Stodden DF, Fleisig GS, McLean SP, Lyman SL, Andrews JR. Relationship of pelvis and upper torso kinematics to pitched baseball velocity. Journal of Applied Biomechanics 17(2):164-172, 2001.

Matsuo T, Escamilla RF, Fleisig GS, Barrentine SW, Andrews JF. Comparison of kinematic and temporal parameters between different pitch velocity groups. Journal of Applied Biomechanics 17(1): 1-13, 2001.

Stodden, DF, Fleisig, GS, McLean, SP, Andrews, JR. Relationship of Biomechanical Factors to Basebal Pitching Velocity: Within Pitcher Variation. Journal of Applied Biomechanics 21(1): 44-56, 2005

Methods

In three published studies, Dr. Glenn Fleisig and Dr. James R. Andrews from ASMI worked with other researchers in studying many of the parameters that affect baseball pitch velocity. Two of the studies looked between different pitchers and one study looked at variations within each pitcher. Motions during delivery were analyzed using a high speed (200 frames per second) infrared three-dimensional motion analysis system.

Results

In the study by Matsuo and others, pitchers with higher ball velocity were compared with pitchers with lower ball velocity. Four significant differences were found between these two groups. Compared to the low ball velocity group, the higher ball velocity pitchers demonstrated less lead knee flexion velocity after front foot contact and greater lead knee extension velocity at the time of ball release. Extending the lead knee in this manner may provide stabilization allowing better energy transfer from the trunk to the throwing arm, and could be a critical factor in pitch velocity. Maximum shoulder external rotation and forward trunk tilt at ball release were also greater in the higher velocity group. Greater shoulder external rotation causes a stretch of the internal rotators allowing energy to be stored in these muscles, and creating greater internal rotation during the arm acceleration phase.

Two variations were found in the timing of events. Maximum elbow extension angular velocity and maximum shoulder internal rotation angular velocity occurred earlier in the motion of higher velocity pitchers. The maximum shoulder internal rotation angular velocity also occurred closer to the moment of ball release in the higher velocity pitchers. This optimal timing may aid in generating higher velocity pitches.

Another finding of interest is that early in the pitching motion, the two groups were dissimilar in the timing of their movements, while their later movement timing was much more similar. This implies that early trunk and torso movements are more varied among pitchers than late arm movements.

In the first study by Stodden and others (2001), pelvis and upper torso variables were studied in 19 elite baseball pitchers. The study found that when the arm was completely cocked back (that is, maximum shoulder external rotation, or “MER”), more “open” pelvis and upper torso orientation correlated with increased ball velocity. More open pelvis angle at the time of ball release (REL) also correlated with increased pitch velocity increased. Additionally, pelvis angular velocity from front foot contact to MER, and upper torso angular velocity from MER to REL increased with increased velocity.

The data indicate that a pitcher who is able to position himself properly, and rotate his pelvis and upper torso more quickly is able to generate greater momentum. Theoretically, this increase in momentum leads to greater velocity of the throwing arm and thus greater pitch velocity.

The most recent study by Stodden and others (2005) showed that for a given pitcher, increased elbow flexion torque, shoulder proximal force and elbow proximal force produced greater ball velocity. In addition, the maximum shoulder horizontal adduction occurred later and maximum shoulder internal rotation occurred earlier at greater ball velocities. Higher ball velocity also resulted in decreased shoulder horizontal adduction at foot contact, decreased shoulder abduction during acceleration, and increased trunk tilt forward at ball release.

Conclusion

A pitcher with increased shoulder external rotation, faster pelvis and upper trunk rotation, and greater front knee stabilization and extension will throw with greater ball velocity. Improved timing to maximize arm velocity closer to the time of ball release will also help ball velocity. Increased torque and force produced at both the shoulder and elbow will also lead to greater ball velocity.

