Friday, July 29, 2011

(Nearly) Barefoot Running: Why?

There is lots of online discussion about barefoot running, including running in very thin shoes such as Vibram Five Fingers (VFFs).  There are many aspects to the discussions, including topics such as benefits, risks, how to transition, how to train, and many more.

My favorite running information source is RunBlogger Pete Larson, who has had many interesting recent posts on this and related topics.  His coverage tends to be observation-driven, with occasional guest posts by true experts and highly respected authorities (most with PhDs).  And his readers post some great comments and links.

His blog, along with my own research, convinced me to incorporate VFFs into my own training regimen.

My goal has not been to give up my "running slippers" or my racing flats, since I'm too much of a committed road runner for that.  Plus, I've already had one metatarsal stress fracture and I'm not looking for another, so I like the idea of having some padding between my feet and the ground.  Finally, I've looked at the soles of barefoot runners (generally thick, cracked leather), and talked with them about their experiences (frequent discomfort, especially on gravel and hot asphalt), and I'm not inspired to emulate their dedication.

Given the above, why should I do any VFF running at all?  My reasoning is simple but not obvious, so please bear with me.

The online discussions tend to center on two primary tenets:  Barefoot running is more "natural", and traditional running shoes can damage some runners.  My personal experience emphatically supports that last point, but I'm a "broken" runner, so my case isn't typical.

So what about that "more natural" claim?  The arguments for it are passionate, with some interesting evidence I found to be persuasive but not conclusive.  However, my curiosity was spiked: What would change if I tried running in VFFs?  How would they affect my comfort and performance?

I got my VFFs right after Christmas, while I was still recovering from my stress fracture, though I didn't start running in them until early this spring.  When I did start with them, I ran only on soft surfaces (sand, turf, padded track), and only for 5 minutes at a time. I slowly built up to 20 minutes running, about 2 easy miles, then stopped adding both distance and speed.  These days, I run in them only twice a month.

Why so little use?  Because I immediately learned what was most important to me: Running in VFFs reveals where my gait can improve, and provides instantaneous feedback as I find and incorporate the needed improvements.

From my perspective, having less between my feet and the ground gives me much more sensitivity and input from my feet, and I become much more aware of irregularities and imbalances in my stride.  Conversely, swaddling my feet in socks and shoes (even minimalist shoes) is equivalent to making my feet slightly numb.  Occasionally experiencing the "direct" sensations from running in my VFFs also helps me be more aware of what my feet are doing while wearing shoes.

I use my VFFs as a way to check that my shod stride is OK, since the first 100 yards in VFFs will let me know if there is any discomfort or awkwardness I should address.  Rather than thinking of my VFFs as running shoes, I view them as another training tool that provides important information, right up there with my Garmin Forerunner 305.  Somewhat similar to how I sometimes ride a spin bike instead of my road bike:  Doing a given activity with different equipment and/or in a different environment permits subtle aspects of the activity to be sensed and focused upon.

I believe many of us can benefit by becoming "more natural" runners.  A good way to do this is to run barefoot or in VFFs.  But I do not believe we need to completely give up our regular running shoes and socks to achieve the desired results.  I suggest the following three-phase process:
  1. Starting out, do lots of short and easy barefoot/VFF runs to let your stride stabilize and find a comfort zone.  This may take 1 to 3 weeks.  If possible, try to limit regular running shoe use during this time: For example, do this in the off-season.
  2. Continue light/easy running for the next 1 to 2 weeks.  During each run, frequently switch back and forth between shoes and barefoot/VFFs until the transition between them is smooth and effortless.
  3. Return to normal training in shoes, and periodically do some short/easy barefoot/VFF runs to ensure the stride is still OK.
I'm presently doing 15 minutes of VFF running twice per month.  I believe I may be getting 99% of the positive benefits of barefoot/VFF running with none of the negatives.  Plus, with such light use, my VFFs are going to last forever.

Thursday, July 21, 2011

Increasing Running Cadence / Turnover Rate

The single most prevalent feature I see among miserable / uncomfortable runners is a slow cadence / turnover rate.  A very low rate means a very long stride, and the slow rate and long length makes for a harder impact.

Rather than have a low rate of hard impacts, why not have a higher rate of softer impacts?  Even if you don't go any faster, a more rapid cadence can make running much less stressful on the feet and legs.

A note about Cadence vs. Turnover Rate:  Cadence has units of revolutions per minute (rpm), and in running it is the number of times per minute a given foot (either right or left) hits the ground. Turnover rate has units of beats per minute (bpm), and in running it is the number of times per minute any foot (both right and left) hits the ground.  That is to say, cadence looks at only one leg, while turnover rate looks at both.  So a cadence of 90 rpm is the same as a turnover rate of 180 bpm.  Most running articles and books talk about turnover rate, but most shoe pods measure cadence.

When I started to increase my own cadence, I noticed another effect:  I stopped twisting my ankles!  I've always been plagued by "weak" ankles that would twist and sprain with the slightest provocation, such as stepping off a curb.  I can't count the times I've "rolled" my ankles while running, where my normal pronation would keep going and I'd "run over the side of my foot".

Of course, a physical therapist would instantly identify the true cause as being chronically over-stretched tendons and ligaments combined with weak stabilization muscles.  Once this state is entered, it is tough to recover without severe activity limits combined with physical therapy.  As a new triathlete returning to running after a 25+ year absence, I didn't want to have to quit running so soon after returning to it!

