Running Shoes

Hey, 

Ive had some running shoes for a while. However, I have noticed that I am easily able to fit my fingers inbetween my heel and the end of the shoe. 

Does this mean the shoes I have are too big? also, if they are, does it have much of an impact?

If you recommend buying new shoes, what shoes would you recommend? Because im a student id ideally like cheap ones. However, is it worth paying that little bit more? 

Thanks for your help!! 

do they rub you?

a bit, but thats because when i tie them tighter I tend to get pins and needles after a longer run

Damien this is not uncommon, and it could mean two things, 1) Your shoes or worn or 2) Your feet are too small, there is a third possibility but it is quite remote, 3) Your feet might be shrinking.

To eliminate the thrid drastic possibility - I would suggest you measure your feet before and after any runs that you do, this way you could monitor their progress over maybe a 6 month period. This would enable you to make the decision as to whether or not you need new shoes or indeed new feet. My guess is (and I speak purely as a layman) it is probably related to the shoes.