Jan 29, 2015Kicking It Up
To optimize skills while preventing ACL tears and other common injuries, Boston University developed a successful women’s soccer training program based on the sport’s unique physical demands and injury risk factors.
By Victor Brown III
Victor Brown III, MS, ATC, CSCS, NSCA-CPT, is Associate Strength and Conditioning Coach at Boston University. He can be reached at: [email protected].
Soccer competition at the elite college level requires a distinct set of skills and attributes. A player must be technically sound at running, dribbling, passing, and shooting, must change speed and direction in the blink of an eye, switch back and forth between the aerobic and anaerobic energy systems, and perform all of the above while observing and reacting to constantly changing game situations. With every offensive push, clearing pass, corner kick, and 50/50 ball fought for, players show what skills they bring to the table, and weaknesses are exposed by their opponents.
All that is obvious to anyone who has watched soccer–so let’s get a bit more specific. A match involves roughly 90 minutes of moderate aerobic activity interspersed with short bursts of high-intensity exercise that combines walking, slow running, intense running, and sprinting. Soccer studies have found that a typical player performs 800 to 1,000 distinct changes of movement, speed, and direction per game–an average of one every five to six seconds. When a player has the ball, dribbling increases energy demands by roughly 15 percent.
I present these facts to illustrate a simple point: To train athletes for maximum performance gains, it’s essential to first understand their sport from the inside out. At Boston University, we’ve extensively studied the demands of soccer while developing the training regimen for our women’s team, and we tailor every aspect of our program around maximizing the most essential and valuable skills and preventing injuries. With the success we’ve experienced on the pitch, including berths in the NCAA tournament in each of the past four years, it’s clear that our efforts are paying off.
READY TO COMPETE?
All performance improvements–fitness gains, technique advancements, and strength and power building–rely on athletes being healthy enough to complete workouts on a daily basis. When new players arrive in our program, they must prepare to compete against opponents who have been in collegiate strength and conditioning programs for one to three years. So when we evaluate new players, the first question we ask is: Are they ready?
The foundation for that answer is laid long before a player sets foot on a college campus. For example, in a recent study of young athletes, a surprising percentage of females were found to have nearly stagnant levels of hamstring strength from age 11 to 16, and only minimal improvements at ages 17 and 18.
Why is this important? Many first-year players enter a program having played high-level club and high school soccer, where they develop the technical skills to excel at the game. But that doesn’t mean they’re physically prepared for college workouts and matches. A college athlete whose hamstrings are only marginally stronger than those of a pre-teen is clearly overmatched, and the posterior chain demands she’ll face at this level will put her at serious risk for anterior cruciate ligament (ACL) injury if her training program doesn’t address her weaknesses.
As one of the main stabilizers of the knee, the ACL’s primary function is to prevent the tibia (shinbone) from shifting forward. It’s susceptible to non-contact injury whenever an athlete changes direction, abruptly decelerates, or lands from a jump, all of which happen routinely in soccer. Several intrinsic and extrinsic risk factors place female athletes at greater risk for non-contact ACL injuries than males competing in similar sports–four to six times greater, according to several studies.
This elevated risk can be attributed to a variety of sources. Ligament dominance, due to lack of dynamic control of the knee, often leads to a valgus movement at the knee joint, which creates excess ground reaction force (GRF) on knee ligaments. Studies have found that females experience GRFs at the knee up to five times their body weight, while males don’t typically reach GRFs above 2.5 times their weight.
In addition, strength disparities of 15 percent or greater between the left and right leg have been shown to increase injury risk. Females also display more quadriceps activity relative to hamstring force during athletic movements, again highlighting the problem of inadequate hamstring strength. Various other hormonal, anatomical, and environmental factors have been cited as special risk factors for females as well.
PRIORITIES & TESTING
In a recent year-to-year injury analysis of our women’s soccer players, we discovered a consistent trend. First-year athletes suffered injuries, and ACL injuries in particular, at a much higher rate than returning players. In fact, in my five years at Boston, we have never had a returning player tear her ACL.
