281 - Age grading 2

I find many people asking whether a time and distance combination is 'good' and increasingly I find this irritating. So, in an attempt to have a prepared answer, I look at that general problem here.


Of course, 'good' is a personal self-reference usually, and so requires you, the individual, to have an idea of your previous data and therefore how the most recent data compares with this. Personally, I have found that age-grading provides this well, since it removes the degradation that goes with advancing age. 1    

As a general guide, I found agreement with these labels: 90% = world class, 80% national class, 70% regional class, 60% local class —  where we understand that the 'local' class is from 60% and upwards. Which puts me solidly in the 'regional' range, borne out by the associated experience. I'm not at all sure what 'local' means, but it would be unlikely to produce a win in any race. A male of 35 at 5km is looking at a time difference of a couple of minutes for the 10% between 65 and 70%  [21 minutes is 63%, 20minutes is 66%, 19 minutes is 70%, 18 minutes is 73%, so around 3.3% per minute improvement and 0.4% for each additional year.


I think it is sufficient to know how your own performance changes, but I appreciate that for many they want to know where they stand in comparison to everyone else. So how does 60% or 75% on age-grading fit into the population? This requires us to have large data sets and we must immediately recognise that the best we can do is sample the population that has chosen to turn out in a timed event, whose data is then shared. I looked at this in the other essay, too. A male of 35 at 75% does a 5km in 17:11   and at 60% takes 21:29 [grading calc], the faster time represents just inside the 99th percentile [data table] and 21:29 in the middle of the 88th percentile. A male of 65 at 75% would take 21:52 and be in the 99.1th percentile, while at 60% would be on 27:20 at in the 92.4th percentile. While both of these are good runs, in the sense that they lie inside the top decile, that 15% difference in performance (speed as an expression of the corresponding world best at that age) represents around ten times the number of folk in front (0.9% vs 7.6% or 1% vs 10%).  This large dataset is from US 5km races, which is not the same as, say, parkrun, nor club runs in the UK, though we're rather assuming that they are very similar.

But the percentile expression doesn't tell you anything about what that means for any particular race, unless the results are themselves graded by age. At 75% this means that at a local level an age-category win is quite possible, but someone at that standard might well already recognise the other runners around that standard. At 60%, much further back in the field you would recognise only that these people around you are varied in body shape. I have a local aged runner twenty years older than me running at 63-68% (i.e. pretty good) — but he is in the last five or ten in the parkruns we both attend. His standard is high but his age is sufficiently large that 'good' running doesn't equate to 'good' for  all the other males who turn up, since he is usually the last male to finish. I say he is fantastic to be still running in his late eighties but the same speed for a 35-year old is really not very good at all.


DJS 20190612

Also see Essay 263 

top pic from wikipedia

1. I stand around 75% on age-grading irrespective of my age at the time. There is surprisingly little change in that, from a peak of 85% such as when running for 360/365 days a year, to 75% when running perhaps twice a week. I only count the runs that meet some internal standard that differs from a 'jog' but includes any attempt to go running. A sub-70% performance represents being provably, observably, patently unwell, injury included, and probably happens around once a year. 

AgeGradesMembers

75% translates to 5km times of around 22:15 at 65 (hard in 2019), 20:30 at 55 (often, at 62), 17:30 at 35 (probably,4:40 for the 1500m and 2:15 for the 800 occurred often and are close to 75%). At 17 (when I left school) I was doing around the same and 75% would be 4:47 and 2:20 respectively. I used this calculator for these figures.  I note that the parkrun calculator says 22:30 is 75%, but I think that uses a fines age adjustment than the runbundle one linked.

2  At 85, 37:30 is 63.4% on age-grading but at 35 it is 34% for a man and 37% for a woman. I've gone round the two lap park-run course a third time after the post-run chatter in that time. But at least those running at 30% have turned up and had exercise: very few park-runners are at this standard for long.



[2] http://www.bigdatarunning.com/tag/5k/

[3] https://www.goodrunguide.co.uk/AgeGrading.asp

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