Copyright © 2000, American Sports Medicine Institute
December 18, 2007

http://www.asmi.org/asmiweb/research/usedarticles/highlowpitches.htm

During the prime of the likes of Nolan Ryan, the popular way of generating more momentum back then was the “Stand Tall and Fall” style developed by Nolan Ryan and his pitching coach Tom House, who may have coined the term. This proceeded the popular style of “Drop and Drive” used by the great Tom Seaver. These two styles of pitching are still used today. What is changing is pitching mechanics are evolving from an art form into the world of science.

Instead of hearing terms like “Stand Tall and Fall” or “Drop and Drive,” we are now hearing terms like “Core Torque,” “Triple Extension” or “Scap Loading.” What we are learning is the more science we can put into pitching, the more benchmarks we have to help pitchers make their improvements. If pitching mechanics are only seen as an art form, then they are based on opinion, which has been the case for some time now. When pitching mechanics are seen as a science then through analysis pitching mechanics must meet certain benchmarks to be labeled efficient and effective.

What we have learned from these two styles, “Stand Tall and Fall” and “Drop and Drive,” is more momentum equals more velocity. What we know today is that digital science has proven that momentum is only effective if it transfers from the lower half to the upper half of the body before it can move into the ball at release. This is the importance of “Separation.” “Separation” is when the front leg lands and the back leg is extended, the back hip is around and the back shoulder and body weight is still back. Notice the picture of Tim Lincecum above in this position. You can develop all the momentum in the world with a Nolan Ryan leg lift or a Tim Lincecum jump off the mound but if you do not let that momentum travel up your body into the ball with proper “Separation” then this means you will be stuck with just your arm to generate the velocity of the pitch.

I like to use the analogy of a moving car. Imagine a car traveling at 100 mph. The drivers side door is closed but it isn’t closed all the way. All of a sudden the driver slams on the brakes and stops the car in its tracks. What would happen to the door? It would fly open because once the momentum of the car is stopped by the brakes, the momentum moves into anything that is not secured down. The door was not secured down, so it picked up the momentum and flew open. This is exactly how momentum must travel through a pitchers body. To transition from the moving car analogy into the delivery of a pitcher we could say the car is the legs and core of the pitcher and the door is the shoulders and arms. Once the pitcher puts on the brakes with his front leg during front foot strike and the shoulders are closed with weight back, then the momentum will travel into the shoulders and arms driving them open towards the front knee. If the front leg continues to stabilize, the momentum will jump into the ball once the shoulders and arms cannot travel any farther.

This analogy makes it sound simple but it is not because there is a sequence of rotational pivots that must rotate perfectly in order for the ball to reach your potential velocity. To learn more about these pivots read Pitching-torque-and-the-3-pivots. It is also a major feat to train your muscles to move your “car” at speeds that cannot be seen by the human eye but I believe it is possible and so should you. Purchase the Ace Pitcher Handbook for a complete training program to help you grow bigger, stronger, faster.

The major misconception of pitching, that continues to ruin arms, is the belief that velocity comes mainly from the arm. Stop thinking with your arm! This will cause so many problems mechanically and physically your career will eventually come to a halt. You need to beat it into your head everyday that your legs and core throw the ball and the arm follows and guides the pitch. When starting your delivery on the mound your first step should NOT be lift leg so I can break my hands and get my arm moving fast. This is pitching with all your arm. This is only recruiting your arm to handle the workload of the pitch. You must learn to recruit from the major muscle groups in the legs and core, to handle the workload of the pitch. In return this will generate so much more velocity and save your arm from absorbing all of the stress.

Pitching from the bottom or ground up is visualizing your lift leg as a log you are about to role down the hill or mound. Pick it up, feel its weight, hold back your upper body and throw the log down the hill leading with your butt to the target. It is extremely important that you load your weight back while the front leg moves to the target. Notice the picture above of Gagne in this “Load” position. Notice his weight is back, his back leg is sitting and his lift leg is moving to the target. This is the essence of bottom up pitching. Now notice the young man in the picture to the right of Gagne. He is almost at the same moment in the delivery but he is in a different position. His weight is forward, his arm is up and his stride is short. The difference between the two pictures is, once Gagne’s foot lands he can then transfer all the weight that he is loading in the back leg into the pitch. The young man has no weight loaded and is forced to only whip his arm to generate any velocity. The young man is pitching from the top down and he will be one of Dr. Andrews next patience if he does not make the adjustment.

