Category Archives: IDBI

You Might Run Slower Sooner Than You Think

Land, Air or Sea - Natural Limits Exist

Land, Air or Sea – Natural Limits Exist

Do you sometimes wonder for how long you will keep improving your race times? Do you see some friends (appear to) continue to improve year after year, and yet others (seem to) not improve much at all, and some even (seem to) be get slightly worse every year? What could your own benchmark be for athletic performance as the years roll past? Would be good to have a handle on that, right? (Did you wonder why I have those few words in parentheses and emphasized in italics? It is because what ‘appears to’ be, or ‘seems to’ be, might not always be!)

Now, what if you could follow almost 200 recreational distance runners for 7 years over the same race that they ran year-after-year? That might tell you a lot about where your own running might take you, right? Well, here’s some evidence based guidance, based on data never seen before, that I have put together for you.

After listening to what I have to say here, mostly facts, and some conjecture, you will be able to plan your own distance running or other athletic targets for the years to come.

Quick Background

From early childhood to post-puberty, children keep improving for years in various measures of fitness. There is a difference between boys and girls and, depending on what feature of athletic performance one looks at, for a given youth the path will follow periods of rapid improvement, stagnation, and then further improvement followed by tapering off in improvements. What can we say for adult recreational athletes?

Some studies suggest that it takes about 4 years of training for an adult to reach their peak potential. Of course, it is quite likely that the results from controlled studies on adult sporting professionals might not apply to you. That is especially the case if you are an urban recreational athlete. So, let us listen to the story from a unique data set that I have prepared for us.

Unique Data

I look at the case of my ‘home race’, the Standard Chartered Mumbai Marathon, and examine the performance of all the runners who raced the exact same half marathon or full marathon every single year for 7 years in a row (2010 to 2016). This is a small subset of the urban running population. But it is a very valuable subset as it allows us to follow the exact same population of runners over multiple years. Recreational runners in Mumbai face all the constraints and challenges of life in a city with a very high population density, stupidly high real estate costs, terrible public infrastructure and not the most pleasant weather in the world. Having said that, I believe the broad pattern of results will apply to any pairwise population cohort and race combination.

Earlier Work on this Race Event

In a much earlier conversation I presented what happened between 2010 and 2014 to the overall numbers of all participants in the races and average race times over those 5 years. Earlier this year I presented here how that overall quality (race times) and quantity (number of participants) had changed in the period 2010 to 2016. Neither of those investigations had controlled for individual runners being identified and tracked separately across races. Then, when I addressed the question Are Recreational Marathoners in India Getting Faster? I tackled the issue of identifying runners across consecutive races and examining their performance. I identified and tracked 50,719 consecutive period race pairs. However, this repeated pairing was done only across consecutive races – not across the entire span of multiple years. Now, for the first time, here, I identify and examine the same runner across a long span of 7 years and always running the same race – either the half marathon 7 years in a row, or the full marathon 7 years in a row.


There will be a few cases within the data where the race times are not representative of the ‘true state of athletic performance’. Examples include: transfer of racing bibs to friends who are a lot slower/faster, pacing a slower set of runners, sudden bout of food poisoning during the race. Cramping or running injuries mid-race are not equivalent examples because they do indicate the state of the runner – unprepared for the race!

What happened to Race Times over 7 Years?

There were only 158 participants who ran the half marathon in all 7 years. The equivalent number for the full marathon is just 35, so I exclude them for now but will refer to them shortly.

Same Race, Same Runners, Net-Finish-Times

As the bar graph shows, in terms of the average finish time of the group, the absolute athletic performance does not keep improving each year endlessly. In fact, besides being numerically similar, the average race time sometimes does not prove to be statistically different from one year to the next (i.e. given the variation in individual timings from one race to the next, the average of the race times of all runners in each year does not change enough for that change to be distinguished to be different from zero). So then what can we say about the variation from one year to the next?

Factors Affecting Performance

Factors Affecting Aggregate Race Performance

Factors Affecting Aggregate Race Performance

Of the broad factors affecting performance, the (i) Temperature on race morning and (ii) Humidity on race morning which can, confusingly, often vary in opposite directions to each other can be cleverly combined into the single Heat Index for those race mornings for neater analysis. The process followed by (iii) Ageing is deterministic (a year every year!) even if its effect is not constant, and so can be ignored to a very good first approximation between consecutive years (even if not across a 7-year jump). The (iv) Elevation profile was approximately the same for the years 2010 to 2015 (inclusive) and we can note the effect of the noticeably changed route in 2016. The process followed by (v) Training is the big unknown, and is individual runner specific, and is into which we can subsume all variation unexplained by the other factors when comparing successive years for any individual runner. This includes physical conditioning over a year, psychological training for athletic performance, and any other on-race-day individual behaviour.

