Background Medical encounters in mass-participation community-based cycling events are not uncommon and may be related to underlying chronic disease or risk factors for chronic disease in race participants.

Objective To describe the prevalence of medical conditions, including cardiovascular disease (CVD) risk factors, amongst participants in a mass-participation community-based cycling race.

Design Cross-sectional observational study.

Setting 100mile mass-participation community-based cycling race.

Participants All participants who had registered to take part in the event were invited to complete an online medical survey in the week before the event. 4099 cyclists (16.8% of 24431 finishers) completed the survey and were included in the analysis.

Assessment of Risk Factors Prevalence (%) of cyclists with risk factors including age and gender, medical history, smoking and use of medication.

Results The average age of respondents was 46 years (range 18–80 years; 41% were >50 years) and 76% were male. Respondents trained for an average 83 miles per week over 16 weeks for the event. 28% of all respondents reported using a prescription medication while the prevalence of a long-term medical condition (LTMC) was 23%. The prevalence of specific CVD risk factors or medical conditions in all respondents was: males > 50 years (34.8%; n=1428), current or ex-smokers (32.1%; n=1314), hypertension (4.2%; n=171), a known cardiac disease (including atrial fibrillation and myocardial infarction) (2.2%; n=91). 3.6% were taking medication for hyperlipidaemia (n=149).

Conclusions In a sample of entrants for a mass-participation community-based 100-mile cycling event, approximately 1 in 3 participants reported prescription medication use, and 1 in 4 reported a long-term medical condition. Risk factors for CVD were reported by a third of entrants, while 2.2% reported a known CVD. Medical teams at such events should be prepared to manage medical complications related to long term medical conditions and CVD risk.