various other positions (3). A program to improve acceleration capabilities in sports such as rugby union, league, AFL or football would therefore necessitate drills where acceleration is performed from a selection of starting positions and conditions to increase the specificity of training. Take 5 Read the article Specificity of sprint and agility training methods which discusses the specificity of sprint and agility training programs and the results this can have on performance found in Appendix 1 The purpose of this article is to present a periodized six- week field based training program to improve acceleration performance in athletes using unassisted, assisted and resisted training techniques during the specific preparation phase of a yearly training plan. Specifically, the article is going to use rugby union as its example for drills etc but the concepts presented can be transferred to almost any sport.

6 6 Although this program is outlining a phase of the periodised yearly cycle where acceleration training is emphasized, it is the belief of the author that if a physical capacity is left untrained than a detraining effect may result and therefore some form of acceleration training should be performed throughout the season. It should also be noted that the strength and resistance gym- based training is vitally important to improve acceleration in athletes and is covered in a separate section. Warm Up A well-designed warm up assists an athlete in mentally focusing on an upcoming task and will bring about physiological changes that will enhance the training activity. An active warm up raises core body temperature, leading to improved range of motion, increased oxygen uptake, decreased lactate accumulation, increased muscle ph, improved speed and force of muscle contractions, and higher rate of nerve impulse transmissions (19). A warm up routine prior to acceleration training should include minutes of static and dynamic stretches along with exercises involving all of the major muscle groups associated with short sprint training, with an emphasis placed on the selection of functional exercises that are based on similar movements to those found in acceleration training.

7 7 Static stretching should be avoided prior to acceleration training on any muscles that are going to be required to produce force during the acceleration training exercises as research (1,9,13) has shown that this form of warm up can lead to reduced force production when performed prior to explosive exercises. Muscles that produce large amounts of force and are required to concentrically contract to propel the body forward during the acceleration phase of a sprint include the gluteals, quadriceps, hamstrings, and calves (20).

8 8 Table 2 outlines an example of dynamic warm up routine to be performed prior to an acceleration training session. TABLE 2 Dynamic Warm Up Routine Pre- Acceleration Training Exercise Time/ Distance Giant arm swings 20secs Walking A's 20m A Skips 20m Heel Flicks 20m High knee's 20m Calf pumps 30 secs Static Hip Flexor Stretch 30sec each side Lower back swings 30sec Scorpions 30sec Carioca 20m (swap lead leg after 10m) Lung walks with twist 10m Backwards run 10m Side shuffle into sumo squat 20m (swap lead leg after each squat) Leg swings 10 each leg Adductor swings 10 each leg Walking spiderman 10m Lying Hamstring raises 10 each leg Stop and Go's- 5m 1 x 20m 10m acceleration runs 1x 10 70% 1x 10 90% 1 x % Watch the videos for exercises found on the course page

9 9 Program Design As previously stated, this article will use the example of a six week cycle of acceleration training to be performed in the specific preparation phase of a professional rugby union teams pre season training cycle. Acceleration training will be performed twice a week during this phase, with a minimum three-day break to be given between each session. As sprint and acceleration training are taxing on the body and rely heavily upon the speed of movement and correct technique, any excessive neuromuscular fatigue will interfere with skill acquisition (2). Due to pre season training for rugby union also involving high volumes of weights based training, skills, conditioning, and contact sessions, it is vital that adequate recovery is given between acceleration sessions, with running volumes of every session monitored to avoid fatigue and minimize the potential for over training. It is imperative that sessions progressively overload the neuromuscular system by either an increased volume of meters, or through augmented intensity of each session, ensuring an overcompensation effect is achieved that will result in improved acceleration ability. View the following table which outlines the six-week acceleration training cycle and illustrates the goals, methods, and total weekly running volume of each phase.

10 10 SIX WEEK ACCELERATION PROGRAM Specific Prep Phase Wee k Goal Methods Weekly Volume 1 Acceleration Technique Unassisted 590m 2 Acceleration Unassisted 640m 3 Acceleration Stride Frequency Resisted methods 610m 4 Acceleration Stride Frequency Incline/ resisted incline 460m 5 Acceleration Stride Length Decline/ over speed methods 520m 6 Rugby Specific Acceleration Unassisted 670m Week One Emphasizes technique and strong posture during acceleration, with a moderate volume of running. Week Two Focuses on more pure acceleration with a noted increase in volume and intensity. These sessions also involve some competition between players in an attempt to ensure that they are truly striving for maximal intensity. Week Three Attempts to increase the players stride rate through the use of resisted methods. Running volume drops during this phase, however, training intensity and loading on the body increases as a result of the resistance. Week Four Again focuses on increasing stride rate, this time by means of uphill running. The lower volume of running is again due to the higher loading parameters on the body as a result of the incline.