With that in mind, we decided to develop a program for soccer-specific training that acknowledges an important fact: Athletes enter our program with vastly different levels of training experience and development. Using an integrated approach, we created a multi-faceted system to promote injury resistance, while also optimizing physical traits critical for soccer performance.
In our system, the first step is to determine where players fall in the athlete development continuum. To classify training age, we separate our players into two sub-categories–first-year players and returnees.
Our first-year player assessment begins with a training history questionnaire, which we send to new players over the summer to assess physical preparedness on and off the field. It covers health history, past and present injury status, past exercise and training habits, current training (including soccer participation), nutrition, and lifestyle behaviors. This helps us determine how seriously an athlete has trained prior to entering our program, and it red flags those who may have overtraining tendencies or special risk factors for ACL injury.
When the athletes arrive in August, we evaluate first-year players through a functional movement screen to assess movement pattern strengths and weaknesses across a variety of joint and muscle functions. For instance, players perform the hop-and-stop test to evaluate single-leg force production and force absorption. This test objectively allows us to identify imbalances between the right and left legs, while also assessing the structural integrity of each knee. Force production and absorption both play key roles in landing and change of direction skills, and poor mechanics in these areas greatly increase ACL injury risk.
Meanwhile, our preseason evaluation for returnees is based on a few specific performance measures. We test power through one-rep max on the hang clean, assess upper-body strength with one-rep max on the bench press, and judge upper-body muscle endurance based on chin-ups for maximum reps. We evaluate baseline explosive capabilities using a vertical jump test for power and a 10-yard sprint for acceleration. Ability to change direction is measured with the pro agility test.
Once these evaluations are complete, we create our training program for the upcoming season. I coordinate with the soccer coaches to identify team objectives, discuss areas where the team needs to improve, and decide which corrective exercises and methods can best achieve our goals. We also customize some exercises for each athlete based on structural problems, strength needs, landing skill level, lower-extremity symmetry, and any other individualized concerns.
In our soccer training program, we combine multiple components in a systematic and progressive fashion to maximize performance and improve injury resistance. The program centers on teaching and training proper technique for linear and lateral deceleration, landing, center of gravity control, and balance. We also emphasize core stability, dynamic flexibility in all three planes of motion (frontal, sagittal, and transverse), and foundational strength, with an emphasis on single-leg work.
To illustrate the way we break down these elements, let’s look at our approach to landing mechanics. In our jumping-landing training sequence, we begin with foundational double-leg training. Players don’t perform counter-movements at first, since the focus is simply getting each athlete to master the mechanics of a jump and a landing. To emphasize neuromuscular control, we set a goal of coming to a complete stop in under one second upon landing, with full control of the center of gravity and no lingering sway, then stabilizing each landing for two seconds. When the players are proficient with two legs, we progress to single-leg training.
As landing mechanics and efficiency develop, we reach the next level with task-specific training. Players perform two tasks, such as landing while reaching for cones with the upper extremities, which helps develop center of gravity control and stability in various planes of motion. Or, they might have to land while catching objects, such as medicine balls. This forces an athlete to activate the entire kinetic chain to balance and stabilize, and it trains the body to absorb gravity’s force while mentally engaged in another activity. For an extra challenge, we add rotational movements as well.
Additional balance training includes single-leg exercises that incorporate cervical rotation and develop proprioception in different planes of motion, such as opposite-leg reaches at a variety of angles. We utilize various stationary single-leg hip dominant exercises, such as eccentric partner hamstring raises, glute marches, and slideboard leg curls, to develop strength, mobility, and integrity of the hips.
On the field, players have only a split second to react to a situation as it unfolds. They cannot think about which muscles to activate when slowing down, jumping, or landing–those reactions must become second nature through training. The ability to absorb force and then change direction effortlessly often determines which player gains control of a loose ball or wins a one-on-one battle.
Once the players have developed mastery of single-leg jump training, we add more game-like challenges that increase unpredictability. For example, we’ll have the players pair up, with player one turning her back to player two. On command, player one jumps vertically, and once she is in the air, player two pushes player one’s hips forward. Player one must react to this stimulus, which can vary in both force and direction, and land with correct mechanics.
