Cadence, stride length and Mo Farah’s finishing kick

To run faster you need to increase cadence, stride length or both.  The question of which it is best to increase is not easy to answer. In particular, the question of the optimum cadence has long been an issue of discussion among runners and coaches.

On the basis of observations of athletes racing distances ranging from 800 m to marathon at the Los  Angeles  Olympics in 1984, Jack Daniels suggested that across various distances, cadence should be at least 180 steps per minute.  The figure 180 became enshrined in folklore.  There have been two niggling concerns about this. First, many recreational athletes tend to adopt a slower cadence.  Secondly, it is clear that among both recreational runners and elites, cadence tends to increase with pace.  For example, observation of a video recordings of 5000 m races reveals that many elite athletes increase cadence to 200 steps/min or more in the final lap.

Consideration of  the effect of increasing cadence on the peak height of the centre of gravity during the airborne phase illustrates why a fairly high cadence is beneficial from the point of view of both efficiency and minimizing risk of injury.

First, we need to consider the question of what proportion of the gait cycle should be spent airborne. Much empirical evidence indicates as speed increases, a shorter time is spent of stance.  For example in his study of the factors influencing running speed, Peter Weyand found that the proportion of gait cycle spent on stance typically decreased by around 40% as speed increased from 3 m/sec to 8 m/sec.  This is understandable as the shorter the time on stance, the less the braking.  To minimize braking at high speed, at least half of the gait cycle should spent airborne.

However when airborne, after mid-flight, the  body inevitably accelerates downwards under the influence of gravity.  The total vertical distance fallen in one long hop is greater than the fall in a series of short hops of equal total duration because the body accelerates to a greater average speed in a longer fall.  As a result, the total gain in height and the energy that must be spent on getting airborne increases with increases of step duration.  In addition, the impact forces are greater the longer the step duration.  Conversely higher cadence and shorter step duration result in lesser expenditure of energy on getting airborne and lesser impact forces.

However, the saving in cost of getting airborne must be set against the increased cost in repositioning the legs, The swing leg must overtake the torso before footfall, and the cost of accelerating the swing leg increases in proportion to the product of cadence and speed (see calculations in the side bar).  The need to avoid large repositioning costs sets an upper limit to cadence. The most efficient cadence is that which minimizes the total cost of getting airborne; overcoming braking; and repositioning the legs.

However, self-selected cadence differs  greatly between individuals. Recreational runners tend to have relatively low cadence, often less than the 180 recommended by folk-lore.  A study of recreational runners  by Heiderscheit and colleagues  demonstrated that a typical recreational runner might decrease both airborne costs and braking costs by increasing the self-selected cadence by up to 10% .  Heiderscheit reported that at a pace around 3 m/sec, a 10% increase in step rate from a self-selected mean step rate of around 170 resulted in a reduction of approximately  20%  in energy absorbed at hip, knee and ankle joints., It is likely than many recreational runners would  benefit by increasing cadence.

Elite 5000 m runners

Even elites differ greatly, with typical cadence during the mid-stages of a 5000 m ranging from 180 to over 200 steps/min.  Why is there such a large range of cadence among elites? I suspect it is largely determined by the efficiency with which the athlete can capture the energy of impact at footfall as elastic energy and use it to help get airborne again.  An athlete who can achieve a greater saving through elastic recoil will require less energy to get airborne and therefore can afford a lower cadence and longer stride at a given pace.  If such an athlete can increase cadence while maintaining his/her long stride in the final lap of  a 5000m, he/she will have an awe-inspiring  powerful finishing kick.

The best illustration of this is provided by Mo Farah.  In a previous blog post, I discussed Mo’s cadence during the indoor meeting in Glasgow in 2009, when he set a British indoor 3000 m record.  In the middle stages of the race, his cadence was around 175.  For example, he covered the sixth lap of the 200 m track at a pace of 6.4 m/sec with a cadence of 175 steps / min and a step length of 2.18 m.    He made his decisive break from the field in 13th lap, by increasing pace to 6.6 m/sec. He achieved this by increasing his cadence to 185 steps / min while his step length remained virtually unchanged at 2.17 m.

