Chapter 18 Shit Flashcards
What is the Mechanical model of plyometric exercise?
-Elastic energy in musculotendinous components is increased with a rapid stretch and then stored
-When the movement is followed by concentric muscle action - stored energy is released, increasing total force production
-Series elastic component (SEC)
+Largely revolves around the tendons acting as springs following the stretch in eccentric muscle action
+Stored elastic energy will contribute to total force output when rapidly followed by a concentric action
+If concentric action does not follow the eccentric immediately, or if the eccentric phase is too long or requires too much motion, stored energy dissipates as heat
What is the neurophysiological model of plyometric exercise?
-Involves the potentiation of concentric muscle action by use of the stretch reflex
+Caused by muscle spindle activity when muscles are rapidly stretched during the eccentric phase
-Plyometric exercise, muscle spindles are stimulated by a rapid stretch - resulting in reflexive muscle action
+Reflexive action potentiates (increases) the activity of the agonist, increasing muscle force during concentric action
-If muscle action does not immediately follow the stretch, the potentiating ability is negated
-Most likely, both models contribute to the increased force production in plyometric exercise
+Unclear the extent to which each plays a role - further research needed
What is the stretch-shortening cycle? (SSC)
-Employs energy storage capabilities of the series elastic component (SEC) and the stretch reflex to facilitate a maximal increase in muscle recruitment in a minimal amount of time
-Phases of SSC
+Phase 1 - eccentric
++Involves preloading the agonist muscle groups
+++SEC stores energy
+++Muscle spindles are stimulated
++++Send signal to ventral root of the spinal cord via type 1a afferent nerve fibers
+Phase 2 - amortization phase
++Time from the end of eccentric phase to initiation of concentric muscle action
++Delay occurs between eccentric and concentric as type 1a afferent nerves synapse with alpha motor neurons in the ventral root of the spinal cord
+++Alpha neurons then transmit signals to the agonist muscle group
++Crucial phase in allowing greater power production
+++Duration must be kept short
+++If amortization phase is too long, energy from eccentric phase dissipates as heat, and stretch reflex will not increase muscle activity during concentric phase
+Phase 3 - concentric phase
++Body’s response to eccentric and amortization phase
++Energy stores in SEC during eccentric phase is used to increase the force of the subsequent movement
+++Stored energy results in more force during concentric phase than would occur with an isolated concentric action
++Alpha motor neurons stimulate the agonist muscle group
+++Results in reflexive concentric muscle action
++Efficiency of SEC and stretch reflex is essential to proper plyometric performance
++High stretch rate in eccentric results in greater muscle recruitment and activity during the SSC concentric phase
-Example - vertical jump tests
+Static squat jump - lowest jump height - no elastic energy due to removal of eccentric phase via pausing in the 90-90 position
+Countermovement jump - fast countermovement acts as eccentric phase to allow the athlete to store and use stored elastic energy and capitalize on the stretch reflex
+Approach jump has the most forceful eccentric phase - allows the greatest jump height
What is the mode when referring to plyo exercises?
Determined by the body region performing the given exercise
What are lower body plyos appropriate for and what are some of the variations?
-Lower body plyometrics
+Some lower body plyometrics are appropriate for virtually every sport
++Each sport has its own requirements regarding vertical, horizontal, lateral movement, and direction changes
+Lower body plyometric drills vary in intensity and include:
Jumps in place
++Standing jumps
++Multiple hops and jumps
++Bounds
++Box drills and depth jumps
What are upper body plyos appropriate for and what are some of the variations?
-Rapid explosive upper body movements needed for several sports and activities
+I.e. pitching in baseball or a golf swing
-Upper body plyometrics are less common than lower body plyometrics but are essential for upper body power
+Medicine ball throws
+Catches
+Certain push-up variations
What are trunk plyos appropriate for and what are some of the variations?
