trewq wrote:
At 19 years and 1 day you might be not eligible, but at 19 years and 364 days you might be - true geniuses at Armstronglivslevel at work.
I assume they have it in place so that championships and records have the same rule regarding age. The people who are eligible to participate in the U20 championships are the same people who are eligible to set a U20 record that year.
Having a year end date makes sense for championships because having any date (be it the end of the year or the date of the championships or another random date during the year) will cause it to be fair to some and unfair to others. You can't avoid it. And if determined based upon date of the championship race instead of year end, then the date of the championships would change who may or may not be eligible to participate. Better to just have a fixed date in time and be consistent.
Personally I don't think it is necessary to have the same rule for championships and records, but I am guessing that is why they have it.