Post by carruthersjam on Sept 5, 2007 9:39:52 GMT -8
Below are a number of resources regarding postactivation potentiation (PAP):
Super - methods of Special Physical Preparation for the High - Class Athlete
Yuri Verkhoshanski, PhD
National Olympic Committee of Italy
University Tor Vergata, Rome
The Stimulation Method. The idea behind this method is to employ the hyper - excitability of the central nervous system created by brief powerful muscular tension, to enhance the subsequent specific work, in order to develop explosive strength and the reactive ability of the neuro - muscular apparatus (16,47).
It is common knowledge in physiology that any irritant which stimulates muscle activity, however short-term, leaves traces in the nervous system. The trace phenomenon remains for some time after the stimulation has ceased. These traces can have a significant effect on the subsequent muscular activity; in particular, enhance the magnitude of this activity (4,8,16,20). For example, the preliminary isometric tension has a positive effect on the subsequent dynamic work. This effectiveness of this preliminary tension is up to 20% higher in comparison with the work conducted without preliminary isometric tension (in detail see 16,29).
The results of a laboratory experiment demonstrate (Figure 8) the affect on explosiveness as measured by the height to which a weight is thrown on the special device (16,20). The affect increases on the average by 38-40% after preliminary stimulating work (pressing a barbell with 80% of maximum, three sets of three repetitions, followed by rest between the first and second bout of work for 5-6 minutes). Here, the movement time is reduced (6.0%), its amplitude is greater (4.8%), the speed of movement has increased significantly (11.7%) and the power of work has increased significantly (47.3%).
The traces phenomena in the nervous system and their affect on the subsequent work are the end result of many factors: the force of the tonic influence, the degree of fatigue and the time separating the preceding and subsequent work. For example, after a back squat (tonic work) the alteration in the parameters of a F(t) curve of explosive isometric effort by extension of the leg is observed (Figure 9). The maximum effort increases by 26% from the initial level after the first minute and then by the 4th-5th minute it reaches 65%. The beginning of the F(t) curve does not change much (F1, F2 and F3) the forces which exceed the initial level and duration with which they are maintained are the smaller the closer to the beginning of effort F(t) is to the ordinate. The amount of time required for the maximum increase in effect (Figure 10) falls 2.6% immediately after tonic work. Then this time drops to 3-4 minutes up to 4.6%; and the subsequent increase exceeds the initial level considerably.
The effect of the stimulation determines the amount of time to reach a maximum of force and duration of the after-effect of the tonic work. Therefore, it is important at which moment the subsequent work starts. For example, maximum height of the vertical standing jump is reached after the 3rd-4th minute. The difference is a 6.8% increase over the initial level. After the back squat an increase of 8.0% from the initial level is realized in the 8th – 10th minute after depth jumps (Figure 11).
The stimulation method consists of two successive muscle activities. The first (tonic) is carried - out slowly with major resistance and a limited number of repetitions. The second activity (developing) is conducted with an extremely concentrated explosive effort with smaller weights (30-40% from the maximum) and significantly more (optimum) repetitions. The preliminary (tonic) activity essentially increases the power output of the subsequent, because of its tonic affect on the central nervous system, which is in effect the main training effect of the stimulation method.
The high effectiveness of the stimulation method has been proven effective for the development of explosive strength and the reactive ability of the neuromuscular apparatus. The value of this method is that it provides a fast and steady increase in these parameters within a short period of time and with a relatively small expenditure and energy (16,20,27,30).
Variants of the stimulation method for the development of explosive strength and reactive ability of muscle-extensors of legs are presented in Figure 12. For example, the vertical squat jump with a weight held between the legs (16, 24 or 32 kg is selected individually) used in the first variant for tonic work. Two sets of 6-8 jumps with the rest of 3-4 minutes are conducted. Then after a rest of 3-4 minutes, the second (developing) exercise is executed for 6 or 8 multiple jumps from one leg to the other with the maximum effort. The work consists of two sets of 5-6 repetitions of exercise with the rest between the sets of 3-4 minutes. This series is repeated for 2-3 times with the rest of 6-8 minutes.
Other variants of a stimulation method are carried out in a similar manner. The back squat is employed as a tonic exercise. Now the main (developing) exercises are the jumps with the weight held between the legs, jumps with the bar on the shoulders, or depth jumps.
