Reducing ACL Injury Risk

In my first summary of a pair of excellent review studies addressing non-contact ACL injuries, I listed the modifiable factors. Review that article here. This article summarizes how and why training can reduce the risk of injury.

You can also access the full review studies here and here. (References in parentheses refer to these articles)

KEY POINT

"The implementation of interventions that incorporate core stability training, including proprioceptive exercise, perturbation, and correction of body sway, has the potential to reduce knee, ligament, and non-contact ACL injury risk in both female and male athletes [79]." By contrast, "continued performance in the presence of faulty technique increases the likelihood of the athlete’s sustaining a training induced knee injury." [56]

It seems that non-contact ACL injuries can be brought down to posture at landing or during movements. Most of the athletes (if not all) who would fall into the the at-risk category are not aware of it. A good start for reducing risk would be education- teach them what it is that is putting them at risk so that they are aware. Consequently, athletes will work with trainers and coaches in their efforts towards "technique modification, proprioception training, and plyometric training [as this] is essential to evoke changes in kinematics and kinetics of joints during sports tasks."

The conundrum of training is that some of the components that will be mentioned here as measures of training effectively, and thereby reducing the risk of injury, are age specific. Young players learn to kick, throw and jump as is appropriate for their level. As they mature physically, training/coaching generally only "matures" in that the intensity is increased- kick further, jump higher, run faster. This is not surprising at all as there is a natural shift from the fun in learning the fundamentals to more results driven competition. Feedback in practice is concerned with tactics, rather than technique; positional play, when it is incumbent upon coaches and trainers to realize that there are fundamentals at every level. But, thus driven, the window at which training technique would be most effective both for performance and injury risk reduction may be passed by. A recent article was published suggesting that "ACL injury risk can be reduced by 72% in players who begin an injury prevention program during their early and mid-teenage years."

STRENGTH TRAINING FOR MUSCLE WEAKNESS

The injury prevention/performance enhancing benefits of strength training do not lie in the strength of the muscle. Instead, they lie in the muscle's ability to activate and react in time and in sequence with the other muscles involved in a movement. Consider the hamstrings.

Hamstrings have an important role in protecting the ACL by preventing or decreasing the anterior, varus-valgus, and rotatory displacement of the tibia on the femur. Hamstring recruitment reduces the load imposed on the ACL from the more powerful quadriceps [155, 185], and by resisting anterior and lateral tibial translation and transverse tibial rotations, may help to provide dynamic knee stability [104].

Strength training is the obvious solution to cases of muscle weakness. Overall, training aimed to improve hamstring-to-quadriceps, hip, and trunk muscular strength is considered adequate to reduce the risk of non-contact ACL injuries. Eccentric loading of the hamstrings was shown, in various studies, to be more effective in increasing hamstring-to-quadriceps strength ratios than traditional concentric exercises in professional and semi-professional male soccer players.

STRENGTH TRAINING FOR ALIGNMENT AND JOINT STABILITY

Dynamic joint stability is provided by muscles as well as the elastic components of the musculotendinous unit, the sensorial and neural system. Single-component preventive programs have limited impact on biomechanical risk factors, as they may be too focused on the muscle component thereby minimizing potential improvements in other important components of the dynamic joint stability function.

Because muscle actions must be coordinated and co-activated in order to protect the knee joint [185], antagonist–agonist relationships are crucial for joint stability. Hence, preseason and continued in-season conditioning focused on hamstring strengthening is indicated. Research also shows that "coactivation of gluteus maximus and medius and hip joint position are essential elements to provide a safe biomechanical profile." Further, "relative weakness of the abductors, extensors, and external rotators, compared to the flexors and adductors, coupled with increased hip flexion , may severely limit the ability of the gluteal muscles to stabilize the hip and maintain a neutral alignment of the hip and knee [69]."

Both joint stability and muscle co-activation were adequately addressed following plyometric training. "The plyometric component of preventive programs trains the muscles, connective tissue, and nervous system to effectively carry out the stretch-shortening cycle and focuses on proper technique and body mechanics [29]. Following training, a significant increase in firing of adductor muscles during the preparatory phase was noted. A significant increase in preparatory adductor-to-abductor muscle co-activation was identified, as well as a trend toward reactive quadriceps-to-hamstring muscle co-activation."

LANDING

Landing presents a load of several time the athlete's body weight on the knee. Typically its the "extended hip and knee joint posture upon landing" that poses a risk. Coaches need to teach their athletes to land softly, "with initial contact at the forefoot with hip and knee flexion with knees over the toes." Also, it was shown that increased trunk flexion during landing avoided excessive anterior translation. This is a more desirable landing technique in order to reduce the risk of non-contact ACL injuries [32, 65]- land on the balls of their feet and sink into the ground, bending knees and hip, as in a squat.

EXPECT THE UNEXPECTED

Cutting maneuvers performed in response to changes in the direction of play, or a dribble constitute a particularly high risk position in soccer. This is mainly because players have so little time to respond if they want to keep up. The results are unplanned movements, unaccompanied by the small steps and other changes in posture which ordinarily decrease the external varus/valgus and internal/ external rotation moments applied to the knee. Warned, players can prepare better and it is therefore advisable to add components of visual cue interpretation to increase the time available for pre-planned movement.

In support, Nyland et al. support programs that focused on coordinated lower extremity closed kinetic chain tasks-

• mini-squats, 
• single-leg vertical and horizontal hopping,
• lateral shuffles in a mini-squat position,
• back pedaling, and 
• quick multidirectional movement responses to cues [56]. They recommended that these tasks should be performed progressively and with an emphasis on movement quality.

Besier et al. further recommended that training should involve drills that familiarize players with making unanticipated directional changes. Applying all reason and precautions for safety, practice should mimic as much as possible the game situation, particularly in speed and tempo. Drills are often slow so that even if players are familiar with certain movements, it is the added speed and perturbations that predispose them to injury during matches.

Applying these will go a long way in decreasing the risk of injury and improving performance as well.

The Wisdom of Coaching II

The Charlie Francis Training System is one of the most powerful books I have ever read. I highly recommend it to anybody who is interested in learning how to train (or become!) a successful athlete. In a previous post, I shared some of the quotes from it. Here I share a few more (all unless otherwise referenced), as well as quotes from other sources:

"The basic principle underlying all training is to bring only a fully regenerated (rested/recovered from a previous performance) athlete to each training element. The element is then performed with the highest quality possible."

"The great majority of athletes are [still] training and performing with hard-spasmed muscle (both organ and skeletal muscle) with the result that a full complement of tissue is not being presented to the training stimulus, let alone involved in performance. This fact becomes doubly significant when one considers that the body must use protective inhibition in the presence of such spasmed tissue in order to survive training and performance without injury."- Paul Patterson

"If you try to communicate with an athlete when he or she is upset, very little of what you say will penetrate."

