What are the biomechanics of a volleyball spike and how can we optimise its power and accuracy?

A volleyball spike is one of the more powerful and aggressive moves in the popular and competitive game of volleyball. It involves a powerful downward ‘spike’ motion over a net with the aim of being unreturnable by the opposition. We as a part of the coaching approach to volleyball are told how to perform a skill or movement with little reasoning as to why we are performing it a certain way. The true reasoning behind this is biomechanics.

Biomechanics is the science involved with the study of forces acting on and within a biological structure and the effects produced by such forces; the primary purpose of biomechanics is to evaluate the laws and principals of mechanics about human performance in order to gain greater in-depth understanding and knowledge about specific details (Blazevich, 2010). It is important to have wide understanding of the applications of physics into sport and on the human body, as physical principles such as motion, resistance, momentum and friction play a part in most sports (Delong, 2013).

This blog will demonstrate the biomechanics behind a volleyball spike and why we need force, gravity, acceleration, power and accuracy to produce the most optimum spike in volleyball.

The four key components consist of preparation/take-off, jumping height, arm swing and the hit. In order to generate the greatest amount of power when spiking, a volleyball player needs to be able to summate these forces as one to make them in to one flowing movement.  The biomechanics of these components will now be explained in more detail.

Preparation

Newton’s First Law states that “An object will remain at rest or continue to move with constant velocity as long as the net force equals zero” (Blazevich, 2010). In relation to this the preparation phase includes a running approach that is important to give the volleyball player maximum momentum for the height of the vertical jump in the takeoff phase (Kessel, 2013). Momentum is the product of the mass of the player, and the velocity of the approach, which in turn relates to the optimal momentum that can be gained for maximum velocity of height in the jump.

The player exerts a force bigger than the present inertia, resulting in an increased running speed on approach to the jump. This leads to Newton’s Second Law which states “The acceleration of an object is proportional to the net force acting on it and inversely proportional to the mass of the object” (Blazevich, 2010).

Newton’s Third Law States that “For every action, there is an equal and opposite reaction” (Blazevich, 2010).  The diagram below highlights the forces and ground reaction forces that are present when the foot contacts the Earth with horizontal and vertical ground reaction forces evident. The ground reaction forces can be manipulated to aid in the acceleration if the force generated is large enough to overcome the inertia (Blazevich, 2010).

 Figure 1 - Ground reaction forces on the foot (Image: Blazevich, 2010).

It is recommended to plant and take off quickly during an approach. This is due to the concepts of kinetic energy and potential energy. During the approach the body has kinetic energy, described as energy in motion, faster moving objects will have greater kinetic energy (Blazevich, 2010). The goal is to transfer this kinetic energy into potential energy in preparation for the jump. If it comes to a stop the kinetic energy will be less, therefore, preventing jumping as high. Since potential energy is the product of the mass of the player, gravity, and the height of the jump, the height is what determines how much potential energy can be attained (Blazevich, 2010).

Jump 

To jump a volleyball player requires quick and synchronised coordination of body movements. The body needs to overcome inertia (Newtons Frist Law), by having a force applied to the player (Newtons Second Law) by applying a force against the ground that provides an equal and opposite force back (Newtons Third Law) (Blazevich, 2010). The power of the jump comes from the vertical force generated from the foot plant and push-off of the legs using the major leg muscles. The transfer of momentum is due to the direction of the foot plant and the use of the arm swing which gives assistance to the height and direction of the vertical jump prior to take-off (Harrison & Gaffney, 2001). During the 'preparation phase' of the jump, the player has their knees bent before the full leg extension including flexion of the foot. Since the sum of forces dictates our acceleration and the forces of gravity act downwards (Newtons Law’s of gravitation), it is beneficial for producing large vertical forces and having a lower body mass, in order to jump very high (Blazevich, 2010).

Elite performer Leonel Marshall can achieve a 50 inch vertical jump. This gives him a huge advantage with the placement of the ball especially with the height and angle of release which is discussed further in the ‘hit’ phase. 

