John De Witt, Ph.D., C.S.C.S
Acceleration/Deceleration Exposure Required to Recreate Match-like Loading
During matches, many physical actions take place
One of the things that coaches should strive for in their training program and periodization is the elimination of soft tissue non-contact injury.
Incorporating activities with speed changes from low to high and high to low is important for player preparation
It is well known that players perform a variety of activities in the course of a soccer game. There is now plenty of research that shows that senior players tend to cover distances of over 10 km during a match, with about 500-1500 m of that being high speed running. Because of the emphasis being able to complete repeated sprints throughout the match, interval training is the best method to improve match fitness.
During training sessions, interval training is often set up as a linear activity. In other words, the exercises completed by the players tend to be in straight lines. This is not necessarily a problem, given that it takes about 30m of distance for an athlete to achieve maximum velocity.
The 30m issue is the heart of a tradeoff that must be made when selecting training activities. Change of directions play a large role in matches as players must consistently adjust to the rapidly changing situations they encounter. However, it is probable that at some time during the match they will also be required to perform linear actions at top speed, such as when attacking or defending a counterattack. For that reason, it is important to include both linear and change of direction activities in your player preparation planning.
A change of direction is simply an adjustment in an athlete’s movement. Some changes of direction occur with little change in speed, depending upon the amount of change in direction and the speed of movement before and after the change.
Stopping and starting while maintaining the direction of movement, such as when a player looks to deceive a defender, may not be an angular change of direction, for the purposes of this article, it will be considered a direction change. The important aspect of the change of direction that we want to focus on is the deceleration (stop), followed by the acceleration (start)
In physiological terms, muscles create force by shortening, or absorb force by lengthening. The shortening, called a concentric contraction, is an active production of force that results in angular accelerations of the joints that the muscle cross. When starting a run, a majority of the muscular actions are concentric, producing the forces across the lower leg joints that result in the gain of running speed.
During force production while lengthening, called eccentric force production, the muscle creates a resistance force to decelerate the joint motion that the muscle crossed. It is during the eccentric activation that microdamage occurs in the muscle. This microdamage can be ‘good’ in that it results in muscle growth, but it can also be ‘bad’ by resulting in injury.
One of the things that coaches should strive for in their training program and periodization is the elimination of soft tissue non-contact injury. Nothing can be done about a contact injury in terms of the external forces that are applied to the injured body part. In the case of a soft tissue non-contact injury, like a muscle pull, there is a different story.
A muscle pull will occur when the muscle is attempting to decelerate the joint, but the force necessary is greater than the muscle is capable of producing. For example, hamstring pulls rarely occur when an athlete is accelerating. These injuries typically occur when an athlete is already at top speed. Often times, the hamstring pull occurs because of the following scenario. During the running stride as the athlete brings their leg forward prior to their heel hitting the ground, the knee extends and the lower leg moves forward rapidly due to the lower leg’s momentum. The hamstrings act eccentrically to slow the knee extension to protect against hyperextension. The lower leg momentum, however, it too large, and the hamstrings tear.
Hamstring tears and similar injuries are avoidable. The key is to include force production (start) and force absorption (stop) activities in your training. These activities, which should be a part of your training program and could be incorporated into your warmup routine, can help your players’ bodies to become more accustomed to both aspects of the speed generation. Coaches often focus on the acceleration aspect; we need to remember to also address the force absorption aspect.
Suggested activities - make these activities a part of your fitness program to help decrease your player’s injury risk.
Sprints with a stop - Perform a normal sprint over 30 yards. Place cones at the start and end of the 30-yard distance. Place another cone about 5 yards from each endline. Make a sprint from the start to end (ignore the cone at the first 5-yard mark) but require the player to be at top speed when reaching the cone at the 25-yard mark, but then they must come to a complete stop before reaching the last cone.
Alternatives - include multiple stop-starts, but make sure the player has enough distance to get to full speed prior to stopping.
Jump and land - a great way to absorb force is during the landing of a jump. Have your players complete a jump, but then they must stick the landing, or they may bounce once. However, they must come completely stationary prior to the next jump. Options
Jump off 2 feet, land on two feet
Jump off 2 feet, land on 1 foot, alternating
Jump off 2 feet sideways, land on two feet
Jump off 2 feet sideways, land on outside foot
Jump off 2 feet sideways, land on inside foot
Jump off 2 feet forward diagonal, land on 1 foot
Jump off 2 feet backward diagonal, land on 1 foot
Jump off 2 feet backwards, land on 1 foot
All of these can be done while moving forward (like during a warmup where your team moves from cone to cone while performing dynamic agility movements)
Forward, backward, forward - work over 40-yard distance with cones at end line, and cones marking 10, 20, and 30 yards
On go, players sprint to 20-yard cone, turn and run back to the 10-yard cone, and the turn and run all the way to the 40-yard cone. This allows for 2 changes of direction, plus a distance that allows the players to reach full speed. Repeat.
Same as above, but sprint to 30-yard cone, turn and run back to 20-yard cone, and then turn and run to 40-yard cone. This allows the players to reach full speed prior to the turn.
Similar at above, but have the cones at angles so rather than working linearly, and angular change of directions occurs
Nordic Hamstrings - this is a strength training exercise that can be completed in the gym or on the field. Research has shown that players completing Nordic Hamstring protocols have decreased injury risk. This is an eccentric activity.
One player (worker) kneels with thighs 90 degrees to the lower legs, with upper body straight up (upper body and thighs are along the same line).
Helper gets behind the worker and holds their ankles to the ground
Worker completes a repetition by slowly leaning forward and lowering themselves until they are on the ground. Try to lower the body slow and controlled. Once the repetition is completed, the worker can use their hands to get back to the starting position. The exercise is completely eccentric.
Start with 2 sets of 5 reps per player, and work up to 3 sets of 8 reps. Do not overdo the sets and reps on a given day, and be prepared for hamstring soreness up to 48 hours afterwards when first completing the exercise.