Saturday, April 20, 2013

Making the Cut: Strength Training and Change-Of-Direction Sprints

Soccer is a very dynamic game. Instead of moving at a constant pace and in only one direction, the nature of the game requires sprints, jogs, starts, stops, jumps and landing. In fact, players can change directions up to 1000 times per match. Often this occurs when a player plants his/her foot to stop moving in one direction and accelerate in another. Such cuts are designed to either elude a defender of respond to the movement of an attacking player or the ball. This can be a critical point the game. Precious inches can be gained of lost when trying to separate from or track an opponent. Thus, the ability to quickly change directions and accelerate in another is an important part o the game. A new study from the Goethe University of Frankfurt found that long-term resistance training improves change-of-direction sprint performance in youth players. Players are able to cut and accelerate better after weight training.

The study enrolled 112 elite youth players. The players ranged in age from 15 to 19 years. The researchers divided the players into two groups – a strength-training group and a control group. Both groups participated in regular soccer training 2-3 times per week. However the strength-training group added 2 days per week of resistance training.

The strength-training program focused on parallel back and front squat exercises. It also included deadlifts as well as upper body lifts (bench and neck presses, standing rows) and trunk exercises. The program was progressive. As players’ strength improved the training weight was increased. It was also periodized with the amount weight (4-10 RM) and number of repetitions within a set altered every two weeks. The program lasted a total of two years.

Sprint change-of-direction performance was measured using a course designed as an equilateral triangle. The sides of the triangle were 5 meters and each angle was 60 degrees. The players began at one point of the triangle, sprinted to the next point, changed directions towards the third point. They again changed directions and sprinted back to the first point. This two-turn course was repeated in both the clockwise and counter clockwise directions. A timer was started when the players passed the 2.5 meter mark on the first side of the triangle. The timer was stopped 2.5 meters after the first and second turns giving researchers measures of one- and two-turn performance. A “flying start” was used to eliminate any effects of reaction time or initial acceleration.

All of the players in the strength-training group increased leg and upper body strength. Improvements in the front and back squat lifts were quite large. In the youngest players, lifts nearly tripled. This was expected given that these players started training at 15 years of age and continued for 2 years. The players of the control group did not show any appreciable changes in strength.

The key finding of the study was that strength-trained players also improved their change-of-direction performance by 5-10% whereas the control group showed no improvements. This held for all ages and for both the one- and two-turn measurements. The researcher also compared the youth performances to a group of elite professional players. In most cases, the players who trained for two years did as well or better than the professionals.

One of the interesting findings was that the gain in strength was not the only factor leading to improved change-of-direction performance. Apparently, there were other neuromuscular changes resulting from strength training. Perhaps better agility, motor skills or reaction timing. This was not specifically studied by the researchers but clearly something else helped improve the player’s ability to sprint and change directions.

How important is a 5-10% improvement in this sort of test and what might that mean on the field? Typical times for the 15 year-old players were 1.8 sec after the first turn and 3.5 sec after the second. After training, these times were lowered to 1.7 and 3.2 sec or about 0.1-0.3 sec improvements. On the field, that small change could result in several feet to several yards gained on an opponent following a change in direction. Soccer is often a game of inches. Games can be won or lost in tight spaces. So, it’s easy to see how this a small improvement in speed could lead to a forward separating from a defender and creating a scoring opportunity. O a defender more easily marking the attacking player and preventing a shot.

Yet another benefit of strength training is highlighted by this study. The SSO has previously highlighted how resistance training can improve sprint speed, jumping ability, shot velocity and aid with injury prevention. Add to this list, the ability to quickly change direction. Given this evidence, players should consider involving themselves in a well-supervised strength-training program. One that emphasizes technique, appropriate progression and targeted exercise designed to benefit performance and injury prevention.

Reference

Keiner M, Sander A, Wirth K, Schmidtbleicher D (2013) Long term strength training effects on change-of-direction sprint performance. Journal of Strength and Conditioning Research, DOI: 10.1519/JSC.0b013e318295644b