11 11 Week Five Uses over speed training methods in an attempt to increase stride frequency. The high amount of eccentric loading experienced during this type of training explains the decreased volume of training. For the same reason these two sessions would also ideally have an extra day recovery between them. Week Six In the final week of the cycle, any gains made in acceleration technique, velocity, stride length, and stride frequency are applied to rugby specific drills. This is done to ensure that the acceleration skills being trained in a controlled setting are transferable to game based situations. Take 5 Read the article Long term metabolic and skeletal muscle adaptions in short-sprint training to gain a better understanding of the adaptions that can result from a properly constructed and loaded sprint training program found in Appendix 2 The Training Program The following tables outline the complete six-week training program in detail. Each week is broken up into the two separate sessions. Click on the exercises to view a video of the correct technique and movement requirements

12 12 WEEK SIX Specific Prep Phase- Acceleration Program Date: Session: 1 RPE: Goal: Rugby Specific Acceleration Timing Activity Volume Duration Rest 0-10min Warmup- accel warm up 10min 10-12min Ankling 15m 1x 2 walk/ 30sec 12-15min Resisted A Series Walking A's, A skips, Running A's 1x 10m walk/ hold In pairs, alternate holding and exercise for partner 15-35min Position Specific Acceleration Starts Differing starts, all 15m accelerations 1x 10 1min Front row- All fours Second row- jump, land, accelerate Back row- off the deck Halves- pass ball, accelerate Inside backs- accept ball, accelerate Outside Backs- walking back, accelerate 35-45min Tackle, Drop, Turn, Accelerations Player hits tackle bag, drives, and 1x 8 drops to deck. On whistle turns and accelerates 10m hold for partner 45-55min Cool down/ Stretch 10min Session Volume 290m

13 13 Date: Session: 2 RPE: Goal: Rugby Specific Acceleration Timing Activity Volume Duration Rest 0-10min Warmup- accel warm up 10min 10-12min Resisted A Series Walking A's, A skips, Running A's 2x 10m walk/ hold In pairs, alternate holding and exercise for partner 12-15min Straight Leg Bounds 1x 2 walk/ 30sec 15-25min Ball Through Hands/ Accelerate In groups of 3 4x 15m walk back Players jog in line passing ball, on whistle they accelerate to set point (approx 15 m) 25-35min Side Shuffle/ Accelerate 4x 20m walk back Players shuffle left to right as if defensive line, folllowing command of trainer On whistle, accelerate 35-45min Ball Return Accelerations In Pairs. Ball is either kicked past player 1x 6 on the ground or over their heads. Player runs back to retrieve ball and then accelerates back to partner (approx 20m acceleration w/ 5m run back) walk and set up/ tow partner 50-60min Cool down/ Stretch 10min Session Volume 380m Watch the exercises videos found on the course page

14 14 Scientific Explanation of the Program Stride length, stride frequency, and the sub qualities of ground contact time and flight time are of particular importance to running speed (18). A person s ability to accelerate their body when sprinting would be dependent upon a number of factors including technique, force production capabilities, increased rate of stride frequency to reduce ground contact time, and increased stride length for longer distance accelerations. The six-week program presented in this article is founded on sound scientific evidence and attempts to progressively train and overload the necessary systems required to improve acceleration performance. Although the program is relatively short at only six weeks long, studies have shown that neurological changes can occur in periods of 4-6 weeks of resistance training and that these have the potential to affect muscle morphology (18). It should also be noted that this six- week cycle is a period in which improvements in acceleration performance is a focus. Acceleration based session sessions will continue throughout the yearly macro cycle. Week one aims to improve the technique competencies.

15 15 It has been shown in a number of studies (3, 16, 18, 20) that field sport athletes with good early acceleration exhibit higher stride frequencies (probably as a result of lower ground contact times), a more anterior positioned center of gravity, an approximate body lean of 45 to the surface of the ground, greater trunk flexion, increased range of thigh movement, and reduced knee extension angles when compared to slower field sport athletes. FIGURE 3 (18) Joint angle conventions of the first two strides of acceleration (Spinks et al 2007) This first week of training consists of a number of maximal sprint efforts over varying distances up to 30m. The week progressively overloads from session one to session two in order to increase the training stimulus. The major focus of both sessions is that all efforts are performed with previously outlined correct technique. It also imperative that the acceleration efforts take place at as close to maximal speed as possible as sub maximal speeds will alter running mechanics, stride frequency, and stride length (12). It therefore thought that failing to train at high speeds train s athletes to run slowly (2). Ankling and fast leg movements are also included in this first week of training and in subsequent sessions. Fast leg drills will allow the player to move their limbs at greater speeds than would normally be possible during the running motion. The continual practice of this over the course of the program could lead to a carryover to sprinting, which would result in an increase in stride frequency, and therefore speed, over time (2).