All the variants are rank - ordered from the top to bottom by the power of work and the training effect on the neuromuscular apparatus. The most potent variants are the fourth and especially the fifth, which should be utilized only in the training of the high level sportsman.
The potential to develop new variants of the stimulation method are limitless and are confined to the realm of developing explosive strength and reactive ability.(review see 16,29). For example, sprinters have experienced an increase in the speed of the initial acceleration and the running speed after intense jumping exercises. It has also been established that three hops from one leg to the other at sub - maximum effort over a distance of 60-80 meters with resting pauses of 1.5 - 2 minutes between bouts, increases the speed by 2-3% in the main part of the training session of middle distance runners. The velocity of short distance runs increases and in this is maintained at a high level during the majority of a series of runs. The after-effect of tonic work (swimming with the resistance of a rubber cord, swimming with towing a resistance, swimming with a harness on the shoulders) will increase swimming speed over short distances by 4-7% (review see 20).
==================
Postactivation potentiation: role in human performance.
Sale, D.G.
Exercise and sport sciences reviews 30(3), July 2002, 138-143
English Abstract
Postactivation potentiation (PAP) is the transient increase in muscle contractile performance after previous contractile activity. This review describes the features and mechanism of PAP, assesses its potential role in endurance and strength/speed performance, considers strategies for exploiting PAP, and outlines how PAP might be affected by training.
==============
Rixon, K.P., H.S. Lamont, and M.G. Bemben.
J. Strength Cond. Res. 21(2):500–505. 2007.—
Postactivation potentiation (PAP) or enhanced contractile
capabilities may be influenced by a number of factors. This study
examined the influence of type of muscle contraction (isometric vs.
dynamic), gender, and previous weightlifting experience on PAP as
demonstrated by changes in jump height and power output.
Thirty young men (n = 15) and women (n = 15), classified as either
having previous weightlifting experience (n = 20) or not (n = 10),
performed 3 different sets of countermovement jumps, with the first
set used to determine baseline measures of jump height and power. The
second set was performed after a maximal isometric squat protocol
(maximal voluntary contraction [MVC]-PAP) to induce PAP, and the
third set of jumps was performed after a maximal dynamic squat (DS)
protocol (DS-PAP). A 3-way repeated measures analysis of variance
determined that jump height after the MVC-PAP protocol was
significantly higher than both the pretest and DS-PAP values, that
men performed significantly better than women, and that the
experienced lifters responded more favorably than the inexperienced
lifters.
Jump power was also significantly greater for the MVC-PAP condition
compared with the other 2 conditions, and DS-PAP power also improved
when compared with the pretest values, with men performing
significantly better than women. All results remained consistent
after accounting for height and weight differences (body mass index)
between the groups. In conclusion, the isometric condition (MVC-PAP)
evoked a greater muscle postactivation potentiation than the dynamic
condition (DS-PAP), and postactivation was enhanced by previous
weightlifting experience. The practical manipulation of MVC by
pushing, squatting, or both against fixed objects, such as walls and
low ceilings, could be a very simple and cost-effective way to arouse
a state of PAP before sports performance that requires high force and
power outputs.
----------------------
Villarreal, Gonzalez-Badillo, and Izquierdo. Optimal warm-up stimuli of muscle
activation to enhance short and long-term acute jumping performance. EJAP 2007;
100: 393-401.
This group investigated the effect of seven different warm up protocols on
jumping performance with both a 5 minute and 6 hour latency period. The two
primary findings were:
1. High-intensity dynamic loading (e.g. 80-95% 1RM), as well as specific
volleyball warm-up protocol bring about the greatest effects on subsequent
neuromuscular explosive responses.
2. Acute positive effects on jumping performance after warm-up were maintained
after long recovery periods (e.g. 6 h following warm-up), particularly when
prior high-intensity dynamic actions were performed.
============
Guellich, A. Schmidtbleicher, D.
Title
MVC-induced short-term potentiation of explosive force. (Les MCV engendrant un potentiel de force explosive a court terme.)
