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[Text on screen: 'Biomechanics of a volleyball spike - Health and Movement Science Year 12']

Speaker

Biomechanics is the study of how and why the body moves.

[Video shows students playing a game of volleyball]

In Health and Movement Science, we apply biomechanical principles like force, motion, balance, stability, and fluid mechanics to explain how individuals can train more effectively and move more efficiently.

In this video, we’re going to break down each component of a biomechanically sound volleyball spike. We’ll explore how biomechanical principles influence each phase of the movement and how applying these principles helps athletes perform the skill more efficiently, more often and with less risk of injury.

Phase 1: the approach.

The first phase is the approach.

[Video shows slow motion shot of a student performing a vollyball spike]

As the player runs toward the ball, they build momentum, which is the product of mass - how heavy they are - and velocity - the speed that they are moving - this motion sets them up for the jump.

To run, the legs apply force by pushing into the ground. According to Newton’s third law, the ground pushes back with equal force. This is known as propulsive force, and it helps the player overcome inertia, which is an objects natural state of rest.

As the player accelerates, they build momentum that can be transferred into the jump.

Key terms to remember are: force, propulsive force, inertia, momentum and motion.

Phase 2: the jump.

Before take-off, the player lowers their centre of mass — the point where gravity acts on the body. By bending their knees, they can store potential energy in their muscles.

As the athlete pushes off the ground, this stored energy along with the momentum gained from running is applied as a force to the ground and transferred into vertical momentum helping them jump higher.

Key terms are: centre of mass, force and potential energy.

Phase 3: the arm swing.

As the player prepares to strike, they twist their torso in the same direction as their hitting arm.

The non-hitting arm moves downward while the hitting arm lifts providing balance. This motion helps generate angular momentum.

The entire body acts as a chain — legs, hips, torso, and arms working together — to build and transfer energy for the hit. This is known as the summation of forces. The coordination of this movement requires each body part to perform its movement at just the right time.

Key terms: balance, angular momentum, and summation of forces.

Phase 4: hitting the ball.

Energy flows smoothly through the chain of movements. As the arm rotates and extends at the elbow the efforts of each body part throughout the whole movement is applied to the ball.

This energy is transferred as a propulsive force, sending the ball downward with speed and power.

Key terms: propulsive force.

Phase 5: the wrist snap.

Let’s take a closer look at what happens when the ball is struck and after the shot.

Just before contact, the player flexes their wrist and strikes the ball slightly above its centre of mass. This creates topspin — a forward spin on the ball.

Because of the Magnus effect, this spin changes how the air flows around the ball. Air pressure becomes lower on top and higher on the bottom, pushing the ball downward faster and helping it dip into the court.

Key terms are: centre of mass, Magnus effect and topspin.

Phase 6: the follow-through.

After the hit, the body continues moving — this is the follow-through.

It helps guide the ball’s direction and allows the body’s momentum to safely dissipate, instead of being absorbed by the joints. This reduces the risk of injury and improves movement efficiency — using the least energy for the best result.

Key terms are: follow-through, momentum, and movement efficiency.

[Text on screen: Review]

What we’ve just seen in this video is how biomechanical principles are applied through each phase of a complex sport-specific movement — the volleyball spike.

From the approach through to the follow-through, we’ve explored how force, momentum, energy, and motion are generated, transferred, and controlled to perform the skill both powerfully and efficiently.

[students playing volleyball]

Each phase not only shows how movement can be made more effective, but also how biomechanical efficiency reduces unnecessary effort and lowers the risk of injury — which is essential for sustained performance in sport.

Understanding these principles allows athletes, coaches, and movement specialists to analyse technique, correct errors, and make training decisions that improve both performance and safety.

[NSW government logo is displayed on screen]

[End of transcript]