特に、今回初めて臨んだトライアスロン会場で目の前を心臓マッサージされながら担架で搬送されていく参加者を目の当たりにしたことは私にとって衝撃でした。帰宅後にwebを検索してみると、その方はまだ51歳の男性だったようで、ご本人もご家族もこのような結末を想像だにしなかったことでしょう。心より哀悼の意を表します。
初めてのレースでこのようなシーンに遭遇した事から、自分がこれからTriathlonという競技に取り組んで行くにあたり、医学的情報を提供し、参加者の健康と安全に微力ながらも貢献していくことが自分の使命のような気がしてきました。
気になったので、Triathlon, deathというキーワードで論文を検索してみたところ、今年のJAMA(Journal of American Medical Association)誌にSudden death during the triathlonというタイトルのResearch letterが掲載されていました。
2006年から2008年にかけて米国で開催されたトライアスロン大会のべ出場者959,214名のうち、14名が死亡しており、参加者100,000万人あたり1.5名が亡くなっている計算になります。そのうち、13名はSwim競技の間に亡くなっており、Bikeで1名、Runでは一人もなくなっていませんでした。Swimの距離別では750mから1500m（恐らくsprintからOlympic distance まで）がやや少ないようですが、他の距離と比較して特に有意な差はなさそうです。
男女別では女性に比して男性の死亡者が多く、2006年から2008年にかけてでは僅かずつではありましたが年々死亡者の割合は増加していました。
さて、今年の日本のトライアスロン競技への参加者は一体どのくらいでしょうか？先日の横浜シーサイドトライアスロンはアクアスロンや親子競技、リレーなどを含めてのべ参加者が990名、トライアスロンの個人参加完走者は630名でした。果たしてこの1年間で何人の方がレースに参加したでしょうか？100,000人も居たでしょうか？2011年の日本で、2名の参加者が亡くなっているという事はこの論文の報告よりも高い頻度にはなっていないでしょうか？
私を含め、多くの人たちがトライアスロンの魅力に気がつき、参加するようになっている日本の現況を鑑みると、やはり健康管理、安全管理という観点でメッセージを発進する事は意義があるのではないかと思うのです。
つづきます。
Sudden Death During the Triathlon
- Kevin M. Harris , MD, kharris@mplsheart.com;
- Jason T. Henry, BA;
- Eric Rohman, BA;
- Tammy S. Haas, RN;
- Barry J. Maron, MD, Minneapolis Heart Institute Foundation, Abbott Northwe
To the Editor: Triathlon is among the most vigorous amateur athletic disciplines, requiring expertise in swimming, biking, and running.1,2,3 Although sudden death risk has been assessed for the amateur marathon,4 it has not been systematically investigated for triathlon.
Participants who completed 2971 USA Triathlon (USAT) sanctioned events from January 2006 through September 2008 were tabulated using online race results (approximately 95% of event results).5 Participants in nonsanctioned races, relay races, or triathlons without full swim-bike-run sequence were excluded. Deaths were identified in the US Registry of Sudden Deaths in Athletes6 and USAT records,5 which have tabulated these events over 30 and 5 years, respectively; autopsy reports were obtained from medical examiners. The Abbott Northwestern Hospital institutional review board determined this study was exempt. Confidence intervals (CIs) were calculated using Poisson analysis (JMP version 7; SAS Institute Inc, Cary, North Carolina).
A total of 959 214 participants were analyzed (mean [SD], 323 [444] per race); 59% were men. Forty-five percent competed in short (swim <750 m), 40% in intermediate (swim 750-1500 m), and 15% in long (swim >1500 m) triathlon races (Table).
Fourteen participants died during 14 triathlons (rate, 1.5 per 100 000 participants; 95% CI, 0.9-2.5), including 13 while swimming and 1 biking (Table). Athletes who died were 28 to 65 years old (mean [SD] age, 44 [10] years). Triathlons with deaths included more participants (n = 1319; 95% CI, 1084-1584) than races without deaths (n = 318; 95% CI, 302-334). Of the swimming deaths, 11 were men and 2 were women.
Six deaths occurred in short, 4 in intermediate, and 3 in long races (2 in an Ironman triathlon). Eight swimmers were in distress and called for assistance, and 5 were found motionless on the water. Deaths occurred in the open ocean (n = 6), lakes (n = 4), reservoirs (n = 2), or a river (n = 1). The bicycle fatality resulted from a fall causing cervical injuries.
Drowning was the declared cause of each swimming death, but 7 of 9 athletes with autopsy had cardiovascular abnormalities identified. Six had mild left ventricular hypertrophy with maximum wall thickness of 15 to 17 mm and mean (SD) heart weight of 403 (77) g, including 1 with a clinical history of Wolff-Parkinson-White syndrome. One other athlete had a congenital coronary arterial anomaly, and 2 had structurally normal hearts.
Although the contribution of cardiovascular abnormalities cannot be definitively excluded in some cases,2 logistical factors and adverse environmental conditions may have been responsible for these events, given that about 95% of triathlon fatalities occurred during the swimming segment. Furthermore, deaths were more common in triathlons involving greater numbers of competitors. Because triathlons begin with chaotic, highly dense mass starts, involving up to 2000 largely novice competitors entering the water simultaneously, there is opportunity for bodily contact and exposure to cold turbulent water.3 Triathlons also pose inherent obstacles to identifying distressed athletes and initiating timely resuscitation on open water. Compared with these triathlon findings, marathon racing analyzed for more than 3 million runners over 30 years reported a mortality rate of 0.8 per 100 000 participants (95% CI, 0.5-1.1).4
Study limitations include the possibility that all sudden deaths may not have been identified, as neither of the registries is based on mandatory reporting. Although it is not possible to determine the precise number of US triathlons annually, USAT events likely represent a large proportion. This study was designed to explore risk per participation; an unknown number of athletes competed more than once within the data set.
Although mass screening before competition may be impractical, awareness of cardiovascular risks may motivate athletes to seek preparticipation evaluations on an individual basis. Efforts to improve triathlon safety could include establishing minimum achievement standards for participation, including swimming proficiency.
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