Source
New studies in athletics 11(4), Dec 1996, 67-81
English Abstract
In numerous sports and sport events performance is, to a great extent, determined by the level of speed-strength. An optimal preparation (warm-up) is necessary to achieve the highest possible realization of speed-strength in training and competition. Some top international athletes are said to have produced the highest speed and speed-strength performances immediately after having performed a few Maximal Voluntary Contractions (MVCs). However, as yet no target-oriented and systematic studies of MVCs, as an element of warm-up programmes, have been conducted. Therefore the focus of the following study is on the following questions: (1) To what extent can the short-term potentiation of speed-strength induced by MVCs be considered a general effect? (2) Can effects of post-tetanic potentiation be triggered in human beings by MVCs? (3) To what extent is there a connection between possible short-term increases in speed-strength and neuronal effects of post-tetanic potentiation? The results of two complex training experiments show that MVCs carried out during the warm-up can really lead to a considerable increase in speed-strength performances of the lower extremities in all athletics sprint and jumping events and of the upper extremities in the shot put and the throws.
====================
3.4.2 THE AFTER-EFFECT OF MUSCLE ACTIVITY
(M C Siff "Supertraining" 2000 Ch 3, p163 - 165)
It is known that, if a muscle is stimulated by a series of impulses, its
activity slows down more after the last one than when it is stimulated by a
single impulse. Any stimulus, whether momentary or not, leaves traces in the
nervous system. The traces or after-effect phenomenon persists for some
time after stimulation ceases, which reveals the relative inertness of the
nervous system and its great significance for motor activities (Pimenov,
1907, Pavlov, 1929, Orbeli, 1947).
In physiology, this specific form of muscular facilitation (see PNF, Ch 7.2)
is referred to as post-tetanic potentiation, in particular when the
preparatory stimulus is produced by maximal or activity or “tetanusâ€* (e.g.
Abbate, 2000; Brown & Euler, 1938;. Burke et al, 1970; Grange et al, 1993;
Marsden et al, 1971; O'Leary et al, 1997; Palmer & Moore, 1989; Vandervoort,
1983). These phenomena and the processes of adaptation associated with them
form the foundation for fitness development. They determine the continuing
rise in fitness, despite periodic interruption in the training process
(Matveyev, 1964; Mateev 1964; Zimkin, 1965).
Research into the after-effects of muscular activity is contradictory,
particularly in Western literature. For instance, a statistically significant
increase in the speed of an unloaded movement was found directly after the
same movement was executed with a weight (Murray, 1959; Van Huss et al,
1962). Conversely, other research could not detect such an effect, despite
subjective claims by the athletes that their movements felt quicker after
using loads (Nofsinger, 1963; Nelson & Lamber, 1965). No increase in the
vertical jump could be measured shortly after preceding resistive exercises
(Stockholm & Nelson, 1965). Shot-put results even deteriorated after
preliminary throws with a heavier shot (Bischke & Morehouse, 1950).
The after-effect has been examined in more detail in Russian research. It
has been noted that preliminary isometric tension has a positive effect on
the subsequent dynamic work. Despite fatigue following isometric tension,
the effectiveness of dynamic work increases, usually by up to 20% when
compared with work executed without preliminary isometric ten-sion. With the
reverse sequence of work, results deteriorate (Shiedin & Kunevich, 1935;
Vinogradov & Delov, 1938; Vereshchagin, 1956; Farfel, 1964; Uflyand, 1965).
The after-effect occurs immediately after preliminary isometric tension. The
first dynamic contraction still retains some trace of inhibitory influence,
but by the second contraction, strength increases sharply compared with its
initial level (Leinik, 1951; Vinogradov, 1966). The data indicates that
isometric tension under certain conditions can serve as a stimulus for
dynamic work and play an important role in developing muscular strength.
Dynamic work with heavy weights (i.e. high tension with relatively few
repetitions) also elicits a positive after-effect in the central nervous
system (CNS), which produces a general toning influence on the motor
apparatus and an improvement in speed and strength (Portnov, 1955; Ratov,
1957; Diachkov, 1961; Muravov & Tkachev, 1964; Letunov, 1965).
In practice, the after-effect phenomenon of strength work is used to exploit
its immediate and delayed effects. It should be noted that there is an
improvement in performance immedi-ately following strong tension; i.e. this
is an immediate after-effect. In addition, intense preliminary strength
tension improves results in jumping exercises (Diachkov, 1958; 1961;
Verkhoshansky, 1961; Tatian, 1964; Tkachev, 1967), in shotputting (Fritsch,
1961; Ivanova, 1964; Markov, 1966), and in rowing (Ermishkin & Vozniak,
1965; Chuprun, 1966).
