Evaluating Muscle Function in Rats

The muscle endurance of Sprague Dawley rats was evaluated using the treadmill test (Exer-6M Treadmill; Columbus Instruments, OH, USA). For 1 week, all rats were trained to run by running on a treadmill for 30 min at a starting speed of 2 m·min⁻¹ and ending at 20 m·min⁻¹ (2 m·min⁻¹ increase). The bottom of the treadmill was considered a low performance section and was equipped with an electrical stimulation component. Muscle endurance was determined by measuring the time spent by the rats in the low performance section of the treadmill during the 30 min test [22 (link)].
The muscle function of rats was evaluated using the grip strength test and hanging grip test. Grip strength was measured using a grip strength meter (Columbus Instruments, Columbus, OH, USA), according to a previous report [23 (link)]. The paws of rats were placed on a wire grid, and their tail was pulled backward; the maximum strength of the grip was recorded according to the strongest grip of the rat on the wire grid. Each rat was tested 6 times at 5 min intervals. The results are expressed in grams.