Add athlete birthdays (to their own calendar obviously) and or US holidays to the athlete's TP calendar.
Make this an option for the coach to enable/disable.
Birthdays and US Holiday notes on the calendar should be hidden by default if this feature is enabled by the coach.

Today, we already capture the discrete data (athlete birthday date), so we could post the information to the athlete's calendar.

WHY DO THIS?
Remembering your customers birthday is just good for business. Period. Forgetting this is well ... disheartening to the athlete. Ask me how I know.
awkward moment and fail on my part, big time!

US Holidays - having this helps remind the BUSY coach of upcoming holidays and helps with planning around fun holiday races and events.

The coach - This is for the busy coach who does not do this full time and wants to do a good job.

The athlete - For the athlete who depends on the coach to remember and plan accordingly!!