A 1990 report from the Centers for Disease Control (CDC) noted that,

On September 19, 1988, 50 police trainees from local police departments began a 14-week ”mental stress” and physical training program at a state-sponsored academy in western Massachusetts. On the evening of September 21, the Massachusetts Department of Public Health was notified that five trainees had been hospitalized.

The first three days of the training program were physically strenuous and included push-ups, squat-thrusts, and running.