Tuesday, January 1, 2008

Some thoughts about improving running technique with the help of the KISS method

Note: I wrote this in 2005. Reading it now, there are certainly some things that I don't agree with, but as a whole, it reflects my thoughts about running technique. The "book readers" among you will recognize some passages of a well-known running book.


The school of thought that argues that one's so-called natural style is not only best but unchangeable represents a defeatist attitude. It ignores the reality that the nervous system has great adaptive capabilities to incorporate subtle changes in data input that create an improved movement pattern. In so many sports-golf, tennis, swimming, gymnastics, and more-the guidance of coaches expert in designing corrective exercises and instructional commands can bring observable changes in style that contribute to improved performance. The same can occur in running.
With each running stride, the muscles of the landing leg store impact energy as they contract eccentrically to absorb the shock of landing. Most of the stored energy is then used during the concentric muscle contraction that propels the body forward during the next stride; that is, we use the impetus of landing to assist the muscular effort of takeoff.
Indeed, there is growing evidence to suggest that the elastic recoil provided by the tendons contributes a significant proportion (about 30%) of the energy for propulsion, at least when running on flat terrain. It is possible that the muscles of the more economical runners have a greater ability either to store or to utilize this form of impact energy.
A popular idea, implicit in the description of how muscles work is that it is the shortening of contracting muscles that propels the body forward when we run. But running is really a series of bounces in which muscles, tendons, and ligaments alternately store and release the energy absorbed as the feet hit the ground. Indeed, it is similar to the action of a pogo stick or a bouncing ball. The realization that the legs alternately store and release elastic energy during running, that this elasticity probably contributes to running ability and possibly also explains some forms of exercise exhaustion.
The most current biomechanical model of leg action during running is that all the elastic elements in the lower leg muscles act as a single linear spring. The stiffness of that spring can be varied, however, particularly in response to the softness of the surface over which the athlete runs. This is important because the stiffness of the spring determines how the body reacts with the ground during the contact phase of the running cycle.

I believe that good running technique is based on the following three aspects:
- Stride frequency – Keeping it above 88 cycles/minute
- Stance time/Support time – Keeping it as short as possible
- Point of impact – Keeping it below the center of gravity

Associated with these three aspects, which can be called primary, are secondary aspects that basically relate to balance issues:

- Upper body balance
- Head position
- Correct tracking of the lower limbs


Primary aspects

Stride frequency

Daniels is the author that emphasises stride frequency more. Upon studying the stride frequencies of runners in the 1984 Olympics, he found that elite runners from distances from 400m to the 10000m use stride frequencies above 90 cycles a minute.
Most average to good runners, even those with evident technical deficiencies, employ a stride frequency above 90. This variable is also a good way to find runners with a poor technique, so it is always a good point to start when working with new runners.
The stiffness of the leg spring is independent of running speed but alters with changes in stride frequency. Thus, at the same running speed, the leg spring becomes stiffer the higher the stride frequency (and the shorter the stride length). The stiffer the spring, the less energy that will be absorbed. These findings suggest that the naturally chosen stride frequency when running at the same speed by different runners (of similar mass), must reflect individual differences in the elasticity of their legs.

Support time

About this technical aspect, I’m always reminded of a quote from Chariots of Fire. When working on the track with the athlete, the coach says “Run like you’re running on a hot plate”. When trying to minimize the support time, that is the exact feel that we want to achieve.


Point of impact

Having the point of impact on the ground as below was possible to the center of gravity (CG) of the body is very simple biomechanics. The further forward the point of impact is from the body’s CG, the longer the “braking” phase of the stride, since forward aceleration can only occur after the support point passes the vertical of the CG.


