Obesity is a multifactorial condition that increases the risk for several chronic diseases (Hruby and Hu, 2015; Who, 2014). A total of 58% of the worldwide adult population will be overweight in 2030 and 20% will be obese (Kelly et al. 2008). The main causes of obesity are an energy imbalance between calories consumed and calories used, or a lack of physical activity sufficient to compensate for the consumed calories (Hruby and Hu, 2015; WHO, 2010; Casazza et al., 2013). Around 31% of adults aged 15 and over are insufficiently active worldwide (Hallal et al., 2012).
Approaches to prevent and treat obesity include performing physical exercise in addition to habitual physical activity and reducing time spent in sedentary behavior (Innerd et al., 2018). In this context, different physical exercise training protocols have been applied to increase adherence to exercise in obese individuals, including high-intensity interval exercise (HIIE). Systematic reviews and meta-analyses have shown that HIIE improves cardiometabolic risk factors in overweight/obese people (Batacan et al., 2017; Weston et al., 2014). Despite the HIIE protocol being effective to improve health-related fitness in obese/overweight people, it is suggested that the sudden increase in the amount of physical exercise will be compensated by a reduction in habitual physical activity levels and by an increase in time spent in sedentary behavior in order to preserve an individual's set point (Thivel et al., 2014; Fedewa et al., 2017). Thus, this compensatory effect could result in negative health-related outcomes, since a single physical exercise training session does not seem to eliminate the impairment of prolonged and excessive sedentary behavior (i.e. [greater than or equal to] 13 h) on cardiometabolic health (Duvivier et al., 2013).
Although there are guidelines in the literature about the exercise prescription for obese individuals according to the FITT (Frequency, Intensity, Time, Type) principle, the intensity that should be recommended for weight loss remains unclear, as well as the compensatory effect promoted by different exercise intensities (e.g. light, moderate, and vigorous). In overweight adolescent boys, a single session of HIIE and MICE increases sedentary behavior and decreases habitual physical activity compared to a control condition, without a difference between HIIE and MICE (Paravidino et al., 2017). In adults, Alahmadi et al. (2011) found no compensatory effect on the habitual physical activity after a HIIE and MICE session in overweight and obese males three days pre- and post-session, while Nugent et al. (2018) demonstrated a decrease in sedentary behavior time and an increase in physical activity level for three days after HIIE and MICE intervention (two weeks of) in adults with pre-diabetes, without difference between sessions. Despite these interesting results, to the best of our knowledge there is no data about the effect of a single low-volume HIIE and MICE sessions on habitual physical activity and sedentary behavior levels throughout 7 days after these exercise sessions in inactive obese males. This amount of time is necessary for better describing the habitual physical activity and sedentary behavior levels after a traditional exercise prescription (MICE) and an alternative exercise prescription approach (HIIE) for obese individuals.
Previously, we have demonstrated that both MICE and HIIE elicits a mild muscle damage and delayed onset muscle soreness and no acute phase inflammation in inactive overweight/obese individuals (Farias-Junior et al., 2019a; 2019b; Souza et al., 2018) up to 48 hours post-exercise. This, in turn, could generate a similar impact of MICE and HIIE on the habitual physical activity and sedentary behavior levels in this population. Therefore, the aim of this study was to analyze the effects of a single low-volume HIIE and MICE session on the habitual physical activity and sedentary behavior levels in inactive obese males. It was hypothesized that the inactive obese males would decrease their habitual physical activity levels and increase their sedentary behavior levels similarly following a single low-volume HIIE and MICE sessions compared to a day without exercise.
This is a randomized controlled crossover trial conducted to analyze the effects of a single low-volume HIIE and MICE session on the habitual physical activity and sedentary behavior levels in obese males. The CONSORT guideline was followed (Boutron et al., 2017). The study was conducted from September 2016 to August 2017 in the Department of Physical Education, Federal University of Rio Grande do Norte, Natal, Brazil. The protocol of this study was in accordance with the Declaration of Helsinki and was approved by the Institutional Ethics Committee
(Protocol: 976.389/2015) and registered as clinical trials (ReBEC: RBR-62kr6f).
An a priori statistical power was conducted considering an increase in time spent in sedentary behavior following both exercise sessions compared to the control session, an estimated effect size of 16.5% for a time by condition interaction effect (Paravidino et al., 2017), a statistical power 1-[beta] of 80% and an alpha of 5%. The minimum sample size required for the study was 16 participants. Considering a dropout rate of 25%, we recruited a total of 20 participants (G*Power software, version 188.8.131.52).
Thirty-two obese males were initially recruited from the invitation disclosed in university settings, e-mails and online social networks in the city of Natal, Brazil, however only 20 met the inclusion criteria. A total of 17 individuals completed the study (Figure 1). Inclusion criteria were: i) men aged 18 to 35 years; ii) body mass index (BMI) above of 30 m/[kg.sup.2] and body fat above of 25%, with stability of body mass in the last six months; iii) being physically inactive (perform
Exclusion criteria used were: i) smokers; ii) patients with overt hypothyroidism, diabetes mellitus, hypertensive, anemic, active infection, cancer or any contraindications to exercise; and iii) participants who began the study but did not complete any one of the experimental sessions or did not remain with the accelerometer for at least 10 hours per day during at least 4 days per week, including 1 day on the weekend were excluded from the study.
The participants were initially screened using the Physical Activity Readiness Questionnaire and then completed the short-version International Physical Activity Questionnaire to assess their physical activity level (Matsudo et al., 2012). The participants subsequently performed a maximal graded exercise test on a treadmill. At the end of the maximal graded exercise test, the exercise and control sessions were randomly scheduled with a one-week interval between each one. A computer-based simple randomization (www.graphpad.com) was used to determine the order of the exercise and control sessions. Due to logistics, only the participants were blinded for the order of the sessions. Participants were asked to avoid moderate-vigorous physical activity, caffeinated products, and alcohol consumption, as well as to maintain a good sleeping pattern 24 h before the maximal graded exercise test and experimental sessions. All procedures were performed in the morning (between 8:00-11:00 a.m.) in a quiet and temperature controlled room (23-25[degrees]C). Physical activity and sedentary behaviors were monitored during seven consecutive days after the end of the exercise and control sessions.
Maximal graded exercise test
Participants performed a warm-up on a treadmill (RT250, Movement[R], Brazil) at 2.0 km/h during three minutes and then they started the protocol maximal graded exercise test at 3.0 km/h and increments of 1.0 km/h every minute until voluntary exhaustion. The MAV was considered as the highest velocity sustained by a...