A long time ago (over 2 years ago in fact) I wrote this post about why diet is the missing link from my training.
Though a few things have changed since then, broadly speaking most of it hasn’t. I am still around 18kg overweight for my ideal running weight, which means every time my foot hits the floor 18kg more weight is flowing down through my leg and impacting the ground.
According to this article Ground reaction forces when walking or running, as your foot strikes the ground you exert somewhere between 2.0 and 2.9 times bodyweight through that foot. So in my case, at 90kg I am putting 180-260kg through each foot each time it hits the ground. If I was to lose 15kg, so I was running at 75kg, this would reduce the impact to 150-217kg each time my foot lands. So a reduction of 30-47kg per foot strike. If we take a middle figure of 40kg for each foot fall, and work out that over a marathon distance I probably have around 50,000 individual foot strikes, that is a total reduction of a whopping 2,000,000kg less weight going through my limbs. 2 MILLION KG !!!!!!
An average fully grown elephant weights 5000kg. So due to being overweight, I am exerting the equivalent of 400 fully grown elephants through my body and into my feet for every marathon distance I run. Staggering really.
Also this is a very good indication as to why marathons are so tough. You have to condition your body to take all of this weight through your feet. Luckily for us, we are Born to Run (if you haven’t read that book and you run, or even if you don’t run, then you really should), I passionately believe in running in minimalist shoes (I actually prefer sandals) and I know I can condition myself to complete marathons at almost any weight,
But my challenge is not a marathon. My challenge is an Ultra Marathon. 100 miles of Ultra Marathon in fact. So carrying even 1kg of extra weight is simply not an option.
So it is time to lose weight. I have a plan for this, but that can wait for another blog post. So in the interim, if you are a keen runner and are looking to increase your performance or endurance, addressing the elephant in the room could be a good place for you to start.