The
Volleyball Spike
The volleyball spike is perhaps one the
most iconic movement in sports. When one performs the spike, it showcases the
mastery of the balance between timing and skill. However the spike may also
represent one of the most biomechanically complex movement. The spike comprises
of 3 phases: the approach, the jump and the swing. The seamless transition
between the three phases is essential for a score-winning spike. In the approach
the player moves horizontally towards the net. Once the play has reached the
optimum velocity and position, they transition to the jump phase, which
transforms the forward momentum upwards to reach the highest point possible. As
the player approach the top of the jump, when the ball is within reach, the
player then enters the swing phase and contacts the ball. Of course this is a
broad overview of the movement in whole. This article will focus on the latter
2 parts of the movement (the jump and the spike). After incorporating the
approach (left-right-left step) the player will have decreased the distance
between the player and the ball. Using these steps to generate the momentum
needed to launch the player into the air and to spike/hit the ball.
Overview
of the swing:
The swing phase in this article will be defined as the time between when the player is fully airborne and when the player contacts the ground. When the player is in the air they will bring their dominant arm back to their ear level and the elbow bent. The player should incorporate an arch in their back in order to generate more power in their hit (stretch shortening cycle). As the player approaches the highest point of the jump and the ball is within hitting distance the player will swing their arm, leading with the elbow, to the anterior aspect of the player’s body. The player will then proceed to “snap” (hip flexion, accelerating the arm anteriorly while extending the elbow and flexing the hand) and contact the ball. At this point the player should keep their hand spread open as it allows a greater surface area contact and more accurate hit. The player should strive to achieve topspin. The generation of topspin creates a velocity difference between the top and bottom of the ball and therefore an air pressure difference (Bernoulli's principle). The lower air pressure at the bottom of the ball modifies the trajectory and as a result it would move towards the ground at a steeper angle. This ultimately eliminates the horizontal translation of the ball that would cause it to become out of play. As the ball makes contact with the hand the player will also snap their wrist generating as well to push the ball down. After the contact is made the arm will follow through and bend in order to avoid contact with the net (which is a fault).
Biomechanical Analysis of the Spike:
To analyze the spike in more detail we must
consider the 3 phases of the swing briefly highlighted in the overview
The
Arm cock: (Reference to the “Upper Limb Biomechanics during the volleyball
spike”)
The
arm cock phase includes the movement of arms move towards a “cocked” position.
That is, when the non-dominant arm is extended at the elbow and internally
rotated at the shoulder (Reeser et al., 2010) and points at the ball, tracking
it, while the dominant arm is flexed and brought up beside the head. The
dominant arm achieves this by, “abducting and externally rotating the dominant
upper body limb at the shoulder,”(Reeser et al., 2010). The non-dominant arm’s
position relative to the body has a two effects. One of the purposes of the arm
movement is to act as a counterweight to balance out the dominant arm when it
is in the cocked position. The other functionality of the extended non-dominant
arm is to act as a driving force in creating rotational momentum of the trunk
in the arm swing, which will be discussed in the swing phase. In addition to
the arm movement, the body concurrently arches back (back extension). The
purpose of achieving the “cocked” position is to allow the body to create a
stretch-shortening cycle across the dominant limb’s shoulder and body. At this
position the player will be ready to rapidly and forcefully swing and contact
the ball.
Figure
2 Cocked arm phase. This and that, Ripple’s page. http://ripley.za.net/2012/08/sport/olympics-phelps-makes-more-history
The Arm Swing
It
is essential for the player to time the initiation of the swing as they reach
the maximal height of their jump. This provides an advantage that is, “the
higher the spiking point, the higher the spiking height, the harder for the
opponent to block the ball, and increased spiking ability,”(Hu et al., 2005). When
the condition is right that is the maximal height has been reached and the ball
is in position the play can initiate the swing phase. During the swing phase,
“the attacker uncoils the upper limb (described as “cracking” the whip) to
contact the volleyball at the desired overhead position,”(Reeser et al., 2010).