Note that although we cannot distinguish between those who commenced running in 2010 and those who might have been active distance runners for 30 years, by aggregating numbers, we can smoothen out individual idiosyncracies and examine the overall impact of Training and the other factors on the entire cohort over that period.

Reasonable Factor Variability Reduction

Reasonable Factor Variability Reduction

Plotting the Heat Index for each of the race mornings along with the average finish times we can see that, from 2011 to 2016 the Heat Index stays within a narrow band, but the performance does not really improve much with time. The effect of training of these runners over a year is not strong enough to drive race performance to faster finish times.

Weather within a Narrow Band - Performance Stagnates

Weather within a Narrow Band – Performance Stagnates

Worsening Performance in 2016 – Route Change, Ageing or Training?

When the changed route for the Half Marathon was announced for 2016 I spoke to you about the challenges. My estimate then was that it would add between 1%-3% to your race time. Given that the Heat Index was almost identical on the race mornings of 2015 and 2016, one might conclude that (all other things remaining equal) the (2.56%) slower time in 2016 vindicated my forecast estimate of 1%-3%. Of course, the runners were a year older. But, let’s assume that the extra year of ageing didn’t really affect performance. Then, since the Full Marathon had the same route for both 2015 and 2016, perhaps we can say that those who had been running it for 7 years in a row displayed worse performance! The effect of a year of ageing had now overpowered an extra year of training! In that case we cannot separate out the effects of the route change for the Half Marathon and the worsening because of ageing versus training.

Same Weather - Same/Changed Route - Worse Performance!

Same Weather – Same/Changed Route – Worse Performance!

Why we should Love this Special Population?

It is instructive to note that this population of runners who had run the same 7 races for 7 years in a row is a unique subset of the 45,000 humans who ran in either the half or the full marathon in those 7 years. They are not representative of the typical recreational runner (who clearly did not run the same race for 7 years). However, they are an especially useful segment of the running population because they tell us what we can reasonably expect of ourselves when we set out to make running (or any other physical activity) a part of our lives for the long run. You can also see that their athletic ability spans a wide range and you will be able to identify your own ability within this range.

2016 SCMM Half Marathon Finish Times for the Cohort of 158 runners

2016 SCMM Half Marathon Finish Times for the Cohort of 158 runners

What does this Story Really Mean for You?

I have told you why you need not run and even why I don’t care about your podium finish (or mine). I love to include running as one very very tiny part of the many activities I engage in for a happier life. I ran my first half marathon (accidentally) in that same Half Marathon in 2010 but am not part of this data set. However, the numbers speak to me very clearly and form evidence based guidance on what could be appropriate benchmarks for my own running as the years roll by. Even as I write this closing paragraph, I noticed that my regular weekend long-run buddy features in the data. He has a Half Marathon PB of 1-hour-12-minutes (many years ago) and is the fastest runner in this cohort of runners. I like the guidance that these numbers give me. How will you benefit from their story?


Dr Purnendu Nath spends his waking hours focusing on helping individuals and organizations reach their goals, to make the world a better place. He speaks, writes and advises on topics such as finance, investment management, discipline, education, self-improvement, exercise, nutrition, health and fitness, leadership and parenting.

Learning from the IDBI Mumbai 2016 Race Event

Learning from the IDBI Mumbai 2016

The IDBI Federal Life Insurance Mumbai Race had its first edition on 21 August 2016. What are some of the things that we can learn from it as pacers, race runners, organizers or coaches?

Learning from – The Route

Two days before the race I chatted with you to provide a few tips specific for this race day. It seems like there was indeed some (fortunately, only minor) confusion in stages where the 5-km, 10-km and 21-km routes overlapped. Hopefully that did not cause any problems for your pace.

