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Wednesday 22 May 2013

Length Matters




Back in High School (a long, long, long time ago) I managed to win 3 awards in the Australian Mathematics Competition.  Maths I could do (Geography not so much).

So I often look at sporting challenges from a mathematical or physic perspective.

Consider these Maths.

The average good runner has a cadence of around 94rpm or 188 Steps per Minute (spm).  If it takes them 3hours and 10minutes to run a marathon then they take 190 x 188 steps or 35720 steps.

As a side point here can you see why a lighter shoe is better ?  A shoe that is 100g lighter means lifting 357 LESS kilograms in a marathon.

Back to the maths.

To take 35720 steps over 42.2 means each step takes 118 cm.  Press M+ to remember that number.

If, like most people, you want to run a sub 3 hour marathon (2:59:00) then we are taking 179 x 188 steps which is 33652 steps.  These 2000 odd less steps means our stride length is 125cm - a difference of 7 cm or 5%. Grab a ruler and look at 7cm - it aint that much.  In fact it's 3/4 of the length of the average soft drink can.

So to go from a 3:10:00 marathon to a 2:59:00 is a 5% increase in stride length.

If you wanted to go from a 3:10:00 marathon to a 2:59 marathon WITHOUT changing stride length it  would mean still taking 35720 steps but this time in 179 minutes which means your cadence would need to go up to 200 steps per minute.  This is a 6.3% increase in cadence (and a much higher energy consumption) and from my experience holding a cadence greater than 97 for a marathon duration is almost impossible.  Most World Record holders have broken the record using a cadence of 90-94.  If we look at the maths for that it means 182 steps x 123 minutes or 15129 steps which means a stride length of 278cm (wow)

When cadence starts to max out the only way to get faster is to increase stride length.  As you can see from the maths - even a relatively small (5%) increase can be the difference between languishing just above 3 hours and breaking that magical barrier.

Stride length can be increased in a number of ways.  Drills, stretching (PNF or Ballistic), Bounds/Strides etc  Of course care must be taken to avoid overstriding.

As in cycling and swimming cadence or turn over is extremely important but when you reach the max in cadence and seem to be languishing - look at stride length.

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