The JCAB medical standards are quite high and, in some cases, a bit unusual.
For example, the JCAB has a maximum weight/height limit. Take your height in centimeters, subtract 100, then multiply by 9. That's your ideal weight in kilos. Multiply that by 1.3 and you get your JCAB weight limit. One kilo over that and you fail the medical, even if you've been flying for the Japanese for years.
If you're a serious marathon runner, you could fail the resting pulse test. Minimum is around 48.
And you must be able to stand on one foot with your eyes closed for 2 minutes (although this can be learned).