For the delayed effects, preliminary stimulation is used to improve the
functional state of the neuromuscular apparatus during the athlete's
preparation for competition or in training for speed-strength (Diachkov,
1961; Vrzhesnevsky, 1964; Khodykin, 1976). The positive effect is obtained
only if this state is promoted at an optimal level of stimulation.
Over-excitation of the CNS has a negative effect on the precision and
coordination of movements, i.e. on athletic skill (Diachkov, 1961; Yakimova,
1964).
The after-effect phenomenon in the nervous system and its influence on the
subsequent work is influenced by many factors, in particular, the strength of
the stimulus, fatigue and the time interval separating the preceding activity
from the subsequent activity. Thus, after tonic work (with barbell squats)
the following changes in the parameters of the force-time curve F(t) of
explosive isometric force in a controlled task (leg extension), may be
observed (Fig 3.27):
1. maximum force increases significantly over the first minute, by 25% of
the initial level
2. after 4 to 5 minutes the force continues to grow to 65%.
The beginning region of the F(t) curve undergoes less significant change
because the magnitude and duration exceed the initial levels by a smaller
amount, the closer the beginning force is to the F(t) ordinate. The time
required to reach maximum force was reduced by 2.6% immediately after tonic
work and by 4.6% after 3-4 minutes (Fig 3.28). Later it began to increase
until it exceeded the initial level (Tatian, 1964).
Figure 3.27 The force-time curve of explosive isometric effort achieved for
leg extensions with different resis-tances F1, . . . , Fmax at various times
after squatting.
Figure 3.28 Variation in time taken to produce maximum explosive isometric
force at different times after pre-ceding tonic work
Figure 3.29 Change in height of a vertical jump executed after different
types of tonic work (1 = barbell squat; 2 = take-off after a depth jump).
For moderately qualified athletes, the largest increase (90%) in dynamic
strength after a static effort corresponds to a load of 50% of 1 repetition
maximum (1RM), while the smallest increases corresponded to loads of 25% of
1RM (6.7%) and 100% of 1RM (5.8%). With increase in fitness, the post-work
improvement can occur with large loads of up to 100% of maximum (Ilin, 1961).
Consequently, with the rise in fitness and the strength of the stimulus,
the ability to evoke a subsequent positive effect also rises. However, in
principle, the optimal and not the maximal load is necessary for obtaining
the greatest post-work improvement.
The strength of the stimulus also determines the time taken to achieve the
maximum lifting force and the duration of the after-effect. Therefore, from
a practical standpoint, the moment at which sub-sequent work begins is of
some importance. For example, vertical jump height varied in the post-work
period, depending on the nature of the tonic work (Fig 3.29). Three to four
min-utes after barbell squats the height of the jump was 6.8% above initial
levels, and 8-10 minutes after depth jumps, it was 8.0% above initial levels
(Tatian, 1964).
In experiments with preliminary isometric tension (Ilin, 1961), the maximum
was achieved most rapidly with loads of 25% of 1RM (after 12 minutes), and
most slowly with 100% of 1RM (after 15.4 minutes) and 50% of 1RM (after 17.2
minutes). Research has determined that the optimal rest interval between
sets in weightlifting (during the presence of the after-effect phenomenon in
the CNS) is 2-5 minutes, with the rest period increasing with the bodymass of
the lifter (Ermolayev, 1937; Krestovnikov, 1952; Budze, 1959; Kazakov,
1961). It has been established that weightlifters who time their rest
intervals carefully make 20% fewer failures than those who do not (Klimonov,
1965).
The delayed-effect of strength work depends on the volume and intensity of
the preceding loads. For example, a moderate volume of barbell exercises
produces a positive tonic influence on the motor apparatus of athletes on the
next day or the day after (Diachkov, 1961). The use of depth (plyometric)
jumps as a means of stimulation delayed this effect for 5-6 days
(Verkhoshansky, 1963; Khodykin, 1976).
The use of the after-effect phenomenon offers some interesting opportunities
for increasing the effectiveness of strength preparation via a more limited
volume of training work. Athletes and coaches have great potential for
creativity, which can significantly enrich the theory and practice of sports
training.
