Telogen effluvium refers to a
rapidRapid shallow breathing shedding of resting (telogen) hairs. Instead of 10% of the hairs being in the resting state, certain stressful events can increase the percentage to 30-40%, resulting in lots of hair coming out for a while. This can thin the hair but not cause baldness. More important, it is reversible, as the body's rhythm reasserts itself. I assume that's what happened the other times.
It's possible that the rigors of training can increase the rate of fall for a while. There's not much to do except wait for regrowth. If you have any doubts that regrowth is occurring in 3-5 months, you should see a dermatologist. Keep in mind that we all thin as we age, even if we aren't "going bald," so you may not be as thick as you were at 20.
Regular shampooing, conditioning, and coloring are all OK.
Take care.
Dr. Rockoff