Weekly distance tells you how much you ran, not how demanding the week was. Fifty kilometres dominated by easy running is a different training stimulus from 50 kilometres containing intervals, sustained hard work and a faster long run. Intensity, terrain, conditions and physiological response change the cost of the same distance.
Two runners can both log 50 kilometres and finish the week with very different levels of training stress.
The mileage matches. The work does not. That is why distance is useful for describing training volume, but incomplete as a description of training demand.
But imagine two runners who both complete 50 kilometres.
The first runs most of those kilometres comfortably, with one moderate session and an easy long run. The second completes intervals, a sustained harder session and a long run containing faster work.
Their watches both say 50 kilometres, but their training weeks were not the same.
Distance tells you how much you ran, not how demanding it was
Fifty kilometres tells you how much you ran. It does not tell you how hard those kilometres were.
That is why training load needs to consider both volume and intensity. Fifty mostly easy kilometres place a different demand on you than 50 kilometres containing intervals, faster sustained running and a hard long run.
Research in more than 150,000 marathon performances illustrates the point. Faster runners generally ran more, but much of that extra distance was completed at lower intensity. So, it was not simply a case of doing more kilometres. How those kilometres were divided between easier and harder running mattered too.
That does not mean there is one perfect intensity mix for every runner. It simply means that 50 kilometres is not always the same 50 kilometres.
Pace needs context too
Pace seems to give us the missing information. If you know how far you ran and how fast, surely you know how demanding the run was?
Not always.
Ten kilometres at 5:30/km on a cool, flat morning may feel very different from the same pace on hills or in difficult conditions. Even without knowing what caused the difference, your heart-rate response can show that the physiological demand was not the same.
This is relevant because pacing is not as straightforward for runners as it can look on a training plan. In SmartRunning’s survey of 688 runners, 47% reported pacing as a challenge. We will return to that finding in the later article about what runners told us about their training.
SmartRunning currently uses running information including distance, duration and heart rate, together with training progress, rather than treating mileage as the whole story.
The runner should not have to turn all of that into another collection of graphs. The point of analyzing more information is to understand more accurately what the training has been asking of you.
Why this matters for what comes next
Weekly mileage remains useful. A 70-kilometre week clearly contains more running than a 40-kilometre week. But when the numbers are closer, or the mix of easier and harder running changes, distance alone can hide quite a lot.
This is where SmartRunning does the interpretation for you. It uses the training data available to it to understand not only how much you ran, but how demanding that training was in the context of what you have been doing recently.
You do not need to calculate your own training load or decide what all those numbers mean for next week. What matters is that the next step is based on a better understanding of the training you have been handling.
The same principle matters when training progresses: increases should be judged in context rather than by a single number.
Let SmartRunning interpret distance, intensity and recent training together instead of relying on mileage alone.