How Swing and Reverse Swing Work in Cricket: The Science Explained

Cricket is a game rich in skill, strategy, and science—and nothing exemplifies this more than the art of swing bowling. Ever wondered how a cricket ball swerves in mid-air like it's got a mind of its own? Let’s break it down.

What is Swing in Cricket?

Swing refers to the lateral movement of a cricket ball in the air before it hits the pitch. It’s not magic—it's physics. The key lies in aerodynamics and how the ball interacts with the air as it travels toward the batter.

When a bowler delivers the ball, air flows around it. If the seam (the stitched part in the center of the ball) is held upright and directed towards one side—left or right—it disrupts the airflow on that side, creating turbulence.

Here’s where the magic happens:

• On the smooth (shiny) side, air flows smoothly.

• On the rough side (with the seam tilted), turbulence is created, causing air pressure differences.

The turbulent air clings to the ball longer, pushing it toward the direction of the seam—thus, the ball swings.

Types of Swing :

1. Outswing:
   The ball moves away from the batter (for a right-handed batter).

   • Seam points towards the first slip.

   • Shiny side is on the right, rough side on the left.

2. Inswing:
   The ball moves into the batter.

   • Seam direction is flipped.

   • Shiny side is on the left, rough side on the right.

What is Reverse Swing?

Now, here’s the plot twist—reverse swing.

Reverse swing is essentially the opposite of conventional swing. While a new ball swings toward the rough side, an old, worn-out ball swings toward the shiny side.

This phenomenon occurs due to changes in the ball’s surface:

• One side is kept shiny using sweat (previously saliva).

• The other side becomes rough and abrasive from wear.

As the ball gets older and travels at higher speeds, air starts to behave differently. Instead of following the usual rules, the airflow causes the ball to swing in the opposite direction—toward the smooth, shiny side.

This reverse movement can be unpredictable and devastating for batters.

How Does Saliva Help in Reverse Swing?

Saliva used to play a crucial role in creating reverse swing by helping bowlers maintain the shine on one side of the ball. This contrast between the shiny and rough sides is essential for reverse swing to occur.

Here’s how saliva made a difference:

• Polishing Power: Saliva contains mucus, which is thicker and more effective than sweat for polishing the ball. It creates a smoother, more reflective surface, allowing air to flow cleanly over one side.

• Shine Maintenance: Bowlers would consistently apply saliva to one side to preserve its smoothness, while the other side would naturally get rough due to wear and tear.

• Airflow Disruption: This imbalance in surface texture causes the ball to swing in the direction of the shiny side when bowled at high speeds with an older ball.