1. WHAT IT IS
Rotational Resistance (or traction) is a test which was developed for natural turf fields to assess the amount of grip the field returns to the athlete when a plant-and-turn or change in direction is performed. The Rotational Resistance test uses a circular foot with a typical studded configuration mounted onto a plate. This is planted into the surface and a rotation of the studded plate is executed with the force required to move the plate recorded.

2. HOW IT IS MEASURED
The Sports Labs Rotational Resistance Tester performs the measurements in a simple manner. The weight that provides the kentledge consists of several heavy plates which bear down on the plate holding the studs. The testing device consists of a tripod with bearings to ensure that the free fall and subsequent rotation are executed with as little friction as possible. After the fall, the required torque is determined by using a torque wrench to rotate the test foot over an angle of a minimum of 45-degrees.

3. WHAT THE RESULTS REVEAL
There are a few things to consider here. The results are expressed in N/mm, which highlights the force required to rotate the studded foot located within the artificial turf system under examination. However, the test foot normalises the approach to allow a like-for-like comparison to be done on surfaces. The studs on the standard test foot may differ from the studs or blades used in player footwear. The test is able to differentiate between turf systems that are considered slippy - low grip or high grip to the athlete.

4. WHAT IT MEANS TO THE ATHLETE
The frequency of lower extremity injuries has been linked to surface properties. Excessive resistance to rotation between the shoe and the surface is a known risk factor in the aetiology of knee injuries and excessive traction has been cited as a contributor to the occurrence of diffuse head injuries in some circumstances.

5. HOW TO KNOW IT IS NOT A PROBLEM ON YOUR FIELD
A number of factors affect the resultant rotational resistance values returned from a field test. The assumption here is that the product has already been found to be compliant with the relevant standards for rotational resistance under FIFA, World Rugby, etc. A field which is well maintained and where the infill is regularly decompacted and topped up should return reasonable values of rotational resistance well into its life cycle. Poor maintenance practices and a lack of grooming/topping up infill can have serious implications for player welfare.

Applications where this device is used: Football, Rugby, Soccer, Gaelic Games, Lacrosse

Standards applicable: EN 15301, EN 15330, FIFA 06