This study examined the patterns and socio-demographic correlates of self-reported PA among normal-weight and overweight men. The results revealed that both self-reported PA patterns and associated correlates in overweight men were different from those in normal-weight men, which is consistent with the findings of previous studies [15
]. Our results imply that BMI status should be considered when developing more effective intervention approaches to PA among Japanese men.
With regard to the prevalence of attaining 150 minutes per week of total PA, walking, and MVPA, no significant differences were found in total PA and walking among the BMI subgroups; however, overweight men were significantly less likely to achieve 150 minutes of MVPA than normal-weight men. Numerous studies have reported that overweight or obese individuals spend less time on PA and are less likely than normal-weight individuals to meet the minimum recommended level of PA [13
]. However, few studies have stratified PA time into walking and MVPA, yet this division provides a better understanding of the patterns of walking and MVPA when developing effective PA intervention strategies. Using objective PA measurements, one study showed that overweight or obese children had a distinct pattern of daily MVPA compared with normal-weight children [12
]. Furthermore, behavioral preferences for sedentary behavior or light activity have been reported among overweight and obese individuals [22
]. A possible explanation for the latter result is that owing to their poor physical condition, it may be more difficult for overweight men to engage in MVPA (e.g., leisure-time PA, sports, and vigorous types of recreational activities) compared with walking [12
Regardless of weight status, men who had lower household income were less likely to attain 150 minutes of total PA and walking, which is consistent with previous findings [9
]. In addition, men without a full-time job were more likely to achieve 150 minutes of MVPA. This finding has not been demonstrated in previous studies [9
]. A possible explanation for this result is that job status may be related to whether men have available or limited opportunity to engage in MVPA (e.g., leisure-time PA, sports, and vigorous types of recreational activities) in their leisure time.
In logistic regression models, the interactions between BMI and five socio-demographic variables (age, marital status, educational level, job status, and household income) separately for the three PA outcome variables were tested based on likelihood ratio tests. Only household income was revealed as a different socio-demographic correlate of PA between normal-weight and overweight men. Consistent with the findings of a Brazilian study [15
], we did not observe an interaction between BMI and age. In contrast, an interaction between BMI and education, which was identified in that study [15
], was not observed in the present study. In addition, previous studies have indicated that adults with a higher household income were more likely to be physically active [9
]. However, there has been no discussion or analysis as to whether this association differs according to BMI status. A possible mechanism underlying the observed significance in household income only among normal-weight men is that household income may not be a barrier or facilitator for overweight men to engage in walking compared with normal-weight men. Therefore, the findings of the present study suggest that correlates of specific PA may vary according to BMI status.
Furthermore, in the subgroup analyses, household income was significantly associated with achieving 150 minutes of walking among normal-weight men, whereas no significant associations between household income and attaining 150 minutes of walking were observed among overweight men. Consistent with the findings of a Brazilian study [15
], this result implies that socio-demographic correlates are less important in overweight than in normal-weight men and that other correlates of meeting recommended levels of PA may be more important for overweight men, such as psychosocial correlates and environmental factors.
Based on the findings of the present study, encouraging overweight men to engage in walking could be considered a gateway for them to achieve health-enhancing levels of PA. More factors associated with walking or other specific MVPA behaviors need to be further identified to develop tailored PA for overweight men. In addition, for normal-weight men, the promotion of daily walking (e.g., walking for transportation or recreation) should be targeted at those with a lower household income. Therefore, it is expected that future studies will identify the multiple levels of correlates associated with specific types of PA among normal-weight and overweight men.
There were some limits with the current study. First, the main measurements of the study, which include BMI, socio-demographic factors, and PA, were determined only by means of self-administrated questionnaires, and they could be subject to bias. Self-reported results may cause an underestimation of weight status [23
] and an inaccurate estimation of PA time as a result of recall bias. In addition, diet, which affects weight, was not assessed in the current study [24
]. Finally, the present study had limited ability in obtaining representative samples because it relied on an Internet-based survey. The respondents to Internet-based surveys may possess certain characteristics, such as being younger, being more educated, having a higher income, having greater access to the Internet, and being more likely to respond to a survey if they are interested in the surveys content or are attracted by the incentives offered for participation [25
]. Thus, the results of the present study may be less applicable to the general population, particularly among those with a lower level of education. Despite these considerations, the present study has some strengths. This study has a large sample size (n=1,420) and specifically focused on a sex subgroup with a higher prevalence of overweight (men). In addition, except for educational level, the distribution of age, marital status, job status, household income, prevalence of overweight, and attaining the total PA recommendations was similar to that for the general Japanese population [4
]. Therefore, the findings of the current study could provide important implications in that the patterns and socio-demographic correlates of self-reported PA differed between normal-weight and overweight men. Future studies are needed to further identify correlates of PA by different BMI status in developing tailored PA intervention for the overweight population.