Interval training on track:
Stretch
Jog for 2 rounds to warm up
'Sprint' 2 rounds at mile pace (or basically the speed you would
chiong your 1.6km at)
Jog 2 rounds to recover. May I emphasise, recover, but don't
stop. This counts as one interval.
Repeat the 'sprint' intervals for another 2 times, total 3
'sprints'.
Finally, jog to cool down.
Intervals on treadmill are the same distance-wise. I trust you
know how to do la. Easier to do on treadmill though, IMO.
Controlling the speed mechanically actually forces you to run.
:D
Do on alternate days, preferably 3 times a week. It is
important to rest.
Every week, add one more interval to the training session. 3
weeks and your fitness would have improved dramatically as long as
your diet isn't extreme.
On alternate days, you can do light jogging just to maintain
fitness.