Effect of a short-term whole-body high-intensity interval training on fitness, morphological, and functional parameters in untrained individuals.

BACKGROUND: High-intensity interval training protocols using the body weight (WB-HIIT) as resistance could be an interesting and inexpensive alternative due to the absence of equipment required (low cost) and the possibility to be performed in a wide range of locations. Therefore, the purpose of the present study was to analyze the effects of a short-term WB-HIIT protocol on muscle thickness (MT), muscular endurance (ME), one maximum repetition test (1RM), and maximum oxygen uptake (VO2max) of untrained individuals. METHODS: Fifty healthy men (28.2±6.7 years, 77.5±26.2 kg, 171±10 cm, 23.2±8.2% Fat) were randomized into WB-HIIT (N.=25) or control (CON, N.=25) group. The WB-HIIT performed 9 exercises (40-second stimulus in all out intensity/ 20-second of passive recovery) divided into 3 blocks with 2 sets each for 6 weeks (three times a week). RESULTS: Only WB-HIIT resulted in a significant increase in MT, ME, 1RM, and VO2max (all P<0.05) outcomes and were significantly greater compared to CON (all P<0.05). CONCLUSIONS: Our results demonstrate that a WB-HIIT program can be a time-efficient strategy to promote changes on fitness, morphological and functional parameters in previously untrained sedentary individuals.