Super - methods of Special Physical Preparation for the High - Class Athlete
Yuri Verkhoshanski, PhD
National Olympic Committee of Italy
University Tor Vergata, Rome
The Stimulation Method. The idea behind this method is to employ the hyper - excitability of the central nervous system created by brief powerful muscular tension, to enhance the subsequent specific work, in order to develop explosive strength and the reactive ability of the neuro - muscular apparatus (16,47).
It is common knowledge in physiology that any irritant which stimulates muscle activity, however short-term, leaves traces in the nervous system. The trace phenomenon remains for some time after the stimulation has ceased. These traces can have a significant effect on the subsequent muscular activity; in particular, enhance the magnitude of this activity (4,8,16,20). For example, the preliminary isometric tension has a positive effect on the subsequent dynamic work. This effectiveness of this preliminary tension is up to 20% higher in comparison with the work conducted without preliminary isometric tension (in detail see 16,29).
The results of a laboratory experiment demonstrate (Figure 8) the affect on explosiveness as measured by the height to which a weight is thrown on the special device (16,20). The affect increases on the average by 38-40% after preliminary stimulating work (pressing a barbell with 80% of maximum, three sets of three repetitions, followed by rest between the first and second bout of work for 5-6 minutes). Here, the movement time is reduced (6.0%), its amplitude is greater (4.8%), the speed of movement has increased significantly (11.7%) and the power of work has increased significantly (47.3%).
The traces phenomena in the nervous system and their affect on the subsequent work are the end result of many factors: the force of the tonic influence, the degree of fatigue and the time separating the preceding and subsequent work. For example, after a back squat (tonic work) the alteration in the parameters of a F(t) curve of explosive isometric effort by extension of the leg is observed (Figure 9). The maximum effort increases by 26% from the initial level after the first minute and then by the 4th-5th minute it reaches 65%. The beginning of the F(t) curve does not change much (F1, F2 and F3) the forces which exceed the initial level and duration with which they are maintained are the smaller the closer to the beginning of effort F(t) is to the ordinate. The amount of time required for the maximum increase in effect (Figure 10) falls 2.6% immediately after tonic work. Then this time drops to 3-4 minutes up to 4.6%; and the subsequent increase exceeds the initial level considerably.
The effect of the stimulation determines the amount of time to reach a maximum of force and duration of the after-effect of the tonic work. Therefore, it is important at which moment the subsequent work starts. For example, maximum height of the vertical standing jump is reached after the 3rd-4th minute. The difference is a 6.8% increase over the initial level. After the back squat an increase of 8.0% from the initial level is realized in the 8th – 10th minute after depth jumps (Figure 11).
The stimulation method consists of two successive muscle activities. The first (tonic) is carried - out slowly with major resistance and a limited number of repetitions. The second activity (developing) is conducted with an extremely concentrated explosive effort with smaller weights (30-40% from the maximum) and significantly more (optimum) repetitions. The preliminary (tonic) activity essentially increases the power output of the subsequent, because of its tonic affect on the central nervous system, which is in effect the main training effect of the stimulation method.
The high effectiveness of the stimulation method has been proven effective for the development of explosive strength and the reactive ability of the neuromuscular apparatus. The value of this method is that it provides a fast and steady increase in these parameters within a short period of time and with a relatively small expenditure and energy (16,20,27,30).
Variants of the stimulation method for the development of explosive strength and reactive ability of muscle-extensors of legs are presented in Figure 12. For example, the vertical squat jump with a weight held between the legs (16, 24 or 32 kg is selected individually) used in the first variant for tonic work. Two sets of 6-8 jumps with the rest of 3-4 minutes are conducted. Then after a rest of 3-4 minutes, the second (developing) exercise is executed for 6 or 8 multiple jumps from one leg to the other with the maximum effort. The work consists of two sets of 5-6 repetitions of exercise with the rest between the sets of 3-4 minutes. This series is repeated for 2-3 times with the rest of 6-8 minutes.
Other variants of a stimulation method are carried out in a similar manner. The back squat is employed as a tonic exercise. Now the main (developing) exercises are the jumps with the weight held between the legs, jumps with the bar on the shoulders, or depth jumps.
