Plyometrics is a category of movement which sees a rapid change in direction of forces, such as your foot hitting the floor when running and quickly propelling you onto the next step.
The mechanism behind this is known as the stretch-shortening cycle (SSC), where the muscle stretches upon impact and rapidly shortens to take off again.
Plyometric training is designed to take advantage of the natural structure of tendons, they're strong rigid structures that when stretched love to recoil back to their original length. Tendons are elastic in nature and store energy when they are stretched, the rapid recoil provides propulsion without an energy cost to the body. This is particularly useful for distance runners, East African distance runners have adapted over generation to have very long Achilles tendons and short calf muscles, allowing them to run fast with a much lower energy expenditure compared to those with short Achilles and long calves.
Fast plyometric movements happen in under 0.2seconds and are far too fast for our brains to process the precise amount of force going through the muscles to adjust our movements.
Our muscles have two handy sensors known as proprioceptors to measure the amount of force and stretch occurring in the muscle to process the information almost instantly. Deep in our muscles, we have muscle spindles that measure changes in the length of the muscle, providing feedback when a muscle is lengthened rapidly such as the calf lengthening as your foot strikes the floor. The spindles send a signal that they're being stretched rapidly and the nervous system shortens the muscle, this stretch-shortening cycle provides a little boost of force.
As mentioned in a previous blog on a great way to see this in action is to place your hand on a table, keep your hand on the table at all times, raise your index finger to try and hit the table as hard as you can. Pretty weak hey? Now pull your finger back with your other hand until you feel a stretch, let go. You should have noticed much more force this time. That is the stretch and recoil in action!
The second proprioceptor is known as the Golgi-tendon-organ (GTO) this is essentially a light switch for the muscle and is sensitive to high forces. The GTO is found where muscles and tendons meet, it monitors the force coming from the tendon and decides whether the muscle can deal with this force. If its too much for the muscle the GTO will shut the muscle down to try and prevent an injury, with gradual increases in force and load the GTO will calm down a little and let more force through, this, in turn, will let you run faster, jump higher and react quicker to stimuli.
So how do I train plyometrics?
There are many considerations when training for plyometrics, one myth amongst coaches is you need to be super strong before you even begin. Whilst being stronger will inevitably help because your muscles are able to handle more force and it allows you to practice more advanced movements sooner. It is in fact appropriate for everyone, the key will be to manage your progressions properly and ensure you are healthy before you begin!
The outcome of plyometric training is to be able to create more force in a shorter space of time therefore the focus should be on short ground contact times. If you spend too much time on the ground the energy stored in the tendon is lost as heat or dissipated into the muscle, a short firm impact is essential to improving. A key concept during training is to jump and lift the toes up ready for landing, this is to pre-stretch the Achilles and allow the landing to occur on the ball of your foot. Landing on your toes and flexing through the ankle is going to lengthen the time spent on the ground and the foot will absorb force that could be going into the tendon and calf muscles.
Keep your training simple, when you progress an exercise aim to maintain a similar speed of movement and time spent on the floor. For beginners bilateral (on both feet) plyometrics is the recommended start point. Notice the progressions of these include small increases in height to provide a greater challenge.
This includes:
Stiff Ankle Jumps
Mini Hurdle Jumps
Low box Drop jumps
Low box depth jumps
Notice the difference between these two drop jumps: in video 1 the athlete has been instructed to jump as high as possible. In video 2 the athlete has been instructed to imagine the floor is on fire and to spend as little time on the floor as possible during the jump. Although there is less height in the 2nd jump the ground contact is more effective and over time with improvements in strength and plyometric ability, the gap in height will narrow.
Video 1
Video 2
Progressions of the above exercises:
Hurdle Jumps
Medium Box Drop Jump
When beginning with unilateral (single leg) exercises it is best practice to choose horizontal exercises. It is incredibly difficult to produce vertical forces on one leg and maintain the effective ground contact time required to effectively develop plyometric properties.
Beginner options are:
Hop and hold – although there is no rapid ground contact this is an important exercise to improve muscular coordination of leg and hip muscles to maintain posture upon a single-leg landing.
Continuous hops at a comfortable distance
Progressions for these exercises include:
Forward bounding – comfortable distance
Speed Bounds – Maximal contact aiming for distance
The progressions might feel quite easy because you are not out of breath like you are when training other aspects but it is a high-stress exercise that requires adequate rest, look to take 1-3 minutes between sets to maintain maximal explosiveness throughout the session.
Why should I bother?
Plyometrics have been shown to improve performances for athletes across a huge variety of sports, whether it's basketballers working up to their first dunk, long-distance runners looking to become more economical, sprinters getting quicker or field athletes looking to develop all-round performance.
For explosive sports plyometric training allows you to produce more force and complete movements more quickly, endurance runners will experience improvements in running economy, where you run at the same pace with less energy expenditure or run quicker small changes to your running economy.
Parameters
|
Training Variable |
Beginner |
Intermediate |
Advanced |
|
Sessions per week |
2 |
2-3 |
3 |
|
Exercises per session |
2-3 |
3-4 |
4-5 |
|
Total foot contacts per session |
30-50 |
50-100 |
100+ |
|
Sets of each exercise |
2-4 |
3-5 |
3-5 |
|
Repetitions per set |
4-6 |
4-6 |
6-8 |
|
Recovery |
2-3mins |
2-3mins |
2-3mins |
Beginner example session
Pogo Jumps 3 sets of 6 Jumps (18 contacts)
Hop and Stick 3 sets of 6 (18 contacts)
Mini Hurdle Jumps 2 sets of 5 jumps (10 contacts)
Total: 46 contacts
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