The contraction of the muscles in dominant arm (allowing it to move from the
cocked position to an extended position) in addition to the contractions of the
abdomen (causing hip flexion) generates momentum that will be transferred to
the ball as the player contacts it. The swinging motion of the arm which is
synonymous to the, “effectiveness of tennis serves and baseball pitches has
been attributed to and energy transfer in a kinetic chain concept from the
lower limb to the upper extremity,”(Forthomme et al., 2005). However the
difference is that the lower extremities (basically legs) are not directly
involved in the execution of the volleyball spike.
Figure
3 Top of Swing Phase. Volleyball 1on1. http://www.volleyball1on1.com/volleyball-spike/
Follow-Through
and Landing:
After
the ball has been hit, the player is now in the last phase of the spike, the
follow-through. The follow-through is perhaps the most overlooked part of the
spike. As previously mentioned, during the approach, it is vital that the
player positions themselves close enough to the net to allow the spike to
travel downwards, yet far enough from the net to allow a proper follow-through.
The follow-through in volleyball serves the same function as the follow-through
in a golf swing or a tennis serve. A component that would increase the force
transferred to the ball is accelerating through the hit. That is to accelerate
the swing past the point of contact.
Figure
4 Follow-through phase. Strength and Performance
training, Inc. http://saptstrength.com/2012/01/13/vertical-jump-initial-testing-is-it-really-the-bees-knees/volleyball-spike-2/
Directing
the spike:
Following the
swing phase, after the player hits the ball, the non-dominant arm will now be
used as a driving force for trunk rotation. Trunk rotation functions mainly for
directionality of the spike and has some secondary functions as a torque
generator. The main purpose of the trunk rotation is to send the ball
cross-court. It was observed that, “players were more rotated through their
trunk toward the cross-court target,” (Mitchinson et al., 2013). After the
trunk rotation the dominant limb will follow through and now be in a position
that is in front of the body. After making the hit the player will follow
through and proceed to land bending their knees to absorb the shock from the
land. (Maybe you can put a bit more information here about landing and
injuries?)
How to generate the max velocity of
the ball during a spike?
The answer to
this question depends on one key variable. That is, is the player hitting
against an opponent? In this article, the execution of the hit is done at the
highest possible point of the jump. The reason being, it makes it more
difficult the defending player to block the hit. One of the most prevalent
factors in achieving the maximum spike velocity is the activation of muscles
from the most distal part of the spike (the abdomen). The summation of rotational
angular momentum starting from the most distal body part will allow the
greatest velocity to be achieved at the hand; this is synonymous to throwing a
baseball. Another factor is at what position the contact of the ball happens.
As with a baseball throw, a thrower would not throw with their arm at the
highest point. The third and final factor would be to which direction the ball
is hit. When a play hits a cross-court spike, due to the angle between the ball
and the net, the ball would have to travel a larger horizontal distance before
clearing the net. Such a hit is easier to perform but presents a few drawbacks.
That is a player must provide a greater horizontal component of force to allow
the ball to stay in play. The second type of hit is the line hit. In this type
of spike the player aims along the sideline on which player is. The player then
hits the ball straight down. Less emphasis on the horizontal component as well
as an increased applied vertical force allows the player to hit a much faster
spike compared to the cross-court hit.
Works Cited
Forthomme
, B., Croisier, J.-L., Ciccarone , G., Crielaard, J.-M., & Cloes , M.
(2005). Factors Correlated With Volleyball Spike Velocity . The American
Journal of Sports Medicine , 33 (10), 1513-1519.
Hu, L.-H., Chen, Y.-H., & Huang, C. (2005). A 3D
ANALYSIS OF THE VOllEYBAll SPIKE . 290-292.
Mitchinson, L., Campbell , A., Oldmeadow, D., Gibson, W.,
& Hopper, D. (2013). Comparison of Upper Arm Kinematics During a
Volleyball Spike Between Players With and Without a History of Shoulder
Injury. Journal of Applied Biomechanics , 155-164 .
Reeser, J., Fleisig, G., Bolt, B., &
Ruan , M. (2010). Upper Limb Biomechanics During the Volleyball Serve and
Spike. 368-374.
Wagner, H., Tilp, M., von Duvillard, S., & Mueller, E.
(2009). Kinematic Analysis of Volleyball Spike Jump . Int J Sports Med ,
760–765 .