 Figure 2 - Leonell Marshalls 50 inch vertical jump (Image: fenervoleybol.blogspot.com) 

Arm Swing 

Hsieh and Heise (2006), found that the arm swing was one of the most important factors which contributed to volleyball spike jump height, one study by MacKenzie, Kortegaard, LeVangie and Barro (2012), found arm swing to increase jump height by 10%27%. In performing the arm swing phase the hitting arm is pulled back with the elbow and hand at shoulder height or higher. The hand is open and relaxed, with the palm facing away from the ear. The elbow then swings forward and is raised above the head. Then the arm and hand swing over the top as the heel of the hand contacts the ball. The summation of these forces travels through the torso to the shoulders, arm and wrist until the force is realised on to the ball. This process assists the arm to store and release the energy from the muscle and tendon at lower extremities, meanwhile helping the trunk to move upward (Hsieh & Heise 2006). The internal rotatory muscles within the arm act concentrically during the arm swing wind up phase, while the external rotatory muscles act eccentrically during the deceleration phase (Dangelmaier & Coward, 2001). Increasing this range of motion for the arm swing allows the arm to generate more energy, which is transferred to various body parts which can improve the overall vertical jump performance (Li-Fang & Gin-Chang 2008). Long levers are another principle in place used to increase an applied force (Blazevich, 2010), whilst short levers are used for fast and accelerating movements. The combination of both long and short levers allows maximum force and acceleration to be applied to the volleyball during the arm swing. The spike combines these two levers; the long lever is made up of the radius and ulna whilst the wrist is the short lever.

Hit

Height is a physical trait common in most dominant volleyball players especially for the spike allowing them to generate more power when striking the ball (Lynch, 2013). The ball should be contacted reaching up high with the arm straight, elbow extended, reaching directly above or slightly in front of the body. The contact point of the ball and hand should be at the peak of the jump to gain the most power and accuracy (Lithio, 2006), by using a wrist snapping type motion to direct the ball downward into the opponents court. Newton’s 3rd law of motion “action and reaction force” and the conservation of angular momentum are used by the athlete to transfer power to the ball. Continuing the extension after the ball is released avoids segmental deceleration which may result in a decreased ball projection velocity and a slower time of delivery (Shierman & Wehrman, 1998). If the angle of projection is steep enough over the net the spike may be unreturnable and to optimise the angle and the speed of the shot the player needs to aim to be as close to the net as possible. MacKenzie, Kortegaard, LeVangie and Barro (2012), found results to indicate that a higher contact point was associated with an increased volleyball speed, they also came to a conclusion that the speed of the ball after contact was made 24% faster when focusing on achieving a high jump. 

More joints used when making the spike approach means more muscles there to contract and lead to more force exertion. The kinetic chain allows for the sequential acceleration from the legs, knees, hips, torso, shoulders, arms, elbows, wrists and fingers, all possible joints for maximum efforts to contract and produce maximum force and power to be projected on to the volleyball. The summation of all these movements can be seen in the picture below resulting in a fluent and effective action being produced which allows the player to generate greater height, arm swing and ball contact accuracy and power.

Figure 3 - Volleyball sequence of the spike (Image: www.examplesof.com)

The Magnus effect and air resistance

The airborne time of the volleyball can be reduced by putting top-spin on the volleyball. This causes the ball to experience an aerodynamic force known as the Magnus effect, which “pushes” the ball downward so that it lands faster (Linnell, Wu, Baudin, & Gervais , 2007) it also reduces the time the opposing team has in deciding how to return the ball. The figure below illustrates the Magnus effect.

Figure 4 - The Magnus effect. F = Force,  V = Velocity. (Image: www.airsoftza.co.za) 

As the ball spins, friction between the ball and air causes the air to react to the direction of spin of the ball. As the ball undergoes top-spin (shown as clockwise rotation in the figure 2), it causes the velocity of the air around the top half of the ball to become less than the air velocity around the bottom half of the ball (Linnell, Wu, Baudin, & Gervais, 2007).

This is due to the tangential velocity of the ball. The top half turns in the opposite direction to the airflow, and the ball in the bottom half turns in the same direction as the airflow. This causes a net downward force (F) to act on the ball. Interesting flight paths can be made with volleyballs due to the surface of the ball being uneven and a varying surface roughness from the panels during the flight (Blazevich, 2010). This force is useful for reducing the balls airborne time decreasing reaction time for opposing team.

The Answer 

To effectively generate the greatest amount of power when spiking, a volleyball player needs to perform these components fluently and summate the forces as one (Lobietti, Coleman, Pizzichillo & Merni, 2010). The kinetic chain allows for this sequential acceleration of the trunk, torso and limbs during the spiking action resulting in a fluent and effective action being produced which allows the player to generate greater jumping height and optimal contact and power trajectory on ball. The power can be optimised in a volleyball spike by jumping higher by applying a greater force against the ground. In doing so the vertical jump gives huge advantage with placement of the ball especially with the height and angle of projection when taking the shot. The contact point of the ball and hand was found to provide the power and accuracy at the peak of the jump, producing the most speed with contact higher on the ball, with the conservation of angular momentum used by the athlete to transfer the most power on to the ball. The Magnus effect was also an important factor in producing the most power and accuracy and for players to know how this factor affects the ball in play. It is evident that the understanding and mastery of the biomechanical principles can lead to the efficient and effective spiking technique being delivered. It is the role as teacher/coach to understand these biomechanical principles to express and apply these principles to an athlete’s chosen sport to maximise the effectiveness and efficiency of the chosen skill sequence while minimising the chance of injury occurring. This leads to our final question of ‘how else can we use this information’?

