Table 1. Mean absolute values of oxygen uptake, carbon dioxide output, ventilation, and respiratory exchange ratio during the 60/60 s and the 30/30 s LV-HIIT protocols. 60/60 s 30/30 s p ES VO2 (L/min) Interval 3.25 ± 0.57 2.83 ± 0.50 < 0.001 3.08 Recovery 1.85 ± 0.27 2.38 ± 0.46 < 0.001 1.95 Protocol 2.55 ± 0.40 2.61 ± 0.47 0.239 0.44 VCO2 (L/min) Interval 3.15 ± 0.61 2.93 ± 0.58 0.011 1.09 Recovery 2.15 ± 0.35 2.44 ± 0.45 0.022 0.93 Protocol 2.65 ± 0.45 2.69 ± 0.51 0.624 0.18 VE (L/min) Interval 108.59 ± 27.39 94.28 ± 24.98 < 0.001 1.88 Recovery 74.78 ± 15.96 80.50 ± 18.07 0.100 0.62 Protocol 91.69 ± 21.16 87.39 ± 21.42 0.102 0.46 RER (a.u.) Interval 0.98 ± 0.05 1.03 ± 0.03 0.005 1.28 Recovery 1.20 ± 0.05 1.03 ± 0.05 < 0.001 2.49 Protocol 1.09 ± 0.05 1.03 ± 0.03 0.003 1.53 Values are presented as mean ± SD. LV-HIIT, low-volume high-intensity interval training; VO2, oxygen uptake; VCO2, carbon dioxide output; VE, ventilation; RER, respiratory exchange ratio; ES, effect size (Cohen’s dz); ES < 0.2 reflects a trivial effect, ≥ 0.2 and < 0.6 reflects a small effect, ≥ 0.6 and < 1.2 reflects a moderate effect, ≥ 1.2 and < 2.0 reflects a large effect, ≥ 2.0 and < 4.0 reflects a very large effect, and ≥ 4.0 reflects a nearly perfect effect.