Another sign of pitching from the top down is driving your glove hand to the target. This will also throw your weight forward preventing the “Load.” If you are a pitcher who pitches from the top down then thank God you read this article. You know need to understand what you are doing to cause this and learn to pitch from the bottom up. If you can make this adjustment, you will not only save your career as a pitcher, but you will increase your velocity by about 10-15 mph. The problem is this adjustment isn’t easy! It will not happen over night or within the year. It is a long process of changing muscle memory that you developed when you were very young. This means you will need a coach or video analysis to make this adjustment. You will also need to understand how to finish your delivery from the “Load” position and most important you must work on this adjustment everyday.

Please do not let this article discourage you. You have been given a gift with this knowledge. Most pitchers in high school and even college do not understand this consciously or subconsciously. Therefore this will put you ahead of the game.

If you would like TopVelocity.net to analyze your pitching video, please follow the instructions below.

How to shoot your video?

Shoot two angles for your video. An angle from behind the pitcher and an angle from the throwing arm side of the pitcher. Make sure that the camera is not higher than the pitchers shoulders. Also make sure the camera is stationary.

Each angel should have two or three pitches of video.

How do you package and send your video?

Compress your video into a digital format. For example, DVD, Divx, AVI, MOV, WMV, MPG or any other common format. Burn the format to a CD or DVD. Visit the “Contact Us” page and request our mailing address to send the video too.

Video Analysis

At TopVelocity.net, once we receive your video, we will analyze your mechanics with advanced video software. This software will allow us to do a comparison of your delivery to a Professional Pitcher with a similar frame as yours. We will then use the software to generate overlays and slow motion clips to give you an extremely detailed analysis. We promise you will be impressed.

Once the video has been analyzed, we will post your analysis here on the forums. You can then watch your analysis.

Our video analysis is very popular with the pitchers we have worked with. It is a great tool because they can always go back and look at the video. We do recommend that you have a video analysis done at least every 2 months.

If you are interested and would like to send your video in today, your first analysis is FREE. Contact Us

Many athletes today have the desire to reach a higher level of athletics. Whether it is an athlete going from Jr. High to High School, or an athlete making the transition from high school to college athletics and the big one college to professional athletics. All throughout America, young athletes have dreams to make it to the top of their sport; many try only a few succeed.

To make it to the professional level it takes all the intangibles of practice, hard work, heart, desire, skill, strength, speed, etc; but, one of the most important traits is a simple word and it is genetics. Some athletes can top out their genetic potential only running a 4.97second 40 yard dash or topping out their fast ball at 78mph and that is ok, but ask yourself as a parent or an ex athlete, did I max out my potential? When did I start really training and being educated by my coach on how to and why? Did my coach teach me the right way to train and perform the different tasks, drills, or tests?

Like many of today’s strength and speed specialists, we have all heard of the NFL Combine and different combines being held around the nation that tests the athletic ability of the athlete. One of the questions in football is how fast the athlete’s 40 yard dash is, in baseball it is how fast the athlete can run a 30 or 60 yard dash. Some athletes are born with being able to run a 4.23 second 40 yard dash or other talented gifts such as being able to throw a baseball 98mph at only 18 years old but how about the athletes who are not blessed with these abilities and genetics. I am a speed and strength professional and I am going to tell you these things can be taught. In theory, can every athlete train and run a 4.2 second 40 yard dash or throw 98mph NO but if coached properly and if an athlete starts early enough in their life to program their body then they can get the most out their genetic make-up. In an athlete’s life they will be timed by a scout or coach to see how fast they are. Keep in mind, this does not tell the coaches or scouts how talented the athlete is at the particular sport but just their speed. Therefore, this is just a test and should be treated like a test which means being educated and studying for the test. This brings me to Fitts and Posner Three Stage model of learning a motor skill.

