Rotarod performance test

The rotarod performance test is a performance test based on a rotating rod with forced motor activity being applied, usually by a rodent. The test measures parameters such as riding time (seconds) or endurance. Some of the functions of the test include evaluating balance, grip strength and motor coordination of the subjects; especially in testing the effect of experimental drugs or after traumatic brain injury.

In the test, a rodent is placed on a horizontally oriented, rotating cylinder (rod) suspended above a cage floor, which is low enough not to injure the animal, but high enough to induce avoidance of fall. Rodents naturally try to stay on the rotating cylinder, or rotarod, and avoid falling to the ground. The length of time that a given animal stays on this rotating rod is a measure of their balance, coordination, physical condition, and motor-planning. The speed of the rotarod is mechanically driven, and may either be held constant, or accelerated.

A human analog to rotarod test might be treadmill running. Hamster, gerbil, and mouse owners can observe the principle in action when an animal climbs on the outside of its wheel, instead of inside of it. In the rotarod test, however, the rotation of the cylinder in experiments is mechanically driven.

The advantage of this test is that it creates a discretely measurable, continuous variable (length of time) that can be used for statistical purposes to quantify the effects of different drugs, conditions, and procedures. This test does not use subjective judgments of ability, and inter-rater reliability will be virtually perfect. Inter-laboratory reliability will only be achieved if the various parameters (size of cylinder, speed of cylinder, composition material of surface, and amount of practice/training given the animal) are also replicated. The experiment is also very replicable from lab to lab (ibid). Moreover, these parameters may be adjusted variously to optimize the statistical separation of different conditions. For instance, alcohol effects on mice become less apparent when the speed is increased.

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