"I never write programs on paper for an athlete because....this [manner] will prevent the athlete from ever taking responsibility for their own training. Athletes must interpret training programs through their bodies; programs written on paper redirect the athlete's focus and encourage athletes to interpret training programs through their heads."

"Some coaches dump too much information on the their athletes which is either an attempt to prove to the athletes that they are smart or it is a reflection of the coaches' poor communication skills."

"Whenever you are in a really pushy type of program and are always trying to get athletes to do stuff, you can't be listening to them because they are not listening to themselves; they are simply busy trying to do what you asked them to do."

"You must keep the lines of communication with your athletes open, otherwise you are both in real trouble."

"Plan your work, work your plan."

Some thoughts from other authors:

Direction-Specific Leg Power: The traditional test for power has been the vertical jump test, highly relevant considering that we jump quite often for headers- depending on the position, of course. However, to suggest heading is the only place power is utilized in the game is to grossly underestimate its demands. Kicking, running, cutting maneuvers all require power but they are not vertical in direction. As such Jennifer K. Hewit, PhD, CSCS discusses Direction-Specific Leg Power. This seems obvious but we rare quantify power in these 'other-direction' movements, giving them their proper value in the testing process. To quote, "... testing athletes's power capabilities in only one direction limits the amount of information gained from testing that is used to develop and implement appropriate training programs.." "...therefore, assessing athletes' unilateral leg power capabilities across multiple directions is recommended when compiling a complete athlete profile for programming, performance and progression purposes." More info here.

Mechanisms of non-contact ACL injuries

In a review of data spanning over a decade, a number of risk factors were identified as far as non-contact ACL injuries are concerned. Female athletes, it appears are at 6 times greater risk than their male counterparts in the same sport and when matched by age, level of play, etc. The review studies are very technical, with the authors having used biomechanical terms for large sections of it. It would negate their work to try to present their work any differently so I have highlighted the key things in an attempt to make it more "user friendly." For those with the prowess for biomechanics, anatomy and physiology, I have posted links to the actual studies at the bottom of the page.

Risk Factor Summary

• The "Position of No Return"
• Weak hamstrings (I discuss risk factors for hamstring injury here, and here.)
• Inefficient gluteal muscles
• Poor or lack of Pelvic Stability
• Poor or lack of Knee Stability
• Core Stability
• Decreased Muscle Stiffness
• Decreased Proprioception
• Fatigue

The greater majority are related to valgus collapse- the knees coming together when you drop down into a squat. This is not a risk factor in itself, but it increased the potential for an ACL injury in the presence of load. However, there is a position the authors dubbed "the position of no return" - hip low forward flexion, hip adduction, hip internal rotation, knee valgus, knee extension, and knee external rotation may place the ACL to a high risk of rupture.

Boden et al. reported a lower extremity alignment associated with non- contact ACL injury in which the tibia was externally rotated, the knee was close to full extension, the foot was planted during deceleration with valgus collapse at the knee [17]. Teitz reported very similar deceleration positions and indicated that most often the center of mass of the body was behind and away from the base of support (area of foot to ground contact) [177].

Anterior pelvic tilt places the hip into an internally rotated, anteverted, and flexed position, which lengthens and WEAKENS THE HAMSTRINGS and changes moment arms of the GLUTEAL MUSCLES [37]. Hamstring muscles are important to prevent static and dynamic genu recurvatum and to prevent anterior tibial displacement. Gluteal muscles are important to assist hip flexion (gluteus maximus) and to prevent a dynamic valgus collapse (gluteus medius). Anterior pelvic tilt also increases knee valgus and subtalar pronation. It is debated whether the risk is caused by the altered pelvic position itself, or by the functional malalignment it creates [167]. What is important in any case, is that PELVIC STABILITY IS KEY.

Femoral torsion is defined as the angle between the axis of the femoral neck and a transverse line through the posterior aspect of femoral condyles [122]. Femoral anteversion, an increase in the mentioned angle, may cause GLUTEUS MEDIUS INEFFICIENCY. A WEAK GLUTEUS MEDIUS may influence dynamic valgus collapse because of the muscles’ inability to keep the hip abducted, especially during weight-bearing activities such as landing, cutting, or changing direction.

Landing, cutting, and pivoting maneuvers in some females have been shown to differ from males [51, 52, 115]. Essentially, female soccer players perform playing actions with increased adduction and internal rotation of the femur, reduced hip and knee flexion angles, increased dynamic knee valgus, increased quadriceps activity (with a concomitant decrease in hamstring activity), and DECREASED MUSCLE STIFFNESS around the knee joint [69].

Studies show that ISOLATED QUADRICEPS CONTRACTION near extension strained the ACL more than exercises with co-contraction of both quadriceps and hamstrings [48]. Chappell et al. [28] found that female soccer, basketball, and volleyball players prepared for landing with increased quadriceps activation and decreased hamstring activation, which may result in increased ACL loading during the landing of the stop-jump task and the risk for non-contact ACL injury.

In contrast, WEAK HAMSTRINGS contribute to a greater ground reaction forces that place the ACL at a higher risk of rupture [71]. On the other hand, peak landing flexion (reflecting net quadriceps muscle activity) and extension moments (reflecting net hamstrings muscle activity) at the knee did not change after training and were not significant predictors of peak landing force.Hamstring muscles are important to decrease anterior shear forces and greatly reduce load on the primary restraint to anterior tibial motion, the ACL [7, 126]. Through knee joint compression, hamstrings limit anterior tibial translation by allowing the concave medial tibial plateau to limit anterior drawer [82] and by allowing more of the valgus load to be carried by articular contact forces, protecting the ligaments [71]. Moreover, hamstring compression could protect against torsional loading, which has been found to be greater for females compared to males [104, 189]. Women demonstrate decreased hamstrings-to-quadriceps peak torque ratios and increased knee abduction (valgus) moments compared to males [71]. Hamstring muscles are activated by ACL receptors when the ligament is placed under stress, which evinces the hamstrings' support to the ACL as an antagonist. This ACL receptor- dependent muscle activation suggests that DECREASED PROPRIOCEPTION could have an impact on KNEE STABILITY.

Muscles crossing a joint provide stability to that joint. In other words, muscle stiffness, or the resistance to dynamic stretch may protect ligaments from rupture when a load is applied. The quadriceps and hamstring muscles provide anterior–posterior joint stiffness. Others suggest that sagittal plane knee joint stiffness is also relevant for ACL injury prevention. Studies demonstrate that female athletes show less muscular stiffness than their male counterparts [58, 59, 67, 79, 88, 161, 186, 189]. Males activate their lower extremity muscles significantly earlier [67], and have longer activation duration in muscles that initiated and maintained knee (gastrocnemius) and lower extremity stiffness (gluteus) than women [88]. DECREASED MUSCULAR FITNESS in females was shown for both anterior tibial translation [58, 59, 81, 88, 186] and rotational forces [58, 59, 161, 189].