1st Stage of Learning

Paul Fitts and Michael Posner presented their three stage learning model in 1967 and to this day considered applicable in the motor learning world. The first stage called the cognitive stage of learning is when the beginner focuses on cognitively oriented problems (Magill 265). This is when the beginners try to answer questions such as: What is the objective of the 40 yard sprint? Where should my hand be on the line coming out of a three-point stance? How and where do I place my feet? How is the weight distributed? There are many questions that an athlete has when they first try to learn a three point stance for the 40 yard dash. And surprisingly the older the athlete, the harder it is to teach the proper mechanics of the start. This is because they have been doing it their way most of their life. Remember it is easier to teach new habits than to try to fix bad habits. Fitts and Posner explain the learner must engage in cognitive activity as he or she listens to instructions and receive feedback from the instructor (Magill 265). Of course during the first stage the learner or athlete is going to make many errors and the errors they make have a tendency to be large. The learners or athletes in this stage are conscious incompetent. This is when the athlete realizes that they not as skilled as perhaps they thought they were or thought they could be. One of the ways to help the athlete through this first stage and show their mistakes is through video analysis. From experience, once the learner or athlete can watch their errors they tend to correct them at a faster rate.

2nd Stage of Learning

The second stage of learning in the Fitts and Posner model is called the associative stage of learning. The transition into this stage occurs after an unspecified amount of practice and performance improvement (Magill 265). The learner or athlete reaches this stage when they have developed the knowledge of what, how and when to do the different tasks in a sprint to achieve the goal of the skill. Of course the athlete makes fewer mistakes in this stage and is more consistent with the different stages of the 40 yard dash. The athlete now understands how to start, how to load the arm and legs in a three-point stance, how to breathe, when to breathe, arm placement, etc. In the associative stage, the athlete is going through conscious competence. The learner or athlete knows how to do something; but, in spite of this, demonstrating the skill or knowledge requires a great deal of consciousness or concentration. This great deal of consciousness and concentration usually makes the athlete tense or disturbs breathing which could inhibit the athletes’ sprint performance.

3rd Stage of Learning

The third and final stage is called the autonomous stage of learning. In this stage the skill has become almost automatic or habitual (Magill 265). Learners or athletes’ in this stage do not think about all the steps required to run a fast time, the athlete just performs and runs. In this stage as a coach we like to call it unconscious competence. The learner or athlete has had so much practice with a skill that it becomes “second nature” and can be performed easily with only little thinking. During this stage the learner or athlete can go up to the line knowing all the answers he or she was asking, thinking, and being coached on during the cognitive and associative stage.

In closing, Fitts and Posner’s Three Stage Model of learning can be used in any athletic drill or movement. Of course, there are other different theories of learning but with the Fitts and Posner model it is simple and it works. As a coach you can use this model with all of your athletes learning a new skill or movement. Remember coaching means teaching, of course it is easy to go out and train a bunch of athletes just running them into the ground and many coaches still do that because they think the harder the better. To be a great coach remember sometimes less is more. This means that sometimes less work and more coaching towards the athletes’ can be more beneficial. Finally, in motor learning and motor control the whole basis is being able to program your body to learn and do different things. The earlier you start programming the correct way to do specific movements, like run, jump, throw, lift, etc. the better student or athlete you will be. The important aspect is learning the proper technique sooner because the longer an athlete waits there is a greater chance of the athlete picking up bad habits. That is why it is so important to find a qualified, educated coach or teacher who can show and teach and explain why the proper techniques of training.

