I've been sailing hard these last couple of days and i've been having my front foot keep coming out of the straps due to lack of pressure in it. I have to curl my toes up and wedge my foot in there to keep it from slipping out and this is causing fatigue and cramping in my lower legs and feet. I'd normally have to curl my toes up to keep it in the strap but i can also push down a little bit as well and its not as bad.
Is this normal and how can I fix it?
Hi, you can first try lowering your boom a little, in most cases it'll work.
If not, adjusting the mast plate position.
I sometimes have this issue sailing upwind on the slalom boards. All I do is slightly twist my foot sideways to jamb it in the footstrap tighter. 
I struggle with this often on my boards. I am not sure if I have an usual ratio of arm length to leg length or something. I find as a result I tend to run my boom lower and mast base further forward than most (5mm can make all the difference to me). As a result of that I tend to run my harness lines a little shorter than average also. Certainly lowering boom and/or moving mast base will help. I also move my front straps to the most rearward position and that helps. I find that if I chase the recommended settings (boom height, base position, harness line length) that most people like to use for tuning gear fast, I really struggle to get comfortable and go slower as a result, so I just set it up so I feel comfortable and enjoy my sailing more and go quick enough for me.
