Coach 2's


March 2002

A Cautionary Tale (from George Black)

(sent before Christmas - so cut out and keep for next Christmas - ed)

For those who took part in the Abbey Dash or other 10k and are thinking of over-indulging over the festive season, you may find the undernoted disconcerting,

Dr David Costill, Exercise Physiologist, in his book "A Scientific Approach to Distance Running" uses the following formula to calculate an estimate of an athlete's VO2max which is widely accepted as being the best method of predicting a distance runner's performance potential.

VO2max, the maximum amount of oxygen our hearts can pump, measured in millilitres per minute per kilogram of body weight, is calculated from the 10k time using the formula

VO2max = 120.8 - (1.54 x 10k time in minutes)

But if you know your VO2max, you can predict your race time using the reverse formula:

10k time in minutes = (120.8 - VO2max) / 1.54

This leads to the following table









Potential 10k time








In practical terms, for someone doing a 38:40 10k, the VO2max works out as follows:

VO2max = 120.8 - (1.54 x 38.67) = 120.8 - 59.55 = 61.25

Now for the interesting part. VO2max is calculated in ml/min/kg i.e. the weight of the runner is a factor. Lets assume our 38:40 runner weighs 11 stones (69.76kg). Then multiplying the VO2max of 61.25 by the weight in kilos gives a total of 4273 (millilitres of oxygen the heart delivered per minute).

If this runner loses 7lbs, going down to 10st 7lbs (66.59kg), the 4273 would be divided by 66.59 giving a VO2max of 64.17. Using the reverse formula, the 10k time becomes (120.8 - 64.17) / 1.54 = 36.77 = 36mins 46secs (114 seconds faster!)

However should this runner gain 7lbs, going up to 11st 7lbs (72.93kg), the VO2max becomes 4273 divided by the 72.93 equals 58.59. Using the reverse formula again, the 10k time now becomes (120.8 - 58.59) / 1.54 = 40.39 = 40mins 23secs (103 secs slower!)

If this is all too much, then use Max's rule-of-thumb formula of 2 seconds per mile per lb of body weight gained or lost i.e. 7lb equals 14 seconds per mile.

In our example our 38:40 10k runner would gain / lose 87 seconds (2 x 7 x 6.21), giving 10 times of 37:13 and 40:07.

So no matter which system you use, Costell or Jones, you can see the effect of losing or gaining 7lbs of FAT.

So remember when you want to get your money's worth at the Christmas buffet just what the cost can be in terms of performance!