Friday 13 November 2009

Understanding plyometric training and its application to weightlifting: a guest article

Here is a guest article from the one and only Dr Eamonn Flanagan. He has generously agreed to host some of his ideas on the blog, so here is his bio and I hopes everyone enjoys the article and thinks about how/if it can be applied to our training. I have taken the liberty of providing some videos to support Eamonn's ideas, all of which he suggested of course! Here is a link to his other guest article on the use of creatine for weightlifters.

Eamonn Flanagan is a strength and conditioning coach with the Scottish Rugby Union. He has formally worked with Munster Rugby and in hurling,athletics, rowing and AIL rugby. He is an 85/94kg lifter and represents the University of Limerick Weightlifting Club.

Plyometrics is the term now applied to exercises that have their roots in Eastern Europe where they were first known simply as “jump training” (Chu, 1998). They are exercises involving rapid, explosive movements for the development of athletic power. Examples of plyometrics include depth jumps, hurdle jumps and bounding. Plyometric training has been shown to have a number of beneficial effects for athletes. These primarily include the development of an athlete’s power production. Plyometrics can increase the speed at which athletes can develop force and injury prevention for athletes in sports where there is a high degree of jumping, landing and side-stepping movements. Plyometrics have been shown to be highly effective in ACL injury prevention programs for athletes in sports such as volleyball, basketball and soccer (Hewett, 1996).

The training adaptation to plyometrics takes place at a neural level (Markovic, 2005). Plyometric training does not increase muscle size. It increases the efficiency and speed of muscular contraction by training the body to activate more muscle fibers with better timing during these explosive exercises. It trains the muscles to use the stretch shortening cycle (SSC) more efficiently.

The stretch shortening cycle (SSC) is the basis of plyometric exercises. The SSC is a natural type of muscle function in which muscle is stretched immediately before in is contracted (flexed). This eccentric/concentric coupling produces a more powerful contraction than that which would result from a purely concentric action alone (Komi, 1992). For example, crouch down to a half squat position. Hold this position for one second and then jump as high as possible (without going down any further). This is a purely concentric jump, it can be difficult to get good jump height with such a jumping technique.
video


Now try a regular vertical jump in which you can crouch down and jump up very rapidly. This is an eccentric/concentric jump. You are sure to jump higher and develop more force, more rapidly in such a jump.
video

This eccentric/concentric coupling of the SSC is the natural form of muscle function, and it is evident in everyday activities, such as running, throwing and jumping.

There are a number of biomechanical mechanisms that contribute to the SSC. More about these involved mechanisms can be read in this article

All stretch shortening cycles are not created equally. The type of stretch shortening cycle can be described as fast or slow (Schmidtbleicher, 1992). Different biomechanical mechanisms are used in these different stretch shortening cycles. As a result, training in the fast SSC will not improve slow SSC performance, and vice versa.

The fast SSC is characterized by very short ground contact phases, quick eccentric/concentric (“up/down”) movements and limited range of motion at the knee hips, knees, and ankles. A typical example would be depth jumps. Other examples are fast, repeated hops over hurdles or repeated standing long jumps with short ground contact phases.

The slow SSC involves longer ground contact or contraction times, larger ranges of motion at the knee, hips and ankles and slower overall movement of the working muscles. An example would be maximal effort vertical jumps or box jumps. Other examples would be single standing long jumps and single hurdle jumps.

To understanding the application of plyometrics into a training program it helps to have an understanding of the force velocity curve. The force velocity curve dictates that humans can produce their highest levels of total force at very slow velocities and in activities of very high velocity, low total forces are produced. For example, a maximal effort back squat will generally be performed at a low velocity, but one will generate a very high level of total force. In sprinting, with each foot contact, a low total force is produced but the movement speed is very high velocity. The weightlifting movements, most likely, lie somewhere in between these extremes as moderate force, moderate velocity movements – cleans lying a little more toward maximal strength and snatches lying a little more toward maximal speed.


Plyometrics' position on the force velocity curve can be seen also. They are quick powerful movements. Many sport scientists and strength and conditioning coaches suggest that for optimal athletic development one must train across the force velocity spectrum. In powerlifting the conjugate system of Westside training also works from a similar principle with maximal high level loads lifted in the same training block as dynamic, high velocity lower loads. In most weightlifting programs this principle is also included: front and back squats are high force, low velocity. Heavy pulls are next down the curve. Then the weightlifting movements themselves.

Plyometrics could then be used to train faster force production abilities. By training across the whole force-velocity spectrum, the athlete is less likely to be inhibited by a deficiency in any one particular aspect of his performance be it speed, speed-strength or maximal strength. Plyometrics are a highly suitable way for weightlifters to train speed strength. Exercises such as box jumps, vertical jumps, depth jumps and hurdle jumps are all biomechanically similar to the weightlifting movements. They are bilateral (double legged), they use the same major muscles and joints, have similar range of motion at the active joints and similar timings of muscular activation. Uni-lateral (single leg) plyometrics such as bounding and hopping drills are probably not as biomechanically well matched to the weightlifting movements. Dreschler (1996) states that plyometrics can help to decrease the time it takes for a lifter to reach maximum force and improve their power output. But, he cautions that the modality of training is unlikely to produce any dramatic improvements in weightlifting performance.

