Long Distance Running VS Sprints

Hey Guys


So as most of you know I have been doing 2x2.4km runs at Norwest for around 5 weeks and my time has dropped from 26minutes something to 19:58 (my best time).  


I need to be able to do the 2.4km in under 15 minutes in order to pass my fitness test next year which is why Rob has got me running now.  However there is also the possibility that I have to do the Beep Test instead of the 2.4km run, but I haven't been doing any sprints at all, just been concentrating on the longer distance (well 2.4km is a longer distance for me!!)  I plan on talking to Rob about this tomorrow or Friday, but do you guys think I should be including some sprints into my training for the beep test or would long distance running suffice?