Yeung wrote:
This research project enabled further research in isolated muscle activities for performance enhancement.
There are several neurophysiological consequences of this stretching which are relevant to listening energy. Muscle spindle (located in muscle fiber), Golgi tendon
Sinking Sinking
Figure 1 - Elements of the Pa Kua Posture
organs (found in tendons close to their muscular origin) and certain other receptors in the skin are all stimulated by stretching the muscles. By maintaining this graded activation of receptors, the Pa Kua practitioner, upon contact, can detect slight changes in the force or position of an opponent. This occurs because more receptors are stimulated above the threshold levels or the receptors that are already stimulated fire at faster rates than with passive stretching alone.
In addition, the stretch reflex, which maintains muscle tonus, “increases the tension of selected groups of muscles in order to provide a background of postural tone on which voluntary movements can be superimposed.”
(Kandel, p. 18). In our case, the voluntary movements will be the learned Pa Kua techniques to be executed at the desired angle of collision to neutralize the oncoming Force.
Sticky energy is the ability to catch an opponent’s strike and maintain contact with it without gripping with the fingers. It may sound amazing and supernatural, but it is a normal physical activity which can be explained by Newton’s mechanical laws, the law of conservation of momentum, the law of resultant force and the ratio of friction.
When the force of an opponent’s strike is met by an elastic force created by the extension of the Pa Kua practitioner’s extremities, a force equal and opposite to the strike will result.
The force is not met head on, however, but is evaded in a circular path using the Pa Kua footwork. This force is combined with the spiraling upward corkscrew movement of the practitioner’s intercepting arm which unites his own force with that of the strike, or, as we say, “borrow the enemy’s energy”.
The arm then corkscrews down and the ox-tongue palm flattens out to create enough friction to adhere to the striking force. By calculating the angle of collision, the striking force can be redirected and the resultant vector will conserve the force of the strike (Fig. 2). Combining these movements with the kinesthetic sensitivity and
the concentration of mind and ch’i results in an ability unique to the internal schools - sticky power.
Yet, the study of human anatomy shows that our bipedal structure and upright posture are designed for the initiation of forward movement rather than speed or stability.
Our centers of gravity are high above the ground and our feet provide a small supporting base. We can increase our stability along either the front-to-back or side-to-side axes by increasing the distance between our feet, but an increase on one axis causes a decrease on the other and vice versa. When in motion we must constantly move our feet quickly so that the supporting base can catch the falling center of gravity before it is too late.
Yeung wrote:Oral presentation at the 23rd annual Congress of the European College of Sport Science, Sport Science at the Cutting Edge, 4th – 7th July 2018, Dublin, Ireland, Book of Abstract, p. 566
Biomechanics of Non-concentric Martial Arts
Yeung, Y
United Kingdom Pangration Athlima Federation
.
middleway wrote:Yeung, will you produce a paper on this? Or other material we could have a look at.
Sounds great!
Thankyou.
Non-concentric Martial Arts are those arts that claim to be not using any concentric muscle contraction
oragami_itto wrote:I was wondering that, too. I mean it sounds technical but exercise is either concentric, eccentric, or isometric. If something is not concentric then it's either eccentric or isometric, so which category are you putting these under?
Yeung wrote:The result is established a list of techniques identified and verified as follows: passive stances with various distribution of body weight; rotation of the crotch in moving between forward stance and backward stance; movements of the rib cage which included open, close, ascent and decent; push and pull by arm rotation; connection and coordination between joints; transitions between movements.
This research project enabled further research in isolated muscle activities for performance enhancement.
cloudz wrote:. . . The whole exercise seems futile to me - with all due respect, you surely could spend the time better if you can't give good example of why what I have said here is wrong or does not apply to your thesis. I think you really should consider approaching this whole thing from another angle and get away from the denial of concentric movement.. The elastic component of musculature is recognised nowadays as is the relationship with plyometric exercise for example (to the best of my knowledge, which is not great); trying to divorce or exclude any of it from the concentric phase of muscle activation, or its terminology, is an impossibility by the very definition of the terms as they apply to the body and given the way in which the body, in fact, moves and works.
Science for Sport wrote:Though there is controversy surrounding the mechanics responsible for the performance improvements observed from using the SSC, it is likely to be a combination of the active state and the storage of elastic energy within the tendon. Due to the negative effects of the electromechanical delay, it may be suggested that training methods which improve muscular pre-activity, such as plyometric and ballistic training, may be beneficial for improving athletic performance. . . .