There are a couple of other specific applications of plyometrics which could be useful in a weightlifting context. The first of those involve very young lifters or very novice lifters. With such lifters, they may not be technically proficient enough to perform cleans and snatches with enough weight to illicit a good training effect. If this is the case then from a force-velocity perspective, their training could be very lopsided toward maximal strength at low velocities. By incorporating simple plyometric exercises such as box jumps, hurdle jumps and standing long jumps the young or developing athletes can get a degree of speed-strength development in their training and also learn control and coordination of their bodies. Here is a video demonstrating this principle with Scottish coach Charlie Hamilton having his young lifters perform dynamic jumps onto plates:
video


Another very useful application of plyometrics is when weightlifters are suffering from upper extremity injuries such as wrist injuries. Here the weightlifter should still be able to squat heavy and develop their maximal strength capabilities. They are unlikely to be able to perform any cleans, jerks or snatches however. So plyometrics can be used extensively to keep their training volumes up and to develop their speed-strength capabilities while injured.

Lifters should use a variety of slow and fast plyometrics. The slow plyometrics such as vertical jumps and box jumps are good to use first as it is easier with these slower movements to teach good jumping and landing mechanics. Once athletes have mastered good jumping and landing mechanics they could begin to incorporate low-level fast plyometrics like repeated jumps over low hurdles. The degree of difficulty of these fast plyometric exercises could be slowly increased over time. One should exercise caution with fast plyometrics however. They are more intense than slow plyometrics and the strain they place on the nervous system is likely to be higher.

Dreschler (1998) comments on the placement of plyometrics into the weightlifter’s periodized training plan. It should be limited to one or two periods of several weeks per year. This could be one or two 4-6 week blocks of plyometrics in general preparation phases of training. The amount and intensity of the jump training should be carefully limited in the phases. Dreschler (1998) also suggests that once a weightlifter has learned the plyometric movements and begun to express fast force production well and effectively that quite a low amount practice (or the mere practice of the weightlifting lifts themselves) should be enough to retain the benefits of plyometric training. This could be as simple as the lifter performing 3 or 4 sets of 3 in the box jump at the beginning of a training session in his general preparation phase.

Overall, plyometrics offer a simple and effective way to promote fast force production and to train speed-strength capabilities of athletes. Their inclusion is probably most suitable for young or novice athletes and those with upper body injuries which limit their actual weightlifting movements. The benefit of plyometrics may be less for adult, mature lifters but they could still be used to train across the force-velocity spectrum and benefits (or maintenance) of fast force production can be achieved with a low volume of plyometrics.

14 comments:

Anonymous said...

I did the P90X plyometrics Dvd a couple of times and it is tough. I find it hard to believe it doesn't build muscle becasue i was sore for 2 days after... :D

Eamonn Flanagan said...

Its a bit long, like.

Eamonn Flanagan said...

Also, Sami seems to be one of those freaks who squat jumps as high as he vertical jumps.

homemadegymstuff said...

It's nice to see the 'young lifters' doing some real ballistic movements - not often seen in the school gym

Anonymous said...

HIGH HORSE ("ABADJIEV 2009")

David Woodhouse said...

Weightlifting IS plyometric (the double knee bend in the pull and jerk dip) so it's doubtful whether additional plyometrics adds any value. Additionally, plyometrics is incredibly fatiguing even in low volumes.

DW

Barry said...

Good point David. I think Eamonn was stating that plyometrics are most relevant to weighlifters when they are injured and cannot lift properly or for younger lifters to teach movement skills.

Zag said...

Thanks Eamonn, Myself and Barry test each other on our cmj every monday before our workouts. We're both improving every week and I'm sure it'll drop from time to time and we're hoping to use it as an indication to judge when to take download weeks. What would your uptake be on that??

Eamonn Flanagan said...

DW,

I agree with you mostly. But slow SSC plyometrics such as box jumps and standard vertical jumps are not very fatiguing at all. High level fast SSC plyos certainly are very stressful and fatiguing on the CNS. But there is a massive difference between the two.

Eamonn

Eamonn Flanagan said...

Hey Sami,

My opinion would be that the measure of jump height in a CMJ every week may not be sensitive enough to really detect symptoms of overtraining etc. When fatigued you may jump to a similar height but fatigue may cause you to take longer to generate the force necessary to jump to this height. Fatigue may not just affect jump height but also the rate at which you are developing force. So because of this I think it might be better to use a jump that incorporates a ground contact phase: a rebound jump or a depth jump from a fixed height. You can then look at jump height in relation to ground contact time. Height might be staying constant but ground contact time could be getting longer, which would be as indicative of fatigue as a decrease in jump height in my opinion. The only problem is that not all the jump mats can measure this ground contact time. I've done a wee bit of work on this in the past with Cathal and with a few of the lads over here.

Eamonn

David Woodhouse said...

Grip strength is an alternative test of CNS fatigue.

Anonymous said...

Great Blog!!!!

Hi, my name is Jacob and I run a company called A1supplements.com. We are always looking for great sites, like yours, to add to our network of affiliates. We are also always looking for writers like yourself, to provide us with original content that we can turn into articles.

I would love to discuss this with you further. Send me an e-mail and we can discuss all the possibilities.

For more information on our affiliate program, here is a link:

http://www.a1supplements.com/affiliate/affiliates/index.php

J.US said...

I've read a lot of great success stories about Jump USA's program. But any program really requires dedication and commitment, that's where jumping ability will start to develop. It will only work through consistent training.

komal said...

when you are a basketball or volleyball player then there is need to jump higher in the game so that you can perform better. this blog provide very nice informtaion.

Post a Comment