Table 1

Risk factors for heat illness during military activities8 10

Intrinsic risk factorsExtrinsic risk factors
Low level of physical fitnessSleep deprivation
Obesity/excess body fat/high BMI*Dehydration (insufficient water intake or excessive loss)
Medications (eg, antihistamines, β-blockers)Nutritional deficit
Intercurrent illness (eg, gastroenteritis, cellulitis)Inadequate heat acclimatisation
Chronic disease states (eg, cardiovascular disease, sickle cell trait)Type of activity (eg, running or loaded route march)
Older age (>40 years old)Type of clothing
eg, body armour, impermeable and/or encapsulating uniform
  • *Categorised by body composition measurement (BCM) in UK military personnel, according to associated general health risk.

  • BMI, body mass index.