What are Plyometrics?
Plyometrics can be described as drills or exercises that are aimed at linking strength and speed of movement to produce an explosive-reactive type of movement often referred to as power.
Plyometric exercises are thought to stimulate various changes in the neuromuscular system, enhancing the ability of the muscle groups to respond more quickly and powerfully to slight and rapid changes in muscular length. In general terms, plyometric training is one form of resistance training that involves the rapid stretching of a muscle(s) followed by a rapid concentric (shortening) contraction of the muscle(s) to produce a forceful movement over a short period of time. The aim is to develop the reactivity of the muscles.
The Stretch-Shortening Cycle
All plyometric movements involve three phases.
- The first phase is the pre-stretch or eccentric muscle action (preactivation). Here, elastic energy is generated and stored.
- The second phase is the time between the end of the pre-stretch and the start of the concentric muscle action (stretch). This brief transition period from stretching to contracting is known as the amortization phase. The shorter this phase is, the more powerful the subsequent muscle contraction will be.
- The third and final phase is the actual muscle contraction (shortening). In practice, this is the movement the athlete desires – the powerful jump or throw. This sequence of three phases is called the stretch-shortening cycle. In fact, plyometrics could also be called stretch-shortening cycle exercises.
A simple trick to increase your vertical jump height
- One very quick and simple way to demonstrate the effect of the stretch-shortening cycle is to perform two vertical jumps.
- During the first vertical jump the athlete bends the knees and hips (eccentric muscle action or pre-stretch) and holds the semi-squat position for 3-5 seconds before jumping up vertically (concentric contraction) as high as possible.
- The 3-5 second delay increases the amortization phase.
- On the second jump the athlete bends the knees and hips to the same degree but immediately jumps up without a delay.
- This keeps the amortization phase to a minimum and makes best use of the stored elastic energy.
- The second jump should be higher.
What Effect Does Plyometric Training Have on Performance?
- A wide variety of training studies shows that plyometrics can improve performance in vertical jumping, long jumping, sprinting and sprint cycling.
- It appears also that a relatively small amount of plyometric training is required to improve performance in these tasks.
- Just one or two types of plyometric exercise completed 1-3 times a week for 6-12 weeks can significantly improve motor performance.
- Additionally, only a small amount of volume is required to bring about these positive changes i.e. 2-4 sets of 10 repetitions per session or 4 sets of 8 repetitions.
- While upper body plyometrics has received less attention, three sessions of plyometric push-ups a week has been shown to increase upper body power as measured by medicine ball throws.
Plyometrics & Concurrent Strength Training
- A conditioning program consisting of both plyometric training and resistance training can improve power performance in the vertical jump and 40 yard sprint time.
- It appears that concurrent resistance and plyometrics training can actually improve power to a greater extent than either one along.
Plyometric Training for Sport
Plyometric Exercise Selection
- There are many plyometric exercises for both the upper and lower body.
- Exercise selection should mimic the movement patterns of the sport as closely as possible.
- The effectiveness of a plyometric training session depends on maximal effort and a high speed of movement for each repetition.
- Rest intervals between repetitions and sets should be long enough to allow almost complete recovery.
- As much as 5-10 seconds may be required between depth jumps and a work to rest ratio of 1:10 is recommended. For example, if a set of bounds takes 15 seconds to complete, the rest interval between sets would be 150 seconds or 2.5 minutes.
- If sessions are limited by time, non-fatiguing exercises utilizing other muscles may be incorporated into the training block.
Typically, 2-3 sessions of plyometrics can be completed in a week. Alternatively, recovery time between sessions can be used to prescribe frequency and is recommended at 48-72 hours.
Example Plyometric Training Program
Below are sample plyometric training sessions for Rugby athletes.
Level 1 Plyometric Training Program
|Ankle Jumps||With hands on hips, perform 10 ankle jumps, pushing off the balls of the feet and minimising contact time on the ground. Perform 2 sets of 10 reps.||90s Rest between sets and exercises|
|Long Standing Jumps||From a standing start, feet square, jump for distance landing softly and repeating, stick and hold last rep. Focus on minimising ground contact time and landing softly. Perform 2 sets of 4 reps.||90s Rest between sets and exercises|
|Bodyweight Squat Jumps||With hands on hips, jump vertically into air, landing softly and repeating for required number of reps. Perform 2 sets of 5 reps.||90s Rest between sets and exercises|
Level 2 Plyometric Training Program
|Ice Skater Bounds||Standing on 1 leg, bound diagonally forward landing on opposite leg, explode off landing on original leg repeat process 3 times each leg. Perform 2 sets of 3 reps each side.||90s Rest between sets and exercises|
|Split Jumps||Start with feet shoulder width in a split squat position. jump vertically landing in the same split stance immediately upon ground contact jump vertically and repeat. Perform 2 sets of 4 reps each side.||90s Rest between sets and exercises|
|Low Hurdle Jumps||Jump over initial hurdle, land and take off with minimal ground contact time, repeating process for the desired number of hurdles. If needed small jumps can be used between hurdles to maintain balance and control. Perform 2 sets of 4 reps.||90s Rest between sets and exercises|
Level 5!! Plyometric Training Program
|Single Leg Hurdle Hops||On a SL hop over initial hurdle, land and take off with minimal ground contact time, repeating process for the desired number of hurdles. If needed small hops can be used between hurdles to maintain balance and control. Perform 2 sets of 3-5 reps each side.||90s Rest between sets and exercises|
|Borzov Jumps||Start in a split stance, back foot on bench. Jump up and cycle front leg while in the air, landing will be a return to start position, immediately upon ground contact jump up and cycle through again. Perform 2 sets of 5 reps each side.||90s Rest between sets and exercises|
|Depth Jumps||Starting on top of a box, drop to ground with a DL landing, upon hitting ground immediately jump explosively into air. Perform 2 sets of 5 reps.||90s Rest between sets and exercises|
To determine the optimal drop height for depth jumps
- Step off and jump from increasing box heights (e.g. 20, 30, 40, 60cm).
- Observe when athlete can’t stop heels from touching the ground during the contact phase.
- Use the height prior to failure as the ceiling for depth jumps.
Plyometric Contrast Example Program
|Bench Press||3||6||85%||2-4 mins|
|Clap Push Ups||3||6|
|Bench Pull||3||6||85%||2-4 mins|
|Dynamic Sled Pull||3||6|
The pre requisites for effective application of plyometric training are fundamentally good co-ordination, balance, body control and awareness. Core control and core strength are also very important in maintaining good dynamic posture during movements. Leg strength relative to the level of the athletes development is a must. Athletes deemed competent in these areas of assessment may then commence plyometric training.
The load on the body during plyometric activities is increased because of the stretch reflex component and the velocity of movement. Variables such as bodyweight, coordination and injury history of the athlete play an important role in the determination of a plyometric session and should be considered carefully before devising and planning any training program. The specific plyometric requirements of an athlete with regard to his position on the field should also determine the type of program to be implemented. Coaches should be aware that the body weight of an athlete presents an important factor when considering the type of exercise to be performed.
Cameron is the Director of Pro Training Programs