Jo Pavey
Tempo Run
Beginners -
Tempo running is one of the most important training components. It's essentially a fast run but not flat out. The objective is to improve the fastest pace you can sustain throughout a run. I'll explain what tempos are and why we do them.
When you run fast you produce lactate and if this builds up exponentially you will start to feel a burn and have to slow down. However, as I'll explain later, lactate is not actually a bad thing,* the main culprit is actually hydrogen ions. It's these ions that make your muscles more acidic, which then interferes with the muscles nerve endings and causes the problems you experience including jelly legs at the end of a race!
Just prior to the paces at which lactate levels rise exponentially there are a series of paces that you can sustain. Lactate levels are elevated above resting levels but remain steady at these slower paces but then start to rise when you go faster. It's commonly referred to as your lactate threshold when the lactate shifts from resting levels to elevated but stable levels and lactate turn point when the lactate shifts to elevated but unstable levels. Think of a gradual curve on a graph indicating rises in lactate, the x axis is your speed and the y axis you lactate levels & heart rate levels. You can refer to points on the plotted curve of rising lactate as inflection points and it's this series of points that we look at from the lab testing and not one sudden threshold point. We place tempo pace between two of these inflection points, so it's a pace range and not an exact single pace.
So why do we want to know all this?
When you run, even at slow paces, you are continually producing and clearing lactate but when you exceed a certain pace the rate you produce lactic acid exceeds the rate that you can clear it. This is based on the availability of oxygen. As you run faster you need more oxygen and if your oxygen uptake falls behind the demand then you will enter a state where lactate increases and eventually it does so exponentially. We observe this happening in the lab and can produce a graph with the inflection points shown. So were are trying to find out when your oxygen demand isn't being met by the amount of oxygen being delivered.
However, if you run fairly fast and very close to the lactate turn point you can still deliver enough oxygen and therefore run at a max pace you can sustain constantly throughout the run. This is what we aim to achieve in some of our faster threshold or tempo runs. We're simply trying to keep our pace at a point where we can still meet the oxygen demands. you can also use slower tempos for longer durations runs.
I prefer to use the term tempo run as opposed to threshold run due to the misconception about it being a single point of going from aerobic to anaerobic.
During some of our faster tempos we’re running at the quickest pace where we still meet our oxygen demands and if we do this repeatedly over a lengthy period of time we will gradually adapt so that the pace at the lactate turn point improves - we can therefore sustain a faster race pace!**
How do we determine tempo pace?
In brief, we use a physiological test to ascertain the heart rates when the lactate inflection points occur. As I now know what's going on at a given heart rate I can then run my tempos using a heart rate monitor to control effort.
I must admit that I have not had a test like this since 2011 as I thought I would be retiring! I now simply rely on how I feel and I have found that with experience I am able to run at roughly the desired pace. For me it's slightly quicker than the pace I can sustain for a half marathon. This pace is however variable and can even vary slightly day to day! However we also use slower tempos closer to the lactate threshold rather than the lactate turn point - these are mostly for longer tempos and progression runs.
A good way to run a tempo without expensive physiological testing is to run fast but with a sensation that you feel you could go just a little quicker. So not all out! You keep a gear or two in reserve.
You can use a gps watch to help monitor your pace. A good way of doing this is to base the high tempo or faster tempo pace on the pace you could sustain for about an hour in a race. So which of your personal bests is close to an hour? For some it could be their 10k pace, for others it might be 10 miles and for a world class male it might be their half marathon. My high tempo is somewhere between my 10 mile and half marathon pb.
However, it's not this simple as I use more than one tempo pace. I'll run a 20 minute tempo at closer to 9 miles /15km pace and a 30 minute tempo at closer to half marathon pace.
Scientists will refer to vOBLA which is the velocity at onset of blood lacate accumulation and this roughly corresponds to the pace that you can sustain for an hour. Scientists also refer to VAT which is is the velocity at anaerobic threshold. However it might be the case that your marathon pace or VM / MP is better for you. So this would be a slower tempo.
Intermediate and advanced runners -
For those of you who already understand tempo runs then the following explains my approach a little more.
There are many ways to approach tempo running. There isn't really one specific tempo pace and there are also numerous durations you can use for a tempo run. For me it's the duration which determines which pace or heart rates I will use. Longer tempos are slightly slower than shorter ones.
I will sometimes break my tempo run up. For instance, two times ten minutes. I also use tempos mixed with interval sessions and also tempos within a longer run.
My interval sessions are very varied but here is an example: 5x1000m (5k pace) (2 minutes recovery), (4 minutes rest), 20 minutes at tempo pace, (4 minutes rest), 6x400m (3k pace) (35 seconds recovery). With this type of interval sandwiched tempo I am actually running a slower tempo pace so as to not increase lactate levels but I'm doing this whilst I'm actually clearing lactate / shuttling lactate - that accumulated during the 1000m reps. My coach used to use a hand held lactate monitor and we find that lactate levels actually continue to rise in the minutes after the last rep prior to the tempo. Lactate tolerance is something you will encounter and improve during interval sessions and this tempo allows for an element of lactate clearance whilst still running at a reasonable pace rather than during rest. Lactate clearance mostly occurs during prolonged rest or when you dramatically slow down.
My long run is normally not at a slow easy pace. They vary between about 90 minutes and 2 1/2 hours in duration. My runs are varied and can be multi paced, such as 30 minutes steady, 30 minutes tempo, 30 minutes steady. Here I am including my tempo within a longer run. You can see this as killing two birds with one stone but it also means you don't start your tempo totally fresh. This is important as it enables you to more closely mimic the later stages of races (although you might not be exactly at race pace). So for instance, if you ran an hour steady and then increased your pace over the next hour you are able to run in a state closer to the physiological state you might be in during a marathon. It's not precise but it's closer than running from fresh.
Sometimes I will also run a progressive, progression or accumulation run where each 15 to 20 minute segment is slightly quicker than the last, until I'm at high tempo pace. This means I'm again running a tempo when already tired. You can also run tempos when glycogen levels are partially depleted.
I also tackle my tempos fresh, especially during the summer track season. My coach uses these different approaches for various reasons and during the year as I progress from winer to summer the emphasis shifts.
Tempo running is one of my favourite sessions. I love zipping along a country lane or good quality trail. When I was younger we weren't set tempo runs, back then I used to just go flat out. I still occasionally do this, almost like a race simulation. I also use time trials in this way. It's sometimes nice to just let rip and find your flow. However, with a tempo you feel nippy but you are slightly holding back. If you don't use a heart rate monitor you can just run quick but not totally flat out. Nowadays I run as many of my tempos without a heart rate monitor as with one as I have found with experience you get to know the pace and how it should feel.
My coach describes tempo running via the mitochondria. Our easy running predominantly uses fatty acids and beta oxidation but when you go faster you exceed the capacity of the mitochondria to do this. That's because it's a slow process than can only meet the demands of slower running. As you quicken your pace you eventually shift to using pyruvate and lactate as your dominant fuel source and your mitochondria are able to do this until the oxygen required is insufficient to meet the demands of this process. At this point you then exceed the capacity of the mitochondria to use pyruvate and lactate and you switch to glycolysis as the dominant system. Glycolysis takes place outside the mitochondria. Tempo running falls between the capacity to use fatty acids being exceeded (LT) and the eventual switch to glycolysis when you exceed the capacity of the mitochondria to use pyruvate and lactate (LTP).