Young athletes should get a right to finish their military service when they are over 35. Doing 2 year military service while being 19-30 is a career suicide.
30+ men won't help the military much, it'll probably be too expensive to train one than the useable years you get from him in reserves (and 30+ men are more prone to getting injured and will probably have issues with taking orders from younger men). I think the Estonian system is decent, a mandatory 9 months or 11, depending on what your job is going to be, but for professional athletes, they just need to complete the basic training of 3 months and during that time they'll be able to train decently.
There was a football match between Estonia and England where one of our LB-s was actually serving at the military at the same time. Kid had to rush back after the game because he wasn't given a leave for longer than 22.00