-Difficult to perform true plyometric drills for trunk musculature
+Stretch reflex less involved in many trunk exercises
+Latency in reflex largely determined by nerve conduction velocity
++Increases with greater distances from spinal cord
++I.e. quadriceps and gastrocnemius reflexes typically 30-45ms, respectively
++Latencies assumed to be shorter for trunk muscles due to proximity to spinal cord
+Trunk plyometrics can be performed with movement modification to be made more “plyometric”
++Movements must be shorter and quicker to allow stimulation and use of stretch reflex
++Decreased ROM
How can one vary intensity for plyometrics?
-Represents the amount of stress placed on involved muscles, connective tissues, and joints
-Intensity covers a large range
+Low intensity - skipping drills
+High intensity - depth jumps
-As intensity increases, volume should decrease -
+Careful selection of proper drills required for each training cycle
How should one think about frequency with plyometrics?
-Typical frequency is 1-3 sessions per week
-Depends on:
+Sport
+Athletes experience
+Time of year/season
-Recommended to have 48-72 hours of recovery between sessions
-Also depends on total training volume from resistance and sport-specific practice
-Due to limited research, focusing on adequate recovery and practical experience as a coach may be the best determinant for frequency
How does plyometrics affect recovery?
-Plyometric drills involve maximal efforts of anaerobic power
+Require adequate recovery between repetitions, sets, and workouts
-Examples
+Depth jumps - 5-10 seconds between reps, 2-3 minutes between sets
-Rest time determined by a proper work-to-rest ratio
+Specific to volume and type of drill being performed
+The typical recommended work-rest ratio is 1:5 to 1:10
-Plyometric drills should be considered power training as opposed to cardiorespiratory conditioning
-Recovery must be adequate between sessions - 2-4 days of recovery
-Drills for a given body area should not be performed 2 days in succession
How should volume be considered for plyometrics?
-Workout volume for plyometrics is typically expressed as the number of foot contacts per workout
-Can also be expressed as distance - i.e. in plyometric bounding
+I.e. athlete progresses from 98 feet of double leg bounding to 328 per repetition of the same drill
-Appropriate plyometric volume
+Beginner - 80-100 contacts
+Intermediate - 100-120 contacts
+Advanced - 120-140 contacts
How long should a plyometrics program be?
-Typical program range from 6-8 weeks
-Vertical jump height shown to -improve in as little as 4 weeks
-Should be prescribed similarly to aerobic and resistance training
-For sports requiring quick, powerful movements, it is beneficial to perform plyometrics throughout the -macrocycle
-Intensity and volume should vary with the sport and season
How should progression be done for plyometrics?
-Should follow the principles of progressive overload
Systematic increase in frequency, volume, and intensity
Typically as intensity increases, volume decreases
Example - off season program for american football
Can be performed twice a week
Should progress from
Low-to-moderrate volumes of low intensity
Low-to-moderate volume of moderate intensity
Low-to-moderate volume of high intensity
How should you warmup for a plyometric session?
-Plyo sessions should begin with general warm up, stretching, and specific warm ups
-Specific warm up should be low-intensity dynamic movements
-Warm-up drills
+Marching
+Jogging
+Skipping
+Footwork
+Lunging
What are age considerations for plyometrics with adolescents?
-Can benefit from plyometric training programs
-Increases muscular power
-Prepares youth athletes for the demands of sports practice and competition
-Analysis of development determine appropriate programming
+Prepubescent children
++Should avoid depth jumps and high-intensity plyometrics due to open epiphyseal plates
+++Can result in premature closure if injury occurs
+Must have the maturity to follow directions and understand the benefits of plyometric training
+Should Focus on neuromuscular control and anaerobic skills to promote safer participation in sporting activities
++I.e. proper landing technique (no valgus knee) reduces risk of injury and can be trained via plyometrics
+Programs for children should progress from simple to complex drills
+Between-workout recovery must be sufficient to avoid overtraining
