What makes you a faster runner - pace or distance?

Before I show what actually happens if one trains in the lands where 'dragons may lie' (long distance slow running), I thought it might be a good idea to consider what we know or think we know about those lands. Common phrases suggest that running high mileage at slow pace is not a useful strategy for a performance runner - Running slowly makes for a slow runner - Junk miles - Quality not quantity - Race pace training - Tempo running is a key session - He's a plodder - No pain, no gain! However, we also know that elite runners engage in high mileage - or at least relatively high mileage - compared to most club runners. So, what does that training space look like when plotted on a graph?

In the figure below (just one - I am short of time this evening!) I have plotted three versions of training space (the 8 week average of training pace against daily distance run). All of the panels have the Tanda (2011) dataset plotted as filled circles together with a thick black line to the right of which there is no data - runners normally don't train with those types of averages. In panel A I have plotted shortened Tanda marathon prediction lines (i.e. without extrapolating the formula into areas where there is no data). This is a pure form of use of the Tanda prediction equation. We have no evidence that the formula correctly predicts data that extends beyond the dataset shown by the black circles. So, the space to the right of the thick black line is uncharted territory - and in keeping with tradition (we are in Cambridge!) we mark our map "Here be dragons". But, of course, most people believe that there is greener grass the other side of the line, just not quite green enough to be worth taking the time and effort to explore.

Figure 1. Training parameter space (8 week average pace versus distance) with three views of the unexplored area to the right of the thick black line. A, Tanda (2011) contour lines plotted approximately over the space for which data exists. Within this region the equation predicts marathon performance time reasonably accurately from average training data. B, The Tanda contour lines have been extrapolated beyond the dataset to longer distances in the general form that many people believe may represent the performance from training - running longer makes you faster, but not much faster. C, The Tanda (2011) equation extrapolated well beyond the original dataset - it is a mathematical prediction of a very different training load on marathon performance. The extrapolation contradicts notions of specificity and suggests that training load is a 'scalable' function.

In Panel B I have attempted to capture that in the form of modified Tanda contour lines. These coloured lines (in Panel B) are not a mathematical equation - although they could be - but represent the commonly held notion that running further does make you a faster runner, but not by much. So, the pink arrow in Panel B shows that a 3:00 marathon runner could train at 4:25 mins per km at about 11 km per day - or at 4:55 mins per km at 24 km per day. But, the extra mileage (twice as much) gets him/her no gain in performance just a potentially slower training pace. The obvious cost-benefit analysis - if one believes that the unexplored territory has performance benefits of that shape - is that adding on additional miles is of limited value: they are Junk miles. The underlying assumption is that pace is critical and that high mileage is just necessary for the fastest runners. However, the Tanda (2011) equation, when extrapolated into the dragon infested land suggests something rather different. In Panel C I have extended the Tanda prediction curves by simple extrapolation. The coloured lines suggest that a marathon runner of a given speed can train much slower if he/she runs further. Indeed, as the pink arrow indicates, a runner who covers a greater distance can afford to run slower and still show a performance improvement. Junk miles do still exist: if you run too slowly the all that happens is that you move along the same performance curve. I have calculated what pace would cause that to happen here.

The shape of these performance prediction lines suggest that the uncharted territory might actually be a rich source of potential improvement and personal bests - not dissimilar to Dick Whittington's streets paved with gold (helpfully protected by the 'Dragons'!).

But, to believe such an extrapolation one also needs to believe that the physiological systems which limit a marathon and are being trained are being done so by 'scalable' stresses rather than by highly specific types of training. The tempo run is no more important or effective than an easy longer run as far as producing marathon fitness - one just feels an awful lot harder than the other. This is somewhat heretical. Can it really be the case that a 5 km interval session produces no more benefit than a 20 km easy run? If so, it removes the focus from the leg muscles as the main system that is being trained since long slow running is a completely different stimulus to the muscles from fast running.

My feeling is that most people don't believe there are dragons to the right of the line - but, nor do they believe there is gold either - they see fatigue, injury, loss of form and speed: a pointless waste of time. Now, that is surely worth a test - time to train with the dragons!

Next: Junk miles