Comparison of Ultrashort Versus Short High-Intensity Interval Training for Body Composition, Anaerobic, and Aerobic Performance

Abstract

PURPOSE: This study compared the effects of ultrashort (UH) versus short (SH) high intensity interval training (HIIT) in conjunction with functional training on body composition, anaerobic, and aerobic performance. METHODS: Thirty-four recreationally active participants were randomly assigned to SH (8 males and 9 females) and UH (8 males and 9 females) groups and completed 6 cycles of 6 exercises at ~90% of maximal heart rate (i.e. kettle bell snatches; step-up jumps; jumping jacks; front squat; burpees; high knees) 3 days a week for 4 weeks. SH was performed with 20s:10s work-to-rest ratio, and a 2-minute recovery within cycles, while UH was completed with 10s:5s work- to-rest ratio, and 1-minute recovery. Fat mass (FM), fat free mass (FFM), vastus lateralis cross sectional area (VL CSA), Wingate anaerobic capacity (i.e. peak power [PP] and anaerobic power [AP]), and aerobic fitness (i.e. VO2max) were measured before and after the training interventions and analyzed with 2-way mixed factorial ANOVAs. RESULTS: FM did not significantly (p>0.05) change, however, both groups significantly (p<0.05) improved FFM (UH: 60.8 ± 15.0 to 61.5 ± 15.2 kg, SH: 54.3 ± 11.5 to 55.5 ± 11.0 kg), as well as VL CSA (UH = 24.8 ± 6.2 to 27.1 ± 6.3 cm, SH = 25.6 ± 5.1 to 27.9 ± 5.5 cm). Additionally, anaerobic (UH: PP = 913 ± 305 to 1033 ± 300 W; AP = 11.5 ± 1.1 to 12.6 ± 1.1 W/kg, SH: PP = 839 ± 162 to 887 ± 181 W; AP = 11.8 ± 1.1 to 12.5 ± 1.2 W/kg) and aerobic capacity (UH: VO2max = 35.8 ± 6.9 to 38.9 ± 6.1 ml/kg/min, SH: VO2max = 39.7 ± 9.3 to 42.6 ± 9.1 ml/kg/min) significantly (p<0.05) increased in both groups. There were no significant (p>0.05) differences between groups. CONCLUSION: Current literature has shown a 20s:10s work-to-rest ratio to be the shortest, most effective HIIT protocol, as performed by the SH group. However, in the present study, the UH group improved FFM, VL CSA, anaerobic, and aerobic fitness in a similar manner to the SH group. These findings suggest that individuals may be able to achieve similar health benefits as the SH protocol, despite exercising for less total time by performing HIIT with a 10s:5s work-to-rest ratio.