Chapter 17 plyometric and speed training program design and technique
Benefits:
- Improve sport performance but also job performance and activities of daily living
- Injury prevention
- Increased bone mass (for those at risk of osteoporosis)
- Combating aging-related issues
- Overall enhanced coordination
- Increased agility
- Improved anaerobic and general conditioning
A plyometric movement is a quick, powerful movement consisting of an eccentric muscle action, also
known as a countermovement or prestretch followed by immediate powerful concentric muscle
action. Speed is simply the ability to achieve high velocity.
Stretch-Shortening Cycle and its Effects on Plyometrics and Speed Training.
The stretch-shortening cycle is a crucial mechanism that underpins both plyometric exercises and
speed training, as it plays a pivotal role in achieving the desired outcomes in these training
modalities. Plyometric exercises serve to harness the potential of the stretch reflex and the inherent
elastic properties within muscles and tendons. The overarching goal is to enhance the power
generated during subsequent movements and, simultaneously, to fortify the functional capacity of
muscles and tendons. Speed training exercises leverage the same mechanical and neurophysiological
components, coupled with proper technique and muscular strength, to amplify ground forces. This
augmentation in ground forces empowers individuals to achieve higher running speeds. When
properly employed, plyometric training consistently exhibits the capacity to enhance muscle force
and power generation. This heightened power production can be explained through two principal
models: the mechanical model and the neurophysiological model.
Mechanical Model of Plyometric Exercise: The mechanical model hinges on the concept of elastic
energy accumulation. Following a rapid stretch, elastic energy is stored, and subsequently, during the
concentric phase of muscle contraction, this stored energy is released, leading to heightened total
force generation. Within the musculotendinous unit, three pivotal mechanical components are
involved: the series elastic component (SEC), parallel elastic component, and contractile component.
The SEC, predominantly constituted by tendons with limited muscular elements, emerges as the
primary force contributor during plyometric exercises. Functioning akin to a spring, the SEC stores
energy when subjected to eccentric contraction, subsequently releasing this stored energy during
concentric contraction. This orchestrated energy transfer elevates the overall force production
during the concentric phase. Should a concentric action not immediately follow, the stored energy
dissipates as heat.
Neurophysiological Model of Plyometric Exercise: The neurophysiological facet revolves around
modifications in force-velocity characteristics within a muscle's contractile elements due to stretch-
induced alterations. The stretch reflex governs the enhancement of concentric muscle force. The
stretch reflex constitutes the body's involuntary response to an external stimulus that swiftly
stretches the muscle. This rapid stretch triggers a signal transmission to the spinal cord, which, in
turn, prompts a message returning to the muscle, culminating in a concentric contraction of the
same overstretched muscle. Accelerated muscle stretching results in more substantial concentric
force following the stretch, ultimately leading to amplified power output. A quintessential instance of
this phenomenon is the reflex test performed by physicians, where a tap on the patellar tendon
elicits the well-known knee jerk response. The speed of the stretch directly correlates with the
intensity of the ensuing contraction.
,Stretch shortening cycle
The SSC is a model explaining the energy-storing capabilities of the SEC and stimulation of the stretch
reflex that facilitate a maximal increase in muscle recruitment over a minimal amount of time. The
SSC involves three distinct phases:
The stretch-shortening cycle describes the stretch reflex and stored elastic energy-induced
increaseds in concentric force production that follow a rapid eccentric muscle action
, Utilizing Plyometric Exercise: Identifying Appropriate Applications
The utility of plyometric training for enhancing athletic performance is evident, as many sports
necessitate swift and forceful movements to achieve success. However, it's important to consider
which other populations might also benefit from the power-enhancing effects of plyometric training.
Plyometric Training for Enhanced Sport Performance:
• Athletes seeking to enhance explosiveness in their sport can reap substantial benefits.
• Integrating exercises that mirror sport-specific movements into training regimens is essential.
• The marked increase in muscle power production achieved through plyometric training is known to
correlate with improved sport performance.
Extending Benefits to Work Performance:
• The advantages of improved performance may extend to occupational settings, especially for jobs
requiring physical exertion.
