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

<b>Background/Objectives:</b> 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 <i>Rattus norvegicus</i> species to study adaptations to aerobic exercise. <b>Methods:</b> In this study, rats were randomly allocated to training (<i>n</i> = 20) and sedentary (<i>n</i> = 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. <b>Results:</b> A significant effect of time (η²_p = 0.430, <i>p</i> < 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 (η²_p = 0.266, <i>p</i> < 0.001, large effect). There was a significant interaction between time and condition (η²_p = 0.152, <i>p</i> < 0.001, large effect). <b>Conclusions:</b> 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 <i>Rattus norvegicus</i> species without the use of noxious stimuli.