PlayerLoad™: reliability, convergent validity, and influence of unit position during treadmill running

Area of Science:

• Sports Science
• Biomechanics
• Exercise Physiology

Background:

• PlayerLoad™ is a measure derived from triaxial accelerometer data.
• Assessing the reliability and validity of PlayerLoad™ is crucial for its application in sports performance monitoring.

Purpose of the Study:

• To determine the test-retest reliability of PlayerLoad™ during standardized treadmill running.
• To assess the convergent validity of PlayerLoad™ with established measures of exercise intensity.

Main Methods:

• Forty-four team-sport players completed two incremental treadmill tests one week apart.
• PlayerLoad™ (at scapulae and center of mass), oxygen uptake, and heart rate were recorded.
• Individual PlayerLoad™ planes (anteroposterior, mediolateral, vertical) were analyzed.

Main Results:

• PlayerLoad™ exhibited moderate to high test-retest reliability (ICC .80-.97).
• PlayerLoad™ was significantly higher at the center of mass compared to the scapulae.
• Within-subject correlations between PlayerLoad™ and exercise intensity measures were nearly perfect (r = .92-.98).

Conclusions:

• PlayerLoad™ is a reliable and valid measure of exercise intensity on an individual basis.
• Caution is advised when comparing PlayerLoad™ data between athletes.
• Scapulae-based PlayerLoad™ may not accurately reflect lower-limb movement patterns.