Since muscles contribute to joint stability, muscular fatigue might be a risk factor for ligament injuries. FATIGUED MUSCLES are able to absorb less energy before reaching the degree of stretch that causes injuries [108]. Gastrocnemius muscles act as a synergistic and compensatory dynamic knee stabilizer in a closed kinetic chain situations as the quadriceps femoris muscles fatigue [140]. McLean et al. concluded that fatigue-induced modifications in lower- limb control, such as this, may increase the risk of non-contact ACL injury during landings.

Comparative studies have demonstrated that female subjects prepared for landing with a decreased hip and knee flexion angle which may result in increased ACL loading during the landing of the stop-jump task and the risk for non- contact ACL injury [28]. It was postulated that a decreased hip and knee flexion angles at landing places the ACL at a greater risk of injury, because a GREATER PEAK LANDING FORCE is transmitted to the knee [74]. Burkhart et al. [25] reported in a prospective research study that an athlete who landed with an increased heel to flat-foot loading mechanism was more likely to sustain to a non-contact ACL injury during competitive play.

Trunk displacement in any plane was greater in athletes with knee, ligament, and ACL injuries than in uninjured athletes. Lateral displacement was the strongest predictor of ligament injury. Trunk displacements, proprioception, and history of low back pain predicted knee ligament injury with 91% sensitivity and 68% specificity. This model predicted knee, ligament, and ACL injury risk in female athletes with 84, 89, and 91% accuracy, but only history of low back pain was a significant predictor of knee ligament injury risk in male athletes [199]. Therefore, CORE STABILITY may be an important component of ACL injury prevention programs.

Here is the link to Part 1 of the original review article.

In this article, I discuss ways of reducing the risk of injury, now that we know what the risk factors are.

What Makes You Think You Can Coach- Part 2

There is often the question of whether a great player will necessarily (and automatically) be a good coach. Maradonna has provided evidence that that is not a given. Sir Alex Ferguson, Jose Mourinho and Arsene Wenger have and continue to argue that a great career as a player is not a prerequisite for a great coaching career. However, we cannot ignore the runaway successes of Pep Guardiola, Frank Rikjaard, Jurgen Klinsman and many others. At the end of the day, what matters is results.

But, concerned with youth sport as I am, the result-oriented approach is misguided, inappropriate and even dangerous. Many a poor coach have destroyed the dreams of young players whether it is by inappropriate practices which have led to injuries or simply discouragement that has turned players away from the game. For my part, the opportunity to compete in an environment in which I could have proven my worth and gone on to greater things was frustrated. Others have not been as lucky- unlucky?

CASE STUDY

Not long ago, I met an athlete 17 years of age. She's been playing basketball for a few years. Her love for the game is not left to question- she is officially in the off-season and is playing community basketball to stay in shape. Her regular season had ended poorly as it had the year before. They had played for 2 hours a day, five times a week, six if you counted the game on the weekend. Not seeing the results he wanted, the coach had requisitioned an additional before class session 2-3 times a week, for the players to put extra work towards their weak areas.

• Where was periodization? Is it possible that the ridiculous volume of work could be part of the problem?

What are your strategies/techniques for recovery? In typical teenage speak, she said, "I don't know. I just sleep or watch TV when I'm not going to school, or if I'm not working."

What are you eating before and after the game? "Does it matter that much? Like in the mornings, I don't eat anything because I'll be late for the session. Then I'll have a bagel or something like that. Generally, I eat whatever I feel like from the stuff we have at home."

What are your athletes eating?

She came in to see me because she wanted to lose a few pounds- she thought she was a little too slow. Also on her list of goals: increase endurance ad upper body strength. Other than a few ankle sprains here and there, and occasional aches in her hips, she had no major injuries to talk about. I proceeded with a basic movement screen to establish a baseline. Her scores were poor and I wasn't surprised. After doing the deep squat, she added as one of her goals she wanted to jump higher. Her knees collapsed as soon as she started her descent, but I thought explaining valgus to her would not be very productive. Instead, if I could ask her to jump, point it out, do some correctives, and then have her jump again, she could see and feel the difference.

(Image from fitnessgoop.com)

"I don't know how to jump. I've always been told I don't know how to jump but nobody has ever shown me how."

If a basketball coach is meeting his athletes 5 times a week, sometimes twice per day, and his forward can't jump, what is he coaching? Was this athlete lucky to have gone through several coaches, all of whom told her she can't jump but didn't show her how to? After all, she is still playing the game she loves. Or was she unlucky, for the same reason? After all, she is still playing the game she loves, whereas I walked away.

As a youth coach and personal trainer, my job, I believe is set the foundation so that my athletes can go on to collegiate and/or professional careers if they wish. Regressing to teach an athlete how to jump, or cutting down the number of sessions so that they rest adequately- these will give my athletes durability. This should not be sacrificed for a good win-loss record at the end of the season.

Ever had a bad coach? Tell me your story in the comments section below.

What Makes You Think You Can Coach?

As I reflect on my own experiences and those of others, I have to say I am disappointed. There is even a hint of anger, but I have a better hold of my emotions than that. I just can't help wondering though, what is it that makes some people think they can coach?

I remember trying out for the university soccer team. I even bought new cleats. We were allotted two hours to practice. With a good practice plan, clear objectives, tests and/assessments of some sort, by the end of the first session, the coach would know who's who and start to develop his roster. Mentally, I was prepared. On course to earn my bachelor's in Human Movement, I knew the science. Having completed a national level coaching course, I knew how to win the game from the side line, the dug-out and the locker room. More than just the weekend warrior when it came to actually playing, I was ready to go. After a brief intro, the man in charge blew his whistle start us off on a warm-up jog around the field.

                               

Perhaps I approached it with too much head knowledge, or maybe, that knowledge spared me from a season that would have been very frustrating. Seventy-five minutes after that first whistle, we were still running around the field. We had had more touches of the ball when we were messing around before practice had officially started. I couldn't find the coach anywhere. Until he came back, we were to keep running. The rest is an ugly blur in my mind, except for the questions that ravaged my mind then (and now).




Why were we running? Why is perhaps the most powerful question and the answer has the capacity to make or break the spirit. When personal training, I don't enter into any agreements with clients who do not have a definite why. Why do you want to lose weight? Why 15 pounds? Why? Why? Why? Why will energize you when you lose the drive to carry on? "When you are about to give up, remember why you started in the first place."
                     

Question. It's a good question. It also rarely gets asked. soshable.com (This caption was so good, I felt I should leave it as is.)

