FAQ: Training paces

What determines how well I can run?

Your running ability is determined by a combination of factors:

Efficiency of lungs, heart and blood in delivering oxygen round the body x Efficiency of muscles translating oxygen and fuel into energy x Efficiency of body in translating movement into speed across the ground = Running performance
(VO2 max)   (Lactate threshold)   (Running economy)    

Your running performance depends on how well your body can perform each of these tasks. If you are a distance runner (eg marathons), you need to have not only efficiency but endurance in each of these dimensions.

How does my training programme improve my performance?

When you train, you put your body under stress. Afterward, when you resting, your body then adapts to that stress. It rebuilds muscle fibres, creates more of the different types of cell you need (eg red blood cells, mitochondria etc), increases the size of energy stores, and so on, all to make sure that it is better able to cope with the stress next time it occurs. The benefit of training comes from this process of physical adaptation. Note that the benefits occur after you train, not while you are actually exercising.

Why do I need different sorts of training in my programme?

The physical changes that will improve the efficiency of your oxygen system are different in important respects from the physical changes that will make your muscles work better. Different sorts of training will are most effective in causing these different physical adaptations. So a good training programme should include components to make the biggest improvement in each of the components in the relationship above.

You should think of your training programme in the same way as you think about a balanced diet. Carbohydrates are good for you, in the right amounts; but you will not be healthy if you only eat carbohydrates. You also need protein, fat, vitamins and minerals. A good training programme will have long and easy runs making up the bulk of your training mileage; but you need specific components to improve other aspects of your running as well, in smaller amounts. You can think of these like vitamins in your training programme: essential for overall health.

Note that it is not the case that running faster is "better for you" than running slower. That is like saying that protein is "better for you" than carbohydrate. Whatever Dr Atkins might have said, you need both, in the right proportions.

For example, there are some important physiological adaptations that are best encouraged by slower running, and you will miss out on these if you always run fast. The body's ability to metabolise fat is encouraged by running at relatively low effort levels (since the body switches to glycogen metabolism if it needs energy quickly) - you won't get this adaptation if all your training is fast.

What kinds of training do I need to include?

This table summarises the key workouts

  VO2 max workouts Lactate threshold workouts Running economy workouts

Interval training
(3k & 5km)

Threshold runs
Cruise intervals

Track speedwork
Endurance Long, slow distance runs Hill sessions
Leg strength exercises
Long, slow, distance runs
Marathon pace runs
Easy runs

Your training programme should combine these various workouts in the right proportion for your goals. Clearly, the balance will be different if you are targeting a 5km than if you are targeting a marathon, though broadly the same components will be in each programme).

How do I know how fast to do each workout?

The best way - pioneered by Jack Daniels - is to base your workouts on an estimate of your VO2 max. You can use the training paces tool on this website to help you to calculate the right pace for each workout. Alternatively, if you prefer to base your training on heart rates, you can use the heart rate training pace calculator tool.

As the table above shows, you should be aiming to do most of your running at a slow pace: only a small proportion of your mileage is run fast.

It is not efficient to train at paces that fall in between the paces shown. In other words, you would get much more of an improvement in relation to the time and energy invested if you target the particular workouts that will have most impact on your performance.

How are the VO2-based training paces calculated?

The calculations are based on your estimated VO2 max - that is, the maximum level of oxygen consumption that you can sustain. From your VO2 max, you can estimate the speed at which you could run at your maximum level of oxygen consumption. This is called your vVO2 max (velocity at VO2 max). This is not the same as your fastest possible speed, since you can run for short distances anaerobically - that is, without using oxygen. The estimate assumes that you have broadly the same running economy - that is, capacity to turn energy into speed - as the typical runner.

From your vVO2 max, it is possible to estimate the training paces for each type of workout:

  • easy pace = 75% of vVO2
  • threshold pace = 90% of vVO2
  • VO2 max pace = 100% of vVO2

A tool to calculate these paces is here.

Using your VO2 max, you can also estimate your race pace for each distance from 1 mile to the marathon. These paces can then be used in your training programme.

How accurate are the VO2 estimates?

These calculations are based on generalisations derived from data from a number of athletes, and they are subject to a wide margin of error.

Two athletes with the same VO2 max may perform (and so need to train) at quite different paces if they have very different running economy.

The calculations are quite sensitive to the initial estimate of VO2 max. It is well worth getting several different estimates of this (eg using race performances, bleep test, balke test, lab measurement etc) if you are going to base your training programme on it.

Serious athletes should certainly get their own measurements of their VO2 max in a lab, and calculate their own training paces directly.

How are the heart rate based training paces calculated?

The heart rate estimates are based on an estimate of the runner's maximum heart rate and resting heart rate. The gap between these is known as the heart rate reserve or the working heart rate.

Heart rate zones are based on broad percentages of the heart rate reserve. For example, the aerobic zone is said to be 70%-80% of the heart rate reserve. [More information on heart rate zones.]

But heart rate zones are too broad to be useful: training needs to be targed more precisely at the levels of effort that will obtain the maximum adaptation. Howeer, there is a reasonably close relationship between heart rate levels and VO2 max:

HR max (%) = 37 + 0.64 x percent of VO2 max

Zone Why you should do it Frequency Heart rate
% of reserve
Recovery runs Gives you time to recover from harder workouts. Use recovery runs the day after hard workouts. < 70%
Long, slow runs. Builds endurance, and develop the strength of your muscles, bones and joints. Helps develop the metabolic system to enable you to burn more fat. Burn more calories, and so reduce weight. At least one long, slow run a week. 80-90% of your training mileage should be at recovery run pace or long slow run pace. 67% - 77%
Lactate (or anaerobic)
threshold pace
Increases the ability of the running muscles to use available oxygen to convert carbohydrate and fat fuel into output. No more than once a week. No more than 10 to 15 percent of total training mileage. About 3-8 miles a week.

77% - 83%

82% - 88%

VO2 max pace Improves the body's ability to transport blood and oxygen. Improves running economy. No more than once a week. No more than 4 to 8 percent of total training mileage. 95% -98%

The heart rate training paces tool calculates the heart rate zones corresponding to these key training paces.

How accurate are the heart rate based estimates?

In my view, the VO2 max or pace-based estimates are more reliable than the heart rate based estimates, because your heart rate is affected from day to day by a broad range of factors (such as dehydration, temperature, health etc). But some coaches argue that this is the merit of heart rate based training: it automatically adjusts for factors that should lead you to speed up or slow down your effort levels.

Provided you have an accurate estimate of your maximum heart rate and resting heart rate, using heart rate based training should give you good results. But it would not be sensible to base a training programme on your predicted maximum heart rate, as this can be wrong by 15-20 bpm.

What is the link between % heart rate max and % VO2 max?

According to Swain et al,

HR max (%) = 37 + 0.64 x percent of VO2 max

See also