How Fast Should You Run During Training?

Fitness is a function of training volume and intensity.  A challenge that most of us face is in determining the appropriate level of intensity. For cycling, it is based on your functional power threshold (FTP), which is calculated using a 2 x 20 minute test. I was never certain how to do it for running until I was introduced to Jack Daniels VDOT running formula. This is an excellent tool for any runner, as it uses recent performance to estimate optimal training paces.

Before I go into the theory, let me give an example using the VDOT calculator found here. You enter a recent race time (in the example below 19:13 for 5 km) and from this the VDOT is calculated. The calculator also gives you estimated times for different races at this VDOT.

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While that is of academic value–there is absolutely no way that I am a 3:04 marathoner and my best 10km time is +1:30 over their estimate. You never train at the equivalent race paces given above, or you can but you will soon injure yourself.  What is important is the other information: your training paces.

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There are other calculators available which also give you your interval pace such as this one here. I like to check a couple of them since the numbers are slightly different. On the basis of these calculators I have the following training paces:

  • Easy/Long Runs: 8:16 min/mile
  • Marathon: 7:02 min/mile
  • Threshold: 6:38 min/mile
  • Interval: 6:12 min/mile (But the maximum time should not be more than 5 minutes at this pace – hence it not being shown in the table above)

Now for the theory which is from Jack Daniels excellent book, loaned to me by my work colleague and running ‘advisor’ Jerry. A detailed explanation, including equations, on the web is here.

Running performance depends upon how much oxygen can be delivered to muscles while running, how well muscles process the delivered oxygen, and how easily the muscles can deal with the carbon dioxide and lactic acid produced ruing exercise. Fitness can be measured by the volume of oxygen you can consume while exercising at your maximum capacity. VO2 max is the maximum amount of oxygen in millilitres, one can use in one minute per kilogram of body weight.

For example, if two runners run a 6:00 mile, and one consumes 50 ml/kg/min of oxygen and the other 55 ml/km/min then the first runner is more economical–and could run a faster pace for the same rate of oxygen consumption.

In his research, Daniels developed a curve representing the relative intensity at which a runner can race for various durations.  Duration, not distance, is the key because the intensity at which any race can be run is a function of how much time it takes to complete the race. 

Basically, Daniels is starting with a known time and calculating the “effective VO2max” score–VDOT. The word “effective” just means that the score is VO2max multiplied by a mitigating factor that is determined by one’s running economy, running efficiency, biomechanics, and mental toughness.  So my recent 5 km time of 19:13 gives me a VDOT of 52.2 ml/kg/min.

Daniels suggests that having determined your VDOT and the training intensities, you stay at that intensity for at least three weeks, even if a race suggests you have moved to a higher VDOT value. During a period of prolonged training it is safe to increase the VDOT value by a single unit after four to six weeks.  However, realistically there will be a point where you have reached what is your maximum VDOT, which is why you should test it regularly.

Three years ago I endured a proper VO2max test through my coach Margie Shapiro. I say endured because it was very, very unpleasant. You get on this treadmill with a ventilator in your mouth connected to a hose. This records your oxygen use in L/min. You then start running and every 1 minute she increased the speed of the treadmill. It started off easy at 10 minute miles, but got harder as the speed increased. Then, with a wicked grin on her face (or at least that is how it seemed) she began to increase the grade. At 6 minute miles with an unknown grade I could not go any further and my legs turned to rubber. All this for the graph shown below …

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From this, my VO2max was calculated at 70.6 ml/kg/min.  At my lactate threshold my VO2 was 49.7 ml/kg/min.  From this test, the following heart rate  (HR) training zones were calculated:

  • Zone 1: 120- 126 (Active Recovery)
  • Zone  2: 127-138 (Aerobic Threshold)
  • Zone  3: 139-155 (Tempo Training)
  • Zone  4: 156-161 (Lactate Threshold)
  • Zone  5a: 162-166 (Super Threshold)
  • Zone  5b: 167-173 (Aerobic Capacity)
  • Zone  5c: 174 & Higher (Anaerobic Capacity)

When training at my VDOT values, I have found that my heart rates correspond very well to the zones above: for example the 6:38 threshold pace puts me into Zone 4/5a. So there is some consistency between the results from the two tests–and the VDOT test is a lot easier to do (and less expensive!).

Coupled with a good running training plan, the VDOT approach is very useful and better than focusing just on your heart rate. I would recommend to give it a try and you will hopefully see an improvement in your VDOT score and running performance as you follow the recommended training intensities.

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