Abstract
This study evaluated the effectiveness of an innovative strategy which combined low-frequency ultra sound (LOFU) with high-intensity interval training (HIIT) to improve physical fitness and promote body fat loss in overweight sedentary women. A placebo controlled, parallel group randomized experimental design was used to investigate the efficacy of a 2-week combined LOFU and HIIT program (3 sessions per week). Participants were allocated into either the Experimental HIIT group (HIITEXP, n = 10) or Placebo HIIT group (HIITPLA, n = 10). Baseline exercise testing (maximal oxygen uptake, lower limb strength and substrate oxidation test), dietary assessment, anthropometric measures and blood sampling were completed in week 1 and repeated in week 4 to determine changes following the program (Post-HIIT). During each training session, the HIITEXP and HIITPLA groups wore a non-thermal diffuse ultrasound belt. However, the belt was only switched on for the HIITEXP group. Delta change scores were calculated for body weight, body fat percentage (Fat%), muscle mass, O2max, hip and waist circumferences, and all lipid variables from Baseline to Post-HIIT. Statistical analysis was completed using a repeated-measures factorial analysis of variance by group (HIITPLA and HIITEXP) and time (Baseline and Post-HIIT). Results showed significant improvements in maximal oxygen uptake (HIITEXP; Baseline 24.7 ± 5.4 mL kg–1 min–1, Post-HIIT 28.1 ± 5.5 mL kg–1 min–1 and HIITPLA; Baseline 28.4 ± 5.9 mL kg–1 min–1, Post-HIIT 31.4 ± 5.5 mL kg–1 min–1) for both groups. Significant decreases in Fat% (HIITEXP; Baseline 32.7 ± 3.2%, Post-HIIT 28.9 ± 3.5% and HIITPLA; Baseline 28.9 ± 3.5%, Post-HIIT 28.9 ± 3.4% kg), waist circumference (HIITEXP; Baseline 95.8 ± 9.6 cm, Post-HIIT 89.3 ± 8.9 cm and HIITPLA; Baseline 104.3 ± 3.5 cm, Post-HIIT 103.6 ± 3.4 cm) and triglycerides (HIITEXP; −29.2%, HIITPLA; −6.7%) were observed in the HIITEXP group only. These results show that HIIT combined with LOFU was an effective intervention to improve body composition, lipid profile, and fitness. This combined strategy allowed overweight, sedentary women to achieve positive health outcomes in as little as 2 weeks.
Highlights
Sedentary behavior and physical inactivity are closely associated with the development of risk factors for metabolic syndrome including glucose intolerance, insulin resistance, hypertension, dyslipidemia, and obesity (Eckel et al, 2010)
There was a tendency toward a greater rate of fat oxidation in HIITEXP following combined high-intensity interval training (HIIT) and lowfrequency ultra sound (LOFU) at 60 W (Baseline: 0.45 ± 0.03 g min−1 to Post-HIIT: 0.65 ± 0.4 g min−1) (Figure 3) and at 80 W (Baseline: 0.31 ± 0.02 g min−1 to Post-HIIT: 0.41 ± 0.4 g min−1) (Figure 4)
The main finding of this study was that HIIT combined with LOFU resulted in a significant reduction in Fat% (−4.5%)
Summary
Sedentary behavior and physical inactivity are closely associated with the development of risk factors for metabolic syndrome including glucose intolerance, insulin resistance, hypertension, dyslipidemia, and obesity (Eckel et al, 2010). Due to the increasing prevalence of overweightness and obesity, combined with the significant health costs and economic burden of sedentary behavior, it is important to investigate strategies that induce a loss of body fat and promote long-term weight management (Ogden et al, 2006). In this context, a balanced diet and physical activity interventions are the main approaches used to reduce body fat and improve an individual’s blood lipid profile (Donnelly et al, 2009; Johns et al, 2014). Evidence suggests that high-intensity interval training (HIIT) is an effective strategy for reducing body fat (Boutcher, 2011; Maillard et al, 2018) and could lead to a greater loss in fat mass than MICT (Wewege et al, 2017)
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