For my part, there was no justification for running around the field, seventy-five minutes later no less. My why would receive no satisfactory answer. You will never see anyone running around the field at a soccer match. What we were doing would have been more appropriate back in primary school when I ran cross country. It doesn't take a genius to figure out that soccer is an intermittent sport- stop and start. Sprint, jog, walk, sprint. Running at the same pace for over an hour does nothing for the aspiring soccer player. You can't even justify it with the old soccer players need a good heart or aerobic conditioning. Research shows that interval training has benefits for both aerobic and anaerobic capacities. I have already discussed these in this article here and this one as well. The evidence suggests different positions have different requirements for maximal performance. Surely you train them differently, holding them to different standards?

                     

Bottom line, this guy did not know what he was doing. I walked away sensing conflict between he and I. Of course, as the man in charge, in any confrontation I would always be on the losing end. His coaching style was nothing more than what his coach had made him do. That philosophy probably came from his coach's coach, and his before him. Coaching is an art- a mix of science, practice and some simple common sense. Common sense was not on the field that day- if you could somehow convince me why it was necessary for the outfield players to run like that, what would be the rationale for the goalkeeper running around the field for over an hour?

The Wisdom of Coaching

Every now and then, you come across someone who blows your mind. Someone who has put into eloquent words things you have only had musings about. Someone who has perfected what you have stumbled upon. Someone who draws a 'wow' from you, and has you looking into everything he/she said or did. One such a man for me is Charlie Francis. Charlie represented Canada at the 1972 Olympics in Munich before coaching sprinters, as well as professional football, hockey and soccer players. Of the many things he said and taught, I thought I'd share these.

FOR COACHING YOUNG ATHLETES

"Correct technique is the necessary prerequisite for an athlete...for optimal development to occur. The neural motor patterns of correct technique must be wired in place [as young as possible]." This quote from Siff, out of the book Supertraining, explains adequately Charlie's thoughts. "It is not only the exercise which modifies the body, or more specifically, the neuromuscular system, but the way in which the exercise is performed. In this regard, it is vital to remember that all exercise involves information processing in the nervous and neuromuscular systems, so that all training should be regarded as the way in which the body's extremely complex computing systems are programmed and applied in the solution of all motor tasks."- Siff (I have used this concept of programming in another article: Specificity of training).

"Always reinforce correct technique for the purpose of developing positive self esteem. Give athletes praise for their efforts- never criticize or ridicule."- Over the years, as I have coached different sports and different age groups, I have learnt the difference between developmental and biological age. There is a continuum when it comes to maturation on the physical, emotional and mental facets of every person, athlete or not, youth or adult. With this realization, I like to invoke loco parentis as soon as my time starts. This means taking charge over the content and even the tone used to address my players, even from their parents. I have seen careless sarcasm hinder and eventually turn away youth from participating from a sport they would have otherwise enjoyed and become very good at. Bottom line, coaching is building. Does your style enhance the self-esteem of the players in your charge?

"Coach one element at a time...Don't move away from one training element until it is correct. Teach increasing levels of skill- according to the individual's needs when the athlete's body and performance of training elements indicate a readiness to handle them."- I am a big fan of testing. My experience as a personal trainer has contributed to my thoughts on this point. Too many coaches and trainers do not bother with assessment with a couple of consequences. First, athletes are exposed to increased risk for injury as we, to quote Gray Cook, "add strength to dysfunction." Plyometrics are high impact and I have seen them imposed on weak ankles and knees that constantly display valgus collapse.

Secondly, the appropriate periodized program is important and can pretty much guarantee results. However, amongst those that use it, some hold rigidly to their micro and macrocycles. The attention that athletes and clients deserve is sacrificed leading to frustrating results. In most cases, the reaction from the coach is to blame the athlete for lack of effort, and push the even harder. Take the case of this seventeen year old girl.

Charlie's words are gold dust. Let the athlete's response determine progression.

"Youth training must not have too much low intensity. There must be enough high intensity so as to:

1: maintain and improve specific skill

2: Prevent loss of and maintain correct volume of fast twitch fibre

3: Promote differentiation of transitional fibre to fast twitch rather than slow twitch fibre."

Although this is specific to sprinting, I think it applies to other areas too. I have previously posted an article citing the ACSM's position on resistance training for juniors. It basically says that under qualified and careful instruction, strength training in safer than football, basketball and many other sports. The majority of athletes go through the prime years for instruction in elements that would lay the ground work for elite performance without that instruction because the coaches just don't know about it. The differentiation and specific instruction Charlie addresses here is foreign to many a program.

To be successful coaches, we must read more, and read our charges even more.

Specificity of Training

Tiger Woods hits about 1000 golf balls a day- he is back at the zenith of the PGA tour, and its only a matter of time before he wins another major. Michael Phelps reportedly swims for six hours a day, six days a week, without fail. He is now the most decorated Olympian- ever. These, and many others, are pros already, so why persist? Because they are programmers.

"It is not only the exercise which modifies the body, or more specifically, the neuromuscular system, but the way in which the exercise is performed. In this regard, it is vital to remember that all exercise involves information processing in the nervous and neuromuscular systems, so that all training should be regarded as the way in which the body's extremely complex computing systems are programmed and applied in the solution of all motor tasks."- Siff

THE SCIENCE OF A FREE KICK

An approximate 10 000 hours of practice is required before a skill can be mastered, before it can become second nature, automatic, and you can be called an expert. This automated response, in neurophysiological terms, however simplistic, is the formation of an exact pathway. Take for example, a David Beckham free-kick. As he prepares, he stands with his right leg slightly forward, his body at an angle. Were he standing upright, legs together, his hip flexion / extension would be at neutral, or 0°. Fast forward his run-up and single out the right foot he is going to strike the ball with. According to Levanon and Dapena, (1998), during the backswing phase, the kicking leg moves backwards, with the hip slowly adducted, externally rotated and extending up to 29° and moving somewhere between 171.9-286.5 deg·s-1 (also Nunome et al., 2002). At the same time, the knee, with some internal rotation, flexes at an angular velocity of 745-860 deg·s-1 (Nunome et al., 2002). Again, in that pre-run up position, feet on the ground, his ankles would be at 0°. While the hip extends and the knee flexes, the ankle is plantarflexed (10°), abducted (20°) and slightly pronated (Levanon and Dapena, 1998) reaching maximum plantarflexion velocities of 860 deg·s-1 (Nunome et al., 2002). On muscular level EMG activity suggests high activation of the iliopsoas during the start of the kick which was followed by a high activation of the rectus femoris during backswing. The biceps femoris and gluteus maximus demonstrated their peaks just prior to ball impact. (Dorge et al., 1999) All this, and he hasn't touched the ball yet.