Mechanisms of the Stretch-Shortening Cycle (SSC)
There are numerous neurophysiological mechanisms thought to contribute to the SSC, some of which include: storage of elastic energy (18, 19, 20, 21), involuntary nervous processes (22, 23), active state (1, 24), length-tension characteristics (25, 26), pre-activity tension (27, 28) and enhanced motor coordination (1, 24). Despite this large list, it is commonly agreed that there are three primary mechanics responsible for the performance enhancing effects of the SSC (2).
These three mechanisms are:
1. Storage of Elastic Energy
2. Neurophysiological Model
3. Active State
Storage of Elastic Energy
The concept of elastic energy is similar to that of a stretched rubber band. When the band is stretched there is a build-up of stored energy, which when released causes the band to rapidly contract back to its original shape. The amount of stored elastic energy (sometimes referred to as ‘strain’ or ‘potential’ energy) is potentially equal to the applied force and induced deformation (5). In other words, the amount of force used to stretch the band, should be equivalent to the amount of force produced by the band in order to return to its pre-stretched state.
In humans, this stretch and storage of elastic energy is instead placed upon the muscles and tendons during movement. However, due to the elastic properties of the tendon, it is commonly agreed that the tendon is the primary site for the storage of the elastic energy (29, 30). Unlike muscles, the tendons cannot be voluntarily contracted, and as a result they can only remain in their state of tension.
This means that the muscle must contract and stiffen prior to the beginning of the SSC during ground contact – known as ‘muscular pre-activity’. The muscle must then remain contracted/ stiff during the first two processes of the SSC (eccentric and amortisation phases) in order to transmit the isometric forces into the tendon. This causes the deformation/ lengthening of the tendon and the development of the storage elastic energy.
During the concentric phase of the SSC (often referred to as the ‘positive acceleration’ phase), the muscle is then able to concentrically contract and provide additional propulsive force (2). Failing to stiffen during the eccentric and amortisation phases, means the performance enhancing effect of the SSC will be lost and the joint would likely collapse. This demonstrates the importance of muscle stiffness during the SSC and its ability to improve performance. It also suggests that athletes’ with higher levels of muscular strength can absorb more force (i.e. higher rate of loading), and therefore have a better ability to use the SSC.
An abundance of research has demonstrated that stronger athletes have a better ability to store elastic energy over weaker individuals (31, 32, 33). Elite athletes from both power- and endurance-based sports have also been demonstrated to possess a superior ability to store elastic energy (31, 32). Furthermore, efficient utilisation of the SSC during sprinting has shown to recover approximately 60% of total mechanical energy, suggesting the other 40% is recovered by metabolic processes (34, 35). In aerobic long-distance running, higher SSC abilities have also been shown to enhance running economy – suggesting that athletes with a better SSC capacity can conserve more energy whilst running (33, 36, 37). This indicates the importance of the SSC for both energy release and energy conservation. However, this storage of the elastic energy within the tendon cannot last forever, and has been shown to have a half-life of 850 milliseconds (38).
Neurophysiological Model
The muscles and tendons contain sensory receptors known as ‘proprioceptors’, these send information to the brain about changes in length, tension and joint angles (39). The proprioceptors within the muscle are known as ‘muscle spindles’, whilst those in the tendon are called ‘Golgi tendon organs’.
When a muscle is forcefully lengthened, the muscle spindles engage a stretch-reflex response to prevent over-lengthening and limit the possibility of injury. The engagement of these muscle spindles is thought to cause an increased recruitment of motor units and/ or an increased rate coding effect (40, 41). An excitation of either or both of these neural responses would lead to a concurrent increase in concentric force output and may therefore explain the performance enhancing effects of the SSC.
The increase in concentric force output would therefore then lead to an enhanced power output during sporting movements (e.g. jump), and thus may improve performance. However, many studies have reported no increase in muscle activation after a pre-stretch activity (e.g. CMJ) when compared to non-pre-stretch activity (e.g. SJ) (26, 42, 43). This suggests that muscle spindle reflex activity does not have any impact on the increased force by the SSC (1).
Furthermore, when a muscle is forcefully lengthened, the Golgi tendon organs (GTO) engage an opposite stretch-reflex response to the muscle spindles. Their role is to inhibit (i.e. prevent) the excitation of the muscle spindles during forceful over-lengthening to prevent the possibility of injury (5). Though this may seem as a bizarre trade-off between the muscle spindles and the GTO, the muscle spindles activate when muscle-tendon unit is forcefully lengthened, whilst the GTO activate when the forceful lengthening becomes too large (39).
