Benitez-Flores, S, de S. Castro, FA, Lusa Cadore, E, and Astorino, TA. Sprint interval training attenuates neuromuscular function and vagal reactivity compared with high-intensity functional training in real-world circumstances. J Strength Cond Res 37(5): 1070-1078, 2023-The aim of this study was to compare the acute cardiovascular and neuromuscular effects of 3 time-matched sessions of high-intensity training. Eighteen moderately active adults (9 women and 9 men [age: 23 +/- 2.9 years; maximum oxygen consumption (V虈 o2 max): 47.6 +/- 4.1 ml.kg -1 .min -1 ]) performed three low-volume ( approximately 9 minutes) sessions in a randomized order: sprint interval training (SIT), burpee interval training (BIT) (10 x 5 seconds efforts x 35 seconds recovery), and vigorous intensity continuous training (VICT) (6 minutes 5 seconds of running at approximately 85% of peak heart rate [HR peak ]). Indices related to heart rate (HR), neuromuscular performance (counter movement jump height [CMJ height ] and squat and bench press power), and autonomic balance (heart rate recovery and heart rate variability [HRR and HRV] )were monitored during exercise. Sprint interval training and VICT elicited a higher HR mean (171.3 +/- 8.4 and 166.5 +/- 7.5 vs. 150.5 +/- 13.6 b.min -1 , p < 0.001) and time of >/=90%HR peak (133.3 +/- 117.4 and 110 +/- 128.9 vs. 10 +/- 42.4 seconds, p < 0.01) than BIT. Sprint interval training exhibited a slower HRR and lower HRV than BIT and VICT ( p < 0.05) postsession. Moreover, only SIT resulted in a significant decline ( p < 0.01) in CMJ height (34.7 +/- 7.2 to 33.5 +/- 7.2 cm), relative squat mean power (25.5 +/- 4.5 to 23.8 +/- 4.9 W.kg -1 ), and relative bench press peak power (6.9 +/- 2.4 to 6.2 +/- 2.5 W.kg -1 ). Results revealed that SIT diminishes the sympathovagal reactivation and neuromuscular performance compared with work-matched BIT and VICT.