Secondary aspects

Upper body balance

The shoulders and upper arms are also important in running. Though they primarily provide balance at relatively slow speeds, they increase in importance in assisting the leg muscles as running velocity increases and as a runner climbs hills. Adequate arm and shoulder interaction reduces the need for counterrotation of the trunk musculature, which is more energy wasteful. Efficient running style suggests that the arms swing fairly loosely and be held quite naturally. Neither should the shoulders be hunched or pulled back, nor the chest thrust out in front. Unnecessarily tensed muscles suggest a needless waste of energy. The shoulders should be carried above the hips.
Arm action varies with running velocity; it is much more vigorous at faster than at slower velocities. Elbows kept close in toward the body minimize the tendency for the hands and lower arms to cross the midline of the chest. Hands and arms normally should only approach the midline. At a wide range of running velocities the elbow joint is flexed at about 90° and remains that way through the range of arm swing. However, at very fast racing velocities this elbow flexion angle unlocks and varies on either side of 90° to provide more fluidity. Arm swing and leg action are inextricably interwoven. If arm swing tends to be erratic, it detracts from optimal style and is energy costly. The hands should be kept loose and relaxed at all times.

Head position

The head should be poised well above the shoulders. It is a very heavy piece of anatomy, and if it is not positioned properly, it can cause either of two problems, both bad. If it is too far backward, it places an unnecessary strain on the neck muscles. If it is too far forward, it can restrict the airways and make breathing difficult.

Correct tracking of the lower limbs

This aspect is best exemplified by watching sprinters running. Every movement they make is towards the direction of motion, especially the lower limbs. For a correct tracking of the limbs, a correct activation of the hip flexors is very important.

Up-and-Down Movement
There is evidence to suggest that uneconomical runners expend more energy bobbing up and down when they run than do more economical runners, who tend to glide over the ground with very little vertical oscillation. Clayton has described how he thinks he became an economical runner:
“When I started training for marathon distances, my style changed naturally. Running 20 miles a day cut down on my stride length. It also eliminated the tendency to lift my knees. Gradually, my power stride evolved into one of economy. Despite the energy-draining action of my upper body, I developed a very natural leg action I call "The Clayton Shuffle. " Through miles and miles of training, I honed my leg action to such a degree that I barely lifted my leg off the ground. "The Clayton Shuffle" is probably the best thing that ever happened to my running. It was economical and easy on my body.”

12 comments:

khai said...

Hmmmm... running 20mi/day produces the "Clayton Shuffle".

Running 20mi/year produces the "Khai Shuffle".

These two "styles" are about as opposite as one can fathom, yet share so much... I think I'm on to something!

Neil said...

Everything makes sense to me except the last part about the clayton shuffle. I've been recently working on the discipline of lifting my lower leg/ankles higher thus getting a more acute knee angle but not increasing the up an down motion of my whole body. Helping this is the development of the hip flexor muscles via use of power cranks. Overall this has helped increase my cadence, keep the strike under my COG and thus reduce the contact time with the ground.

Paulo Sousa said...

Neil,

I've published your comment because I don't believe in censorship. However, I don't agee with some of the things you mention, namely about the effect of Powercranks on running technique. Powercranks are a completely useless device that doesn't not help both cycling and running. Simply put, they're a waste of time that only serve to put food on the table of Mr. Frank Day.

hak said...

One particular running form that has always perplexed me is the guy whose head rolls around like it is connected to his body by a weak spring. I imagine the energy loss through that unnecessary motion would be detrimental, but the last guy I saw with the Rolling Noggin Syndrome was one of the top finishers at a local 5K.

Paulo Sousa said...

hak,

You will notice that I classified "head position" as a secondary aspect of running form. A better example than your local hero is Paula Radcliffe. If you have a chance of seeing her run, you will notice that the primary aspects of her running form are very solid.

pteles said...

Paulo,

What are the symptoms (on running form) when you are not tracking the limbs correctly?

Trevor S said...

You mentioned that there are somethings you don't agree with now. Maybe I missed it. But where or on what has you're opinion changed?

Thanks
Trevor

Ashburn R. said...

Hey Paulo...good stuff here.

I was thinking of writing to you about this very topic. You have mentioned the value of plyometrics in the past. Now that I have a better understanding of the "spring" dynamic, it is apparent (to me, anyway) that a slogger like myself would benefit from specific exercises intended to tighten up that spring. I've quickened my running turnover and I do weekly sets of quick-step-and-high-springing strides. Do you have any additional advice to add to this adaptation effort?