Although some of you who ran the half marathon version have reported that you found the distance measure was slightly short of 21.1 km, my analysis from various independent GPS devices suggests that the distance was correctly measured within an acceptable range. Please be aware that if your GPS device has a sampling frequency that is not very high then you will typically get a distance reading that is biased to be shorter than what you actually ran. Also, be aware that running the shortest distance between any pair of the 20+ twists and turns will lead to a shorter measure than the official measurement device which has been used for internationally approved races. That device is specifically used with the protocol of traversing a path in the middle of the road-route, not the shortest distance between two turns.

Learning from – The Weather

The weather was not a surprise to us. My own rudimentary forecast was almost bang on target. The temperature and humidity were both as I expected. Also, there was some drizzle which is always nice. And, the wind was less forceful than than my forecast and also gentler than in the mornings leading up to the race. In summary, the weather was, at best, a small positive surprise!

Learning from – The Pacing

I have already reported on the failure of pacers at this race. This aspect definitely needs to change in race events. Western businesses often complain about Indians’ approach to winning projects – reassurances of “yes, we can do that” – followed by under-delivery!  Let’s root out such repeated failures! Whether you are a race organizer, a pacer, a wannabe pacer, or someone who is selecting a pacer for help in their next race, you would be well advised to read my guide on it.

Learning from – The Post-Race Breakfast

I do not have much to comment about the post-race nutrition – I rarely find that it is what I want to eat after a tough race. Because everyone has different preferences, when I suspect that what is offered will bother me, I ensure that I arrange for my own post-race food and drink.

Learning from – Expectation v Actual

IDBI Mumbai 2016 – Performance – Actual v Expected

I asked, and many of you responded (thank you for that) about your own performance versus target. Given that the weather conditions were not different from expected, in fact less headwind where we might have had some (“between the 17-19km markers”), my guidance is the following. Think back to each and every step of your process for setting up the expectation that you had for your target. In parallel, read what I said a few weeks ago about process for performance. Going through this exercise is likely to generate a more accurate ex ante forecast of your next race finish time. Not necessarily because you might be faster, but because you will understand your own ability more accurately.

Mat Placement Error for the Half Marathon

Click to enlarge

I happened to come across the following error about the race organization. On scouring the GPS records of my mentees who ran the race, compared with the official timing records, I noticed that the official 16.0 km timing mat was not at the 16.0 km point – it was actually placed a significantly further distance down the route. I do not have any reason to think that this error is directly related to the wrong placement of Km markers on the official route map, that I mentioned in my pre-race guide, but you never know! So, why do I think that the mat was in the wrong place, and where exactly was it? Here are my answers to these two questions.

Why do I think the 16.0 km mat was in the wrong place?

Wrong mat distance suggests wrong pace

If you pick anyone who ran the race without any “odd or unusual” pattern you will notice that their ‘average pace’ up to the 16.0 km mat according to the official distance/time splits was unusually slower compared with the ‘average pace’ up to the 12.1 km mat. Now, all that would be fine, except that the ‘average pace’ up to the 21.1 km (finish) mat is then faster again. This will strike you as slightly unusual, and prompt you to ask a question like “ah, but maybe the person actually ran really slowly between 12.1 km and 16.0 km and then ran much faster between the 16.0 km and 21.1 km mark?”  However, that argument falls apart when you calculate that the pace the recreational runner would have to run the last 5.1 km is significantly faster than what they ran in the earlier parts of the race, when in fact they had been gradually slowing down from the very start (as recreational runners typically do!).

So where was the 16.0 km mat actually placed?

Highly likely that the 16.0km mat was at 16.75km

Highly likely that the 16.0km mat was at 16.75km

It is 30 elite and 2,213 non-elite half marathoners for whom there exist valid readings across all the 8 timing mats (km = 0, 3, 5.7, 9.1, 10.4, 12.1, 16.0, 21.1). Taking all their mat timings and building a few linear and non-linear models I concluded that the 16.0 km mat was actually placed at the 16.75 km mark. This is clearly a glaring error, not a small one! Perhaps you do not need to look at the official splits because you (a) are not interested in your performance details (b) have your own GPS device readings (c) don’t see what the big deal is. After all most racers do not bother to do an ex post quantitative analysis of their race. However, my more serious question is, what went wrong with the race organization process and the (non-existent?) checks that should be in place?

Concluding Remarks

Each of us individually has to focus on what we can do, as well as we can do it, and in every aspect of our personal and professional lives. We are happy to pay the equivalent of a household maid’s weekly wages for a single Sunday morning run.  We expect fairly high performance from our domestic helpers. How often do we stop and ask ourselves if we get that from others, especially organizations, that we are paying for a service or product?