All the variants are rank - ordered from the top to bottom by the power of work and the training effect on the neuromuscular apparatus. The most potent variants are the fourth and especially the fifth, which should be utilized only in the training of the high level sportsman.
The potential to develop new variants of the stimulation method are limitless and are confined to the realm of developing explosive strength and reactive ability.(review see 16,29). For example, sprinters have experienced an increase in the speed of the initial acceleration and the running speed after intense jumping exercises. It has also been established that three hops from one leg to the other at sub - maximum effort over a distance of 60-80 meters with resting pauses of 1.5 - 2 minutes between bouts, increases the speed by 2-3% in the main part of the training session of middle distance runners. The velocity of short distance runs increases and in this is maintained at a high level during the majority of a series of runs. The after-effect of tonic work (swimming with the resistance of a rubber cord, swimming with towing a resistance, swimming with a harness on the shoulders) will increase swimming speed over short distances by 4-7% (review see 20).
==================
Postactivation potentiation: role in human performance.
Sale, D.G.
Exercise and sport sciences reviews 30(3), July 2002, 138-143
English Abstract
Postactivation potentiation (PAP) is the transient increase in muscle contractile performance after previous contractile activity. This review describes the features and mechanism of PAP, assesses its potential role in endurance and strength/speed performance, considers strategies for exploiting PAP, and outlines how PAP might be affected by training.
==============
Rixon, K.P., H.S. Lamont, and M.G. Bemben.
J. Strength Cond. Res. 21(2):500–505. 2007.—
Postactivation potentiation (PAP) or enhanced contractile
capabilities may be influenced by a number of factors. This study
examined the influence of type of muscle contraction (isometric vs.
dynamic), gender, and previous weightlifting experience on PAP as
demonstrated by changes in jump height and power output.
Thirty young men (n = 15) and women (n = 15), classified as either
having previous weightlifting experience (n = 20) or not (n = 10),
performed 3 different sets of countermovement jumps, with the first
set used to determine baseline measures of jump height and power. The
second set was performed after a maximal isometric squat protocol
(maximal voluntary contraction [MVC]-PAP) to induce PAP, and the
third set of jumps was performed after a maximal dynamic squat (DS)
protocol (DS-PAP). A 3-way repeated measures analysis of variance
determined that jump height after the MVC-PAP protocol was
significantly higher than both the pretest and DS-PAP values, that
men performed significantly better than women, and that the
experienced lifters responded more favorably than the inexperienced
lifters.
Jump power was also significantly greater for the MVC-PAP condition
compared with the other 2 conditions, and DS-PAP power also improved
when compared with the pretest values, with men performing
significantly better than women. All results remained consistent
after accounting for height and weight differences (body mass index)
between the groups. In conclusion, the isometric condition (MVC-PAP)
evoked a greater muscle postactivation potentiation than the dynamic
condition (DS-PAP), and postactivation was enhanced by previous
weightlifting experience. The practical manipulation of MVC by
pushing, squatting, or both against fixed objects, such as walls and
low ceilings, could be a very simple and cost-effective way to arouse
a state of PAP before sports performance that requires high force and
power outputs.
----------------------
Villarreal, Gonzalez-Badillo, and Izquierdo. Optimal warm-up stimuli of muscle
activation to enhance short and long-term acute jumping performance. EJAP 2007;
100: 393-401.
This group investigated the effect of seven different warm up protocols on
jumping performance with both a 5 minute and 6 hour latency period. The two
primary findings were:
1. High-intensity dynamic loading (e.g. 80-95% 1RM), as well as specific
volleyball warm-up protocol bring about the greatest effects on subsequent
neuromuscular explosive responses.
2. Acute positive effects on jumping performance after warm-up were maintained
after long recovery periods (e.g. 6 h following warm-up), particularly when
prior high-intensity dynamic actions were performed.
============
Guellich, A. Schmidtbleicher, D.
Title
MVC-induced short-term potentiation of explosive force. (Les MCV engendrant un potentiel de force explosive a court terme.)