It was interesting to contrast his long-loping style with that of Galen Rupp as they ran together in the middle of the pack, with Galen about metre behind Mo, along the back-straight in eighth lap of the 5000 m in the London Olympics in 2012.  Mo’s cadence was 190 steps/min while Galen’s was 204 steps/min.  In the fiercely contested final lap Galen was dropped as Mo increased his cadence to 208 steps per minute while maintaining  a step length of 2.18 m to hold off six strong contenders.

In the World Championships in Beijing in 2015, again it was Mo’s ability to maintain his long stride while increasing cadence that carried him 8 metres clear of Caleb Ndiku in the home straight.   Mo’s cadence of 204 steps per minute was only  marginally faster than Ndiku’s 202 steps per minute, but the telling difference was Mo’s step length of 2.24,m  compared with Ndiku’s 2.08 m.

The secret of Mo’s powerful finishing kick is his ability to maintain his long stride as he increases cadence to match that of his opponents in the final lap.   It is most likely that this is based on very effective elastic recoil allowing him to re-use impact energy to get airborne.  It is noteworthy that he had this ability in 2009, before he joined Alberto Salazar’s training group in Oregon. It is probable that the discipline of Alberto’s coaching took him from the status of UK record holder to World Champion, but the foundation for his later achievement had clearly been laid before 2009.  It is an intriguing question to wonder how much of this reflects his genetic endowment and how much reflects the trainable features of his running style.

At footfall, his right foot splays outwards in an ungainly manner, but perhaps more relevant, to my eye, he typically exhibits about 10 degrees of dorsiflexion of his ankle immediately prior to foot-strike.  This is clearly illustrated by contrasting the orientation of Mo and Galen’s feet an instant before footfall as they run lock-step (though with Mo landing on the left while Galen is on the right) along the back straight at 9:05 in the 5000m at London, 2012, captured in  Michael Wilson’s slow motion video.   This small degree of dorsiflexion will pre-tension Mo’s Achilles and promote efficient capture of elastic energy.

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11 Responses to “Cadence, stride length and Mo Farah’s finishing kick”

  1. michael troup Says:

    Interesting. You imply that to win runners have to run in the most efficient way – but the ultra-elite like Mo may have energy/strength to spare – they can run in a way that wastes energy yet still win. So copying them is not necessarily the best way for others to run.
    It is my understanding that to make the most of elastic recoil, the stance time has to be small, so the stride frequency needs to be high – correct me if I am wrong. So it may be that Mo is being less efficient than the runners around him when his cadence is low, but that he is so talented it does not matter, and he can improve his efficiency later in the race by increasing his cadence, when those around him can only maintain theirs.

    • canute1 Says:

      Michael
      Thanks for your comment

      I think that in most instances, to beat the rest of the world’s best in any event consistently, an athlete needs to have almost all aspects of their fitness and skill highly developed. It is likely that the disciplined training under Alberto Salazar has ensured that Mo’s aerobic capacity and endurance are highly developed. However even before he joined Salazar, the seeds of his brilliance were there. Since 2009, he has had an awe-inspiring ability to increase pace in the final stages of races from 3000m to 10,000 m. I suspect that this is because he has the ability to get airborne with the efficiency typical of a middle distance runner.
      .
      Many middle distance runners have a long stride and relatively low cadence. For example, in the recent Diamond League 1500 m in Monaco Absel Kiprop (currently the world’s leading 1500m runner) had a relatively low cadence in the range 183-186 steps per min, and step length around 2.36 m for most of the race. So like Mo, Kiprop has a low cadence and is clearly very efficient at getting airborne. To my eyes he has a similar dorsiflexion to Mo, possibly even more marked.

      Appreciable, dorsiflexion immediately prior to foot-strike is common in sprinters, it is not unusual for a 1500m runner, but it is less common in a 5000 m specialist.

      Mo’s own performances over 1500m (including a 3:28) confirm that he has at least some of the attributes of a middle distance runner.

      In essence Mo combines the efficient use of elastic recoil typical of a 1500 m runner with the aerobic capacity and endurance of a 5000/10000 m specialist.

