Interview with Dr. George Giatsis about th kinesiological analysis of arm swing techniques in Beachvolleyball Players
Dr George Giatsis is an Associate Professor in Kinesiology of Volleyball with an emphasis on Beach Volleyball at Aristotle University of Thessaloniki, Greece. He played for Greece on the World Tour and has been a top-level coach for many years in Volleyball and Beachvolleyball.
His current scientific project in Kinesiology is about the arm swing technique in spike attack in Volleyball and Beachvolleyball. He has analysed all the top players (male and female) since 1982 in Volleyball and Beachvolleyball in the major events of Olympic Games, World Championship and Champions League. He is focusing on differences in the movement during the cocking phase (arm movement from jump to “turning point” (elbow is back)).
Please tell us a bit about your project, the kinesiological analysis of arm swing techniques of elite Volleyball players!
The arm swing technique in Volleyball spike is important for maximizing attack performance. There are various techniques used by players, but from the kinesiological analysis of the players participating in the finals of the Olympics, World and European Championships and the Champions League, it is clear that certain techniques are preferred by the top players in the world as their primary technique. We analysed the situation where the reception and the set were perfect. We exclude the other situations from our analysis but the technique they used was the same in most cases.
The classification of the different arm swing techniques was processed by me and other Volleyball and Beachvolleyball experts in coaching and kinesiology, ensuring statistical reliability.
What are the different techniques?
In literature you could find the Bow and Arrow, the Straight, the Snap and the Circular. In my recent article concerning the players who participated in world championship 2017, I made a distinction of the Bow and Arrow technique in Low and High as differences occurred during the cocking phase. In general, the degrees of shoulder flexion, abduction, horizontal abduction, the external – internal rotation of the humerus, forearm, hand and the flexion of elbow have proven to affect the arm swing technique. To be able to distinguish between the different techniques, the position of the elbow and the wrist joint in relation to the shoulder joint and the forearm were used for the different definitions:
Straight:
Hitting arm goes up all the way together with the other arm. When almost fully stretched, the elbow of the hitting arm goes back. The hand is high up above the head.
Bow and Arrow high:
Like in Straight but the arm goes back a bit earlier (but wrist clearly above shoulder). During and at the end of the cocking phase, elbow and wrist/hand are above the forehead.
Bow and Arrow low:
Like in Bow and Arrow high, the wrist goes above shoulder level before the elbow is moving backwards. During the cocking phase, the elbow is at same height or above shoulder. The wrist is between forehead and shoulder height.
In the final cocking position the elbow is at the same height or above shoulder. The wrist is between forehead and shoulder height.
Snap:
Wrist is at shoulder height when hitting arm is moving backwards. Elbow and wrist at shoulder height during and at the end of cocking phase.
Circular:
Wrist is below shoulder height when hitting arm is moving backwards (Circular extended) or at some height or above shoulder height (Circular limited).
During cocking phase the elbow and wrist move down below or at same height as shoulder.
In the final cocking position elbow and wrist are below or at same height with shoulder (shoulder abduction less than 90°).
While in all the other techniques there is a full stop at final cocking position, in Circular the arm movement is continuous during the whole attack movement!
Figure 1. Arm swing techniques. (a) bow-and-arrow high, (b) bow-and-arrow low, (c) snap, and (d) circular. The “a, b, and c” techniques have a full stop at final cocking position while “d” technique has a continuous arm movement during the whole attack movement.
You argue that the Circular and Snap techniques are superior. What are the pros and cons?
The benefits of Circular (limited or extended) or Snap are the following:
1. Safest technique regarding injuries
2. Better performance in spike speed due to physics laws
3. More difficult for blockers and defenders to react as the arm is moving continuously (Circular)
4. Better Adjustments in contact with the ball in poor sets or out of body
5. Better performance in service
6. Faster game for Beachvolleyball (especially using the handsets or “over on 2” attacks)
The only thing that could minimise the efficiency of the Circular technique in Beachvolleyball could be the accuracy of shots, due to higher angular velocity of the arm. However, with practice this could be solved. Also, some of the players that used this technique in Beachvolleyball in the past were very good in playing shots. Some players are “shooters” so maybe they want to stop the movement of the arm and see the defender, thus making the Snap or the Bow and Arrow low technique ideal for them.
You are mentioning that Snap/Circular allow faster spikes. Could you give us a short and simple biomechanical explanation for this?
There are some scientific articles that present evidence about that.
