Ethical, methodological, and translational framework for animal studies in physical exercise research

Experimental research involving physical exercise (PE) in animal models has contributed significantly to advancing knowledge in several areas, including physiology, biochemistry, and translational medicine. Despite the widespread use of these models, important concerns remain regarding methodological heterogeneity, limited experimental standardization, reproducibility of findings, and the translational validity of preclinical outcomes. In this context, the present article proposes an integrated decision-making framework for animal-based PE research. The framework complements existing guidelines linking ethical justification, animal welfare, experimental design, exercise prescription, and translational interpretation throughout the different stages of study development. The manuscript is based on international guidelines for animal experimentation, including ARRIVE 2.0, PREPARE, the Guide for the Care and Use of Laboratory Animals, AVMA recommendations, the APS Resource Book for the Design of Animal Exercise Protocols, and recent methodological recommendations for preclinical exercise research in metabolic and cardiovascular diseases. The topics address aspects related to ethical decision-making in the use of animal models, the principles of the 3Rs, selection of species, strain, sex, and age, sample size calculation, inclusion and exclusion criteria, translational validity, and the definition of exercise protocols, including intensity, frequency, duration, equipment, and experimental monitoring. This framework is intended to support more consistent experimental decisions, including selection, justification, and implementation, according to the research question, animal model, and intended translational inference.