High-Intensity Interval Resistance Training (HIRT) influences resting energy expenditure and respiratory ratio in non-dieting individuals

Background: The benefits of exercise are well established but one major barrier for many is time. It has been proposed that short period resistance training (RT) could play a role in weight control by increasing resting energy expenditure (REE) but the effects of different kinds of RT has not been widely reported.Methods: We tested the acute effects of high-intensity interval resistance training (HIRT) vs. traditional resistance training (TT) on REE and respiratory ratio (RR) at 22 hours post-exercise. In two separate sessions, seventeen trained males carried out HIRT and TT protocols. The HIRT technique consists of: 6 repetitions, 20 seconds rest, 2/3 repetitions, 20 secs rest, 2/3 repetitions with 2^′30″ rest between sets, three exercises for a total of 7 sets. TT consisted of eight exercises of 4 sets of 8-12 repetitions with one/two minutes rest with a total amount of 32 sets. We measured basal REE and RR (TT₀ and HIRT₀) and 22 hours after the training session (TT₂₂ and HIRT₂₂).Results: HIRT showed a greater significant increase (p < 0.001) in REE at 22 hours compared to TT (HIRT₂₂ 2362 ± 118 Kcal/d vs TT₂₂ 1999 ± 88 Kcal/d). RR at HIRT₂₂ was significantly lower (0.798 ± 0.010) compared to both HIRT₀ (0.827 ± 0.006) and TT₂₂ (0.822 ± 0.008).Conclusions: Our data suggest that shorter HIRT sessions may increase REE after exercise to a greater extent than TT and may reduce RR hence improving fat oxidation. The shorter exercise time commitment may help to reduce one major barrier to exercise.