I keep getting blisters after about 5 or 6 miles. I have bought decent trainers fitted for my feet at a running shop but the blisters are still in the same place.

If you feel your running shoes aren’t the problem, the next culprit to look at would be the socks you are running in. A blister is the direct result of a combination between friction and an excessively moist foot environment. 

You should avoid running in regular cotton socks, as these have a tendency to absorb moisture. Instead, spend a bit extra on specialist running socks which are designed to wick moisture away from the foot. Good quality pairs will also be multi-layered, which will absorb some of the friction caused by running.

However, it may not be time to completely rule out your running shoes. Watching you run on a treadmill will allow experts to make an educated guess on the right running shoes for you, but this process can never be 100% accurate. Over the course of a longer run, your running gait will change slightly, but this might not be apparent on a short treadmill test.

Now that you’ve done some ‘real world’ testing of the shoes and found you’re consistently getting blisters, a good running store should have no problem with you going back in to pick a different pair. These experts should be able to analyse your blister placement to reassess their initial recommendation and provide a shoe that is more suitable to you.