Lecture 12: Power development principles Flashcards
What is power?
Force x velocity
Motor recruitment and power
Want exercises that involve high motor recruitment
Is power task specific?
Yes, power produced is relative to a specific exercise
Ballistic exercises
Exercises that involve either you or a med ball becoming a projectile; follows through the end range of motion
Examples of ballistic exercises
Med ball throw
Bench press throw
BB squat jump
Benefit of ballistic exercises
Improved maximal power output that caries over to sport demand
Force velocity relationship
Inversely related
Heavier loads= slower
(force= y-axis, velocity= x-axis)
Order of types of exercise on the force velocity curve
- Max strength
- Accelerative strength
- Strength-speed
- Speed-strength
- Speed
How does resistance training change the force-velocity relationship?
Moves force end to the right
How does ballistic/ explosive training change the force-velocity curve?
Shifts velocity end up
What is power on the force velocity curve?
Strength-speed and speed-strength
Strength-speed training
Moving traditional barbell/db exercises with submaximal weight as fast as possible
What is strength speed also called?
Dynamic effort method
Speed-strength training
Moving traditional Olympic lifts/jumps or other triple extension movements with high speed
How does intent impact power production?
Most crucial aspect in regards to improving power production, moving as rapidly as possible
Plyometrics
Involves body weight exercises that aim to maximize utilization of the stretch shortening cycle
What happens when the muscle spindles are stimulated such as with plyometrics?
Stretch reflex is stimulated, sending input to the spinal cord via Type Ia nerve fibres
After synapsing with the alpha motor neurons in the spinal cord, impulses travel to the agonist extrafusal fibres causing a reflexive muscle action
What is the stretch shortening cycle?
Muscle action where an essentric contraction is immediately followed by a concentric contraction
Combines mechanical and neurophysiological mechanisms
Basis of plyometrics
How does the stretch shortening cycle work?
- A rapid eccentric muscle action stimulates the stretch reflex and storage of elastic energy
- Increases the force produced during the subsequent concentric action
Why does the SSC occur?
Tendons store elastic energy
The greater the release of elastic energy, the greater the reduction in cross bridge formation and force output from muscle(energy conservation)
Beneficial for power/speed sports and endurance sports
What is the half life of SSC?
0.85s and therefore at 1s the ability to use SSC is diminished by 55%
You want the ground contact time to be as short as possible
What does tendon recoil do?
Responsible for increases in power output and energy conservation
Tendon stiffness
Constant
Muscle stiffness
Variable and depends on forces exerted
What is required when we develop muscular stiffness?
Greater stretch of the tendon
What does higher tendon stiffness result in?
Shorter ground contact times and greater rates of force production
Short SSC
100-250 ms ground contact time
Examples of short SSC exercises
Sprinting
Long jump
Vball attack
Basketball block
High jump
Multiple hurdle jump
Long SSC
> 250 ms ground contact time
Examples of long SSC exercises
CMJ
Broad jump
Vball block
Box jump
Drop jump
Three components of the stretch shortening cycle
I. Eccentric
II. Amortization
III. Concentric
Eccentric phase of stretch shortening cycle
Stretch of agonist muscle
Amortization
How long you spend on ground
Concentric phase of SSC
Shortening of agonist muscle fibres
Creating force in opp direction
Plyometrics to enhance SSC
Progressive and based on technical mastery
Precede with strength training to improve strength of musculotendinous system and improve quality and quantity of type 2 muscle fibres
Prioritize jumping and landing components
Focus on quality of movement
Things to consider with plyometrics
- The greater the speed of movement, the greater the intensity
- Single leg drills are more intense loading than double leg but shorter ground contact time (harder)
- The greater the amplitude (jump height) the greater the intensity
- Consider the impact of extra load and athletes body mass as indicators of higher intensity
Plyometric principles
Slow before fast
Bilateral before unilateral
Low before high
Extensive before intensive
Uniplanar before multiplanar
Simple before complex
Quality over quantity
Strength before power
Leave room to adapt (dont rob yourself twice)
What does leave room to adapt mean?
If you introduce advanced plyometrics too early, athletes can’t properly perform it. But then when you go to reintroduce it their body wont have that initial adaptation to a new stimulus and wont see novel training effects
Philosophy of training power for team sports
- Triple/hip extension (lower) and end range (upper)
- Multi-directional
- Teachable to all training ages
- Time appropriate
Example of an exercise to improve power in baseball pitcher
Rotational med ball throw
How much should we increase jumping volume by each week?
<10%
What is the foundation for true power development?
TRIPLE EXTENSION
What is key to improve for plyometric activities?
Improvements in amortization phase
Queens plyometric progressions
- Landing (snap down-drop-mini hurdle)
- Extensive (pogos)
- Box jumps (seated to standing)
- Jumps in place (broad jumps)
- Continuous jumps
- Jump over object
- Loaded jump
- Depth jumps (jump off box)
- Drop jumps (immediately jump back up)
Example of uniplanar to multiplanar progression
Vertical–>horizontal–>lateral–>rotational
Reactive strength index scores (RSI)
<1.5 low reactive strength ability
1.5-2.0 moderate
2.0-2.5 Well established
>2.5-3.0 High
>3.0 World class
Plyometrics
Rapid engagement of muscle spindle
High velocities
Short ground contact times
Maximal intent
