Which individuals are more susceptible to heat illnesses during exercise?

Overweight individuals with poor fitness levels are more susceptible to heat illnesses during exercise due to several physiological factors. When a person has excess body fat, it can act as an insulator, preventing efficient heat dissipation through sweating and other cooling mechanisms. Poor fitness levels also mean that the individual's cardiovascular system may not be as efficient in regulating body temperature during strenuous activities. This combination can lead to a greater risk of dehydration and overheating, making it critical for individuals in this category to monitor their exposure to heat when exercising.

Other groups, such as athletes with low muscle mass or those with a history of cold weather training, may have different adaptations or efficiencies in heat regulation that typically lessen their susceptibility to heat illnesses. Additionally, underweight athletes with high fitness levels generally have a better ability to manage body temperature due to their fitness, making them less prone to heat-related issues compared to overweight individuals with poor fitness.