In reply to XXXX:
hi, its a long time since I did any running, and I am rusty with all the training terms, but will try and give you a bit of advice.
Looking at a training, i don't think speed is holding you back, more a lack of speed endurance.
The sessions you do, could be improved by building them up to 30mins worth of effort, say 5 x 1 mile with getting down to a 1 minute recovery, i would also aim to build up to doing two of this type of sessions a week, or 1 plus say a park run or other race at weekend initially. Then you could manage two tempo sessions plus a race or park run a week.
eventually you could look at replacing one of the tempo session with more anaerobic type training totalling 15 mins effort, say 4 to 5 x 1km, or 400 and 800 reps which total about 15min or 5km, you can also have longer recover between reps. but jogging as recovering is a good idea, and easy to judge distances if doing this on a track. i think the recommendation is to look at doing this sort of training 8 weeks prior to a specific race your aiming to do well in.
with regards to the sprint training, i would just try and incorporate some easy short sprint, towards you the end of your normal training runs, but nothing which is going to leave you out of breath, again is lack of speed endurance not speed which will prevent you from breaking 40 mins 10km.
hopefully someone will come on and give you better advice, about exact reps and recovery times etc.