16 16 The second week of training has similar training outcomes to the first week of the program, with an increased volume of running ensuring further stimulation of the neuromuscular system. Ankling and fast leg drills are continued, with technique at maximal speeds a focus. This week also includes some drills that involve competition between the players. This is done so that the players can push themselves against each other to attain maximal acceleration rather than the speed of the efforts being self monitored. The third week of training sees the commencement of resisted and assisted methods of training to increase stride rate and stride frequency. Week three begins with resisted fast leg movements and accelerations with a resisted towing device. It is thought that such techniques increase neural activation and hence muscular force output of the leg, resulting in an increase in stride length over time (2). Resisted sprint training in the form of weighted sled towing is a training protocol often prescribed for field sport athletes in an effort to improve acceleration and sprinting performance (18). It is thought that this mode of training increases neural activation and hence muscular force output of the leg, resulting in an increase in stride length over time. This training stimulus may also increase pelvic stabilization, which may have a positive effect on sprint performance (2). There have been concerns in the past that weighted sled training may not transfer to acceleration performance because of negative influences on acceleration kinematics (10). A previous study by Spinks et al (18) has shown that resisted sprint training provides an overload stimulus to acceleration mechanics and increases the recruitment of the hip and knee extensors, resulting in greater application of horizontal power with no adverse affects on acceleration kinematics and gait. There is much conjecture in the literature as to the correct loading parameters that should be used when performing resisted sprint training. It has, however, been identified in a number of studies (and anecdotally by the author) that towing loads of roughly 10% of body mass have been recommended to ensure that gains can be achieved without any detriment to performance, but much of this information is based on practical observations rather than research (3). Others studies have stated that loads up to 15% of body mass will not affect technique (11). Further to this, it has been suggested that greater resistance should be used for training the acceleration phase and light loads for increasing maximum velocity, with increased loads increasing forward body lean and stance phase duration when accelerating (3).

17 17 For the purpose of this training program and for practical applications for implementing sled training into a teams repertoire; 10m accelerations will be loaded at 15% of individuals body weight 20m accelerations will have 12.5% of body weight added as resistance 30m accelerations will have 10% of players body weight added. It can also be observed that the second session of week three incorporates some resisted accelerations with a 10m-released acceleration added. This is done to teach the athlete how apply the gains made in force production from being resisted directly into free sprinting, hopefully increasing the transference of the resisted drill into their natural skill set. Week four of the training program utilizes uphill running as a method of resisted training to improve acceleration performance. It has been show that uphill running places an increased load on the thigh extensor muscles as athletes attempt to maximize their step length up the hill. This leads to improved running on flat surfaces as thigh extensor activity is thought to be a very important factor in increasing the propulsive phase of sprinting (3). Other studies (14), have presented the idea that uphill running may result in long term adaptations, with increases in step length and shortened stance phases on flat surfaces being the result of implementing this form of training. In terms of the gradients of the incline that the runs in this program are to be performed, Dintiman et al (5) suggest the use of steeper inclines to improve the acceleration phase of sprinting. They prescribe an incline of approximately 8-10 and a time frame of approximately seconds per repetition. The fifth week of the training program involves assisted sprint training, with downhill running and towing being used in an attempt to have the players run at velocities greater than what they may be normally capable of achieving. This training theoretically allows the athlete s body to learn how to run at greater stride frequencies, which will then transfer to their non assisted running (2).

18 18 Downhill sprinting and towing will increase horizontal velocity and stride length. However, declines greater than 3% may lead to excessive stride lengths that will result in increased braking during the sprints and athletes that allow themselves to be pulled will defeat the purpose of the assisted training. (8). Cissik (2) presents some guidelines for assisted sprinting, including: a) For towing, distances should not cover more than 30 to 40m b) Downhill sprints should not exceed an angle of 2 to 3 degrees to prevent any changes in mechanics c) Athletes should not achieve speeds greater than % of their maximum speed to prevent changes in running mechanics, and d) Sound technique must be emphasized during assisted sprinting. The program will adhere to all of these guidelines, with a specific emphasis being on technique for performance improvement and injury prevention. The final week involves the application and performance of acceleration in game simulated situations and under fatigue. The principle of specificity states that training should go from generalized to more specific means of preparation, and that to become better at a skill it is necessary to perform that skill as it would be done in a game situation. In order to achieve this goal, the final week of the training program involves acceleration under fatigue as well as acceleration prior to, and after, executing game specific movements such as tackling and passing.