• Professions such as police officers, firefighters, and military personnel can notably benefit from
enhanced physical capabilities, aligning with the nature of their roles.
Injury Prevention through Plyometric Training:
• The potential of plyometric training in injury risk reduction has generated significant interest.
• Plyometric exercises contribute to improved bone mineral content, muscle recruitment, strength,
and overall body control and balance.
While plyometric training predominantly targets athletic enhancement, diverse populations can
harness its advantages. In conjunction with augmented power, well-structured plyometric programs
have demonstrated potential for lowering injury rates and promoting better bone health, muscle
engagement, strength, and overall body stability.
Plyometric Safety Considerations: Although research has yet to pinpoint populations for whom
plyometric training is contraindicated, assessing clients' age, experience, and current training level
can help discern their readiness for plyometric training. To mitigate injury risks and optimize
plyometric exercise performance, clients must grasp proper technique and possess a foundational
base of strength, speed, and balance. Furthermore, clients should exhibit both physical and
psychological maturity to participate effectively in a plyometric training regimen.
Age and Maturity Considerations: Plyometric exercises, when appropriately modified for intensity,
can generally be safe for most age groups. However, adjustments in intensity and volume are
necessary based on age.
• Youth: Focusing on proper technique, particularly for jumping and landing, is pivotal. Emphasize
personal growth over competition. Incorporating low-intensity exercises at the session's outset,
infused with an element of fun and creativity, is recommended.
• Adolescents: Incorporate low-intensity plyometric exercises as long as safety criteria are met.
Emphasize technique improvement due to ongoing neuromuscular development. Begin with low-
intensity exercises as a warm-up and progress to moderate-intensity exercises once safety standards
are met. Adherence to trainer instructions is crucial, indicating readiness for plyometric training.
, Posture, Flexibility, and Stability: The foundational stance for lower-body plyometric exercises
originates and concludes in a partial or half-squat position. Evaluating a client's ability to maintain
this position is essential to ensure proper landing execution. Clients should be proficient in partial
squat and body weight squat movements before engaging in low-intensity plyometrics. The focus is
on maintaining alignment, offering a robust base for dynamic actions. Adequate mastery of a single-
leg squat position, as demonstrated in balance tests, is pivotal before progressing to higher-level
exercises.
Strength Assessment: Preliminary strength assessment is vital before commencing plyometric
exercises. Clients inexperienced in resistance training should engage in standard exercises before
embarking on plyometric programs.
• For lower-body plyometrics, a client's one-repetition maximum (1RM) squat should be at least 1.5
times their body weight.
• Caution is advised for clients exceeding 220 pounds (100 kg) in body weight, as increased mass
elevates compressive forces. High-volume and high-intensity plyometrics should be approached with
care.
• A prerequisite upper body strength measure is the ability to perform five clap push-ups
consecutively.
High-intensity plyometric activities necessitate adherence to these strength prerequisites. Core
strength evaluation is also imperative, as it significantly influences balance and postural stability,
integral to plyometric effectiveness and injury prevention.
Speed Evaluation: For lower-body plyometrics, clients should perform five repetitions of a squat with
60% body weight in 5 seconds or less. Comparable criteria apply for upper-body plyometrics
involving the bench press. If clients fail to meet these standards, they should initiate lower-intensity
plyometrics with less reliance on speed.
Landing Technique: Efficient landing technique is crucial to optimize exercise effectiveness and
minimize injury risks. During landing, shoulders should align over knees, knees over or slightly
posterior to toes, and ankles, knees, and hips should be flexed with feet approximately shoulder-
width apart. Clients must execute a soft landing and maintain dorsiflexion of the ankle, ensuring full-
foot contact with the ground. Weight should be centered on the ball of the foot, not the heel.
Landings can be refined through exercises like vertical jumps followed by freeze landing positions for
analysis. In plyometric activities involving jumps, hops, leaps, bounds, skips, and quick foot drills,
focusing on elevated knees and thumbs facilitates balance by centralizing workload around hips and
legs. Upright thumbs force an upright torso alignment.
