Comparing Time Efficiency of Sprint vs. High-Intensity Interval Training in Reducing Abdominal Visceral Fat in Obese Young Women: A Randomized, Controlled Trial

Abstract

<b>Introduction:</b> High-intensity interval training (HIIT) is an emerging lifestyle intervention strategy for controlling obesity. HIIT consisted of brief all-out supramaximal sprint intervals was termed as sprint interval training (SIT). This study was designed to examine the time-efficient characteristics of SIT in reducing abdominal visceral fat. <b>Methods:</b> A randomized controlled trial was conducted to compare the specific adaptations of SIT (80 × 6 s all-out cycle sprints interspersed with 9 s passive recovery) with those resulting from a HIIT regimen with training volume relatively higher (repeated 4 min bouts of cycling at 90% <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover><mml:mtext>V</mml:mtext><mml:mo>˙</mml:mo></mml:mover></mml:math> O_2<i>max</i> alternated with 3 min rest, until the work of 400KJ was achieved), and with those of nonexercising control counterparts (CON). Forty-six obese young women (body fat percentage ≥30) received either SIT (<i>n</i> = 16), HIIT (<i>n</i> = 16), or no training (<i>n</i> = 14), 3-4 sessions per week, for 12 weeks. The abdominal visceral fat area (AVFA) and abdominal subcutaneous fat area (ASFA) of the participants were measured through computed tomography scans pre-intervention and post-intervention. Total fat mass and the fat mass of the android, gynoid, and trunk regions were assessed through dual-energy X-ray absorptiometry. <b>Results:</b> Following the intervention, abdominal visceral and subcutaneous fat were reduced markedly (<i>p</i> < 0.05). The reduction in AVFA (-6.31, -9.7 cm²) was not different between SIT and HIIT (<i>p</i> > 0.05), while the reduction in ASFA (-17.4, -40.7 cm²) in SIT was less than that in HIIT (<i>p</i> < 0.05). Less reduction in the fat mass of the trunk (-1.2, -2.0 kg) region was also found in SIT, while the reductions in fat percentage (-1.9%, -2.0%), total fat mass (-2.0, -2.8 kg), and fat mass of the android (-0.2, -0.2 kg), and gynoid (-0.4, -0.3 kg) regions did not differ between the two regimes (<i>p</i> > 0.05). In contrast, the increase in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover><mml:mtext>V</mml:mtext><mml:mo>˙</mml:mo></mml:mover></mml:math> O_2<i>max</i> was significant greater following the SIT than HIIT (<i>p</i> < 0.01). No variable changed in CON. <b>Conclusion:</b> Such findings suggest that the lower training load and exercise time commitments of the SIT regime could optimize the time-efficiency advantage of the traditional HIIT, facilitating the abdominal visceral fat reduction in obese young women.