Faster spikes are possible due to:
- the larger range of motion and acceleration for humerus (upper arm) and elbow
- By bringing part of the mass of the body (here: hand and forearm) closer to the axis (here: the shoulder), the body’s moment of inertia decreases. Because angular momentum is the product of moment of inertia and angular velocity, if the angular momentum remains constant (is conserved), then the angular velocity (rotational speed) of the arm must increase.
- more relaxed hitting arm thanks to lower position of elbow and avoiding the external rotation of humerus/forearm (in the cocking phase) = less muscle activation = better transfer of energy from one joint to the other
- additionally, with Circular technique, the continuous and circulating movement allows an even better transfer of energy
The techniques Circular and Snap seem to have less risk for shoulder injuries. Why is that?
The risk for injury is smaller with Snap/Circular as the rotator cuff is working in a less dangerous (lower) range of motion. There is a lot less pressure on Infraspinatus and Supraspinatus tendons as the abduction and the horizontal abduction of the shoulder is smaller and there is a smaller external rotation during the arm movement.
That’s why a lot of coaches or assistants are instinctively using this technique when hitting from a box during practise!
Not to have an abrupt stop in the end position of the cocking phase but a continuous movement (as in Circular) is even better to avoid shoulder injury.
Is there a danger that the attacker might loose some of his jump height when the hitting arm is moved back early and low?
Jump and force measurements have shown that the arms only have a relevant additional benefit for the jump when swinging through to a position parallel to the ground. In Beachvolleyball, the instability on the sand and the lower centre of mass during the jump will make it almost impossible to move the hitting arm and elbow backwards below shoulder level as some players do in Indoor. But the “opening” with wrist on should level or a bit above will not harm the jump height at all.
But isn’t the attacker loosing too much time when the elbow and hand have to be moved all the way up from such a low final cocking position?
With Snap/Circular the attacker needs a bit less time from the take-off to the ball contact as the final cocking position is lower and closer to the ground and is therefore reached earlier than with Straight/Bow and Arrow. The distance from “final cocking position” to “ball contact” is a bit longer but the hand is moving faster than with Straight/Bow and Arrow. So in total the time needed with Snap/Circular should be even a bit less than with Straight/Bow and Arrow.
But in Indoor the time gained might be even larger than in the sand as the “opening” of the hitting arm side is easier due to the different positioning of the feet for take-off.
Do you see differences between Indoor and Beachvolleyball regarding the use of this technique?
From the analysis of my data in Volleyball and Beachvolleyball players, it seems that the majority of the top players in Volleyball since 1980 used the Circular or Snap technique both in men and women. In addition, in the past most of the top players used this technique for the standing float serve.
However, in Beachvolleyball most of the players are using Bow and Arrow low and Bow and Arrow high. Also, a lot of women used the Straight technique which is -apart from very few exceptions- not used by men.
Which top players are using these techniques (Indoor and Beach)?
Some of the best players are using primarily these techniques. In Volleyball there are so many players so I will name just a few. Circular (extended or limited) is used by Leal, Leon, Lipe, Nishida, Lucarelli, Simon, Kurek, Kubiak, Stankovic, Anderson, NGapeth. In the past Giba, Dande, Snanley, Timmons, Negrao, Dal Zotto and many others. In women, Zhu, Plak, Bruijs, Mijailovic, Robinson, Gabi, Hill, Natalia Pereira and in the past Luis, Ping Lang, Gamova, Shaparova, Jaque, Torres, Carvajal, Artamonova and many others.
Some of the players using the Snap were Juantorena, Sokolov, Michailov and for women Slojters, Godina, Sheilla.
In Beachvolleyball Silva, Pires, Larissa, Shelda, Maria Salgado, Van Iersel used the Snap technique and sometimes the Circular one.
As for men: Evandro, Harley, Ricardo, Stocklos, Miguel Maia, Tande, Pedro Salgado, Krasilnikov, Brouwer, Smedins, Kantor.
Something to be noted is that players who used as primary technique the Circular, sometimes alternatively used the Snap.
Why are many and more top indoor players using that technique than beach players? Different style of game (speed), different circumstances (sand, empty court), a matter of development/evolution?
In Volleyball where speed is the important factor the Circular or Snap seem to be the best solution. Male and female top players (outside hitters) have reduced the time from setter ball contact to spike to less than 1 sec, sometimes 800ms! Even the middle blockers are using these techniques.