19 19 Testing for Acceleration Research suggests that speed testing of team sport athletes should focus on the assessment of acceleration over 5-40m (7). Most elite sporting teams test their players over 5m-10m for acceleration and 40m for maximal velocity using Photocells, commonly known as timing lights. During the six-week program outlined in this article, players would be tested three times. An initial test will be performed prior to the commencement of the program, another test would occur after the third week, and a final test would transpire at the completion of the program. The testing should ideally be performed on a running track with players wearing running shoes to ensure consistency of the testing surface, however, testing on grass would also be suitable for field sport athletes as this would allow for specificity (however, there is some loss in consistency as grass conditions can change dramatically as a results of weather, wear and tear). Players will perform three 40m efforts with timing gates at the 5m, 10m, 20m, 30m and 40m mark. A full 3-5 minute recovery will be given between each effort. There are a number of starting techniques that can be used when performing acceleration and maximal velocity testing, including a standing start, a three point foot start, and a three point thumb start (7). The following figure presents a diagram of each of these starts. FIGURE 4. Three different starting techniques. (a) standing, (b) three point foot start, (c) three point thumb start (Duthie et al 2006)

20 20 For the duration of this program, ideally players would start each effort from a standing start. Duthie et al (7) identified that starting technique used has little bearing on the eventual outcome of the test; however, once one technique is used it should be continued throughout the testing procedure due to their findings that the results from different techniques are not interchangeable. Conclusion The information that was presented in this article is an example of a six- week training program that can be used to improve acceleration performance in field sport athletes (using the example of rugby union players) during the specific preparation phase of a yearly macro cycle. The ability to accelerate is an essential component of competing at a high level in most sports and enhancements to acceleration are achieved through improvement in technique and alteration of the players stride length and stride frequency. The program outlined attempts to increase acceleration ability through six weeks of training based on the scientific research and information as well as anecdotal evidence. Both stride lengthening and stride frequency drills are utilized with a strong emphasis placed on correct technique. It is thought that after completing this training program there would be a significant reduction in 10m testing times and overall improved technique and physiological acceleration capabilities of any athletes being trained. References 1. Behm, D.G., Button, D.C, and Butt, J.C. Factors affecting force loss with prolonged stretching. Canadian J. Appl. Physiol. 26(3): Cissik, J.M. Means and methods of speed training: Part II. Strength Cond. J. 27 (1): Cronin, J., and Hansen, K.T. Resisted sprint training for the acceleration phase of sprinting. Strength Cond. J. 28 (4): Deutsch, M.U., Maw, G.J., Jenkins, D. Heart rate, blood lactate, and kinematic data of elite colts (under- 19) rugby union players during competition. J. Sports. Sci. 16: Dintiman, G., Ward, B., and Tellez, T. Sports Speed. 2 nd ed. Champaign, Il: Human Kinetics, p Duthie, G.M., Pyne, D., and Hooper, S. Time motion analysis of 2001 and 2002 super 12 rugby. J. Sports Sci. 23(5):

21 21 7. Duthie, D.M., Pyne, G.B., Ross, A.A., Livingstone, S.G., and Hooper, S.L. The reliability of 10m-sprint time using different start techniques. Strength Cond. J. 20 (2): Faccioni, A. Assisted and resisted methods for speed development. In: Sprints and Relays (4 th ed.). J.Jarver, ed. Mountain View, CA: TAFNEWS Press, pp Fowles, J.R., Sales, D.G., and MacDougall, J.D. Reduced strength after passive stretch of the human plantarflexors. J. Appl. Physiol. 89: Jakalski, K. The pros and cons of using resisted and assisted training methods with high school sprinters: Parachutes, tubing and towing. Track Coach. 144: , Kafer, R., Adamson, G., O Conner, M., and Faccioni, A. Methods of maximizing speed development. Strength Cond. Coach. 1: Kivi, D.M.R., Maraj, B.K.V., and Gervais, P. A kinematic analysis of high speed treadmill sprinting over a range of velocities. Med. Sci. Sports Exerc. 34(4): Kokkonen, J., Nelson, A.G., and Cornwell, A. Acute muscle stretching inhibits maximal strength performance. Research Quarterly for exercise and Sport. 69(4): Kunz, H., and Kaufman, D.A. Biomechanics of hill sprinting. Track Tech. 82: Mann, R.V., Herman, J., Johnson, B., Schultz, C., and Kotmel, J. The elite athletes project: Sprints and Hurdles. United States Olympic Committee. Colorado Springs. Publication Murphy, A.J., Lockie, R.G., and Coutts, A.J. Kinematic determinants of early acceleration in field sport athletes. J. Sports Sci. Med. 2: Sayers, M. Running techniques for field sport players. Sports Coach. 23: Spinks, C.D., Murphy, A.J., Spinks, W.L., and Lockie, R.G. The effects of resisted sprint training on acceleration performance and kinematics in soccer, rugby union, and Australian football players. J. Strength Cond. Res. 21(1): Swanson, J.R. A functional approach to warm up and flexibility. Strength Cond. J. 28(5): Young, W., Benton, D.M., Duthie, G., Pryor, J. Resistance training for short sprints and maximum- speed sprints. Strength Cond. J. 23 (2):