THE SAME SCIENCE UNDER DIFFERENT CONDITIONS

A complete analysis of the kick is far beyond the scope of this article. What is within it scope is that the environment changes. It may be a shorter, left footed Leo Messi standing over the ball, or an older, medium height but no less competent Zidane. It may be right in front of the goal or some degrees either side of the posts, or even a corner. It may be a direct, or indirect free-kick, a lob during open play or an audacious attempt from the halfway line as Beckham did so many years ago. There could be a wall. Or maybe its the first ten minutes of the game, or the last minute- get this in and win the Champion's league; qualify for Euro, qualify for the World cup. And then there is the variable weather, and the crowd...

In each case, the technique is the same, but the variables must be taken into account if the kick is to be effective. If not- if the hip doesn't swing back far enough, if the knee does not flex that fast or the ankle is not at the optimum angle- I'm sure you know that if you are leaning back, even slightly when you make contact, the ball will rise and Tommy Smyth's 'auld onion bag' wont bulge. That's why they persist.

That's why you must persist. Make your first attempt. Analyze it- what went wrong? How can I change it? Pay attention to that, and try again, factoring in those changes. Got it? Good, now do it again. Whether you got it right or not, whatever you key in to the program will be recorded and that's what the system will produce when its required to. As Siff said, motor skills are a complex business and proper programming is essential. How does the program perform when its really hot outside? What about when its raining? Don't shrink from high pressure situations. Hone your skill during those circumstances just as much as in low pressure ones. Remember skill under demanding conditions is significantly different from skill under less onerous conditions. Program the neuromuscular system to perform optimally- FORM, FORM, FORM.

                                     

We must understand that it is not tireless hours of just kicking the ball that build the skill. Gross repetition of poor quality will never result in the sort of quality that improves play, result, wins trophies, etc. The difference then, between the best and the rest is the feedback they are able to collect during practice and the adjustments that they make as they strive for improvement. To quote Gray Cook (as he reflects on Geoff Colvin's Talent is Overrated), "The specific way practice is executed is what defines the deliberate practice common to those deemed talented." Only perfect practice makes perfect, so practice- perfectly.

References:

Kellis, E and Katis, A (2007). Biomechanical characteristics and determinants of instep soccer kick. Journal of Sports Science and Medicine 6, 154-165 

Levanon, J. and Dapena, J. (1998) Comparison of the kinematics of the full-instep and pass kicks in soccer. In Kellis, E and Katis, A (2007). Biomechanical characteristics and determinants of instep soccer kick. Journal of Sports Science and Medicine 6, 154-165 

Nunome, H., Asai, T., Ikegami, Y. and Sakurai, S. (2002) Three- dimensional kinetic analysis of side-foot and instep soccer kicks. In Kellis, E and Katis, A (2007). Biomechanical characteristics and determinants of instep soccer kick. Journal of Sports Science and Medicine 6, 154-165 

Siff, M. C and Verkhoshansky, Y. V (1999). Supertraining. Fourth Edition.

4 Risk Factors for Hamstring Injury

Have you ever pulled a hamstring? Do you know someone who has? Chances are you answered 'yes' to at least on of these. Several risk factors have been identified, some of which are obvious even to the novice, and some which require a little more skill. Below is a list of 7 factors:

PREVIOUS INJURY

• After examining over 500 amateur players, injured players have been shown to be two to six times more at a risk of sustaining a new hamstring injury. Recurrent hamstring strains have been shown to result in significantly more time lost than first time hamstring strains. 
• Considering the length of a muscle, there is a point at which it is able to produce the most forceful contraction. Graphically, this is the highest point on the length tension curve. Brockett et al., showed that in the previously injured hamstring, when compared to controls, the peak seems to shift to the left. This shift in the length-tension curve suggests that peak hamstring torque occurred at a significantly shorter muscle length, meaning is possible that when an athlete sustains a hamstring strain they potentially return to play with weakness at longer muscle lengths. This predisposing them for a second hamstring strain during the eccentric terminal sprinting movement. 

Image courtesy of FIFA.com

WEAK HAMSTRINGS: EARLY OR LATE? 

• While we know that most hamstring injuries incurred in soccer happen during the sprint cycle, it remains unclear which part of the cycle. Some of the literature supports the early stance phase or while others points to the late swing phase. In the former case, proponents suggest it is during this phase in which the muscle absorbs the most force as a result of high ground reaction forces (GRF). The laws of physics tell us that for every action, there is an equal and opposite reaction. GRF is basically the forced 'produced' by the ground in response to the force applied by the sprinting athlete. Given that the amount of force applied into the surface when sprinting is several times that of the athlete's body weight, it is reasonable to assume that this is a potential cause for injury for the hamstring, whose function is to absorb the the energy. 
• Studies involving the Achilles tendon in sprinting, and patella tendon in jumping and hopping show that the forces are much higher in the concentric stance phase as opposed to the eccentric swing phase and researchers suggest that this may apply to the hamstrings as well. 
• Other studies demonstrate that in the swing phase of the sprint cycle, where the hamstrings eccentrically contract to absorb the kinetic energy and slow the lower limb, they are under significant load. Of particular interest is the musculotendinous area, which is inherently at great risk for injury, because the hamstrings are in a lengthened state. This occurs when the hip is in flexion and the lower leg moves into extension, thus lengthening the two joint hamstring muscle over both articulations upon which they act. From this perspective, eccentric weakness of the hamstrings poses a risk for injury. 

Germany vs Spain.

STRENGTH IMBALANCE

• Legendary sprint coach Charles Francis said, "If an athlete is in a sport where leg strength and power are not required to be maximal, then testing hamstring/quadriceps strength at low to moderate speeds may have some relevance... We looked at five or six of our top athletes [sprinters] and discovered that the average ham/quad ratio was more in the order of 125-130:100." 

IMPROPER WARM UP

• How much time do you spend warming up before a game? Even a recreational one? FIFA's medical research team has found that warming up purposefully can be highly effective, reducing the incidence of injury by up to 50%. See the "11+" program here.
• Poor hamstring flexibility- in a study, it was been shown that soccer players are less flexible than a control group, and that soccer players do not stretch sufficiently.

England National Team warms up. 

TREATMENT

Schmitt et al., proposed a new concept for the rehabilitation and prevention of hamstring reinjury. They suggested the following 3-phase approach:

PHASE ONE

• Immediately following the injury, the basics should be observed. The focus at this stage is to protect the injury while minimizing losses range of motion (ROM) and strength. The RICE principle will be sufficient- Rest, Ice, Compress, Elevate. 
• At 48 hours, the athlete may begin submaximal isometric strengthening. These should be completed as a set of isometric knee flexion contraction at 30, 60, and 90 degrees of knee flexion by placing the injured limb on top of the into opposite limb and contracting the strained hamstring.
• The hamstring should not be stretched into a painful range at this time but available hip and knee ROM should be maintained. 

