Introduction: Heart rate variability (HRV) reflects autonomic modulation and is associated with physical fitness, particularly in aerobic endurance disciplines. However, the relationship between HRV and performance in aerobic capacity tests, such as the Yo-Yo test, has not been fully explored in university athletes. Objective: To analyze the relationship between resting HRV parameters and performance in the Yo-Yo test among university athletes. Methodologic: A cross-sectional correlational study was conducted with 32 male athletes (aged 18–26 years). HRV was assessed in supine and standing positions using time-domain and frequency-domain analyses (SDNN, RMSSD, pNN50%, HF, LF, VLF, and the LF/HF ratio). Subsequently, the maximum velocity reached in the Yo-Yo Intermittent Recovery Test Level 2 (YIRT2) was recorded. Pearson’s correlation test (p < .05) was used to examine the relationships. Results: A moderate positive correlation was observed between the final velocity in the Yo-Yo test and the resting parameters SDNN (r = 0.42; p = .02), HF (r = 0.4; p = .03), and pNN50%. Additionally, a negative correlation was found between the postural change-induced variation in pNN50% and performance (r = -0.46; p = .01). Conclusions: HRV parameters associated with parasympathetic activity show a significant relationship with performance in the Yo-Yo test among university athletes. These findings suggest that HRV could be a useful tool for predicting aerobic capacity and optimizing training planning.

The purpose of this study was to examine differences between squat variations performed with a traditional barbell (TRAD) and a safety squat bar (SSB) in university athletes, focusing on mean propulsive velocity (MPV), peak velocity (PV), and velocity loss (VL). Nineteen university athletes participated in a randomized crossover repeated-measures design. Participants performed squat exercises with both barbell types at 65% and 85% of one-repetition maximum (1RM) across multiple testing sessions. Neuromuscular performance indicators were assessed using a linear velocity transducer. Two-way repeated-measures ANOVA revealed significant main effects of barbell type and load for MPV and PV (all p < 0.05). Higher MPV values were observed with the SSB at both loading intensities, whereas higher PV values were observed only at 85% 1RM. For VL, a significant main effect of barbell type was found (p = 0.013), with no significant effect of load (p = 0.155) or interaction (p = 0.507). In conclusion, the SSB elicited higher movement velocities compared with the traditional barbell. These findings suggest that barbell selection may influence velocity-based performance outcomes during squat exercise. However, due to the cross-sectional design, these results should be considered preliminary.