Does exercise cause asthma?

Area of Science:

• Military Medicine
• Occupational Health
• Respiratory Medicine

Background:

• The Israel Defence Forces investigated the link between physical activity and asthma.
• A need existed to understand asthma prevalence in different military roles.

Purpose of the Study:

• To ascertain if soldiers in combat units (CU) exhibit greater susceptibility to exercise-induced asthma (EIA) than those in other military assignments.
• To compare EIA incidence across combat, maintenance, and clerical units.

Main Methods:

• A 30-month follow-up study involving military recruits with initially normal pulmonary function.
• Participants were assigned to combat units (CU), maintenance units (MU), or clerical tasks (CT).
• Exclusion of individuals with active asthma at induction through early testing.

Main Results:

• Out of 799 recruits, 125 developed asthma; 21% in CU, 15% in MU, and 5% in CT.
• Combat unit soldiers showed a 3.7 times higher relative risk of developing asthma compared to clerical staff.
• Exercise-induced asthma was the sole manifestation in 32% of CU soldiers, versus 13% in MU and 11% in CT.

Conclusions:

• Elevated EIA risk in combat units suggests service conditions may trigger or reveal mild, previously undetected asthma.
• Factors inherent to combat service may predispose soldiers to developing EIA.
• Further investigation into environmental and physical stressors in combat units is warranted.