Does pre-existing medical conditions and pre-competition screening identify athletes at risk of medical intervention in competitive Open Water swimming?

ABSTRACT

Background: Open water swimming is one of the fastest growing mass participation sports worldwide. Analysis of triathlon deaths and cardiac arrests have shown that 75% of these occur in the swimming leg. Less than half had autopsy evidence of cardiac disease, and swimming ability or medical conditions do not appear responsible. Mandatory pre-competition clinical screening has been traditionally promoted in open water swimming to identify athletes at risk of illness or death during competition. The variable nature of this screening however, may not be useful in identifying at risk individuals. Objectives: We aimed to determine whether the presence of pre-existing medical conditions or abnormalities discovered on clinical screening [blood pressure (BP), heart rate (HR), auscultation of heart and lungs and apical palpation] predicted either failure to complete the race or the need for medical contact. Methods: We collected screening and competition data from participants in the two largest regional Open Water competitions in 2017 ­ including international (CCCAN) and mixed ability (ASATT Maracas) athletes. Anonymised data on event medical contacts, failure to finish and screening were analysed, with descriptive results and risk ratios calculated using MedCalc statistical software. Age adjusted values for BP and HR outside the 90th centile was considered abnormal. Results: Overall, 410 athletes participated for which data was available for 400 (mean age 17.9 years, range 7-79; 58% male). There were 30 medical contacts, of which 22 were unable to complete the race. There was no significant sex difference in those unable to complete. The majority of contacts was for the 10k race (60%) with the 5k (23%) the next most common. The most common reason for non-completion was exhaustion. Three scratched due to illness on competition day. 21 athletes were asthmatic, and 2 had cardiac murmurs, however all completed their respective races and none required any medical contact. Asthma (RR 0.3, p=0.39), abnormal physiological measurements (RR 1.32, p=0.84) and other medical conditions (RR 0.94, p=0.96) did not appear predictive. Current illness was the only significant predictor of failure to complete or medical contact. (RR 6.67; 95% CI 2.36 -18.84), however a larger sample may be necessary to show significance. Conclusions: There is much variability in pre-competition screening for Open Water swimming, as with other sports. Intuitively, only current illness predicts failure to complete/medical contact, although it is unclear whether this can be used as a surrogate for athletes at risk of more serious sequelae. Pre-existing medical conditions such as asthma do not appear to be contributory to non-completion, nor does moderately abnormal physiological measurements. Given that cardiac arrythmias or structural abnormalities are implicated in some deaths during open water swimming, adding resting electrocardiography and possible echocardiography to pre-participation medical examination may be reasonable, however the effectiveness of this strategy is disputed. There appears to be little benefit in clinical screening immediately prior to competition, with a more thorough, structured pre-training examination likely to be superior.