In the video below you can see Lionel Messi Scoring vs Real Madrid one of the great El Classico goals. From a purely physical view,alongside his outstanding dribbling ability, the changes of direction from slow to fast were incredible.
Now, football is a sport with frequent changes of direction, which involve slowing down to deceleration and accelerating away. The use of plyometric training can be therefor be beneficial for decreasing the time it takes to change direction in games. The best players in the world, even those from previous generations, all share the ability to beat their opponent with changes of direction ie: Messi, Cryuff, Ronaldo, Maradona, Iniesta. So Surely to be as good if not better than them it would be beneficial to train the body to suit. A method of doing so is through plyometric training.
What is Plyometric Training?
Plyometric training is aimed at producing a greater amount of force generating from a pre-stretch of the muscles involved in a movement that is influenced by the Stretch-Shortening Cycle.
History of Plyometric training
Plyometric training originates from the notorious Soviet Union and stem from a Russian scientist named Yuri Verkhoshansky, who had originally called this form of training “Shock training” due to the shock of the landing phase involved. The term ‘Plyometric’ came from an American athlete called Fred Wilt who had seen the Soviet Union athletes prepare for track and field events. Plyometric training began to gather great attention due to the Eastern European countries domination in power related events.
(Baechle & Earle, 2008)
Plyometric training refers to the manipulation of the performance of the Stretch Shortening Cycle (SSC). This is what produces a high intensity concentric contraction (to shorten the muscle) resulting from a powerful eccentric (lengthening of the muscle) contraction. The key factors in the SSC responsiveness are the Spindles and Golgi Tendon Organs (GTOs) inside of the muscles.
The spindles inside the muscle act as proprioceptors that feed the Central Nervous System (CNS) and relays message to the brain about the length of a muscle. When muscles are stretched, so are the spindles, this therefor causes a heightened neuron response in the muscles via the CNS. This increases the potential contractile force from a future concentric movement.
Similarly to muscle spindles, the Golgi Tendon Organs (GTOs) act as proprioceptors, however GTOs respond to the tension of the muscle compared to length. Upon activation, they cause an impulse to be sent to the muscle, that inhibits motor neuron activity in the muscle, which causes the muscle to relax. This is done to prevent the muscle becoming injured, however the consequence is a decreased amount of force production due to the muscle losing tension.
The contribution of Muscle spindles and Golgi Tendon Organs are vital in the manipulation of the stretch shortening cycle. Through plyometric training, the inhibiting response of the GTOs can be overcome and tension in the muscle can be increased to produce a more powerful concentric contraction from an eccentric contraction, which encompasses the Stretch-shortening cycle.
How the stretch shortening cycle works
(Baechle & Earle, 2008)
The SSC contains 3 phases of action but not all 3 are equal in time, as some may not need to last as long as others.
Phase 1 is the eccentric phase, where the kinetic energy from the agonist (a muscle which causes its own contraction) muscle or muscle group is pre-loaded with elastic, kinetic energy. If we consider a change of direction to be a plyometric movement, then phase 1 would be the time from touch down of the foot to the bottom of the movement. This is where the amortization phase begins.
Phase 2 is the amortization phase or transition phase and is the transition time between the eccentric and the response of the concentric contraction. It is at this point the Muscle spindles play their role to fire neurons into the muscle to generate force. If the amortization phase lasts too long, kinetic energy is released as heat and reaction force is decreased (Cavagna, 1977).
The Concentric phase, phase 3, is the reaction of kinetic energy in the muscles combined with the pure muscle contraction force. This means the movement response is more of the muscle group’s previously achievable force (Cavagna & Dusman & Margaria, 1968; Svantesson & Grimby & Thomme, 1994). Following the change of direction example this would be the push off from the original leg to another direction to get past an opponent.
What is the research saying?
Bruce-low and Smith (2007) review explosive training methods in sport and they conclude that due to the lack of sport specificity of the movements, specifically the vertical jump (Carpinnelli et al, 2004), that it is better to do slow, controlled power movements in combination with sport specific training to improve sporting performance. More recent research however, has attempted to justify its use during training.
In Villeral et al (2010) research review of 56 studies, it attempts to find themes and conclude upon an optimal approach towards plyometric training. It demonstrates that Plyometric training significantly improved Vertical Jump Height and found that those who used a combination of exercises such as Squat Jumps (SJ), Depth Jumps (DJ) or Counter movement Jumps (CMJ) generate greater gains than those who only use 1 type. The research also found that those with greater experience in sport had the best improvement in VJH performance.
Specifically to Football, Thomas, French and Hayes (2009) demonstrate that both Counter movement jumps and depth jumps both can cause an improvement in explosiveness and agility, with no significant difference between the two methods. Vaczi et al (2013) demonstrates similar finding showing the use of uni-lateral and bi-lateral exercises together increase power and football specific agility in the Illinois agility test and T-Test.
Applying theory to training with specific focus on football
Taking a critical view of the research, it can be said that plyometric can improve the testing of the explosive attributes of participants, however with further specificity to a specific sport such as the football specific agility tests, it can be even more beneficial. Therefore I have attempted to replicate the situations that occur in football and create plyometric training exercises that attempt to improve performance.
Counter-movement jump + Header of a ball
1 leg depth jump + sprint
By using plyometric training football players can decrease the time it takes to change direction in a 1v1 situation, improve their leaping ability and their power over a short distance, but what is key is knowledge of how best to achieve those. By manipulating the variables of training to suit your individual attributes of recovery and ability, while maintain the football specific or even position nature of training, plyometric training can be extremely beneficial.
Additional information and examples:
1. Baechle, T & Earle, R (2008). Essentials of strength and conditioning. 3rd ed. Leeds, UK: Human Kinetics. 415-417
2. Bruce-Low, S & Smith, D. (2007). Explosive exercises in sports training: A Critical Review. Journal of Exercise Physiology. 10 (1), 21-33
3. Carpinelli, R.N & Otto, RM & Winnet, R.A. (2004). A critical analysis of the ACSM position stand on resistance training: insufficient evidence to support recommended training protocols. Journal of Exercise Physiology. 7 (3), 1-60
4. Cavagna, G.A & Dusman, B & Margaria, R. (1968). Positive work done by a previously stretched muscles. Journal of Applied Physiology. 24, 21-32
5. Cavagna, G.A. (1977). Storage and Utilisation of elastic energy in skeletal muscleq. Exercise and Sport Science Reviews. 5 (,), 80-129
6. Svantesson, U & Grimby, G & Thomme, R. (1994). Potentiation of concentric plantar flexion torque following eccentric and isometric muscle actions. Acta Physiol Scand. 152 (1), 287-293
7. Thomas, K & French, D & Hayes, P. (2009). The effect of two plyometric training techniques on muscular power and agility in youth soccer players. Journal of Strength and Conditioning Research. 23 (1), 332-335
8. Vaczi, M & Tollar, J & Meszler, B, Juhasz & Karsai, I. (2013). Short‐Term High Intensity Plyometric Training Program Improves Strength, Power and Agility in Male Soccer Players. Journal of Human Kinetics. 36 (1), 17-26
9. Villarreal, E.SD, Requena, B & Newton, R.U. (2010). Does plyometric training improve strength performance? A meta-analysis. Journal of Science and Medicine in Sport. 13 (1), 513-522.