As people discovered Thursday, one must thoroughly warm-up for a sprint like seven minutes of burpees. An inadequate warm-up and cool-down will leave you with Fran Lung. A warm-up like 15 minutes of jogging and five minutes of sprinting, and then five minutes of DU practice afterwards might avoid this cough, which feels a bit like exercise-induced asthma.
Dr. Dave from CrossFit Confluence says:
Since people often ask about “Fran Lung” here’s the basic
explanation. It’s a form of flash pulmonary edema where your body is
essentially drowning itself. Primarily due to ... the short time in which [the intense work is] done, your body
consumes a large amount of oxygen and generates a lot of lactic acid
quickly. These both create a massive drive to breathe to blow off the
acid (as carbon dioxide) and breathe in O2. Your diaphragm and chest wall muscles are
able to generate a huge amount of force when breathing in. This creates
a large negative pressure gradient in your lungs that actually sucks
fluid out of the capillaries within your lungs and into the airspaces
themselves. Although the amount of fluid is relatively small, it’s
enough to slightly impair your ability to exchange O2 and CO2 and make
you feel like you’re drowning (burning, coughing, air hunger). It
generally takes at least 20-30 minutes for your body to reabsorb enough
fluid back into your lung capillaries to get rid of most of the
symptoms, but it can take 12-24 hours to reabsorb all the fluid which is
why it takes so long to feel right again.
Also a discussion here. And a journal article about SIPE from swimming here, which the Special Ops guys say feels a lot like Fran Lung.