A Proposal for a Noxious Stimuli-Free, Moderate-Intensity Treadmill Running Protocol to Improve Aerobic Performance in Experimental Research on Rats.

Animal models can help understand human physiological responses, including the response to exercise and physical activity. However, many of these models incorporate noxious stimuli for various scientific purposes. We propose a noxious stimuli-free treadmill running training program for species to study adaptations to aerobic exercise. In this study, rats were randomly allocated to training ( = 20) and sedentary ( = 20) groups. The training group underwent a program consisting of 30-50 min of treadmill running at 60% intensity, three times per week for 8 weeks. Maximum speed tasks (Tmax) were conducted to determine, adjust, and evaluate changes in fitness conditions. The rats had one week of familiarization with the treadmill, and a rubber ball was used at the back wall of the lane as a painless stimulus to encourage running. All assessments were conducted by two independent researchers in a double-blind manner, with data analysis conducted by a third-blind investigator. A significant effect of time (η = 0.430, < 0.001, large effect) could be found, showing differences between Tmax1 and Tmax2, and between Tmax1 and Tmax3 in both groups. The training group significantly outperformed the sedentary group (η = 0.266, < 0.001, large effect). There was a significant interaction between time and condition (η = 0.152, < 0.001, large effect). The proposed moderate-intensity treadmill running program could effectively differentiate between trained and sedentary conditions within both the short period of 4 weeks and the extended period of 8 weeks. This protocol can be used as a model for running on a treadmill for species without the use of noxious stimuli.