Table 3

Patient background and risk factor of heat-related illness severity on Olympic athlete

OlympicTotal n=100 (%)Minor degreeModerate degreeSevere degreeP value
n=50 (%)n=40 (%)n=10 (%)
Patient factor
Gender*Male54(54.0)27(27.0)23(23.0)4(4.0)0.84
Female46(46.0)23(23.0)17(17.0)6(6.0)
Age†20s69(69.0)28(28.0)35(35.0)6(6.0)0.003
30s30(30.0)21(21.0)5(5.0)4(4.0)
40s1(1.0)1(1.0)0(0.0)0(0.0)
Home continents†European37(37.0)22(22.0)9(9.0)6(6.0)
American28(28.0)9(9.0)17(17.0)2(2.0)
Asian20(20.0)8(8.0)11(11.0)1(1.0)
African11(11.0)10(10.0)1(1.0)0(0.0)
Oceanian4(4.0)1(1.0)2(2.0)1(1.0)
Environment factor
Venue zone†Tokyo bay zone‡27(27.0)4(4.0)18(18.0)5(5.0)<0.0001
Heritage zone§22(22.0)5(5.0)17(17.0)0(0.0)
Sapporo Odori Park (marathon/race walk)50(50.0)41(41.0)4(4.0)5(5.0)
Other venue (Kasumigaseki Country Club)1(1.0)0(0.0)1(1.0)0(0.0)
Location*Outdoors venue100(100.0)50(50.0)40(40.0)10(10.0)0.00
Indoors venue0(0.0)0(0.0)0(0.0)0(0.0)
Time†Morning game (7:00 to 12:00)58(60.0)33(33.0)16(16.0)9(9.0)0.29
Afternoon game (12:00 to 18:00)26(23.0)12(12.0)13(13.0)1(1.0)
Evening game (18:00 to 22:00)17(17.0)6(6.0)11(11.0)0(0.0)
WBGT (°C)*21°C<WBGT<28°C49(49.0)29(29.0)16(16.0)4(4.0)0.05
28°C≤WBGT51(51.0)21(21.0)24(24.0)6(6.0)
Sports factor
Athletic classification*Endurance sports72(72.0)43(43.0)19(19.0)10(10.0)0.002
Non-endurance sports28(28.0)7(7.0)21(21.0)0(0.0)
Endurance sportsAthletics (marathon/race walk)50(50.0)41(41.0)4(4.0)5(5.0)
Rowing10(10.0)0(0.0)7(7.0)3(3.0)
Tennis5(5.0)1(1.0)3(3.0)1(1.0)
Marathon swimming2(2.0)0(0.0)2(2.0)0(0.0)
Cycling1(1.0)1(1.0)0(0.0)0(0.0)
Triathlon2(2.0)0(0.0)2(2.0)0(0.0)
Beach volleyball1(1.0)0(0.0)0(0.0)1(1.0)
Hockey1(1.0)0(0.0)1(1.0)0(0.0)
Non-endurance sportsAthletics (track and field)20(20.0)4(4.0)16(16.0)0(0.0)
Archery3(3.0)2(2.0)1(1.0)0(0.0)
Equestrian2(2.0)1(1.0)1(1.0)0(0.0)
Golf1(1.0)0(0.0)1(1.0)0(0.0)
Canoe sprint1(1.0)0(0.0)1(1.0)0(0.0)
Sport climbing1(1.0)0(0.0)1(1.0)0(0.0)
Treatment factor
CWI6(6.0)0(0.0)0(0.0)6(6.0)
Intravenous injection5(5.0)0(0.0)4(4.0)1(1.0)
Ice towel35(35.0)15(15.0)18(18.0)2(2.0)
Ambulance transportation4(4.0)1(1.0)1(1.0)2(2.0)
Hospitalisation (<2 days)0(0.0)0(0.0)0(0.0)0(0.0)
  • Endurance sports: athletics (marathon/race walk), cycling and marathon, swimming, tennis, rowing, triathlon, beach volleyball and hockey; non-endurance sports: athletics (track and field), sport climbing, archery, equestrian, golf and canoe sprint.

  • *Between the group; in the Ⅰ degree and Ⅱ degree/Ⅲ degree Fisher's exact probability test.

  • †Among the group; in the Ⅰ degree and Ⅱ degree/Ⅲ degree Fisher's exact probability test.

  • ‡Tokyo Bay Zone; Aomi Urban Sports Park, Oi Hockey Stadium, Shiokaze Park, Ariake Urban Sports Park, Yumenoshima Park Archery, Odaiba Marine Park, Ariake Tennis Park, Sea Forest Waterway.

  • §Heritage Zone, Olympic Stadium & Equestrian Park.

  • CWI, cold water immersion; WBGT °C, wet-bulb globe temperature occurred at heat-related illness.