Let us work together to make all races across the country, not just the next edition of the IDBI Mumbai, a more successful event at the individual and organizational level.


Dr Purnendu Nath spends his waking hours focusing on helping individuals and organizations reach their goals, to make the world a better place. He speaks, writes and advises on topics such as finance, investment management, discipline, education, self-improvement, exercise, nutrition, health and fitness, leadership and parenting.

Pre-Race Wisdom for the IDBI-2016 Race

IDBI 2016 – route maps

On Your Marks, Get Ready… Go!

Whether it is the 5km, 10km or the half-marathon you are running at the IDBI-2016 here are some superb last-day tips for you. Before I begin, I would like to remind you that if you are running the half-marathon tomorrow I hope you will have selected your free pacing band for the target times of your choice that I spoke about here. Print, laminate, cut, wear, pose and run! The video is here.

For many of you this might be your first race, for others it might be just another one added to a growing list. For some it might be about taking in the wonderful sights, for others it might be about obtaining a PB (personal best) and, for yet others, it might be about pacing a friend to help them achieve their PB. You might be from Mumbai or from out-of-town but here are some tips especially for you.

Puru enjoyed the sites at the promo event

Puru enjoyed the sites at the promo event

These are some final thoughts from me to you about this race:

  • I went to what was a launch event run on 17th April 2016 to motivate others to run tomorrow. That was well organized so I hope the main race tomorrow is too. There were only a few hundred runners that day, and there are like to be about 20 times as many participants tomorrow, so please pray that there won’t be any hiccups but do allow for glitches and try to not let them affect your mood
  • If you are from out of town and used to running in Mumbai only during the SCMM in January, then here’s some sobering comparison with the SCMM:
    • The temperature is likely to be about 6-degrees Celsius higher than during the typical SCMM race in January
    • The humidity is likely to be about 83% rather than 55% of the typical SCMM race in January
    • The winds are likely to be more like 20kmph rather than the gentle 3kmph you would have faced during a typical January SCMM
    • As there is an 80% chance of rain, beware that your shoes, socks and everything else will get heavier, and that will slow you down
    • Be aware also, that if it rains, there are likely to be more participants who will be running for fun, and so you will need to keep your cool if you are trying to overtake and they don’t give you way as efficiently as you think they could
  • On the other hand, compared with the SCMM:
    • You won’t have the elevation of Peddar Road to deal with and
    • You won’t have the elevation of the Sea-Link (twice in 2016) to deal with
  • If you are running the (10km or the) half-marathon, you are going to face the monsoon winds on Marine Drive. This is likely to help you (but you won’t be able to tell) between the 13-15km markers. However, these winds are highly likely to be a noticeable struggle to deal with between the 17-19km markers (just when you don’t want to face more struggle!)
  • Life is full of twists and turns. The half-marathon has 21 turns of which 7 are pretty much like U-turns. If you are focusing on a blistering pace, this is something to be aware of. I won second place in a half-marathon last October with almost 60 turns so I know it’s not a lot of fun. But that’s not why I told you, soon after that race, why you need not run!
  • Because the overlaps in routes between the 5km, 10km and half-marathon are significant, and we don’t know how diligent the stewards will be, please memorize the route yourself. Empower yourself because race stewards pose two risks:
    • If you are fast and ahead of the pack, you might get sent the wrong way (I’ve won a race because I memorized a route in another city and my primary competitor, who was from that city and noticeably faster, was sent the wrong way).
    • Race stewards are known to get bored after a while and the very runners who need our help (the stragglers who are in need of motivation) get confusing (or no) signals from stewards – I pointed this out when I told you why I don’t care much about your podium finish
  • When memorizing the route, please note that the official route map does not have the distance markers in precise locations on the graphic (notice, for instance, the oddly short 1km between 17km and 18km) but we can pray that the actual kilometer markers on the route will be appropriately placed (and that they sync beautifully with your GPS device)

What next?
The usual… Rest your legs well, sleep on time, and eat/drink sensibly today. Remember what I said about process for performance barely 10 days ago? Give that more thought too! Enjoy the day and have a wonderful experience.


Dr Purnendu Nath spends his waking hours focusing on helping individuals and organizations reach their goals, to make the world a better place. He speaks, writes and advises on topics such as finance, investment management, discipline, education, self-improvement, exercise, nutrition, health and fitness, leadership and parenting.