PHASE TWO

• The objective of this stage is to prepare for the athlete for sport specific movements. Of particular importance are the progressive regaining of strength throughout the ROM and improving neuromuscular control of the hips and pelvis.
• The athlete may begin to strengthen both concentrically and eccentrically at this time. Eccentric training can be achieved by performing exercises such as the straight leg deadlift,
• Single leg windmills.
• To complete an eccentric single leg windmill the patient stands with the uninjured leg on a chair or fixed surface and reaches down in a diagonal plane while keeping stance leg straight and maintaining a neutral spine. (Figure 2), 
• Nordic hamstring exercise. 
• The Nordic hamstring exercise is performed by having the clinician hold the patient's feet while in tall kneeling. The patient slowly falls forward while maintaining neutral hip posture until he or she can't control descent any longer and then pushes back into starting position with upper extremities. (Figure 3).
• The athlete should also be able to jog both forward and backward without pain at a moderate speed at this point.

Single leg deadlift

PHASE THREE

• Rehabilitation focus at this stage is on functional movements and eccentric strengthening in the lengthened state. Plyometric and sports specific training may be initiated as well as advanced balance exercise.
• At the completion of this stage the athlete should have full strength throughout the range of motion and should be able to confidently perform all sport related tasks without limitation.

Below is the the reference and link to the article.

REFERENCE

Brandon Schmitt, B., Tyler, T., McHugh, M (2012). Hamstring Injury Rehabilitation and Prevention of Reinjury Using Lengthened State Eccentric Training: A New Concept. The International Journal of Sports Physical Therapy. Volume 7, Number 3, Page 334

F-MARC's 11+ Warm-up Programme

Various elements mark the elite soccer player, including speed, power, and endurance. Technical and tactical know-how is also prerequisite to reaching high levels of performance. All these elements can be addressed on the training ground. Yet football is a contact sport, and no matter the heights of these elements, there is a substantial risk for injury. Optimal training and coaching, according to FIFA, "should also include exercises to reduce the risk of injury."


                               


The “11+” is an injury prevention programme that was developed by F-MARC's experts. After an extended trial period, across various nations, age groups and levels of play, it is suggested that as "a complete warm-up package" it should replace the pre-training and pre-game warm-up. Their results show that "teams that performed the “11+” regularly at least twice a week had 37% fewer training injuries and 29% fewer match injuries. Severe injuries were reduced by almost 50%."

Like any programme, its efficiency is largely reflected by the level of compliance of those who undertake it. Thus FIFA suggests that the 11+ must become the standard warm-up for all players 14 years and older. the entire programme comprises of 3 parts, representing what the governing body believes to be the key elements of effective injury prevention programmes for football players: core strength, neuromuscular control and balance, eccentric training of the hamstrings, plyometric and agility. Admittedly, it was the plyometric and agility drills (part 2) that proved to be effective in reducing injury, especially of the ACL, but also of other knee and ankle injuries.

As per 11+ manual, "The aim of plyometric training is to decrease the amount of time required between the yielding eccentric muscle contraction and the initiation of the overcoming concentric contraction. Plyometrics provide the ability to train specific movement patterns in a biomechanically correct manner, thereby strengthening the muscle, tendon and ligament more functionally." The correct form, then, is stressed at every point, with every exercise. Lines of alignment between the hips, knees and ankles are highlighted, with soft landings, and it is important that they are observed.

The 3 parts, which should be performed in the specified sequence are roughly as follows:

Part 1: slow speed running exercises with active stretching. A partner is involved later on for some contact in a controlled environment.

Part 2: six sets of exercises focusing on core and leg strength, balance and plyometrics/agility, each with
three levels of increasing difficulty.

Part 3: running exercises at moderate / high speed combined with planting / cutting movements.

Once again, the material can be found at the official "11+" site. http://f-marc.com/11plus/downloads/

Keep the game beautiful!

Passion Is Emotion Under Control

What does it take to get a standing ovation at the Bernabeu?

Heart, vision, control, desire.

I have coached games in which the final results were determined by the man with the whistle. In one game, the opposition were awarded a penalty 2 minutes before time for no reason at all. Even that team's bench and coaching staff were flabbergasted by the decision. We lost, and with that, our chance to go to provincials. In another, my captain was carded; he asked for ten yards for a free kick. The referee walked towards the other team's wall, told them they should know better, and walked away without counting the yards. The addressees shifted a yard or two in response. My captain counted out the yards. The response to the 'you should know better' from the referee was about 5 yards short of the 10. Instead of counting out the yards, and ensuring the wall was where it should be, the ref carded my captain for dissent.

I have also played in matches that were similarly decided. Under the stewardship of men and women that could be influenced, the decisions went the way of whoever could complain the loudest. In one, in the spirit of letting the game flow, the whistle was heard three times in 90 minutes- one to start the game, one to signal the end of the first half and one to signal the end of the match. There were 3 goals in that game. To resume play, the ref simply said "start." He did not blow for fouls, free kicks, off sides- 'he let the game flow.'

Then comes something that every team has and will face at some point- playing a better team. In those 90 minutes, tactics will fall apart. As the game progresses, there will be less of a team, more individuals, each a player and a coach. Fighting ensues between players, and the beauty of the beautiful game is forgotten. It is simply overshadowed by the frustrations of failing to do the simple things well; of impending loss; of the injustices and disadvantages accrued because of poor decisions all around; of playing in front of an unfriendly crowd. Without exception, the emotional athlete will 'lose it', and if you lose it, you lose the game.

I am making a distinction between a passionate player, and an emotional one. The difference- passion is emotion under control. You let what you feel inspire you to believe in your ability to perform, even in a hostile environment. You let what you feel drive you to work hard, never giving up; chasing down every ball; making the pass; making yourself available for one; whatever it takes to win the game. Let passion help you focus on what you can control, what you can change. That is what it takes to get a standing ovation at the Bernabeu. See for yourself...and keep the game beautiful!

Feedback in Practice

I have heard coaches say that what is most important is getting as many touches on the ball as possible. I believe that more important than the number of those touches is their quality.

Considering that the neuromuscular system learns from every trial/touch, a player who has 1000 poor touches teaches his system to perform that skill in that way. Remember, muscles don't know scoring or passing; they know movements. Whatever movements we repeatedly do become the preferred movement. As such, the 1000 poor touches reinforces that movement and the result is a players who has developed a preferred movement which is producing poor results. As a consequence of muscles 'knowing' movements, improvement for this player means that his neuromuscular system must unlearn that movement before it begins to prefer a new one. A simple way to avoid this situation is to consciously interrupt each effort/touch/trial with KR and KP.