Due to the inhibitory stretch-reflex response of the GTO, it is thought that this may counteract the contraction action of the muscle spindles. If so, this would mean that the GTO inhibits the high-muscular stiffness needed during the SSC and therefore reduces the concentric force output and subsequent performance (2). In fact, research has shown that muscle activation levels – and therefore muscle stiffness – have been reduced during the early phases of the SSC in individuals who are unaccustomed to intense SSC movements (28).
Interestingly however, 4-months of plyometric training has been shown to reduce this GTO inhibitory effect (disinhibition) and increase muscular pre-activity and muscle-tendon stiffness (27). As a result, it appears that effective training methods (e.g. plyometrics) can reduce or even eliminate the potential negative effects observed from the GTO inhibitory effect.
Active State
The active state is the period of time in which force can be developed during the eccentric and amortization phases of the SSC before any concentric contraction occurs. For example, during the ‘countermovement’ or ‘dropping’ action of the CMJ, the active state is developed during the eccentric and amortisation phases. The unpinning belief is that exercises which possess longer eccentric and amortization phases of the SSC will allow more time for the formation of cross-bridges, therefore enhancing joint moments, and thus improving concentric force output. Increasing the amount of force, and the time available for force to be developed, typically leads to a concurrent increase in the impulse (Impulse = Force x Time) (24, 44). In other words, increasing the force application will lead to improvements in power output and therefore athletic performance.
There is widespread agreement to suggest that the active state is largest contributor to the performance enhancing effects of the SSC, as it allows for a greater build-up of force prior to concentric shortening (1, 24, 44, 2). . . .
Phil Darue on wrote:. . . Depending on how long I have I will start the camp with a structured block of hypertrophy and joint integrity training phase. This will include slow eccentric movement exercises and higher volume sets. While working on eccentric strength and plyometric exercises to prime there joints for high impact collisions they will be experiencing skills training (sparring, grappling). After a few weeks we then go onto a strength block phase where we are trying to push the envelope of maximal strength output. Work is primarily in the 85-90% of 1 rep max range with sets of 3-5 repetitions.
All exercises will focus on 6 major movement qualities:
• Squat
• Hip Hinge
• Push
• Pull
• Carry
• CORE Work
With these exercises we cover all aspects of physical preparation with a general to specific periodization model. In the beginning of the strength phase we are more general fitness working on overall work capacity and movement efficiency. At the end of the strength phase the focus becomes more specific to the sport. So exercises we choose will have a higher carryover to the physiological demands of the sport. For instance a Zercher Squat, Med Ball Double Under Carry, & DB Hip Bridge Floor Press will carry over well into the competition from a physical preparation standpoint.
. . .
Carl Valle wrote:Eccentric exercise is making a comeback in the trends, but in reality it never left those that stay true to principles of performance. I include some eccentric exercises as a way to help reduce injuries, increase power, and build muscle fast. I don’t do much in-season eccentric work, but during the General Preparation Phase (GPP) eccentric training is a great investment to athletes. I am always cautious when adding or changing things, but after observing changes physically with some athletes in Europe I decided to add more eccentric work this off-season for two reasons. I wanted to know how effective a realistic inclusion of eccentric work was with the sport of soccer and sports with small preparation times and see the exact biological changes to my program. What I have learned was the precision of eccentric work is a very fine line, and it’s essential to measure and monitor.
Eccentric exercises are movements that lengthen muscle under tension, usually creating an adaptation that improves performance. Great interest in this type of training is making a comeback thanks to the work of Cal Dietz, but earlier work of Ian King who promoted a structured tempo of training really accelerated the popularity of manipulating contractile dynamics of training. What we do know is that research is currently pointing to signaling of the organelles and biochemistry of the body to turn on genes, thus creating morphological and biochemical changes. Be warned though, not all speed athletes will benefit from eccentric work and some athletes don’t handle extreme eccentrics. Resilience is a buzzword right now, and it’s professional to understand that durability is about a lifestyle, not an exercise or HRV monitoring. For athletes to be taking advantage of eccentrics, some prerequisite requirements are needed, or you will trash athletes. I have pushed the limits with athletes and have some humbling experiences with training. Here are some lessons I have learned the hard way and suggest you don’t make my mistakes. . . .
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