WK9

Lecture Overview

• Understand the physiology of plyometric and ballistic training methods.

• Identify the phases and roles of the stretch-shortening cycle.

• Identify the components of a safe and effective plyometric/ballistic training program.

What is a Plyometric?

• Activities that enable the muscle to reach maximal force in the shortest possible time.

• Entail the use of the stretch-shortening cycle, involving:

  • Elastic components.

  • Neural components.

• Used to develop the ability of an athlete to rapidly express high levels of force.

The Mechanical Model of Plyometrics

• Elastic energy in the musculotendinous components is increased through a rapid stretch and stored.

• When immediately followed by a concentric action, the stored energy is released, increasing or amplifying force output.

• Concentric action must occur immediately for stored energy to be taken advantage of.

Neurophysiological Model of Plyometric Exercise

• Involves the potentiation of the concentric muscle action through the stretch reflex.

• Primarily driven by muscle spindle activity.

• The concentric action must be immediate for the reflexive action to be taken advantage of.

The Stretch-Shorten Cycle

• Describes a situation where the shortening function of the musculotendinous unit is enhanced by a preceding rapid stretch.

• Broken into three phases:

  • Eccentric phase: Stretch of the agonist muscle.

  • Amortization phase: The time between the eccentric and concentric phases; a very short but crucial phase.

  • Concentric phase: Shortening of the agonist muscle.

Plyometric Exercise

• Ultimately, plyometric movements are a summation of mechanical and neurophysiological factors.

Adaptive Responses to Plyometric Training

• Outcomes that plyometrics bring:

  • Increases in vertical jump height.

  • Increases in horizontal jump distance.

  • Improvements in sprint speed.

Musculotendinous Adaptations

• Common adaptations to plyometric training also occur at the musculotendinous level.

• Exposure to plyometric training leads to increases in stiffness of the overall musculotendinous unit.

• Exposure to plyometric training may lead to some increases in muscle cross-sectional area.

Neural Adaptations

• Neural adaptations to plyometric occur at two locations:

  • Local Adaptations

  • Central Adaptations

• Decreases in Golgi tendon organ inhibition.

• Increases in muscle activation.

• Increases in pre-activation of muscle.

Plyometric Program Design

• Design of plyometric training programs adheres to the same guidelines as the design of non-ballistic training programs.

• Starts with the needs analysis:

  • What are the training goals of the athlete?

  • What is the current training status of the athlete?

  • What is the athlete’s training history?

  • What are the demands of the athlete’s sport?

Training Factors for Plyometrics

Mode

• Dictated by the body region(s) involved in the plyometric:

  • Upper-body plyometrics.

  • Lower-body plyometrics.

  • Torso/trunk plyometrics.

Lower-Body Plyometrics

• Most commonly used mode of plyometric.

• Target the rapid expression of high levels of force.

• Align with the principle of…

  • Jumps in place.

  • Standing jumps.

  • Multiple hops and jumps.

  • Bounds.

  • Box drills.

  • Depth jumps.

Intensity

• Intensity of the plyometric is dictated by the stress applied to the musculotendinous unit.

• Therefore, intensity is dictated by how the plyometric is performed:

  • Number of contact points.

  • Speed of movement.

  • Height of the drill.

  • The body mass of the athlete.

Frequency

• The number of plyometric sessions is typically dictated by the demands of the session and the recovery time required.

• Typically, one to three sessions per week.

Recovery/Rest

• Plyometric exercises are performed at maximal intensity.

• Longer rest periods are required to mitigate the fatigue response and facilitate ATP-PCr turnover.

  • Between sets: 1:5 to 1:10 work:rest ratio.

  • Between repetitions: 5-10 seconds.

  • Emphasis should be placed on the quality of the work performed.

Volume

• Plyometric volume is expressed in the number of “contacts” performed by the athlete.

• General guidelines are similar to prescribing training volume for other modes of resistance training.

  • Beginner (no experience): 80-100 contacts.

  • Intermediate (some experience): 100-120 contacts.

  • Advanced (some experience): 120-140 contacts.

Implementing the Program

• Introduction of plyometric training should follow a similar process to traditional resistance training:

  • Evaluate the Athlete.

  • Conduct a Needs Analysis.

  • Align the Program with Training Phases, Status, and Goals.

  • Teach Appropriate Technique.

  • Apply Sensible Progressive Overload.

Safety Considerations

• General motor literacy must be achieved prior to the introduction of plyometric exercises.

• Athletes will require a level of maximum strength to tolerate the sustained loading of plyometrics.

• The general training environment should also be considered.

Contact Information

• Discussion Boards

• Office Hours: 1300-1400 AWST Tuesday/Friday

• Email: s.guppy@ecu.edu.au