The law of diminishing returns vs. the aggregation of marginal gains.

Today I ran a personal best at the Reading half marathon (hooray)… by 20 seconds (oh) which equates to just over a second a mile (erm…) and that has made me think about running, diminishing returns and what it takes to continue to improve.

A couple of weeks ago a compatriot and training partner ran his first race after months of injury and set a new personal best. However when he replied to my text asking how the race had gone, he did so without mentioning the new benchmark (which of course I knew, but I was hoping he’d mention it). And he said he was a bit disappointed. I must admit that I felt like sending an admonishing text back saying that he should be bloody pleased with a PB, but I think I knew, deep in my heart, what was going on. I will explain.

In really simple terms (‘cause I’m a simple guy) the law of diminishing returns states that if you continue to add more resources to a process there will be an initial increasing return that, as more resources is added, will start to tail off. That is not to say that the addition of resources will result in a fall in output (that is known as negative returns) but the rate of returns will start to flatten. A common example given is that of people building a car – add more people to the process and you’ll get more cars. But continue to add more people and you will still get more cars, but not at a proportional rate.

If you apply this to running, it means (to me anyway) that if you add more training you should continue to get faster but at a decreasing rate. Most novice runners – me included – take massive chunks of time off every time they race. This could due to be a number of factors:

  • fitness increases
  • experience increases
  • running economy increases
  • etc

However as the runner races more, each beneficial factor has a less magnificent impact until we are scrabbling around for seconds here and there.

Now I recognise that almost every factor in racing is non-linear – we are not machines after all – and that it is impossible to apply this type of model to human behaviour, the effect of the weather, the impact of illness, etc but I believe that every runner will acknowledge that running is like ‘bungee running’…

Bungee running? I hear you ask. Last year at a festival in central London, my fiancée and I saw a bungee running sideshow – an inflatable tunnel where people are tied to a bungee cord at the open end and try to run up the tunnel to snatch a prize at the other end. The initial few meters are easy (in a running analogy this is the first few races that a novice enters) with little resistance to forward momentum but as the bungee runner reaches the furthest extent of the cord, the effort needed to go further (in our running analogy to achieve a personal best) increases… until they are flung backwards to the open end of the tunnel, exhausted and defeated. Nice.

But there is something on our side. Something that started being discussed in the GB cycling squad and (surprise, surprise after their results in the Beijing Olympics) made it into the lexicon of the then Prime Minister, Gordon Brown; the aggregation of marginal gains. It is beautifully described here and essentially is the process whereby everything that could possibly have an impact on an outcome is systematically questioned and improved, if only by 1%. This, my friends, is where we find out improvement.

So what do I think this means?

I think it means making sure every training session is a close to perfect as possible (note I do not mean as fast as possible, or as long as possible. I mean as perfect as possible).
It means getting a massage.
It means stretching for a minute more or one more muscle than before.
It means going to bed 30 minutes earlier and making sure there are no distractions in the bedroom (well, apart from that obviously).
It means laying out your breakfast stuff the morning before an early run or a race.
It means thinking about everything that one can do that might have an impact in your A-race.

And where does that leave me? Well, I’m quite a long way up the bungee tunnel and the rope is quite tight. But I am not quite ready to slip back, not yet. I know that to get a little further up the tunnel I will have to work harder. But I am also going to work smarter. And I am going to accept that my days of 15 minute PBs are over and that from now on – if I am improving, I am improving and that is all I want.


  1. Well done on the PB mate, top result. 20 secs is 20 secs – If Paula Radcliffe beat someone by 20 secs it would be called a resounding victory because the athlete she beat would be over 100 metres behind. Bathe in the glory of beating yourself so resoundingly.

    By the way don’t forget the enjoyment factor, it’s easy to forget it in the quest for the great PB!


  2. Good article – completely agree. Also the factor of natural ability. Whether that means we have a ‘limit’ or not I don’t know, but 2 people can do the same training with the same approach off the same endurance base and have a marked difference come race day.

    What is obvious is that some guys can have a 12 month break doing nothing, knocking the beer back – and jump straight back into 70 minute HM shape!

  3. This post made me smile. Although I am runner of considerable less talent (and ambition) I often have similar thoughts.

    There’s always room for improvement but the more successful you become the harder those improvements are to find. That’s true of running and life in general.

    Congratulations on your PB but even more impressive is your continued unwavering commitment and drive. Most folk would have taken their foot off the gas long ago.

  4. In 2003 I set a Marathon p.b. of 2.48.49, it look my 7 years to better it running 2.47.33 last year, this at the age of 49 and with over 17 years of running and racing behind me.
    I looked at the training methods that were working and producing the best results for elite runners then found a coach that could deliver the program.
    I looked at improving my running biomechanics, diet, mindset etc.
    i think overtraining was my biggest sin and the reason my performance went backwards after 2003.
    Most people might have thought it was due to the ageing process!
    This year I’ve taken things a step further, improving my posture, fixing muscle imbalances and moving into more minimal running shoes.
    I guess the process is a bit like tuning up a F 1 car, lots of small changes can add up to a big difference.

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