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.
This study investigated the integrated relationship between systemic hemodynamics, autonomic modulation, and non-invasive intracranial pulse wave morphology (P2/P1 ratio) across na adult age range under basal seated resting conditions. Two hundred ninety-nine healthy volunteers (137 males, 162 females; mean age 48.74 ± 24 years) were evaluated. Blood pressure, heart rate, symbolic heart rate variability (0 V, sympathetic; 2UV, parasympathetic), and P2/P1 ratio via scalp extensometry were recorded. Principal Component Analysis (PCA) with Varimax rotation was applied to eight normalized variables (Age, HR, SBP, DBP, PP, 0 V, 2UV, and P2/P1). Four components explained 85.81
Reliable assessment of neuromuscular function is fundamental for interpreting physiological adaptations, yet sex-related influences in the reliability of these assessments remain poorly characterized across different temporal designs. We determined the within-session and between-days reliability of neuromuscular measurements in physically active men and women across multiple time intervals. Thirty healthy participants (15♀ and 15 ♂) completed six sessions to assess the reliability of motor output such as maximal voluntary contraction and time-to-task failure during isometric plantar flexion, as well as electrically evoked responses such as H-reflex, M-wave and V-wave. Relative and absolute reliability were calculated in pooled and sex-separated data. Maximal voluntary contraction showed excellent within-session reliability in all groups. This outcome was consistently good in pooled data and in men for between-days sessions, yet only moderate in women. Although acceptable, within-session and between-days reliability of time-to-task failure were more variable in pooled and sex-separated data. Reliability of H-reflex, M-wave and V-wave ranged from good to excellent in within-session data for both sexes. However, between-days reliability was more variable, as men showed a higher reliability in H-reflex whereas women showed a higher reliability in M-wave and V-wave. Apparently, reliability of electrically evoked reflexes was influenced by the interval between measurements in women. Maximal voluntary contraction is a reliable outcome to reflect adaptations in plantar flexion-derived motor output regardless of sex and temporal designs. Results suggested that sex-related influences affect the reliability of electrically evoked reflexes, challenging their ability to reflect biological adaptation of neuromuscular function.
Current literature focuses on maximal apneas to improve apnea duration, whereas in practice, apnea training often involves two distinct forms of timed-repeated submaximal apnea protocols: “O2-tables”, intended to progressively decrease oxygenation and purportedly train O2 conservation, and “CO2-tables”, intended to progressively accumulate carbon dioxide (CO2) and purportedly train hypercapnia tolerance. In apnea novices, O2- and CO2-tables failed to induce strong deoxygenation and CO2 accumulation, respectively. Therefore, the aim of this study was to compare physiological responses to maximal apneas, O2- and CO2-tables in apnea trained individuals. After medical screening, fourteen freedivers performed three apnea protocols: maximal apneas, O2-table and CO2-table. During apnea, heart rate (HR), muscle tissue oxygenation index (mTOI) and peripheral oxygen saturation (SpO2) were measured continuously. End-tidal carbon dioxide (EtCO2) was measured before and after apneas. Capillary partial pressure of CO2 (PCO2) was measured after the fourth and final apnea. Perceived Exertion (RPE) was rated after each protocol. RPE was lower after O2- and CO2-tables than after maximal apneas. Changes in HR and mTOI did not differ between O2- and CO2-tables. CO2-tables elicited greater increases in PCO2 and EtCO2 compared to O2-tables and maximal apneas. Maximal apneas induced greater changes in SpO2 than O2- and CO2-tables. These results suggest that, in freedivers, O2- and CO2-tables offer a less mentally and physically demanding alternative to repeated maximal apneas, allowing greater variation in apnea training while still targeting O2 conservation and CO2 tolerance, respectively.