How else can we use this information?

This information can be used to improve spike accuracy, and also learn how to get more power and force into the shot. Having a thorough understanding of these biomechanical principles not only allows for better understanding of how to improve results within a volleyball game context but, the principles can also be applied to other sports involving jumping, arm swinging motions and projection of a ball.  Many other sports involve the use of the body as a projectile. Propelling the centre of gravity to a maximum height can be used in high jump and basketball jump shots. A high jump has the same biomechanical principles applied to the movement as the volleyball jump for the spike. The aim of the high jump is to gain as much height as possible for clearance of the bar. This requires a large amount of force and power to be able to effectively and successfully jump over the bar. The basketball jump shot also uses similar movement patterns, the run up is used to create momentum before changing the direction of the horizontal inertia to vertical to produce the lift off needed. The Magnus effect can also be transferred knowledge of skill between sports, including baseball and cricket on the effect that this has on the swing of the ball. Coaches and athletes can analyse the biomechanics and ideal conditions that the Magnus effect operates under and apply it to the sport and ball variations. Beginner volleyball players are often seen with uncoordinated movements that result in poor spike trajectory and velocity. On the other hand, professional players will perform the correct movement sequence to obtain precise summation of forces. Knowing these biomechanical principles can help teachers, coaches and players to identify errors made by the players in executing the shot and to correct them.

Understanding biomechanical principles has the capability of leading to successful execution of a skill and ultimately the production of athletes who possess greater skills within their chosen sport. It also contributes to the understanding of the process required to further enhance skills as a professional athlete.

References  

Bisseling, R. W., Hof, A. L., Bredeweg, S. W.,  Zwerver, J. & Mulder, T. (2008). Are the take-off and landing phase dynamics of the volleyball spike jump related to patellar tendinopathy? British journal of sports medicine, 42(6), 483-9.

Blazevich, A. (2010). Sports biomechanics the basics: Optimising human performance (2^nd ed.). A&C Black Publishers.
Briner, W. W. Jr & Kacmar, L. (1997). Common injuries in volleyball: Mechanisms of injury, prevention and rehabilitation. Sports Medicine, 24: 65–71.

Dangelmaier, B, S. & Coward, S. M. (2001). Fatigue induced kinematic changes in a volleyball spike. Medicine & Science in Sports & Exercise, 33(5), 239.

Delong, T. (2013). What is biomechanics? National Exercise and Sports Trainers Association. Retrieved 26^th May 2014 from: http://www.nestacertified.com/what-is-biomechanics/

Harrison, A. J., & Gaffney, S., (2001). Motor development and gender effects on stretch-shortening cycle performance. Journal of Science and Medicine in Sport. 4(4): pp. 406-415.

Hsieh, C., & Heise, G. D. (2006.) “Important kinematic factors for male volleyball players in the performance of a spike jump.” Proceeding of American Society of Biomechanics, Blackburg, VA.

Kessel,J. (2013). How can I spike harder, USA Volleyball. Retrieved 18^th May 2014, from: www.teamusa.org/...Volleyball/.../HowCanISpikeHarder 

Li-Fang, L., & Gin-Chang, L. (2008). “The application of range of motion (ROM) and coordination on volleyball spike.” International Symposium on Biomechanics in Sports. Conference Proceedings Archive, 26.

Linnell, W., Wu, T., Baudin, P., & Gervais , P. (2007). Analysis of the volleyball spike using working model 2D. Journal of Biomechanics, 40(2).

Lithio, D. (2006). Optimising a Volleyball serve. Western Reserve University: Hope College.

Lobietti, R., Coleman, S., Pizzichillo, E. & Merni, F. (2010). Landing techniques in volleyball. Journal of Sports Sciences, 28(13), 1469-1476.

Lynch, W. (2013). Traits of a Good Volleyball Player. Retrieved from LIVESTRONG, http://www.livestrong.com/article/539677-traits-of-a-good-volleyball-player/
MacKenzie, S., Kortegaard, K., LeVangie, M., & Barro, B. (2012). Evaluation of Two Methods of the Jump Float Serve in Volleyball. Journal of Applied Biomechanics, Human Kinetics, Inc, 28, 579-586.

Shierman, G. & Wehrman, J. (1998). An analysis of the overhead set. Journal of Physical Education and Recreation, 49, (55).