Download Proposed Title: Is plyometric training effective to increase power

ASCPH02
Plyometric Training
20056202
Name: Karl Thorpe
Proposed Title: Is plyometric training effective to increase power output and
have direct impact in an athlete’s chosen sport? This article will outline the
mechanics and physiology of plyometric exercise and with utilising data, will
demonstrate the effects of plyometric training with regards to power output.
The Eastern Europeans first used Plyometric training to develop Olympic
Athletes strength and power in the 1970’s. Fred Wilt was the first person to
brand the type of training he was using ‘Plyometrics’ in 1975. It is also known
as ‘Shock Training’ and in 1977, plyometric training was developed by
Yuriverkhoshansky. (Sankarmani et al., 2012:172-180)
Physiology of Plyometric Exercise
It is common knowledge that athletes have utilised effective methods in an
attempt to develop explosive strength such as barbell squats or the Olympic
lifts. (Verkhoshansky, 2012:1-74) Using heavy loads during exercises has
been deemed to improve strength where using lighter loads and moving the
load as fast as possible has been described as developing power. (Siff,
2004:265-275) Research has suggested that these methods are not the only
means of developing explosive strength.
Plyometric training has a plethora of exercises, which enable a muscle to
reach a maximal force in the shortest possible time. Plyometric training is
defined as a quick powerful movement involving an eccentric muscle action
immediately followed by an explosive concentric muscle action. (Baechle and
Earle, 2008:414-418) The strength shortening cycle (SSC) is involved in this
process. Muscle force and power have consistently shown a development
when plyometric training has been used correctly and two models are known
as the mechanical and neurophysiological models which best explain this
concept.
Mechanical Model of Plyometric Exercise
The result from a rapid stretch creates elastic energy to be stored within the
muscles and tendons. (Verkhoshansky, 2012:1-74) The stored energy will
only be released if after the stretch there is an immediate concentric muscle
action. The effect is like a spring, which wants to return to its natural length.
(Baechle and Earle, 2008:414-418) The spring is this case a component of
the muscles and tendons called the Series Elastic Component (SEC)
Mechanical model of skeletal muscle function (Potach & Chu 2008)
Neurophysiological Model
There is a response known as the stretch reflex, this resposnse takes place
when a quick stretch is detected in the muscles and an involuntary, protective
response occurs to prevent overstretching and injury. (Yessis, 2009:1-24)
Muscle activity is increased within the muscles from the stretch reflex causing
the muscle to act much more forcefully. (Verkhoshansky, 2012:1-74) This
results in a powerful concentric muscle action. Both the mechanical and
neurophysiological model causes the increase of force production within the
muscles during plyometric exercises. (Baechle and Earle, 2008:414-418)
Neurophysiological Model (Potach & Chu 2008)
The Strength Shorterning Cycle (SSC) is made up of three phases, eccentric
phase, amortization phase and concentric phase. (Yessis, 2009:1-24)
Phase
Action
Phsiological Event
Eccentric
Stretch of the agonist
Elastic energy is stored
muscle
in the series elastic
component
Muscle spindles are
stimulated
Amortization
Pause between phases
Type 1a afferent nerves
1 and 2
synapse with alpha
motor neurons
Alpha motor neurons
transmit signals to
agonist muscle group.
Concentric
Shortening of agonist
Elastic energy is
muscle fibres
released from the series
elastic component.
Alpha motor neurons
stimulate the agonist
muscle group
(Watkins, 2010:3-9)
Is Plyometric Training Effective
A study was carried out to determine the effects of plyometric training on
maximal power output and jumping ability. The aim was to have minimum
foot contact time with the floor when performing plyometric exercises with the
aim of jumping as high as possible. Exercises included the one-legged hop,
depth jumps and box jumps. (Makaruk and Sacewicz, 2010:17-18) The
experiment took place over six weeks and there was a significant increase in
the relative maximal power output when performing the plyometric exercises.
This highlighted that depending on the aim of the training programme;
plyometric exercises could be utilized to achieve certain gains. (Bompa,
2009:46-62) If the programme aim was to develop the athletes jumping
ability/explosive power for their particular sport then plyometric exercises
could be utilized to achieve this. (Myszka, 2012:1-5)
By making use of the SSC, it has been proven that the movements can be
made more explosive and powerful, as previously stated these movements
are know as plyometric exercises. (Wu et al., 2009:1-7) Plyometric drills are
designed to stimulate the series elastic component over and over again and
plyometric drills can mimic an athletes sport and stimulate dynamic
correspondence within their sport. (Sankarmani et al., 2012:172-180)
A recent study was carried out to determine the effects of weight training
using or not using plyometric training. It was carried out over six weeks
involving 40 inter colligate athletes. (Sankarmani et al., 2012:172-180) The
40 athletes were randomly split into two groups of 20. One group performed a
6-week weight-training programme whilst the other group included plyometric
training within the programme. Results outlined that there were significant
increases in vertical jump and 1rm tests with the group who used plyometric
training over the six weeks.
A wide variety of training studies shows that plyometrics can improve
performance in vertical jumping, long jumping, sprinting and sprint cycling. It
appears also that a relatively small amount of plyometric training is required to
improve performance in these tasks. (Verkhoshansky, 2012:1-74) Just one or
two types of plyometric exercise completed 1-3 times a week for 6-12 weeks
can significantly improve motor performance. Baechle and Earle, 2008:414418) Additionally, only a small amount of volume is required to bring about
these positive changes i.e. 2-4 sets of 10 repetitions per session or 4 sets of 8
repetitions. (Makaruk, 2010:17-22) While upper body plyometrics has
received less attention, three sessions of plyometric push ups a week has
been shown to increase upper body power as measured by medicine ball
throws. (Zatsiorsky and Kraemer, 2006:20-45) Using a variety of
plyometric exercises such as depth jumps, counter- movement jumps, leg
bounding and hopping etc., can improve motor performance. While the
majority of studies have focused on untrained subjects, trained athletes such
as soccer and basketball players have improved their performance with
plyometrics.
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