References
Magill RA. Motor Learning and Control: Concepts and Applications. 8th ed. New Your, NY: McGraw-Hill; 2007

Speed Training

Implied in any linear speed discussion with a Strength and Conditioning Specialist, is the concept of resisted speed training strategies. Some professionals consider resisted speed training as the most efficient sprint training technique on the planet, while other consider it not as effective because of a biomechanical stand point. Different resisted speed strategies include, towing, uphill sprints, sand sprints, and weighted sprints. Tahachnik (1992) explained that towing of weighted devices such as sleds and tires is the most common method of providing towing resistance for the enhancement of sprint performance, although the use of parachutes has also been documented. In fact, resisted towing can involve an athlete towing a weighted sled, tire, speed parachute, or some other device over a set distance (Faccioni 1994).

The function of resisted towing is said to improve the acceleration or drive phase of a sprint. Acceleration is integral to successful performance in the various football codes, including Australian rules, rugby union, and soccer and is potentially decisive in determining the outcome of a game (Spinks et al. 2007). It has been said that resisted towing will increase muscular force output, especially at the hip, knee, and ankle. According to researches improved strength levels allow for the production of greater force and decreased ground contact time, leading to a possible increase in stride frequency. Increased stride length may be achieved by improved utilization of elastic energy during the support stage of the sprint cycle (Spinks et al. 2007).

Regardless of the many benefits of resisted towing speed training, the most effective type of resistant speed training for overall speed and acceleration remains for the most part uncertain.

Resistant Towing

Weighted sled towing is a common resisted sprint training technique even though relatively little is known about the effects that such practice has on sprint kinematics. Lockie, R.G., A.J. Murphy, and C.D. Spinks (2003) examined twenty men, which completed a series of sprints without resistance and with loads equating to 12.6% (load1) and 32.2% (load 2) of body mass. Through their findings the participants stride length was significantly reduced by 10% with a 12.6% load and lowered 24% with a 32.2% load. Stride frequency did not change from load 1 to load 2 and only dropped by 6% between the unloaded and loaded trials. In addition, sled towing increased ground contact time, trunk lean, and hip flexion in both loads but, more of an increase happened with load 2. As for the upper body, the results showed an increase in shoulder range of motion with added resistance. The heavier load generally resulted in a greater disruption to normal acceleration kinematics compared with the lighter load. Lockie, R.G., A.J. Murphy, and C.D. Spinks concluded that a lighter load is most likely best for use in a speed training program.

Letzelter et al. (1995) studied the acute effect that different loads had on performance variables with a group of female sprinters during sled towing. The research found that a 2.5-kg load resulted in an 8% decrease in performance over 30 m, and 10 kg resulted in a 22% decrease in sprint performance. Stride length was affected to a greater degree than stride frequency by the increased resistance. As the load increased, the stride length decreased which, accounted for the decrease in velocity speed. Increased loads also caused increased upper-body lean and increased thigh angle at both the beginning and the end of the stance phase. Regrettably, Letzelter et al. did not quantify towing loads relative to body mass or provide anthropometric data on the subjects. It is therefore complicated to relate the results found to earlier recommended loading guidelines.

Spinks C.D., Murphy A.J., Spinks W.L., Lockie R.G. (2007) did a study on effects of resisted sprint training on acceleration performance and kinematics and found that an 8 week resistant speed training group significantly improves acceleration and leg power but, is no more effective than an 8 week non resistant speed training program. Although the study did not find it more effective, how can an athlete increase force production and not increase speed, maybe longer research study should take place.

Both Lockie et al., Letzelter et al. and Spink’s et al. studies concluded that the athletes stride length decreased as the load increased. Mutually, both also found that stride frequency did not change much at all with the different loads. Although this is great information neither one of the researchers put any of this to the real test, “Can towing increase speed?” They both gave great information but what coaches want to see are results. A good number of coaches by now should know that your speed is only as good as your technique but, if a greater load can increase arm speed which both researchers agreed, and arm speed accounts for 15-20% speed how can both suggest a lighter load is better for speed training, more research is needed.

