Stride length v. cadence

In the past few weeks I have been focusing on an attempt to reverse the loss of strength and speed that occurred over the past 40 years.  It appears that I am making appreciable gains in strength and power, as assessed by tests of hopping distance, but so far there has been no clear cut gain in running speed. 

In part the lack of evidence for improvement in speed might reflect the fact that I do not have access to a track and I have been testing my speed over soggy (or snow covered) grass.  Variations in the surface are likely to obscure any improvement in my speed.  However testing of my time over 100m is not my biggest concern at present.  My focus is not primarily on decreasing my 100m time but rather on my capacity to generate an optimum stride length.

Ever since I obtained a foot pod that gives (reasonable reliable) estimates of my stride length I have been intrigued to note that as I increase pace during either a tempo run or an interval session, my cadence rises but my stride length increases relatively little.  At first sight, this might appear to be the inevitable consequence of the running style described on the page Running : a dance with the devil (in the side panel).  For the reasons described in that article, I believe that relatively high cadence is indeed the safest and most efficient way to run.  Focus on increasing stride length creates a risk of over-striding with the resulting wasteful and injurious braking forces that arise when the foot lands too far in front of the body’s centre of gravity. However that belief requires some qualification – almost certainly there is an optimum balance between stride length and cadence.

I believe that when trying to run fast, the mental focus should be on getting the stance foot off the ground quickly, rather than on pushing against the ground, despite the fact that a short time on stance necessarily demands a large ground reaction force.  The conscious initiation of a specific muscular action is slow, so I believe it is more effective to foster a mental image of the goal – a short sharp lift-off, rather than the a mental image of  a downwards push.  Furthermore, the required push is almost certainly not achieved by a deliberate concentric contraction of the quads and calf muscles but more likely by an almost isometric contraction that controls release of elastic energy stored at foot-fall.  While I am still inclined to believe that the principle of focusing on rapid lift-off from stance is correct, implicit in this belief is that the muscles are nonetheless strong enough and sufficiently well coordinated, to achieve the required push against the ground.  Neither conscious intention to push, nor regulation of the required muscular action by an automatic motor program initiated by the intention to get the foot off stance quickly, is likely to succeed if the muscles are not strong enough.

In my sprinting sessions in the past few weeks, I have directed my mental attention towards getting my foot off stance quickly.  The result has been that my step rate increases to around 240 steps per minute (123 with each foot) but my step length increases only to around 1.5 metres.  (I am 1.7 m tall).  Although I did not measure my sprinting step length in my youth, I am fairly sure it was well over 2 metres.   I think it is likely that I now have a sub-optimal step length and that this is almost certainly due to loss of muscular strength and neuromuscular coordination. 

It is well documented that both muscles and nerves degenerate with age.  However it is also well documented that muscle power can be improved by resistance exercises even in old age, and it is probable that the relevant neuromuscular coordination can also be improved.  While it is unlikely that lost nerve cells are replaced to any large extent (though recent studies show even this might in principle possible) there is little doubt that the connections between nerve cells can be made more efficient.  Hence, in the past few weeks I have been again thinking about running mechanics in some detail, with the goal of designing  a program of strength and neuromuscular training that is likely to lead to recovery of a more efficient ratio of stride length to cadence. 

So far I do not see any reason to make major changes in my beliefs about running style.  In fact recordings of my heart rate when running in the low to mid aerobic zones suggest that I am currently running reasonably efficiently at slow paces.   Rather, I need to work on developing the strength and coordination that will allow me to maintain an optimum ratio of stride length to cadence when I attempt to increase the pace.

 I have not yet reached any definitive conclusions though I think I am making some progress.  Now it is time to go for a run before darkness descends.  Tomorrow I will present a summary of my thoughts so far, and my plans for putting those thoughts into action.

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5 Responses to “Stride length v. cadence”

  1. Andrew(AJH) Says:

    I haven’t measured mine for a while (since I swapped the rs800sd for the Garmin 405) but I was the same (an increase in cadence but not much ion stride length when increasing speed). I’ve also been wondering if I need to refocus on my running mechanics to get past these knee and calf injuries I’ve had this year, but am a little worried that making changes will make it worse.

  2. Ewen Says:

    Hi Canute. I haven’t read your post for today, but I’ll get to it next year 😉

    I know for sure that my stride length is much shorter than it was in my 30s, so working on strategies to improve stride length seems sensible if I’m to run 50+ PBs. I’ve been doing drills regularly and my stride ‘feels’ better, but I’m yet to see an improvement on the track.

    My thoughts are that aerobic condition needs to be ‘good’, or one just doesn’t have the breath to maintain an optimum stride throughout a race. In other words, one could have a good stride, but it would rapidly become shorter once fatigue set in. I wonder if long sets of drills (strength endurance) would be helpful?

    Anyway, I’ve enjoyed reading your posts, and look forward to reading on in 2010. Happy New Year!

  3. canute1 Says:

    Andrew, I think there is little doubt that increased muscular strength can help with knee problems. With regard to running style, maybe the most important thing is to avoid over-striding. My expectation (and hope) is that stride length will increase automatically as leg strength increases. Good luck for 2010 – and I hope you are lining up for either a HM or the full distance in Melbourne in October.

  4. canute1 Says:

    Ewen, Thanks for your many informative comments during the year. I agree that aerobic fitness is also crucial over middle and longer distances, but lack of aerobic fitness is not the limiting factor over 100 metres. I hope that increased strength will produce greater efficiency in the upper aerobic zone and hence increased pace at a particular heart rate. I even wonder if it will lead to increased maximum HR, but that is a more speculative idea for exploration next year. I hope the New Year brings an M50 PB in the 3000m

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