| Male (n = 42) | Female (n = 18) | P-value | ||||
---|---|---|---|---|---|---|---|
EHS (n (%)) | 35 (83) | 12 (67) | 0.18 | ||||
ERM (n (%)) | 7 (17) | 6 (33) | 0.18 | ||||
Age at event (years) | 33 (19–65) | 36 (19–57) | 0.97 | ||||
BMI (kg/m2) | 23.8 (20.2–31.1) | 22 (18–25) | 0.006 | ||||
 Exercise type and symptom onset |  |  |  | ||||
  Running (n) | 28 | 12 | 0.77 | ||||
   Distance (km) | 15.5 (4.0–42.2) | 20.0 (5.0–41.1) | 0.28 | ||||
   Time (min) | 60 (15–360) | 75 (20–500) | 0.14 | ||||
  Military exercise (n) | 7 | 1 | 0.41 | ||||
  Other activities (n)* | 6 | 6 | 0.15 | ||||
 Tbody (°C) | 40.4 (36.8–42.1) | 40.4 (37.1–42.7) | 0.38 | ||||
 Peak CK (IU/L) | 1971 (129–1,502,600) | 10,9783 (132–75,720) | 0.19 | ||||
Symptoms (n) | Yes | No | NR | Yes | No | NR | Â |
 Amnesia | 9 | 1 | 32 | 3 | 2 | 13 | 0.24 |
 Ataxia | 19 | 18 | 5 | 12 | 6 | – | 0.38 |
 Collapse | 34 | 8 | – | 10 | 7 | 1 | 0.10 |
 Confusion | 13 | 1 | 28 | 4 | 2 | 12 | 0.20 |
 Hyperactive state | 5 | 1 | 36 | 1 | 2 | 15 | 0.22 |
 Hypoactive state | 8 | 2 | 32 | 2 | 2 | 14 | 0.52 |
 Seizure | 5 | 26 | 11 | 4 | 11 | 3 | 0.44 |
 Myalgia | 25 | 11 | 6 | 13 | 3 | 2 | 0.51 |
 Muscle cramps | 25 | 15 | 2 | 12 | 4 | 2 | 0.53 |
 Muscle swelling | 5 | 20 | 17 | 6 | 5 | 7 | 0.06 |
 Muscle weakness | 20 | 12 | 10 | 10 | 6 | 2 | 1.00 |
Risk factors (n) | Â | Â | Â | Â | Â | Â | Â |
 Not acclimatized to heat | 22 | 15 | 5 | 11 | 7 | – | 1.00 |
 Peer pressure | 11 | 31 | – | 5 | 13 | – | 1.00 |
 Sleep deprivation | 10 | 32 | – | 1 | 17 | – | 0.15 |
 Unaccustomed exercise | 5 | 36 | 1 | 1 | 17 | – | 0.67 |
 Improper fluid intake | 7 | 35 | – | 3 | 15 | – | 1.00 |
Sequelae after 6 months (n) (n = 57) | 22 | 16 | 3 | 12 | 4 | – | 0.08 |
 Subjective heat intolerance | 16 | 22 | 3 | 12 | 4 | – | 0.038 |
 Muscle symptoms at rest | 10 | 30 | 1 | 5 | 11 | – | 0.74 |
 Muscle symptoms during exercise | 9 | 32 | – | 7 | 9 | – | 0.12 |
 CNS dysfunction | 6 | 34 | 1 | 5 | 11 | – | 0.26 |
Sequelae after 12 months (n) (n = 43) | 12 | 19 | – | 9 | 3 | – | 0.045 |
 Subjective heat intolerance | 10 | 21 | – | 9 | 3 | – | 0.017 |
 Muscle symptoms at rest | 7 | 23 | 1 | 4 | 8 | – | 0.70 |
 Muscle symptoms during exercise | 5 | 25 | 1 | 6 | 6 | – | 0.049 |
 CNS dysfunction | 3 | 28 | – | 2 | 10 | – | 0.60 |
Questionnaire scores | Â | Â | Â | Â | Â | Â | Â |
 CIS |  |  |  |  |  |  |  |
  Fatigue | 19 (8–56) | 29 (8–56) |  | ||||
  Concentration | 12 (5–33) | 16 (5–33) |  | ||||
  Motivation | 8 (4–25) | 10 (4–23) |  | ||||
  Activity | 4 (2–15) | 6 (2–14) |  | ||||
  Total score | 47 (20–124) | 68 (20–127) |  | ||||
   > 76 (n (%)) | 13 | 5 | 1.00 | ||||
 HADS |  |  |  | ||||
  Anxiety | 3 (0–12) | 6 (0–16) |  | ||||
   > 8 (n (%)) | 4 | 4 | 0.21 | ||||
   > 11 (n (%)) | 1 | 1 | 0.50 | ||||
  Depression | 1 (0–12) | 2 (0–16) |  | ||||
   > 8 (n (%)) | 5 | 2 | 1.00 | ||||
   > 11 (n (%)) | 2 | 1 | 1.00 | ||||
 SF-36* |  |  |  | ||||
  MCS | 46.1 ± 11.2 | 49.1 ± 9.7 | 0.26 | ||||
  PCS | 51.3 ± 9.3 | 54.3 ± 8.0 | 0.23 |