Leg Pain/New Boots

if your boots are 5 years old they are most likely packed out..... the liners firmed up and is most likely too big for you know.  What your experiencing is shin bang.  It happens to alot of people when your boots don't fit properly or you ski form isn't good.  Your boots most likely are just old and don't fit snug on your calfs.  Idk how you ski but sometimes casing or riding back seat also hurts your shins.  Yes park specific boots are usually work better but you DO NOT need freestyle boots to not have shin bang.  In fact alot of kids think they need rampages or spks and end up with shin bang.  With the exception of salomon most pros ride race boots anyways.  If i were you i would go to an experienced boot fitter.  There's a good chance they'll be able to evaluate whats up.  They maybe able to put shims in and adjust the liner.  But odds are your boots are just packed...... Even if you are looking for new boots i'd still see a boot fitter or check the sticky up top.

Backseat landings contribute to this disease

For any athlete lower leg strength is often overlooked because the muscles just above your ankle are fairly small - nothing like a hamstring or quad that you associate with taking the brunt of the landing. But the muscles that wrap around your lower leg are vital for small movements (such as correcting balance) and especially if you are in packed out boots they are having to work overtime, causing that shin splint feeling as the bone actually becomes irritated where the tendons connect to it. First of all, go get the boots checked out by a legit bootfitter. But second, try doing some exercises for the lower leg to solidify those muscles. Lying on your back, or sitting on the floor, extend your legs out in front of you and try pointing your toes as hard as you can and holding it for a ten count, then dorsiflex them (bring them back up towards you) as hard as you can for 10. Repeat this at least 10 times, then do the same thing flexing the feet inwards towards each other and then to the outside. You can also just do things while sitting around, such as the classic spelling the alphabet with your foot, or if you have one, standing on a balance plate or something with one leg. I've always had shin splints and knee troubles and this is the one thing that has really helped me out in the long term.

Im having similar problems but with 1 year old boots.