Heat acclimation in cystic fibrosis

Area of Science:

• Exercise Physiology
• Environmental Medicine
• Clinical Research

Background:

• Cystic fibrosis (CF) patients exhibit elevated sweat electrolyte concentrations, raising concerns about heat illness risk.
• The capacity of CF patients to undergo heat acclimation remains largely uninvestigated.

Purpose of the Study:

• To determine if cystic fibrosis patients can achieve heat acclimation.
• To compare physiological responses to heat exposure and exercise between CF patients and healthy controls.

Main Methods:

• Ten CF patients and ten healthy controls underwent 8 days of cycle exercise in a hot environment (37°C dry bulb, 24-29°C wet bulb).
• Measurements included rectal temperature, heart rate, sweat electrolyte concentrations (chloride and sodium), and serum chloride levels.

Main Results:

• Both CF patients and controls demonstrated heat acclimation, evidenced by decreased peak rectal temperature and heart rate with acclimatization.
• CF patients maintained significantly higher sweat chloride concentrations throughout the study and showed no reduction with acclimation.
• CF patients experienced significant decreases in serum chloride levels post-exercise, unlike controls, and had lower baseline serum chloride.

Conclusions:

• Cystic fibrosis patients are capable of heat acclimation, similar to healthy individuals.
• Despite acclimation, CF patients retain higher sweat chloride concentrations and exhibit greater serum chloride reductions during heat exposure, indicating ongoing electrolyte imbalances.