When the Play Changes Direction, So Should Your Data

"We cannot solve our problems with the same thinking we used when we created them."

Albert Einstein

Modern GPS systems have revolutionized sports science, providing a wealth of data about player performance. However, the metrics these systems prioritize—distance, speed, and acceleration/deceleration—fall short when applied to field or court-based sports, where change of direction (COD) is critical. By relying solely on linear metrics, we neglect approximately 35% of the mechanical work done in meaningful game maneuvers. This oversight limits our understanding of athlete performance, rehabilitation, and training effectiveness. ADI steps in to complete the picture.

The Problem with Linear Metrics

Traditional GPS metrics primarily focus on distance and speed. From speed, they derive acceleration and deceleration, tracking how quickly an athlete increases or decreases their speed. However, in multidirectional sports, these metrics fail to account for changes of direction (COD). Over the last 20 years, since the inception of athlete tracking devices, we have progressively confused speed with velocity, using the terms interchangeably. This misunderstanding is a fundamental flaw.

All field and court-based sports involve constant changes in both speed and direction—players accelerate, decelerate, and change direction rapidly. While traditional GPS metrics track changes in speed, they ignore changes in direction, which are equally critical in defining acceleration.

Physics Has Been Misapplied

Current philosophies confuse speed with velocity. Speed is the instantaneous magnitude of velocity. It requires only a number to describe it. Velocity, on the other hand, cannot be described by just a number; it has two components: magnitude (how fast) and direction (where to).

In physics, any change in velocity—whether in magnitude, direction, or both—is an acceleration. Ignoring direction changes means overlooking a substantial portion of the work being done on the pitch or the court.

Incomplete Acceleration Measurement

Traditional metrics measure only the acceleration due to changes in speed, neglecting the acceleration due to changes in direction. Together, these two components form the complete acceleration, which captures the full scope of an athlete’s movements. This is physics from first principles—the foundational building blocks of measuring movement.

Multidirectional Sports Demand a New Approach

To grasp why current metrics fail, let’s delve deeper into ADI’s approach. Acceleration can be categorized as:

• Speed-change Acceleration: What you feel when you speed up or slow down.

• Direction-change Acceleration: What you feel when turning a corner (in a car, for example), even at a constant speed.

In multidirectional sports, these two forms of acceleration are constantly at play. A player accelerating straight and then cutting sharply to evade an opponent experiences both. A defender pressing hard and trying to stay with an attacker experiences both. A player performing a curvilinear effort also experiences both. The total effect, or complete acceleration, is the combination of both speed-change acceleration and direction-change acceleration. Traditional GPS metrics fail to measure the latter, providing an incomplete picture.

ADI’s Complete Acceleration Model

ADI automatically detects and analyzes every meaningful maneuver, both linear and multidirectional, offering insight into the distribution and execution of every movement type. By integrating these multidirectional insights, ADI ensures a complete understanding of athlete performance.

Why This Matters

1. Rehabilitation and Training: Understanding complete acceleration is vital for injury prevention and recovery. When athletes change direction, they experience forces far greater than what linear metrics suggest and generate more mechanical power than in linear maneuvers. Training and rehab protocols that overlook these factors risk underpreparing athletes for game scenarios.

2. Mechanical Work in Multidirectional Sports: Work, in physics, is the transfer of energy through force over displacement. Ignoring direction-change acceleration makes it impossible to truly measure the mechanical work athletes perform. This miscalculation affects evaluations of workload, conditioning, and recovery needs. Using traditional GPS metrics, we fail to correctly quantify competition and training loads.

A Call to Action: Rethinking Athlete Performance Metrics

The current reliance on linear metrics is not entirely wrong—it’s simply incomplete. To truly measure player performance in multidirectional sports, we must adopt a complete acceleration model that accounts for both changes in speed and direction. Only then can we accurately quantify mechanical work and optimize athlete care.

Do we need to repeat the research performed on GPS tracking devices to include multidirectional movement analysis? The answer lies in innovation. By leveraging existing foundations and incorporating multidirectional metrics, we can redefine performance tracking without retracing every step.

In the next installment, we’ll explore how mechanical work and power measurements provide a more accurate framework for understanding the demands of multidirectional sports. Stay tuned!