Source
New studies in athletics 11(4), Dec 1996, 67-81
English Abstract
In numerous sports and sport events performance is, to a great extent, determined by the level of speed-strength. An optimal preparation (warm-up) is necessary to achieve the highest possible realization of speed-strength in training and competition. Some top international athletes are said to have produced the highest speed and speed-strength performances immediately after having performed a few Maximal Voluntary Contractions (MVCs). However, as yet no target-oriented and systematic studies of MVCs, as an element of warm-up programmes, have been conducted. Therefore the focus of the following study is on the following questions: (1) To what extent can the short-term potentiation of speed-strength induced by MVCs be considered a general effect? (2) Can effects of post-tetanic potentiation be triggered in human beings by MVCs? (3) To what extent is there a connection between possible short-term increases in speed-strength and neuronal effects of post-tetanic potentiation? The results of two complex training experiments show that MVCs carried out during the warm-up can really lead to a considerable increase in speed-strength performances of the lower extremities in all athletics sprint and jumping events and of the upper extremities in the shot put and the throws.
====================
3.4.2 THE AFTER-EFFECT OF MUSCLE ACTIVITY
(M C Siff "Supertraining" 2000 Ch 3, p163 - 165)
It is known that, if a muscle is stimulated by a series of impulses, its
activity slows down more after the last one than when it is stimulated by a
single impulse. Any stimulus, whether momentary or not, leaves traces in the
nervous system. The traces or after-effect phenomenon persists for some
time after stimulation ceases, which reveals the relative inertness of the
nervous system and its great significance for motor activities (Pimenov,
1907, Pavlov, 1929, Orbeli, 1947).
In physiology, this specific form of muscular facilitation (see PNF, Ch 7.2)
is referred to as post-tetanic potentiation, in particular when the
preparatory stimulus is produced by maximal or activity or “tetanusâ€* (e.g.
Abbate, 2000; Brown & Euler, 1938;. Burke et al, 1970; Grange et al, 1993;
Marsden et al, 1971; O'Leary et al, 1997; Palmer & Moore, 1989; Vandervoort,
1983). These phenomena and the processes of adaptation associated with them
form the foundation for fitness development. They determine the continuing
rise in fitness, despite periodic interruption in the training process
(Matveyev, 1964; Mateev 1964; Zimkin, 1965).
Research into the after-effects of muscular activity is contradictory,
particularly in Western literature. For instance, a statistically significant
increase in the speed of an unloaded movement was found directly after the
same movement was executed with a weight (Murray, 1959; Van Huss et al,
1962). Conversely, other research could not detect such an effect, despite
subjective claims by the athletes that their movements felt quicker after
using loads (Nofsinger, 1963; Nelson & Lamber, 1965). No increase in the
vertical jump could be measured shortly after preceding resistive exercises
(Stockholm & Nelson, 1965). Shot-put results even deteriorated after
preliminary throws with a heavier shot (Bischke & Morehouse, 1950).
The after-effect has been examined in more detail in Russian research. It
has been noted that preliminary isometric tension has a positive effect on
the subsequent dynamic work. Despite fatigue following isometric tension,
the effectiveness of dynamic work increases, usually by up to 20% when
compared with work executed without preliminary isometric ten-sion. With the
reverse sequence of work, results deteriorate (Shiedin & Kunevich, 1935;
Vinogradov & Delov, 1938; Vereshchagin, 1956; Farfel, 1964; Uflyand, 1965).
The after-effect occurs immediately after preliminary isometric tension. The
first dynamic contraction still retains some trace of inhibitory influence,
but by the second contraction, strength increases sharply compared with its
initial level (Leinik, 1951; Vinogradov, 1966). The data indicates that
isometric tension under certain conditions can serve as a stimulus for
dynamic work and play an important role in developing muscular strength.
Dynamic work with heavy weights (i.e. high tension with relatively few
repetitions) also elicits a positive after-effect in the central nervous
system (CNS), which produces a general toning influence on the motor
apparatus and an improvement in speed and strength (Portnov, 1955; Ratov,
1957; Diachkov, 1961; Muravov & Tkachev, 1964; Letunov, 1965).
In practice, the after-effect phenomenon of strength work is used to exploit
its immediate and delayed effects. It should be noted that there is an
improvement in performance immedi-ately following strong tension; i.e. this
is an immediate after-effect. In addition, intense preliminary strength
tension improves results in jumping exercises (Diachkov, 1958; 1961;
Verkhoshansky, 1961; Tatian, 1964; Tkachev, 1967), in shotputting (Fritsch,
1961; Ivanova, 1964; Markov, 1966), and in rowing (Ermishkin & Vozniak,
1965; Chuprun, 1966).
