The purpose of this project is to identify the effects of a severe burn injuries in humans on core temperature responses during work:rest cycles while in a heated environment.

Non-burned control participants and participants who experienced serious burns covering ≥20% of their body surface area will be investigated. Participants will undergo up to three work:rest cycles in the heat (via our environmental chamber) set to no higher than 40 °C. The work:rest cycle will comprise of 30 min of exercise that is followed by up to 20 min of rest, while staying in the heated conditions. Three consecutive work:rest cycles will be performed as illustrated in the protocol document. During one visit, this protocol will be performed in a low humidity state. During the other visit (randomized and crossover), this protocol will be performed in a high humidity state.

Inclusion Criteria for Non-burned Individuals:

• Participants must be free of any significant underlying medical problems based upon a detailed medical history and physical exam, and normal resting electrocardiogram. Participants must be between the ages of 18 and 65.

Exclusion Criteria for Non-burned Individuals:

• Known heart disease; other chronic medical conditions requiring regular medical therapy including cancer, diabetes, neurological diseases, and uncontrolled hypertension, lung disease, etc.; as well as serious abnormalities detected on routine screening. Current smokers, as well as individuals who regularly smoked within the past 3 years will be excluded. Participants may also be excluded if body mass index is ≥ 31 kg/m2 will likewise be excluded. Participants must not have had a serious burn injury requiring more than 1 night stay in the hospital.

Inclusion Criteria for Individuals with up to 40% of their body surface area burned (moderate burn group):

- Participants must be free of any significant underlying medical problems based upon a detailed medical history and physical exam, and normal resting electrocardiogram. Participants who have sustained a burn injury must have a burn covering 20-40% of their body surface area and 50% of those burns must be full-thickness burns requiring skin grafts. Participants must be between the ages of 18 and 65.

Exclusion Criteria for Individuals with up to 40% of their body surface area burned (moderate burn group):

- Known heart disease; other chronic medical conditions requiring regular medical therapy including cancer, diabetes, neurological diseases, and uncontrolled hypertension, lung disease, etc.; as well as serious abnormalities detected on routine screening. Current smokers, as well as individuals who regularly smoked within the past 3 years will be excluded. Participants may also be excluded if body mass index is ≥ 31 kg/m2 will likewise be excluded.

Inclusion Criteria for Individuals with greater than 40% of their body surface area burned (large burn group):

- Participants must be free of any significant underlying medical problems based upon a detailed medical history and physical exam, and normal resting electrocardiogram. Participants who have sustained a burn injury must have a burn covering more than 40% of their body surface area and 50% of those burns must be full-thickness burns requiring skin grafts. Participants must be between the ages of 18 and 65.

Exclusion Criteria for Individuals with greater than 40% of their body surface area burned (large burn group):

- Known heart disease; other chronic medical conditions requiring regular medical therapy including cancer, diabetes, neurological diseases, and uncontrolled hypertension, lung disease, etc.; as well as serious abnormalities detected on routine screening. Current smokers, as well as individuals who regularly smoked within the past 3 years will be excluded. Participants may also be excluded if body mass index is ≥ 31 kg/m2 will likewise be excluded.

1. Non-burn control.
2. Individuals 20 - 40% of their body surface area burned.
3. Individuals with greater than 40% of their body surface area burned.