How Does Plyometrics Improve Your Performance During a Football Game?
Over the next few months players will be completing plyometrics such as the countermovement jump as part of their in season training program.
The information below will overview in simple terms the science behind plyometics and how it can benefit a player’s performance (Cormie, McGuigan, & Newton, 2011). Plyometrics can be defined as a shock method and involves any exercise that creates a fast lengthening of muscle followed by a fast shortening of a muscle (Verkhoshansky, 1966). Plyometric training has been utilised since the 1960s and is widely implemented into many elite sports clubs including at football clubs.
Completing plyometrics within a safe and well planned athlete training program has shown to improve three key areas. Increase power (Finni, Ikegawa, Lepola and Komi, 2001), like jumping for a header or accelerating to a ball over a short distance. Agility (Flanagan & Harrison, 2007) for example keeping track of a fast moving player changing direction and finally speed (Dutto & Smith, 2002), losing a player in the box and reaching the ball first to score.
What happens during a countermovement jump?
Imagine legs muscles are like rubber bands the more you stretch that elastic band before you release it the more potential elastic energy it has stored just like a leg muscle (Wilson & Flanagan, 2008). When released the band will fly further than if you don’t stretch it at all, it will just fall to the ground. The diagram below shows three phases of a plyometric movement in a counter movement jump, a) the pre-activation (the muscles get ready), d) the stretch (muscles lengthen and absorb energy) and finally f) the shortening (the muscles shorten quickly and a jump occurs). When a muscle is stretched and then subsequently shortened it is said to benefit from a “stretch shortening cycle” (Linthorne, 2001).
How does the muscle know when to shorten or lengthen during a countermovement jump?
A movement such as a countermovement jump occurs deep within the muscle and tendon attachments.
The diagram below shows the sequence of events from one through to stage five. These stages occur in the neural circulatory system, which involves passing electrical messages from receptors all around the body to the brain and back out to the muscle.
The first is a primary spindle (found in the muscle), which passes information about the rate of stretch occurring in the muscle. The second is the Golgi tendon organ found in the tendon junction. The Golgi tendon is the body’s protective mechanism to void over stretching and injury (Kutz, M.R. 2000). The final is the secondary spindle, which does the same job as a primary spindle. It measures muscle length however the message is sent directly to the brain.
During a countermovement jump all three receptors pass on information either about muscle length or force during a jump for example such as heading the ball.
Using the aforementioned three stages of a countermovement jump when a player is standing and gets ready to dip down for the jump the body muscles pre-activate, sensory receptors pass information along afferent neurons to the interneurons helping the body prepare for the jump.
When the player then dips down quickly receptors feed further information again long the afferent neurons to the brain were the central nervous system will decide to stop the stretch if it thinks the muscles will potentially be injured or send positive excitatory messages back to the leg muscles along the spinal cord. During this stage extra potential energy is stored in the stretched muscle helping it in the next stage.
When the excitatory message is sent to the leg muscles the body uses all the extra stored energy to help the player jump even higher.
How does the muscle shorten?
Muscle is made up of acton and myosin filaments, which are pulled together mechanically when an enzyme is released just like a ratchet. This shortens the length of muscle and creates the contraction required in the calf and thigh muscles to jump. Muscle can only be shortened if enough enzyme is realised and the whole unit within the muscle shortens. If only a small amount is realised there is no contraction. This is called the “all or nothing law” (Chalovich & Eisenberg, 1982).
A filament within the muscle
How is footballing performance improved?
Completing jumps that involve this type of movement during training sessions has said to improve performance significantly on the pitch by increasing power. Firstly repeating weekly sessions during late pre-season or in season can help athletes improve the efficiency of movement just like practising any football skill (Paavolainen, Hakkinen, Hamalainen, Nummela, & Rusko, 1999). By completing jumps during training footballers can improve neural pathways (Chimera, Swanik, Swanik, & Straub, 2004). Jumping will recruit and enhance fast twitch muscle fibres. Enhancing the recruitment of fast twitch muscle fibres helps an athlete become faster on the pitch (Ebben, 2007).
Recommendations when completing plyometrics
1.) Perform plyometrics on either grass or rubber surface (Impellizzeri et al., 2007).
2.) Do not static stretch before completing plyometics. Complete a dynamic warm-up (Behm & Kibele, 2007).
3.) Complete plyometrics at the start of a session not after a weights or aerobic conditioning.
4.) Only complete plyometric sessions 2-3 times a week.
5.) Rest 5–10 times more than it takes to complete the plyometric drill, example if it takes 4 seconds to complete a drill, a footballer should rest 20-40 seconds between sets. Do not complete more than 10 repetitions in a set.
6.) Beginners should not complete more than 100 foot contacts in any session.
(Potach & Chu, 2000).
Implications in training
A countermovement jump is a moderate level of plyometrics. As player becomes more competent, programs will progress and the difficulty of plyometrics will increase (Ebben, 2007) here are some examples.
To make sure the squad is improving and the plyometrics are at the correct intensity to elicit improvements in power but avoiding injury, the squad will be monitored within the session on a weekly basis using a jump mat and the reactive strength index, which monitors intensity. Players will feel stiff and sore after session therefore sessions will be placed several days before a game. Completing plyometrics will improve player’s power testing results. Importantly these improvements will transition onto the pitch making the squad, more powerful and fatigue resistant during a game.
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Chimera., N.J, Swanik., K.A. Swanik, C.B., & Straub, S.J. (2004). Effects of plyometric training on muscle-activation strategies and performance in female athletes. Journal of Athletic Training, 39, 24-31.
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Impellizzeri, F.E., Castagna, C., Rampinini, E., Martino, F., Foirini, S., & Wisloff, U. (2007). Effect of plyometric training on sand versus grass on muscle soreness jumping and sprinting ability in soccer players. British Journal of Sports Medicine, 42, 42-46.
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Potach, D.H., & Chu, D.A. (2000). Plyometric Training. In: Essentials of Strength Training and Conditioning. T.R. Beachle & R. W. Earle (Eds), Champaign IL: Human Kinetics.
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