Abstract
Purpose: To compare the effects of 8 weeks of two types of interval training, Sprint Interval Training (SIT) and High-Intensity Interval Training (HIIT), on anthropometric measures and cardiorespiratory fitness in healthy young women.Methods: A randomized clinical trial in which 49 young active women [age, 30.4 ± 6.1 years; body mass index, 24.8 ± 3.1 kg.m−2; peak oxygen consumption (VO2peak), 34.9±7.5 mL.kg−1.min−1] were randomly allocated into a SIT or HIIT group. The SIT group performed four bouts of 30 s all-out cycling efforts interspersed with 4 min of recovery (passive or light cycling with no load). The HIIT group performed four bouts of 4-min efforts at 90–95% of peak heart rate (HRpeak) interspersed with 3 min of active recovery at 50–60% of HRpeak. At baseline and after 8 weeks of intervention, waist circumference, skinfolds (triceps, subscapular, suprailiac, abdominal, and thigh), body mass and BMI were measured by standard procedures and cardiorespiratory fitness was assessed by cardiorespiratory graded exertion test on an electromagnetically braked cycle ergometer.Results: The HIIT and SIT groups improved, respectively, 14.5 ± 22.9% (P < 0.001) and 16.9 ± 23.4% (P < 0.001) in VO2peak after intervention, with no significant difference between groups. Sum of skinfolds reduced 15.8 ± 7.9 and 22.2 ± 6.4 from baseline (P < 0.001) for HIIT and SIT groups, respectively, with greater reduction for SIT compared to HIIT (P < 0.05). There were statistically significant decreases in waist circumference (P < 0.001) for the HIIT (−3.1 ± 1.1%) and SIT (−3.3 ± 1.8%) groups, with no significant difference between groups. Only SIT showed significant reductions in body weight and BMI (p < 0.05).Conclusions: Eight weeks of HIIT and SIT resulted in improvements in anthropometric measures and cardiorespiratory fitness, even in the absence of changes in dietary intake. In addition, the SIT protocol induced greater reductions than the HIIT protocol in the sum of skinfolds. Both protocols appear to be time-efficient interventions, since the HIIT and SIT protocols took 33 and 23 min (16 and 2 min of effective training) per session, respectively.
Highlights
Regarding the applications for weight loss, a review found that fat loss after Interval training (IT) was greater than that after moderate-interval continuous training (MICT) (60–80% of HRmax) (Boutcher, 2011)
Studies on the effects of IT on post exercise energy expenditure and fat oxidation (Treuth et al, 1996; Laforgia et al, 1997; Greer et al, 2015) and weight loss (Tremblay and Bouchard, 1994; Trapp et al, 2008; Burgos et al, 2017) suggest that IT is more efficient than continuous models, including MICT (Zhang et al, 2017)
Our results suggest that 8 weeks of high-intensity interval training (HIIT) and sprint interval training (SIT) improve markers of body fatness and cardiorespiratory fitness, even in the absence of changes in dietary intake
Summary
Interval training (IT) has been used for many decades with different purposes, such as improvements to health parameters (Wisløff et al, 2009; Kemi and Wisløff, 2010; Weston et al, 2013), performance (McMillan et al, 2005; Gibala and McGee, 2008; Gibala and Jones, 2013), and weight loss (Trapp et al, 2008; Boutcher, 2011). Weight loss seems to be higher, even if the caloric expenditure obtained with IT is lower than (Tremblay and Bouchard, 1994) or equal to that of MICT (Trapp et al, 2008) These results can be attributed to the effects of IT on metabolism, promoting increased resting energy expenditure and fat utilization (Kiens and Richter, 1998; Knab et al, 2011; Kelly et al, 2013). It seems that fat loss is greater at higher exercise intensities (Tremblay and Bouchard, 1994). We were not able to find any study in relation to the effects of SIT vs. HIIT on body composition in healthy young women
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