S&C Ch 18

What defines plyometric activities?

Concentric muscle actions using the stretch-shortening cycle (SSC) to increase power

T/F: Plyometric activities are rapid eccentric motions

True

What is the Stretch-Shortening Cycle (SSC)?

A rapid eccentric-concentric coupling that stores and releases elastic energy to produce force

What is the goal of plyometric training?

Increase power speed and agility by improving the efficiency of the SSC

What are the two plyometric models?

Mechanical model and neurophysiological model

What is the mechanical model?

Energy is stored in the muscle-tendon unit during stretch and released during contraction

What is the neurophysiological model?

Muscle spindles trigger a stretch reflex causing involuntary contraction

How do the two models work together?

They maximize force production quickly by combining stored energy and reflex activation

What are the 3 phases of the SSC?

Eccentric amortization concentric

What happens in the eccentric phase?

Muscle lengthens stores elastic energy and activates muscle spindles

What happens in the amortization phase?

Transition phase where energy is transferred and should be very short

What is the shortest phase of the SSC?

Amortization

What happens in the concentric phase?

Muscle shortens releases stored energy and produces force

Why must the amortization phase be short?

If too long energy is lost as heat and the stretch reflex is reduced

Ideal amortization phase time?

About 0.1 milliseconds

What is the recommended rest between reps?

5-10 seconds

Rest between sets?

2-3 minutes

What is the work to rest ratio?

1:5 to 1:10

Should you do plyos on consecutive days?

No for the same muscle group

Recommended frequency per week?

2-3 sessions per week

Recovery between sessions?

42-72 hours

How is lower body volume measured?

Contacts per workout

How is upper body volume measured?

Number of throws or catches

Typical program length?

6-10 weeks

When can improvements be seen?

As early as 4 weeks

Key focus for adolescents?

Fun and neuromuscular development

What plyos are NOT recommended for adolescents?

Depth jumps and high intensity drills

Recovery for adolescents?

2-3 days

Master athletes guidelines?

Lower volume lower intensity and 3-4 days recovery

T/F: Resistance training and plyos can be done at the same time regardless of athlete level

False

If combining aerobic and plyos what comes first?

Plyometrics

Balance requirement for beginners?

Stand on one leg for 30 seconds

Balance requirement for advanced?

Single leg half squat for 30 seconds

Box jump height range?

6-42 inches

Bodyweight caution for plyometrics?

Athletes over 220 lbs should avoid high depth jumps over 18 inches

What happens if the amortization phase is too long?

Energy is lost as heat and performance decreases

Why is plyometric training NOT cardio?

Each rep is maximal effort with full recovery

Why is fast stretch important in the SSC?

It increases muscle recruitment and force production

Why do tendons require more recovery than muscles?

They heal slower increasing injury risk

Why does increasing intensity too much eventually decrease performance?

The amortization phase gets longer reducing stored energy use and efficiency

A longer amortization phase will result in?

Decreased stored energy and efficiency

Why should not plyometrics be done when fatigued?

Fatigue reduces neuromuscular efficiency increases injury risk and decreases power output

T/F: Fatigue reduces mechanical efficiency

False

Why are plyometrics effective for improving athletic performance?

They enhance power by improving the efficiency of the SSC and muscle recruitment speed

Why should reps be performed with full effort and rest?

Because plyometrics target power not endurance quality over quantity

Why is it important to evaluate an athlete before starting plyos?

To ensure proper strength balance and technique to train safely

Why do heavier athletes need to be cautious with plyometrics?

Increased body weight places more stress on joints and connective tissue

Are muscles or tendons more prone to injury?

Tendons

What is the highest intensity of plyometrics?

Depth jumps

Why is the stretch reflex important in plyometrics?

It increases muscle activation and force production during the concentric phase

Why is minimizing ground contact time important?

It maximizes elastic energy use and improves power output

Increased tendon stiffness from plyometrics contributes to?

Better energy storage and release leading to more explosive movements

The contractile component CC is the primary source of muscle force during which action?

Concentric

T/F: A more stiff tendon in plyometrics has better energy storage and release

True

The parallel elastic component PEC exerts what type of force?

Passive force

Elastic energy is stored in the series elastic component SEC during which phase?

Eccentric phase

T/F: A fast stretch equals more force

True

T/F: Mechanical and neurophysiological models work together to increase force quickly

True

What is the primary role of the amortization phase in plyometric training?

To minimize the time between eccentric and concentric actions for optimal force production

What is the primary physiological benefit of plyometric training?

It increases tendon stiffness and muscle power for improved athletic performance

T/F: Plyometric training enhances the stretch shortening cycle

True

The stretch reflex is triggered by what?

Muscle spindles

Does a prolonged stretch inhibit or activate the stretch reflex?

Inhibit due to the Golgi tendon organs

T/F: Type Ia afferent fibers transmit information from muscle spindles to the spinal cord

True