Study Design
A subsample of online registrants in a mass cycling event in Sydney, Australia, completed a pre-event and post-event survey about cycling and physical activity. The cycling event is an annual scenic ride across the heart of Sydney organized by the non-government cycling advocacy organization, Bicycle New South Wales. Participants have the option to cycle 20 kilometers or 50 kilometers. The pre-event survey was part of the online event registration form and assessed entrants' self-rated cycling ability and physical activity level. The pre-event survey also included a question seeking permission for follow-up after the event. Informed consent was obtained by registrants' willingness to be contacted again for follow-up. Respondents were approached one month after the mass cycling event to complete the post-event survey. The post-event survey was administered via the Internet. Self-rated cycling ability and physical activity level were reassessed, as well as lifestyle physical activity in the last week. Participants received an email with a brief explanation of the survey, and a link to the survey for completion. Survey completion was voluntary, participants did not receive compensation for responding, and they could end the survey at any time. The study procedures were approved by the executive board of Bicycle New South Wales.
Study Participants
Men and women aged 16 and older were selected for post-event survey from the pool of online registrants that consented to follow-up. Approximately 8,000 men and women participated in the cycling event, and 5,058 registered for the event online. The majority of online registrants were experienced cyclists (83%). The online registrants were significantly (p < .05) younger (32% aged 16–34, 64% aged 35–64, 4% aged 65 or older) than registrants who entered the event via mail-back form (23% aged 16–34, 72% aged 35–64, 5% aged 65 or older). The proportion of women was also significantly higher (p < .05) among online registrants (28%) compared to mail-back registrants (23%). Mail-back registrants did not provide any description of their cycling ability. Unfortunately, registrants via mail-back form were not asked for permission to be contacted for follow-up after the event, and were not included in this study.
Examining change in cycling behaviour among sedentary or low ability participants was the main objective of this study; however, the proportion of participants who self-rated their physical activity or cycling ability as low on the pre-event survey was small (13%). Therefore, to obtain the maximum number of responses from the subgroup of interest, participants were automatically selected for follow-up if they indicated they had low cycling ability or low physical activity level on the pre-event survey. Participants were also automatically selected for follow up if they were female to maximize the number of responses from women because women were underrepresented in the total sample (28%). A random sample of men and experienced cyclists were selected to comprise the remainder of the follow-up cohort. Of 3,325 online registrants who consented to follow-up, 2,068 were sampled to complete the post-event survey, and 1,135 (54.9%) responded.
There was no difference in the proportion of women, persons aged 65 or older, or persons with low physical activity level between responders to the follow-up survey and non-responders. Non-responders were more likely (p < .05) to be aged 16–34 (35%) than responders (25%), and non-responders were less likely to be experienced cyclists (76%) compared to responders (85%); however, there was no difference between responders and non-responders who were not experienced cyclists in the number of times they rode their bicycle the month before the event.
Respondents with missing data pertaining to mass cycling event participation history (n = 58), post-event self-rated cycling ability and/or physical activity level (n = 126), post-event number of monthly bicycle rides (n = 3), and post-event lifestyle physical activity (n = 30) were excluded from analysis, resulting in a final analytic sample of 918 respondents.
Self-Reported Cycling Ability and Physical Activity
When participants registered online prior to the October 2005 mass cycling event they were asked, "How would you describe yourself as a cyclist?" Response choices were novice or beginner, occasional but tentative rider, occasional but competent rider, or regular rider. Participant self-rated cycling ability was dichotomized as either low (novice or tentative rider) or high (competent or regular rider). Participants described their physical activity level compared to others of the same sex and age as much more physically active, more physically active, about the same, less physically active, or much less physically active. Self-rated physical activity level was also dichotomized as low (much less or less active) or high (the same, more, or much more active). Finally, participants reported the number of times they rode their bicycle in the past month and if they had ever participated in this mass cycling event before.
One month after the mass cycling event occurred, the post-event survey was administered. Post-event survey respondents were asked the same questions regarding cycling ability and physical activity level as on the pre-event registration form. Post-event self-rated cycling ability and physical activity level were dichotomized as low or high by the same cut points as for the pre-event assessment. Participants were also asked to report the number of times they rode their bicycle during the month after the mass cycling event.
In addition to post-event cycling ability and self-rated physical activity level, questions from the Active Australia, a national survey of physical activity, were used to assess the amount of lifestyle physical activity respondents engaged in the week prior to the post-event survey [6]. Respondents reported the number of sessions and the amount of total weekly time they spent in walking, moderate-, and vigorous-intensity physical activities.
Physical activity assessed by the Active Australia was categorized as "sufficiently active" or "insufficiently active" in accordance with guidelines outlined by the Australian Institute of Health and Welfare [9]. Minutes per week spent in vigorous-intensity physical activity was weighted by a factor of two to account for additional benefits derived from higher intensity activity, then summed with minutes per week spent in walking and moderate-intensity activity to derive minutes per week of total activity. Respondents were categorized as "sufficiently active" if they participated in 150 minutes of total activity over five or more sessions in the previous week. If they did not meet these criteria they were categorized as "insufficiently active".
Statistical Analysis
General descriptive and multivariate statistical analyses were performed using SAS (Version 9.1, 2000, SAS Institute Inc., Cary, NC). Data are presented as medians with interquartile range or means with standard error for continuous variables and counts (percentages) for categorical variables. McNemar's test was used to examine changes in self-rated cycling ability before the mass cycling event and after. Repeated measures mixed linear modeling (a generalization of standard linear modeling) was used to determine whether average number of monthly bicycle rides changed between pre-event and post-event assessment among participants with low baseline cycling ability and among first-time participants in the mass cycling event. Respondent sex, age, and (for first time participants) pre-event level of cycling ability were included in the models and tested as confounders. Non-significant covariates were removed from the final models. The significance level was set at p < .05.