Gustafson and Rhodes  concluded that there was no evidence of familial patterns of PA based on a systematic review of 24 studies; however, they noted that most of these studies did not employ objective or otherwise validated measures of PA. In contrast, the results of this CANPLAY study indicate a clear and quantifiable association between parent and child objectively monitored ambulatory PA levels. Although these are cross-sectional data, the findings suggest that efforts spent to increase PA levels among parents may also increase their children’s steps/day, and vice versa. This assertion, of course, requires a longitudinal or intervention design to confirm. Specifically, the relationship observed was such that if a father’s daily steps could be increased from the typical 8,759-9,090 step/day observed in this study to 10,000 steps/day  (e.g., as in the successful community-wide interventions to increase the proportion of adults taking 10,000 steps/day in Rockhampton, Australia  and Ghent, Belgium ), his child would be 1.25 times as likely to be in the middle tertile and 1.36 times as likely to be in the highest tertile of his or her peers’ daily steps. Furthermore, if a mother’s steps/day were increased to 10,000 steps/day from the observed mean of 8,215–8,411 steps/day, her child would be 1.21-1.22 times more likely to be in the two highest tertiles of their peer’s steps/day.
Fuemmeler et al.  used accelerometers to examine the relationship between parent–child activity levels, specifically time spent in MVPA, during specific time periods (weekends, weekday mornings before school and weekday afternoons between 3 and 7 pm). They found that parent’s MVPA was correlated with child’s MVPA irrespective of time period, and more specifically that mother’s and daughter’s MVPA were correlated in each of these time periods whereas father’s and daughter’s MVPA were correlated only weekday mornings. In contrast mother’s and son’s MVPA were not related and father’s MVPA was related to son’s MVPA on weekends and with weekday afternoons. These results are similar in part to these CANPLAY findings in that parent–child patterns of overall PA behaviour were related; however, mother-son results differed between the two studies. The largest differences between the two studies, however, is that Fuemmeler et al.  focused on the relationships at higher intensities of the PA (i.e., MVPA) accumulated within specific, possibly parent–child shared time frames, whereas CANPLAY examined parent–child relationships for total volume of PA (recorded as steps/day), and regardless of possible shared time with each other.
It has been suggested that parental modelling of PA is insufficient to influence child PA , but parent’s PA may be indicative of parental support of PA . Based on their review of the extant literature, Gusto and Rhodes concluded that parental support such as encouragement, involvement and facilitation (transportation, equipment, access to opportunities to be active) may mediate any parent–child PA relationship. Bradley et al.  studied the impact of parenting processing, specifically monitoring and encouragement, and parent reported levels of their own physical activity, on changes in accelerometer-determined MVPA of children between 9 and 15 years of age. Each variable demonstrated significant but small effects that were sex-specific and moderated by age of puberty and region, so the mechanisms by which parents may influence their child’s PA may be multifactorial and not necessarily require their immediate presence at the time of the behaviour. These CANPLAY data suggest that relatively modest increases in parent’s PA may facilitate meaningful differences in their children’s PA. In this study, we found father-son and mother-son associations of steps/day with and without adjustment for potential confounders. This suggests that son’s PA behaviours may be influenced by parental modelling of physical activity. However, it may be that parents who are more active are also more likely to encourage and support their child’s activities and that it is this support rather than simply the modelling of behaviour that influences their child’s level of physical activity. The father-daughter and mother-daughter associations of steps/day were less robust. In the unadjusted model, only mother’s steps were associated with daughter’s steps. After adjustment for parent and child age, household income, weight status and television viewing time, mother’s steps/day were associated her daughter’s at the p < .10 level, but only father’s steps/day were associated with daughter’s steps/day at the p < .05 level and contrary to expectation, television viewing was associated with increased steps/day. This lack of consistency in the associations suggests that parents’ direct modelling of ambulatory behaviour may not be as important in shaping girls’ PAbehaviours as other factors such as competing interests (e.g, television viewing) and access to opportunities in higher income households. Further research is needed on moderating and mediating factors to illuminate potential mechanisms underlying successful family-based interventions designed to help parents increase their own PA as well as that of their children.
The CANPLAY data are cross-sectional and these associations, although significant, do not confirm causality. There may be other unmeasured factors that explain both parents’ and their children’s PA level that cannot be addressed simply by targeting parental PA behaviour. These findings are also based on a relatively small subsample of the CANPLAY data, specifically families who agreed collectively to self-monitor their behaviour for this survey. Parents who respond to this survey tended to be more active than their peers and have a university education, and children who responded were disproportionately representing the 5–10 age group , therefore the results of this analysis can only be generalized to those who share similar characteristics. Weight status and television viewing time are based on parental reports and suffer the problems inherent in self report data and likely reflect under-reporting of weight and television viewing time and over-reporting height as well as a large proportion of missing data for height which a large number of parents could not estimate. CANPLAY also uses pedometers to collect objective physical activity, and unlike accelerometers, these less expensive instruments are not designed to collect intensity or bouts of activity. Regardless, these data serve as important reference values  for researchers and practitioners as well as families who are interested in collecting and comparing their own data using a more accessible research tool. The continued use and sharing of pedometer data is defensible as it represents a clear opportunity to bridge science, practice, and real life.