Other Types of Resisted Speed Training

Supplementary, to towing there are many other types of resistant training. Some other types of resistant speed training are weighted vest, uphill running, and sand sprinting.

A study by Bosco et al. (1986) looked at the effect of increasing body weight (7 to 8%) on sprint athletes over a three-week period, training 3 to 5 sessions per week. The added resistance through weighted vests was worn from morning to evening and the athletes were tested for jumping and running on a treadmill, pre and post experiment. The jump tests included squat jumps, countermovement jump, drop jump and 15 seconds continuous jumps on a resistive platform. The squat jump improved 4.5 cm which helped the hypothesis that the increased loading would have a positive effect upon force production and running speed. Another positive effect of weight vest is that the added mass would increase the vertical force at each ground contact; which would increase the stress placed on the stretch shortening cycle (reactive strength). This would improve the muscle’s capacity to tolerate greater stretch loads, store more elastic energy, and improve power output, which may increase in stride length. Although Bosco et al (1986). brings up great and valet points about the SSC, how does he know for sure if increasing vertical force in the ground is even beneficial as far as sprinting goes. Remember, your speed is only as good as your technique.

Uphill sprinting had a study conducted by Kunz & Kaufmann (1981) on sprint kinematics maximal sprinting up a 3% incline. They found the velocity to be slower than that of level ground running (8.35m/s to 8.85m/s) and that the subjects sprint kinematics had shorter stride lengths and longer ground contact times. Kunz & Kaufmann believe that uphill sprinting will increase the stress placed on the hip extensor muscle groups as the athlete will attempt to maximize stride length, therefore increasing this component on the flat surface. They feel this training method will develop a shorter ground contact time if the athlete emphasizes fast push off to conquer the effects of the positive grade. An incline of greater than 3% would still be beneficial in developing the forceful hip extensor movements required but will be less specific in the simulation of the specific technical movements of the sprint.

Sand sprinting had little to no research on it. The little research on sand sprinting concluded that it helped increase hamstring strength as well as its flexibility due to the sands unstable surface. Oviatt and Hemba (1991) wrote an article named Sand Blast and in it, stated that “Walking in the sand, however, is almost twice as costly (energy expenditures for physical activity) as walking on firm turf. It follows that sprinting in the sand will compound energy expenditures of a 50% increase. In other words, you can get twice the cardiovascular conditioning in half the time, which, is important because body fat between muscle fibers inhibit rapid contractions of the involved muscle.

Resisted Towing and Kinematics

Steven LeBlanc and Pierre L Gervais (N/A) researched the basic kinematics of sprinting under assisted and resisted conditions as compared to free sprinting in the acceleration and top-speed phases. Free Sprint and assisted sprint kinematics will not be discussed in this section only resisted kinematics compared to sprint start will be discussed because of resisted sprints have more of an impact on acceleration. LeBlanc and Gervais completed 3 trials of resisted sprinting, and a sprint start, using 1 female and 5 male track and field athletes from the University of Alberta. Each sprint was approximately 50m in distance, the participants were also filmed. The linear kinematic measures of interest included average running speed, stride rate, stride length, and ground support time. Angular kinematic measures of interest included average trunk angle, thigh range of motion and peak velocity. The resisted sprinting condition used a parachutechute approximately 1 m2 attached to a waist belt and subjects were given a 30m acceleration zone prior to the filming area to reach top running speed. For the sprint start condition, the blocks were setup 20m prior to the filming area. They established is that there were no significant differences in any of the kinematics being tested and that RS and SS were very similar in average running speed (8.74 m/s vs. 8.76 m/s), stride length (4.03 m vs. 3.92 m), and support time (0.122 s vs. .123 s). This suggests that resisted sprinting has similar kinematics to the acceleration phase of sprinting much more than the velocity phase.