For the delayed effects, preliminary stimulation is used to improve the
functional state of the neuromuscular apparatus during the athlete's
preparation for competition or in training for speed-strength (Diachkov,
1961; Vrzhesnevsky, 1964; Khodykin, 1976). The positive effect is obtained
only if this state is promoted at an optimal level of stimulation.
Over-excitation of the CNS has a negative effect on the precision and
coordination of movements, i.e. on athletic skill (Diachkov, 1961; Yakimova,
1964).
The after-effect phenomenon in the nervous system and its influence on the
subsequent work is influenced by many factors, in particular, the strength of
the stimulus, fatigue and the time interval separating the preceding activity
from the subsequent activity. Thus, after tonic work (with barbell squats)
the following changes in the parameters of the force-time curve F(t) of
explosive isometric force in a controlled task (leg extension), may be
observed (Fig 3.27):
1. maximum force increases significantly over the first minute, by 25% of
the initial level
2. after 4 to 5 minutes the force continues to grow to 65%.
The beginning region of the F(t) curve undergoes less significant change
because the magnitude and duration exceed the initial levels by a smaller
amount, the closer the beginning force is to the F(t) ordinate. The time
required to reach maximum force was reduced by 2.6% immediately after tonic
work and by 4.6% after 3-4 minutes (Fig 3.28). Later it began to increase
until it exceeded the initial level (Tatian, 1964).
Figure 3.27 The force-time curve of explosive isometric effort achieved for
leg extensions with different resis-tances F1, . . . , Fmax at various times
after squatting.
Figure 3.28 Variation in time taken to produce maximum explosive isometric
force at different times after pre-ceding tonic work
Figure 3.29 Change in height of a vertical jump executed after different
types of tonic work (1 = barbell squat; 2 = take-off after a depth jump).
For moderately qualified athletes, the largest increase (90%) in dynamic
strength after a static effort corresponds to a load of 50% of 1 repetition
maximum (1RM), while the smallest increases corresponded to loads of 25% of
1RM (6.7%) and 100% of 1RM (5.8%). With increase in fitness, the post-work
improvement can occur with large loads of up to 100% of maximum (Ilin, 1961).
Consequently, with the rise in fitness and the strength of the stimulus,
the ability to evoke a subsequent positive effect also rises. However, in
principle, the optimal and not the maximal load is necessary for obtaining
the greatest post-work improvement.
The strength of the stimulus also determines the time taken to achieve the
maximum lifting force and the duration of the after-effect. Therefore, from
a practical standpoint, the moment at which sub-sequent work begins is of
some importance. For example, vertical jump height varied in the post-work
period, depending on the nature of the tonic work (Fig 3.29). Three to four
min-utes after barbell squats the height of the jump was 6.8% above initial
levels, and 8-10 minutes after depth jumps, it was 8.0% above initial levels
(Tatian, 1964).
In experiments with preliminary isometric tension (Ilin, 1961), the maximum
was achieved most rapidly with loads of 25% of 1RM (after 12 minutes), and
most slowly with 100% of 1RM (after 15.4 minutes) and 50% of 1RM (after 17.2
minutes). Research has determined that the optimal rest interval between
sets in weightlifting (during the presence of the after-effect phenomenon in
the CNS) is 2-5 minutes, with the rest period increasing with the bodymass of
the lifter (Ermolayev, 1937; Krestovnikov, 1952; Budze, 1959; Kazakov,
1961). It has been established that weightlifters who time their rest
intervals carefully make 20% fewer failures than those who do not (Klimonov,
1965).
The delayed-effect of strength work depends on the volume and intensity of
the preceding loads. For example, a moderate volume of barbell exercises
produces a positive tonic influence on the motor apparatus of athletes on the
next day or the day after (Diachkov, 1961). The use of depth (plyometric)
jumps as a means of stimulation delayed this effect for 5-6 days
(Verkhoshansky, 1963; Khodykin, 1976).
The use of the after-effect phenomenon offers some interesting opportunities
for increasing the effectiveness of strength preparation via a more limited
volume of training work. Athletes and coaches have great potential for
creativity, which can significantly enrich the theory and practice of sports
training.