The key is to engage the core muscles and maintain rigidity, which will reduce trunk motion during landing and thus limit GRFs. We begin with double-leg landings and progress to single-leg landings as the athletes grow more proficient. The center of gravity control and landing skills will translate into a competitive edge on the field, and the improved force absorption mechanics will reduce stress on the joints, particularly the knee, to help prevent injury. Because we know that mechanics break down as fatigue sets in, this type of movement training is often performed at the end of our workouts to simulate late-game physical demands.
During our training, we often ask players to perform their jump training tasks, landing drills, and other movement skills in low-to-the-ground decelerating positions, staying away from hyperextension and valgus forces at the knee. The goal is for them to be most comfortable in low-risk positions while engaging the posterior chain and core musculature.
We integrate other movement skills into our work capacity training. During the season, we alternate weeks between traditional conditioning (such as shuttle runs and sprint drills) and sport-specific movement conditioning. We’ve designed three agility courses that require the type of cuts, changes in speed and direction, and other movements soccer players use most. The players pass through these courses while performing accelerations, side shuffling, recovery running, backpedaling, decelerations, and angled runs. (See “Web Connection” below for details on our agility courses.)
This type of training is very efficient for soccer development, since it builds key movement skills while also enhancing overall work capacity and muscle endurance. Players pass through a course at high intensity for 30 to 90 seconds, followed by a rest of equal duration.
As discussed earlier, hamstring-quad strength disparities (with the hamstring as the weaker muscle) create major injury risks and performance limitations for female soccer players. Many players engage the quads to stabilize their knees during deceleration and other high-stress movements, instead of relying on both the quads and the hamstrings working together. Thus, the posterior chain and hamstrings in particular are among our top priorities for strength development.
We focus on exercises that strengthen the entire posterior chain, such as straight-leg deadlifts and good mornings, along with various exercises that engage the hamstrings and glutes as a unit, including bridging and leg curl variations. We also use slideboards and stability balls.
We initiate Olympic lifts and movements from either a dead start or block start with our new players, and only the more experienced lifters (usually our returning athletes) will use counter-movements. We begin with basic pulling exercises in conjunction with front squatting, and once players master these foundational movements, we progress to more advanced strength-recruiting Olympic work.
Much of our core training is designed to engage and strengthen the entire kinetic chain. This is especially important for females, whose trunk motion and rotation is typically greater than that of males during soccer-specific movements such as jumping and landing. To develop core strength and lumbar stability, we incorporate an array of belly presses utilizing various stances and movements at different angles. We also use multiple plank progressions, such as planks with walks and planks with reaches. With any four-point plank exercise, you can add an anti-rotational component by eliminating one of the points, thus forcing the core to stabilize in order to maintain a neutral spine and pelvis.
To promote stabilization of the lower extremities while engaging the upper body, and thus training the entire kinetic chain, players work together performing push lunges at various angles, along with Nieder presses. We also use a partner medicine ball lunge-and-catch exercise: Player one stands with her back to a partner, who tosses a medicine ball over player one’s shoulder at any angle she chooses. Player one must lunge forward and/or laterally to catch the medicine ball, a challenge that develops mental reaction speed, deceleration proficiency, and extremity control while maintaining lumbar stability–skills that are essential for becoming “stronger on the ball.”
The foundation of our training regimen lies in our progressive, systematic approach to athlete development. Our blueprint–master the fundamental skills for landing, decelerating, and changing direction; develop kinetic chain and core strength; identify and correct structural deficiencies; develop foundational strength with emphasis on the posterior chain and single-leg work; develop center of gravity control, balance, and mobility; and always look to improve work capacity–has evolved over time and continues to do so. But the positive feedback we’ve received from the athletes, the skills we’ve seen them develop as they progress through our program, and the results our team has produced on the field give us confidence that we’re heading in the right direction. Full references for this article can be viewed at: www.training-conditioning.com/references.
To view diagrams of the movement courses described in this article, go to: www.training-conditioning.com and type “BU Movement Courses” into the search window.