I'm trying to resolve a nagging problem -- I can ride with the best in my AG, but I'm barely a top-20 runner, even after long periods of "high" mileage (45-60 mi/wk).

Cheers,
Ash

Paulo Sousa said...

"Do you have any additional advice to add to this adaptation effort?"

Yes. Run MORE.

Ashburn R. said...

"Yes. Run MORE"

Sh*t. That's what I was hoping you wouldn't say.
;-)

I guess I'm just frustrated that guys who I know run half as much as me can gap me by 3' on the opening 5k of a sprint duathlon. I close that back on <20k of riding, but that's not enough.

The 50-60mi weeks I've done haven't been too tough physically -- it's more just the sheer time involved that is tough. That leaves me time for maybe one bike ride a week. Thinking about my race placing, it is becoming clear to me that I need to just consolidate around my existing bike abilities and really focus on running faster. And that means MORE.

Ryan Levinson said...

Thanks for posting these articles. I appreciate the time and effort you're putting into sharing your perspectives and I respect your experience.

My question is specific to my situation but I hope your response will be informative for all.

I am extremely familiar with the concepts you describe in your blog, primarily through two years of much reading(studying?), watching, and practicing. I can run comfortably at sustained cadence near 90 with 'correct' form as described in your blog. There is are short clips of that at :50 and 1:06 (slow motion) at http://youtube.com/watch?v=ZB4ipo5tDA0
[note, I think my footstrike may be a touch too far forward in the slow mo clip, but I'm close].

The problem is that, despite two years of 'practice' my HR is approx 10 beats higher at an 'endurance' pace (steady aerobic effort without strain, longer run training pace) and I am 1-2min/mi slower over 10k when using this 'technique'. Also, I developed an injury to the arch of my right foot which likely related (explained below).

Due to a muscle disease I have greatly weakened calf muscles, especially the 'medial' calf muscle which is nearly completely atrophied on both legs. My right foot has a decreased range of dorsiflexion relative to my left. After a thorough assessment, an ortho-surgeon (who is also an experienced and pretty fast runner) concluded that most likely the muscle that 'supports' my arch (by connecting through my calf) has atrophied and that the 'spring' motion of running was causing the now less-supported arch to be damaged.

Here's the question- even though faster cadence etc might help increase return from elastic recoil, doesn't it also necessitate a greater number of foot strikes (lighter impacts, but more of them) and a faster leg turnover (thus sort-of increasing effort due to higher frequency of muscle use, if that's the right way to describe it)? If person does not have (nor the ability to develop) the conditioning needed to have an effective 'spring', because of muscle disease or just their particular physiology, then is the technique you describe still likely the most effective? Is it likely some people, without 'spring' legs, are better served by lower cadence running still focused on minimizing vertical displacement, under COG foot placement, etc but substituting slightly greater muscle recruitment (or distribution) for lack of elastic recoil?

Hopefully this makes some sense? It's hard for me to explain. Thanks- Ryan

Paulo Sousa said...

Ryan:

I think I understand what you're saying and in general I would agree with you. But an argument you can think of is that in the "muscular" way of running, which I would equate to kind of a low bounding, you would definitely need more strength from your calf muscles. So if due to your condition you have less strenght, that style wouldn't work so well?! Maybe yes, maybe no.

Another thing to consider is that the "spring" is not only composed of the muscles but also the tendons, mainly the achilles tendon. I noticed that you stretch a lot. One thing that affects negatively running economy is lack of stiffness of the lower leg structure. Now stretching reduces that stiffness, so it affects negatively running economy.

Finally, from the footage of you running, I would definitely focus on running more and not focus on running with a specific technique that you perceive as being better.

pteles:

Things like that are better seen in a video, or with an experienced coach watching. So go out to Estadio Nacional with a video camera and do like Ryan, post it on youtube :-)

Ashburn:

Don't underestimate the differences in genetic predisposition for endurance exercise and their impact in racing, especially at age-group level.