The thin outside fat inside (TOFI) phenotype, an obesity expression, is recognized by a high amount of visceral adipose tissue (VAT) despite average anthropometric measurements such as normal body mass index (BMI). High VAT is a considerable risk of metabolic syndrome. As a beneficial intervention, exercise training can decrease body fat amount. This review aimed to investigate exercise efficiency on VAT in individuals with normal BMI.
Electronic databases were used to detect studies related to exercise training intervention on VAT in normal BMI individuals from 1999 to 2022. Inclusion criteria included acute, four weeks or more; duration intervention of aerobic training (AT), resistance training (RT) or combination training (COM) with adults. Participants BMIs were approximately 26 kg/m2 or less in studies investigating VAT differences between sedentary and active individuals. Acceptable body assessment measurements in the studies used computed tomography, magnetic resonance imaging, or dual-energy x-ray absorptiometry.
The primary search resulted in 217 original studies and 11 were included. The most common intervention was AT, using treadmill running, and the most common mode of RT was weight machines. Frequency of training averaged 3 days per week of 30- to- 90 minute sessions. AT intensity was demonstrated with the percentage of maximum oxygen consumption (VO2 max), peak rate of oxygen consumption (VO2peak), heart rate reserve (HRR), or maximal heart rate (MHR) in the range of 55% to 120%. The most common range was 60–70% MHR. The intensity of RT was determined as one-repetition maximum (1-RM), ranging between 60–80% 1RM. One study used interval modality intervention. Seven studies show a significant decrease in VAT values. The most impactful training was AT with two studies using COM also reported benefits. The most common unit of measurement used for VAT was cm2. Other studies used varying units such as 1) kg, 2) cm3, 3) liter, and 4) percentage of total body fat. The range of significant change in VAT scores was −2.5 ± 7.2 cm2 to −19.3 ± 12.7 cm2. Additionally, one study reported significant differences in VAT observed between active and sedentary individuals and one study reported no demonstrated differences using RT.
The systematic review suggests exercise training could be a beneficial intervention for improved VAT changes. However, exercise modality should be taken into account alongside acute variables such as volume, intensity, duration, and frequency. Based on findings, AT is the most effective modality and RT as another exercise option needs more investigation.
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