KR refers to Knowledge of Results consists of information about the outcome of performing a skill, or whether the intended goal was achieved. It is primarily externally presented, hence 'that was not on target,' 'the ball did no beat the first defender,' etc, are types of KR. KP or Knowledge of Performance, is information about the movement characteristics that contributed to the observed result- 'you were leaning back, and that caused the ball to rise.'

It is important that both types of feedback be provided as players learn individual skills and the game in general, no matter what the sport. There is no saying that one is more important than the other. What must be taught, however, is analyzing the skill with regards to the outcome (KR), and figuring out what was done correctly or incorrectly (KP). The use of video is effective, and easily accessible, considering camera cellphones, etc. Often players are unaware of what they are doing, more so under pressure from the opposition. I have come across players who were told repeatedly that they were doing x instead of y and they could never figure it out or fix it. One responded with, "Why didn't you tell me that's what I was doing?' when he was eventually shown the video and could see himself doing it. Replaying videos will facilitate the learning process, advancing it beyond simple verbal instruction/feedback. Where possible, make it a regular part of practice. It is a common practice of professionals, not only to help them improve but also to learn.

Champions like Kobe Bryant and Tiger Woods, make use of tapes. It is amazing to see the similarities in the moves that Kobe makes from those greats that played before him. Tiger reportedly changed his golf swing four times, when he was number one in the world. If nothing else, the desire that these top athletes have to continue to improve should inspire learner to do the same. I am consistently amazed at the number of young soccer players who don't watch soccer, even if it is just the highlights reel.

I believe that when setting goals, particularly with young athletes, some of those should be expressed in terms of KP. The win-loss column should be secondary to mastering the skills of the game. Heading is a common fear among youth and goals for a game could simply include having more headers that in the game before. Having goals such as this will be helpful when playing a stronger opposition, and will be a source of encouragement even if the game is lost. Did those headers go in the right direction? How did the movement and the preparation for that header affect its outcome? The primary reason for the fear of heading is getting it wrong, and getting it in the face instead, or a throbbing head after. These questions will address both KP and KR separate from the final score and will help the overall goal- skill acquisition.

At a higher level, the ability to analyze a skill, come up with the correct conclusions and make the necessary adjustments for better outcomes, will determine whether a players is effective or not. This concept is best exemplified [for me] in tennis. Regardless of the sport however, this ability must be developed during practice.

Resistance Training For Juniors

At junior levels, training rightly focuses on the technical and tactical aspects of the game. Every now and then, however, a team will field several players that are stronger and faster than their peers. These players evince the observation that chronological age differs from developmental age. In other words, 15-year-old children will vary in the physical characteristics of height, weight, etc, and the athletic capabilities that are resultant. While these cannot be standardized, training can help each player, regardless of their chronological or developmental age, to compete at optimal levels.

Resistance training, plyometrics, high-intensity interval training (HIIT) and repeated sprint training (RST) can be used to achieve these optimal level. However, many parents are unsure of the safety of some these methods of training.

The UPDATED POSITION STATEMENT PAPER FROM THE NATIONAL STRENGTH AND CONDITIONING ASSOCIATION has the following statements:

"In a report, there was no evidence of either musculoskeletal injury or muscle necrosis (death of muscle tissue) after 14 weeks of progressive resistance training." (page 2)

"Youth resistance training, as with most physical activities, does carry with it some degree of inherent risk of musculoskeletal injury, yet this risk is no greater than many other sports and recreational activities in which children and adolescents regularly participate. In a prospective study that evaluated the incidence of sports-related injuries in school-aged youth over a 1-year period, resistance training resulted in 0.7% of 1576 injuries whereas football, basketball, and soccer resulted in approximately 19, 15, and 2%, respectively, of all injuries." (page 2)

"Because weightlifting movements involve more complex neural activation patterns than other resistance exercises, childhood may be the ideal time to develop the coordination and skill technique to perform these lifts correctly." (page 3)

"Another concern related to youth resistance training regards the safety and suitability of plyometric training... plyometric training conditions the body through dynamic movements, which involve a rapid eccentric muscle action that is immediately followed by a rapid concentric muscle action. When the stretching and shortening of a muscle are performed quickly, the force generated during the muscle action is greater than the force that would be generated if the muscle were not stretched immediately before the muscle action. The contention that age-appropriate plyometric training is unsafe for youth...is not supported by current research and clinical observations. Indeed, comprehensive resistance training programs that include plyometric exercises have been found to enhance movement biomechanics, improve functional abilities, and decrease the number of sports-related injuries in young athletes." The NSCA goes on to cite the playground game of hopscotch as plyometric in nature! 'This type of exercise, although game like in nature, actually conditions the body to increase speed of movement and improve power production." (page 3)

"A traditional area of concern related to youth resistance training is the potential for training-induced damage to the growth cartilage...Although children and adolescents are susceptible to injury to the growth cartilage, the potential for this type of injury may be less in a preadolescent child than in an adolescent because the growth cartilage may actually be stronger and more resistant to sheering type forces in younger children...To date, injury to the growth cartilage has not been reported in any prospective youth resistance training research study. Furthermore, there is no evidence to suggest that resistance training will negatively impact growth and maturation during childhood and adolescence." (page 3)

The document is 20 pages in length, including 258 references collected over 38 years (1972-2008). Here is the link for those who may be interested in reading it.

http://www.nsca-lift.org/Education/E-learning/Would-my-Youth-Athlete-Benefit-from-a-Strength-and-Conditioning-Coach-/

Hopefully, this will ease parents' minds, and address some of their concerns over some very important questions they may have had.

Thanks for helping us keep the game beautiful.

Hamstring Injury Prevention In Soccer Players

I was all alone, the ball at my feet. I had a man approaching, but to me that just meant he was leaving space somewhere. A looked over my shoulder and played a perfect, favoured back heel, and off my right-winger went. At the same time, I felt a twinge in my upper right hamstring and my hand was over it reflexively. I had pulled a hamstring. Like anybody else, I tried to walk it off, but to no avail. Ice, heat, rest, foam rolling, and stretching did nothing but tell me how badly I was hurt over the next few days.

While there is no one cause for hamstring injury in soccer players, some factors may be predictive of injury than others. Flexibility abnormalities (Witrouw, 2003), issues related to warm-up and fatigue have been reported as increasing the risk of hamstring strain. Verrall et al., (2005) believe that stretching can improve force absorption for a given length of muscle, thereby making the muscle more resistant to injury that occurs when the muscle is stretched. It has been suggested that strength imbalances play a particularly important role in injury (Crosier, 2004), as it was in my case.

In a study involving 462 professional players, Crosier et al., (2008) found that players with untreated strength imbalances, mostly between the quads and hamstrings, were found to be 4 to 5 times more likely to sustain a hamstring injury when compared with the normal group. They concluded that normalizing the strength profile significantly reduces injury frequency. It goes without saying that performance will be less than optimal in the presence of imbalances as well. Because of the high prevalence of hamstring injuries, a preventive bodyweight and, in time, weight-training program could be undertaken by all players. Programs must include specific sequences targeting increased hamstring strength, particularly in the eccentric mode.