      With regard to your comment about needing a high cadence to optimize elastic recoil, the requirement for optimizing recoil is that time on stance should match the optimum time for recoil. This is determined by the visco-elastic properties of tendons. Tendons are stiffer when force is applied rapidly, and the optimal time is fairly short. The required short time might in principle be achieved a high cadence or alternatively by spending a smaller proportion of the gait cycle on stance. If the capture of elastic energy facilitates a powerful drive off stance, the proportion of the gait cycle spent on stance will be short.

  2. padraigjapan Says:

    Very interesting posting. As a recreational runner, I struggle to get my cadence to 180 without increasing my heart rate as well. As I try to run mainly in Zone 2 while training, this is a big problem to increase speed at a low heart rate.

    • canute1 Says:

      Padraig,

      Thanks for your comment.
      If you increase cadence and while maintaining stride length, heart rate in almost certain to rise (as I expect it does for Mo in the final lap of a 5000m).

      For a recreational runner, who consistently runs with a cadence below 180, it is likely to be worthwhile to increase cadence while consciously allowing stride length to decrease. This is likely to produce at least a small increase in efficiency and thereby generate a small increase in pace, but the main advantage will be less stress on your joints.

      Once you are comfortable at a faster cadence, it is worth seeing if you can increase stride length while maintaining cadence. One approach is dorsiflexion prior to foot strike, as described in my blog. However, it is almost certainly necessary to start with specific drills and resistance work to increase the strength of the muscles that perform the dorsiflexion (mainly tibialis anterior) and also do regular hopping to ensure that the calf muscles are resilient enough to cope with the eccentric contraction that generates the elastic recoil.

  3. Ewen Says:

    Hi Canute. Interesting post. In my view, Mo’s kick is so effective because of his slower (than the other runners) cadence mid-race. Other runners, such as Rupp that you mention, are running at a higher cadence mid-race and haven’t as much “room” to accelerate to maximum cadence. The runner just ahead of Mo in that video, Lagat (?), also has a higher cadence than Mo.

    That’s an interesting point about the energy cost of repositioning the legs. Mo (and other elite runners) have slender musculature and light calves, so the energy cost of repositioning the legs would be low compared to the average recreational runner. Would repositioning energy costs cause the average recreational runner to self-select a slower than 180 cadence, or conversely a very short stride when trying to run at a higher cadence?

    • canute1 Says:

      Ewen

      Thanks for your comment. You make an interesting point about slender legs. Undoubtedly slender legs reduce the cost of repositioning the swing leg. Conversely, swinging bulky legs, (especially bulky calf muscles) requires greater energy. This would encourage a runner with bulky legs to employ a lower cadence. Optimum cadence might be lower for such a runner. Nonetheless, the evidence of Heiderscheit (and others) suggests that many recreational athletes run with a cadence that is too low.

      • Ewen Says:

        Thanks Canute. I agree with Heiderscheit about that. A slight increase in cadence (e.g. 175 to 180) would have these runners running faster.

  4. courir plus vite...efficience, cadence et vitesse... Says:

    […] Cet article est une traduction libre d’un article du site « Canute’s efficient running », avec l’autorisation de son propriétaire. Lien vers l’article original […]

  5. toaof999 Says:

    Hi there Canute.
    Great article, as usual.
    I don’t know if If i maintain my stride lenght, but for sure, my hearth rate increase while increasinge cadence from 170/175 (the cadence while running around 12km/h) to above 190…(around 14.5/15km/h).
    If there is any french reader, you can find a french translationof canute’s post on my blog:
    http://iron.kwaoo.me/run/2015/09/24/courir-plus-vite/

    • canute1 Says:

      Thanks for your comment and for translating my blog into French.

      When you increase your pace to 15 Km/hr while increasing cadence up to 190 you are actually increasing both cadence and stride length, since pace increase by 20% and cadence by only about 10%.. Not surprisingly your heart rate increases

  6. 1, 2, 3, 4… repeat – MdS challenge 2017 Says:

    […] my ramblings help. Before I go… check out this site… Cadence – Running efficient. It deals with the subject in cold hard facts. Enjoy your […]

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