Jay - as far as the Japanese are concerned, PE10 is 130lb! They don't operate off the same scales we do.
Varivas GT in PE10 is 130lb and Varivas GT SMP in PE8 is 120lb.
Again, Luke's post sums it up. Young bloke like you will be able to manage more than 10kg easily.
It is a matter of technique. Do you currently use a gimbal? A good quality gimbal belt can really make a difference in that it provides a fulcrum point. Bend your knees and get one foot in front of the other. The best analogy I can give you is to think what you would be doing if you were in a tug of war. You bend you knees, you turn a little to ensure you are balanced and you brace yourself. You need to get into an atheletic stance.
Of course, there are angles that are bad for rods. At 45 degrees though, I think you would be shocked at how much load the rod can take. I tend to use the really heavy rods like 78UHL and EXH and I'm pretty brutal with them. I don't think a lot of people understand what so-called "high-sticking" is. if the fish is a long distance away, fishing with a high rod is a matter of sensibility sometimes as you want to keep it clear of structure. The rod will not break under such circumstances. I've had drags of 16-18kg as well as my palm on the spool as hard as I can hold it without any trouble whatsoever. I doubt many people can handle a drag setting high enough in such circumstances to break a heavy GT rod. On the other hand, if you have the fish next to the boat and you maintain that same angle, well, you'll be looking for a new rod soon. Most rod breakages happen next to the boat. GTs nearly always make that one last determined run next to the boat and this is when rods go. You have to be aware of and prepared for this. I tend to back the drag off a little once they are next to the boat and when the leader is grabbed, I like to open the bail arm.
Breakages on the strike generally result from the dreaded sideways strike. Generally, you will have a GT chase your popper from behind to eat it. In such circumstances, it is highly unlikely that a strike will break your line, even on 15kgs. On the other hand, a sideways strike where the fish comes from one side, hits the popper at speed and keeps going results in an enormous amount of immediate shock. If you have a long leader, that will absorb some of the shock but if the shock is excessive, something has to go and that will generally be your braid. I've seen quite a number of breakages on the strike but nearly all have been from sideway strikes.
I've seen breakages on settings as low as 10 -12kgs but you have to find the right balance in terms of your drag setting and it is always a compromise.
Thanks for the responses guys.
Brandon, I'm using a SP-78H, PE10 is at the upper limit of what it's rated to, can it handle 130lb line OK? So far we've only been starting off with about 10kg of drag, which for a novice like me is still a fair bit to hang onto (I decided to go a bit easier on the drag until I increased my confidence). I will consider going up to 15kg like you recommended but what sort of impact will it have on the rod, will it handle it OK? Do you ever have strike break off's with 15kg?