She stood by the side of the track after the last 400 metres effort, and she looked really fed up.

“What’s wrong, Lisa? That was a good session.”

“Yeah, I guess,” she said. “I think I’m improving. I know I ought to be improving. But how do I know if I really am?”

It’s a very good question. Every ambitious runner naturally would like some indication that all the hard work is paying off, but you don’t want to be running time trials every day, or all-out races every week.

Now, we all know that there are apps that can bombard us with all the data that we need. Or do they? Or do we?

How many times have you felt aggrieved that, when you’ve pushed really hard, your phone labels your run “unproductive” or merely “maintaining”?

Let’s get real – not virtual.

The simplest “real” way to find out if you’ve progressed is to run a favourite route as fast as you can, and see if you achieve your best ever time.

That, of course, is hard. And how do you know if it was just because you tried that bit harder this time? It might just be that you’ve improved your willpower, rather than your fitness.

But, hang on, that is also something to be valued: runners need to develop their mental strength just as surely as they need to condition their muscles.

But it would be nice to have something rather more objective.

So…. why not run your favourite route at the same speed as before, but see if your heart rate keeps lower? That is a great indication of increased fitness. As is the time it takes you to recover.

How long does it take your heart rate to come down to 80, say (about the normal resting rate in an untrained person)? How much more quickly does that happen than before?

Or let’s take a typical interval session, like the one that Lisa was doing.

Let’s say you run a session of 6 times 400 metres with a 200-metre walk in between. And let’s say you can average 1:45 for those six efforts.

How many ways can you change that session to make it harder?

By my reckoning, there are at least four major variables.

You can run more efforts – so 8 or 10, instead of 6. You can run them faster: try and average 1:40, then 1:35, and so on. You can take less rest: jog the 200 recovery, or even cut it to 100 metres.

And of course, you can run longer efforts: if you can run 600 metres at the same speed as you did for the 400s – keeping all of the other variables the same – then that is definitive progress.

But be careful here, because it is very difficult to go from 400s to 600s whilst keeping the same recovery, and I would argue that, since you had a recovery jog of half the distance for the 400s, you should also have that for the 600s.

So, the “equivalent” session to 6 times 400 with a 200 jog, is 6 times 600 with a 300 jog. The progression resides in the fact that you are maintaining the same speed for 50% longer.

An average of 1 minute 45 seconds for 400 becomes 2:37.5 for 600.

There’s no getting away from the truth in those numbers. But there are also more subjective measures that I put great store by.

If you run a certain distance in a certain time, or complete a particular interval (effort) session, AND YOU FEEL BETTER THAN YOU EVER HAVE BEFORE doing it, then you have made progress.

If you finish a punishing hill session, say, and you still feel fresh, then that is improvement.

If you find that, for the first time, you can sprint at the end of a particular distance run, or maintain your speed to the top of that long hill, then your speed – and strength – are heading in the right direction.

(Remember: the ability to sprint at the end of a run or a race, is not just down to your speed. You also have to possess the stamina and speed-endurance to be able to preserve that bit of speed through the preceding miles.)

Runners use key sessions to test themselves before big races. They normally only do this when they are pretty sure that they are fitter than ever, in order to be certain of receiving that vital confidence boost.

But the sessions have to be relevant to the target race.

Brendan Foster won the 1974 European 5,000 metres by injecting a 59-second lap with 5 to go.

His crucial session in preparing for this – and proving he could pull it off, that it was worth attempting – was a series of very fast 200 metre efforts, with only 30 seconds between. Completing these sessions taught him that he could indeed kick in the middle of a race and not get into debilitating oxygen debt.

Wanting to maximise the value of that session, Foster would often cut the recovery between the last couple of reps down to little more than 20 seconds!

Mara Yamauchi, the third fastest British female marathon runner of all time, undertook a session that emphasised the sustained speed that that event demands. At altitude in Arizona, she completed a session of 3x5km on the track with a one-lap jog recovery. She achieved times of 17:18, 17:23 and 17:28.

Before a major ultradistance race, I used a sequence of three sessions, a few days apart, to test myself.

The first was a 35-mile trail run: here, it was more important for me to finish it feeling relatively fresh, than to run my fastest ever time.

The second was a hilly 10-miler, where I did try to set a new personal best. And the third was a track session, a continuous series of 400s, 600s and 800s, with little recovery.

Completing that little lot in better shape than ever before gave me the confidence to attack the upcoming ultradistance race.

And Lisa? Well, we looked back at her training diaries and identified several key marks from six months before. Over the next few weeks, she undertook four trials to test her raw speed, her short-distance speed-endurance, her longer-interval tolerance, and finally her stamina. Two of these were all-out efforts; and the other two were judged on heartrate.

In all four dimensions, she was streets ahead of where she had been half a year before.

She begged to repeat the tests every three months; I said do them annually; and we compromised on every six months!!

I hope that you too are able to track – and savour – progress in some shape or form along your running journey.