The primary function of the hamstrings, particularly when running, is hip extension. It is the glutes, the hamstrings, and other muscles about the sacroiliac joint that propel the body forward. Thanks to Bret Contreras, I know now about load vector training. Simply put, when we run, our hips move from back to front, (anteroposterior direction), we shout train movements that emphasize that direction as well- remember the principle of specificity. Below are a few exercises that have been my mainstay since my injury and they will, hopefully, help players stay off the sidelines, because of non-contact hamstring injuries, at the very least. This is by no means a comprehensive list, but its a start!

Body weight Exercises

Nordic Hamstring Exercise- I have mentioned this exercise in a previous article. The importance of training the eccentric contraction of the hamstring cannot be overstated. This exercise in particular was included in FIFA's "11+" programme, which has produced such good results, the governing body recommends that it replace the regular warm-ups of players aged 14 and older. This video is from that programme's manual.

Swiss ball hamstring curls

Glute Bridge

Weight Training Exercises- these are for advanced players who have weight training history/experience. Do not attempt these otherwise!

Romanian Deadlifts

Kettlebell swings

Lying leg curls

Lying leg press (legs high on the plate)

Weighted back extensions

Hip thrusts- Since my own injury, I have been doing hip thrusts among my other exercises. Consequently, I have stronger glutes, and for that I am faster without having to worry my hamstring injury recurring. So in honor of the Glute Guy, here's a video of him demonstrating this move he has championed:

References

Croisier et al., (2008). Strength Imbalances and Prevention of Hamstring Injury in Professional Soccer Players. A Prospective Study. The American Journal of Sports Medicine, Vol. X, No. X

Witvrouw E, Danneels L, Asselman P, D’Have T, Cambier D., (2003). Muscle flexibility as a risk factor for developing muscle injuries in male professional soccer players: a prospective study. In Croisier et al., (2008). Strength Imbalances and Prevention of Hamstring Injury in Professional Soccer Players. A Prospective Study. The American Journal of Sports Medicine, Vol. X, No. X

Worrell TW., (1994). Factors associated with hamstring injuries: an approach to treatment and preventative measures. In Croisier et al., (2008). Strength Imbalances and Prevention of Hamstring Injury in Professional Soccer Players. A Prospective Study. The American Journal of Sports Medicine, Vol. X, No. X

Speed and Acceleration in Soccer

Whether it is the forward, collecting a defence splitting pass for a shot on goal, or the defender, trying to prevent that shot, speed is essential to the game. Stølen et al., (2005) recorded that a sprint bout occurs every 90 seconds or so, while high intensity running is separated by 70-second periods. Soccer is, however, a stochastic game, meaning that a player may or may not have to be this engaged in these activities in these specific ways. Still, it makes sense that he or she be well conditioned to do so, should it be required.

Many studies have been conducted in the recent past, with the investigators publishing data that shows that a minute percentage of the total distance covered by soccer players is maximal effort. Amidst different categorizations, technologies and parameters, studies have observed ^[1,4,5,8]  2.1–3.7%, 18.9%, 11.3% and 3% for the total distance covered in sprinting or quick running, considering total distances averaging over 10 000m in a game. According to Bangsbo, sprint speed approximately 30 km/h covered a total of about 400 m only. Notwithstanding, sprints comprise the most crucial moments of the game and “contribute directly to winning possession of the ball and to scoring or to conceding of goals.” (Little and Williams, 2005)

Moreover, an estimated 96% these sprints are less than 30m. Valquer et al., (1998) observed the São Paulo Futebol Clube, who were the top ranked team in the Brazilian national league at the time.

The obtained results were as follows:

Distance (m)	0-9.99	10-19.9	20-29.9	30-39.9	40-49.9	“50	TOTAL	Overall distance
Numbers Sprints	26.4	18.6	7.8	1.4	0.6	0.2	55.0	718.2
SD	5.86	6.23	3.65	1.19	0.51	0.22	12.76	269.7
Frequency	49.0	33.4	13.6	2.5	1.1	0.3	100
SD	9.65	5.32	3.68		1.66	0.74	0.45

Table 1. Frequency of sprints over several distances in elite Brazilian soccer players. Valquer et al., (1998)

The results highlight the importance of acceleration training. Acceleration is the rate of change in speed that allows a player to reach maximum velocity in the shortest possible time. If the majority of the sprints performed during a match are 10m or less, more emphasis must be placed on that aspect of speed development. Currently, tests over 40 yards are administered from a standing start. While there is validity in these results, players most often reach maximum speed from a “moving” start rather than a stationery one. Therefore, it is the change in velocity rather than the initiation of it, that is true acceleration. Cometti et al., (2001) showed that professional and amateur had similar 30m sprint performance, but differed in the former’s 10m times. Theirs were significantly lower, suggesting “the fastest players are, on average 1m ahead of the slowest ones after only 10m of sprint[ing].”

This more recent study, confirms these findings, focusing on the duration of the sprints as much as these report on the length/distance.

The game is not to the fast, but to those who can get fast the fastest!

For your viewing pleasure, one run LONGER than 10m. Enjoy!

Play beautiful!

References

1.    Ali A, Farrally M. A computer-video aided time motion analyses technique for match analysis. J Sports Med Phys Fit 1991; 31: 82–88

2.     Bangsbo J. In Di Salvo V et al. Motion Characteristics in Elite Level Soccer. Int J Sports Med 2007; 28: 222–227

3.     Cometti G, Maffiuletti NA, Pousson M, et al. Isokinetic strength and anaerobic power of elite, subelite and amateur French soccer players. Int J Sports Med 2001 Jan; 22 (1): 45-51

4.     Di Salvo V et al. Motion Characteristics in Elite Level Soccer. Int J Sports Med 2007; 28: 222–227

5.     Little, T., and A.G. Williams. Specificity of acceleration, maximum speed, and agility in professional soccer players. J. Strength Cond. Res. 19(1):76–78. 2005.

6.     Mayhew SR,Wenger HA. Time-motion analysis of professional soccer. J Hum Move Stud 1985; 11: 49–52

7.     Stølen, T; Chamari, K; Castagna, C and Wisløff U (2005). The Physiology of Soccer. Sports Med 35 (6): 501-536

8.     Valquer W, Barros TL, Sant’anna M. (1998) High intensity motion pattern analyses of Brazilian elite soccer players.

9.     Withers RT,Maricie Z,Wasilewski S, Kelly L.Match analyses of Australian professional soccer players. J Hum Move Stud 1982; 8: 159–176