Unfortunately, as I increased my turnover rate, I found it was almost impossible for me to maintain the higher rate:  The moment my attention drifted, I would return to my bad-old slow pounding rate.  And even when I did manage to maintain my focus, data from my Garmin shoe pod made it very clear that my cadence was varying wildly.

After doing some internet searches for more information, I learned that some runners had to resort to running with a metronome to maintain a desired turnover rate.  Many different metronome brands and models were mentioned, but most seemed either too delicate, too heavy, too expensive, or too quiet/loud to be used for daily running.

After several shopping searches I stumbled upon the Seiko DM50, a small, inexpensive metronome with adjustable volume, and it even had a clip on it!  To avoid annoying those around me, I used the quietest setting.  For runs in quiet areas (away from traffic) I clip it to the waistband of my running shorts, and in noisy areas I clip it to the neck of my T-shirt.

But to what rate should I set the metronome?  After more online research and some personal experimentation, I decided I wanted to use a cadence that would be just below the fastest cadence I could sustain during a best-effort 50 meter sprint.  My Garmin said I was averaging a 100 cadence on such sprints, which equates to a turnover rate of 200 beats per minute.  I set the metronome to a 2-beat rhythm ("beep-boop") at 190 beats per minute.

My reasoning behind selecting this setting is surprisingly simple:  My research showed that all the top running authorities agree it is far harder to change to a new cadence than it is to adjust stride length.  Since my goal is to run as fast as I possibly can, I decided it makes sense to learn to use that fast cadence now, then simply extend my stride length as my conditioning and skills improve.  Since I doubt I'll ever be able to sprint during an entire endurance run, something below my maximum sprint cadence is indicated.

After looking at the turnover rates of many top endurance runners and triathletes (mainly done by counting the frames between footfalls in the many running videos on RunBlogger Pete Larson's site and his YouTube channel), it seemed most had rates between 180 and 200 bpm.  But most top runners have fairly long legs.  When I restricted my search to those with legs that looked to be like mine (32" inseam), the fastest runners tended to cluster close to 200 bpm.  So it seems it was no accident that my own top sprint turnover rate was 200 bpm!

I should mention my 50 meter sprint average speed was only a 6:15 pace.  Vastly slower than the top marathoners I was observing.  Which is why I set my metronome to a slightly slower rate of 190 bpm (95 rpm).

One neat aspect of this number is it nicely matches my cycling cadence.  My best hammering on the bike occurs at cadences between 90 and 100 rpm, depending on the terrain, the gear I'm using, and my fatigue level.

Making my legs match this rate while running has been tough!  I soon found that when I did manage to complete an entire training run at this rate while averaging a comfortable 9:30 pace, my legs were much less fatigued, though my lungs were working significantly harder.

The harder breathing at the higher turnover rate clearly highlights my lack of cardiovascular conditioning, while it simultaneously demonstrates the stress on my leg muscles and joints has been significantly reduced.  I suspect part of the issue is that my leg muscles will need lots of time to fully adapt to the higher turnover rate, and I expect their oxygen demand will decrease over time.

One neat side-effect has been that I've been able to reduce some of my bike training and replace it with running:  Running at the higher cadence seems to complement my cycling, so less saddle time is needed to maintain my performance level.  Of course, when it comes time to improve on the bike, I'll have to add that bike time back in.

I do wish it worked the other way:  I'd much rather increase my biking if it would permit me to reduce my running while sustaining or improving my run performance.  Biking is so much easier for me than running.  The universe seems to be a one-way street in that area.

While I consistently train at a 190 turnover rate (95 cadence), I race without the metronome (mainly due to a fear of having small children point at me).  So I occasionally do a test run without the metronome to see how my "free" cadence is changing.  Over time, my free cadence has increased to between 80 and 85 rpm (160-170 bpm), which feels much better than my bad-old cadence of 65-75.

A gratifying change due to my training at a constant high cadence is how I handle hills.  I used to suffer when encountering any terrain that wasn't flat as a pancake.  Now when I go up a hill, I must shorten my stride in order to maintain the 190 turnover rate.  The short, quick steps make me feel like I'm motoring all the way up!  And instead of reaching the top exhausted, I'm now able to smoothly return to my normal stride length.

The best part has been the downhills.  In the bad-old days, my long stride would be extremely punishing when going downhill.  Within half a block I'd get joint pain, PF pain and shin splints as my heel pounded into the road and my foot slapped down.  To limit impact today, I still need to shorten my stride while maintaining my turnover rate, but it now feels like I'm gliding down the hill (though I suppose I must look like a hamster in a wheel).  I reach the bottom feeling fresh, ready to pour on the effort.

Unlike most runners, my downhill speed is slower than my flat-land speed.  The downhills are the only place where I feel I really need all the comfort my shoes and stride can supply.  Any stride fault while going down a hill instantly sends a jolt up my legs, which my spine converts to pain.  My current running shoes have a 4mm heel-to-toe drop.  I believe reducing that drop further, preferably to zero, will accomplish the dual effect of permitting me to increase my downhill stride length (and speed) while simultaneously giving my calves more time to absorb the impact.

That change will have to wait until my sports gear budget gets replenished.  In the mean time, I'll be quite content to watch my overall pace gradually decrease, with no reduction to my running comfort.