Tempo run - treadmill or trail?

I am training for a marathon. I usually do my tempo runs on a treamill as I find it easier to set an exact pace - usually the fast bit is just under my fastest half marathon pace.

Is this good enough - or should I ideally be doing these tempo runs outside? I usually run on a trail at lunchtimes during the week and it would be fairly hard to keep an even pace.

First off it's worth defining exactly what you mean by a tempo run.  If it's the classic lactate threshold run then you ought to be able to run a bit faster than your HM pace.  On the other hand, HM pace is a good level of intensity to train at for improving threshold, but you should be able to hold it for longer.

Having said that, I believe there are benefits to running it outdoors.  Running at the right effort level is more important than the actual pace, because it is this which dictates the energy systems being used and hence the correct fitness adaptations for the session.  So a session run on trails may vary in pace and be a few seconds per mile slower overall than the same session on a flat stretch of tarmac, but it will have the required traning effect.  It will also have the benefit of helping you to judge pace, because this element is no longer taken out of your hands.

If you can get the opportunity to do tempo sessions or race pace sessions on the same terrain as a race you're targetting this is ideal, but failing that anything outdoors will have benefits over and above what you can do on the treadmill IMO.

Well - I ended up doing a sort've tempo run today on a treadmill. Ran 10 minutes at 10kph, then 10 minutes from 13.5kph to 14.5 kph (increasing 0.1kph every minute) , then 10 minutes at 14.5kph, then 10 minutes from 14.5kph back to 13.5kph, then 5 minutes at 10kph.

Next week I'll probably do one outside. My only worry is injury really.

Could this be classed as a tempo run:

1. Warm up for one mile at about 8:10 min mile

2. Then 2 miles fast (I think it is anyway) between 7:50-8:00 min mile

3. 2 miles steady pace at about 8:15-8:25 min mile

 I have only started to try and fit tempo training in in the last 2 weeks and I find it hard to warm up slowly epecially when its a bit chilly outside!  I also find it hard to slow right back down after running at the fast pace, I am not sure if I should be running my fast pace at 7:30 and my slow pace at 8:30-9min miles?

I really only have time during my lunch break to fit tempo runs in and 5 miles is the most I have time for, anymore then that and I would be very late getting back to my desk!

Any advice much appreciated. - Runbug

That's a start. Different definitions for tempo runs, but I go by you shoudl run for between 20 and 40 minutes at a pace you could currently run for about an hour.

So - for me at moment I jog for about 10 minutes, then 20 to 30 minutes at a pace between HM and 10k pace, then jog for 5 minutes.

There's only 10sec/mile between your warm up pace and your Tempo pace?

I like 15West's session, but would increase the warm up to 2 miles.