In Beachvolleyball, especially in the past (larger court, shorter and more ball control orientated players), for many attackers other factors than beating the block with speed are just as or even more important: shooting the ball in the open space of the court, reaching high to play an accelerated hit (not necessarily with maximum speed) etc.. For these purposes, the Bow and Arrow High and Low and even the Straight technique were useful and appropriate. However, as I mentioned, some of the legend players in the past had Circular or Snap.
In Beachvolleyball, for sure the Circular extended technique (hitting arm going back very early and low) could not be used due to instability of sand and the lower centre of mass during the jump (as I explained before). Also, the “pull up” with the arms during the take off the jump is used more than indoors. The players indoors have their elbow already bending in 90° the time of take-off. And the elbow in the same line with the body or just a little in front.
However, Circular limited and Snap could be used by the majority of players as it gives an advantage in spikes against the blocker and the defender.
What about the Bow and Arrow Low technique?
Kiraly, Bruno, Alison, Ludwig, Juliana are examples for Bow and Arrow low. Sometimes in Bow and Arrow low the elbow is as low as in the same line with the shoulder but the forearm has an external rotation (20-50°). This is more efficient than the Bow and Arrow high technique where the abduction is more than 100° and more muscles have to be activated to stabilize the arm over the shoulder. The less the muscles have to be activated, the better the flow of energy from joint to joint.
My opinion is that this kind of players easily could change their technique to Snap where the described benefits are even bigger as the abduction of shoulder is smaller and the external rotation of the forearm can be avoided during most part of the movement. There are several scientific articles mentioning this.
Is it/will it be possible to be top level in indoor men and women and in Beach volleyball with a BAH or straight technique?
I would like to clarify that attack efficiency is influenced by many factors and players could play in the highest level with every kind of technique. Some of the best players who have ever played the game as Emanuel, Rogers, Dallhauser, May, Walsh and Adriana Behar used the Bow and Arrow High. But all these players found a way to give torque with the arm when accelerating, using not a full extension of the elbow but with bending it during contact in some occasions. Sometimes they also used an extra rotation of the shoulder so they could give the maximum of speed and spin. We haven’t found this kind of technique in players that used the Circular or Snap.
In Indoor volleyball the big and still growing number of players using the Circular or Snap technique shows that it is a competitive advantage to use these techniques. Especially in men’s world class level there are only a few players who are still using the Bow and Arrow High technique (for example Taylor Sander (USA)).
Beachvolleyball is becoming more and more physical (higher blockers, faster defenders) and more and more teams are using a faster style of set up (including higher percentage of hand setting). Therefore, the tendency could be similar because being able to beat the block/defense by speed is becoming more crucial.
What are the experiences teaching these techniques? And how difficult it is to learn it?
I have had the privilege to teach volleyball in Aristotle University of Thessaloniki for the last 11 years and a large number of students (21 years old) with no experience in Volleyball followed the lessons. 50% of them could perform the Circular technique and a 35% the Snap in 9-11 lessons. The rest was Bow and Arrow low. The first steps in learning are crucial for the kind of technique which will be acquired. This project will soon be published in a scientific journal.
Furthermore, recreational athletes sometimes older than 30 years old, who have participated in a project with the approval of my University, acquired these techniques on Beachvolleyball.
As for professional players, some more time will be needed, depending on the technique they are using (from my experience the Straight and Bow and Arrow high are more difficult to change) and it depends a lot on the players’ willingness. However, there is a large number of athletes, both in Volleyball and Beachvolleyball who managed to change their technique in a period of 20-30 days and sometimes a little more, especially when they continue to play competitive games. The feedback from the coach, the usage of video analysis and the willingness of the player are important for this procedure.
As a coach, when I have top level players that have good efficiency in attack and serves and are free of injuries, I will not try to change them. I will inform them, but I will not try to change them because it needs a lot of time and psychology is important for this kind of athletes. However, for younger athletes or for players that have injuries in shoulder, I will give as much time as it is needed to change it.
To get a better understanding of the different movements of the arm, Dr. Giatsis provided the following playlist of youtube-videos. Highly recommended!
Indoor Volleyball: https://www.youtube.com/playlist?list=PLTHKnELRZnHi2P5v1AFcdwHss1oVZX2Gp
Beachvolleyball: https://www.youtube.com/playlist?list=PLTHKnELRZnHgelm09XIdrH170BYoT2Fs8