Conclusion

Resistant speed training’s research on overall effectiveness indicated that all but sand sprinting decreased stride length and had little or no change to stride frequency. Most of the research confirmed that resistant towing is very similar to the acceleration phase of a sprint which is the start. However, there is no well-built indication any of these types of resistant training are better than the other.

From a coaching stand point many professionals today prefer towing because of the trunk position having a forward lean. An athlete cannot have that much of a forward lean with any other resistant speed exercise because of gravity. Sprinting uphill may come a very close second but still one cannot accomplish the lean of that with a weighted sled. Even with the weighted vest the research indicated that the force in the ground hit vertical meaning the athletes’ ground time was too long. The reason for this may be because the athletes in the research could not handle the weight of the vest and stood up tall to not fall over; keep in mind, many coaches look at a sprint as just a controlled fall. Sand sprinting is also a great resistant speed exercise but, there just is not enough research and data on this type of resistant exercise to put it at the top.

Resistant towing had the majority of the research in all the resistant training modalities but, all had the same conclusions decreased stride length and had little or no change to stride frequency and increased muscular force output, especially at the hip, knee, and ankle. In fact, Mero (1998) found a high correlation between force production in the start and in the velocity phase of the sprint. This indicates a high level of fast force production in top sprinters and reaffirms the importance of strength during the acceleration phase of sprinting which, one can get through resisted speed training.

In the future, there needs to be more research with resistant speed training. For instance, the Spinks (2007) study indicated that there was not significant increase in sprint performance comparing resisted sprint training and non resistant sprint training but, did they take sprint technique or start technique in consideration. As mentioned previous if an athlete can increase ground force through resisted towing as Spinks (2007) mentioned, how can the athlete not become faster with the proper coaching on the technique of sprinting. That is what wrong with the research, there is a lot of research but very little coaching in the research.

Issues in research for resistant speed training should compare different types of resistant training with proper speed technique coaching and see how they compare to overall speed improvement and kinematics. The reason kinematics is still important is because again an athletes’ speed is only as good as their technique. It is great to know from all this research what is happening biomechanically or muscularly but, the important outcome to all is which will help make you faster in the shortest amount of time. Coaches and athletes want to know the best modalities of resistant speed training and how they compare to each other, more importantly how they compare to overall speed improvement.

References

1. Bosco, C., Rusko, H., and Hirvonen, J. (1986). The effect of extra-load conditioning on muscle performance in athletes. Medicine and Science in Sports and Exercise. 18(4), 415-419.
2. Faccioni, A., (1993) Resisted and assisted methods for speed development. Part 2. Strength & Conditioning Coach. 1(3), 7-10
3. Gervais, P., LeBlanc, J. S. (N/A). Biomechanical analysis of assisted and resisted sprinting. Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Alberta, Canada. 1-4.
4. Kunz, H., Kaufmann, D.A. (1981) Biomechanics of hill sprinting. Track Technique. (82), 2603-2605.
5. Letzelter, M., Sauerwein, G., and Burger, R. (1995). Resistance runs in speed development. Modern Athlete and Coach. (33), 7–12.
6. Lockie, R.G., A.J. Murphy and C.D. Spinks. (2003). Effects of resisted sled towing on sprint kinematics in field sport athletes. The Journal of Strength and Conditioning Research. 17(4), 760-767.
7. Mero, A. (1988). Force-time characteristics and running velocity of male sprinters during the acceleration phase of sprinting. Research Quarterly for Exercise and Sport, 59(2), 94-98.
8. Oviatt, R. and Hemba, G. (1991). Oregon State: Sandblasting through the PAC. National Strength & Conditioning Association Journal. 13(4), 40-46.
9. Spinks C.D., Murphy A.J., Spinks W.L., Lockie R.G. (2007). The effects of resisted sprint training on acceleration performance and kinematics in soccer, rugby union, and Australian football players. The Journal Of Strength And Conditioning Research. 21 (1), 77-85.
10. Tabachnik, B. (1992). The speed chute. National Strength & Conditioning Association Journal. 14(4), 75- 80.