Newton's Running Formula (with apologies to Jack Daniels)

When we hear new things, we think about the new information in terms of what we already know and believe to be true, and decide if it both fits and adds something new. With engineers, this process includes thinking about new information in terms of scientific principles and laws.

Now, Newton (Isaac, not the South African running Arthur - though both would be fun to talk to about this) observed in his laws of motion that the acceleration of a body is proportional to the force acting on the body, and is inversely proportional to the mass m of the body, i.e., F = ma (see Wikipedia).

I thought of the F = ma law when I read that sprinters exert a force equal to several (five?) times their own weight on the track. For larger runners this can be many hundreds of pounds of force (think about a large football running back accelerating to record his best 40 yard time).  I'm trying to reconcile this with the idea that runners might want to be "light on their feet". For sprinters this doesn't seem to be possible while applying such large forces.  The track has to take that pounding!

Getting back to Newton, and knowing that the distance traveled equals 1/2 a * t^2 we could make some dramatically simplifying assumptions and think about running 100 meters fast (most importantly, this calculation assumes acceleration is constant over the entire race, and it isn't - Usain Bolt seems to hit top speed and then cruises a good portion of even 100 meters ...).

But since distance (d) = 100 meters, and Mr Bolt's time in London 2012 was 9.63 seconds, let's assume we can solve for Usain Bolt's acceleration - it is about 2.157. We can call that number "one Usain Bolt".

Let's run Usain's numbers for a hypothetical 9.5 second run ... it is a 1.3% improvement in time but he's going to need an acceleration of 2.216,which is a 2.7% improvement in "Usain Bolt" force. Now Usain Bolts acceleration, just like everybody else s is proportional to the force he can apply and his own mass. This is a lot because there really isn't much he can do to get his mass down (run naked?).  And he's awfully strong already.

In addition to appreciation for the real forces involved, one can only accelerate during the time that force is being applied. The implication is that when you stop pushing and pick that back foot up, acceleration stops. Once you are off the ground you are decelerating. A long 'push time' would seem to be good.

Now, referring back to our man Newton, he tells us an object in motion tends to remain in motion ... doesn't a distance runner only need to accelerate for a very short period, and then simply remain in motion? Why does it feel like it continues to take significant effort? Drag (wind resistance) is actually very low at my running speed. There is little friction with the ground (the foot is not providing sliding friction, but is closer to a rolling wheel). I think the largest component of drag must come from the landing foot. In essence the landing (forward) foot is providing a stopping force, that needs to be matched during the push if we are going to maintain speed.

Joe Friel just blogged about cyclists who might try to 'pull up' in addition to pushing down on the pedals. He concludes that it isn't possible to provide a real contribution to pedaling force by pulling up, that at best one can only partially compensate for the effort it takes the downward pushing foot  to lift the rising pedal. In other words, the best one can do is reduce the amount of drag caused by the rising foot..

The same thing must be happening with running - an efficient runner wants to reduce the drag coming from landing force and minimize the corresponding force required to maintain constant speed.  Fitting this in with what we think is true about running form means that landing the forward foot under your center of gravity (very close to where it can start to push!) is a good thing.  And looking at the stride angles of elite distance runners, they actually do keep that pushing foot on the ground through quite a few degrees of the running stride cycle.

gear update

There's nothing like getting new shoes to mark the early days of a new training cycle ... I just got the new Brooks Cascadia 8 trail shoes.

Brooks Cascadia 8 trail shoes

I have run in the Cascadia shoes a lot over the past years.  I've been buying and wearing the size 15 shoes, because I have pretty big feet and like some room in the toe box.  The new Cascadia 8 shoes fit differently - I actually found the size 15 to be too big.  Maybe I'm shrinking (I wish!).  But for now I'm happy running in size 14's for a change.

Another gear update is coming.  I've had my Garmin FR60 watch for a while now.  I like the feature set (I run with the heart rate monitor, and the shoe pod that gives me speed, stride turnover rate, and distance).  And I really want to keep resisting going to a watch with GPS, as the required charging discipline guarantees 1) the watch will be dead when I need it and 2) I'm going to leave that charger behind on some trip one day. The FR60 system just works for me. BUT ...when the FR70 came out with the same feature set, it seems one of the real changes was a better band.  A lot of users were reporting the non-replaceable band on the FR60 was breaking.  My own FR60 is now showing the signs that the band is failing.

Garmin FR60 watch band cracking

I'll probably go with an FR70 when the band breaks.  The one big (unlikely?) improvement I would like to see in the FR70 is a barometer that would record the elevation profile for a run.

starting over

I'm starting to plan my next training cycle after taking some time off from running.  Of course I try to apply some lessons learned at the start of each new cycle, but there is something to be said for just doing what you do as long as it works.  I hope that doesn't sound defeatist.  I understand the relationship between intensity and duration of work and the resulting training benefit, but doing too much - or doing something poorly - and getting injured is a bad thing.  It may be better to leave some potential performance gains on the table than to push too hard and miss out more running adventures.

So let me tell you about a workout I've added to my routine.  CrossFit.  I've joined a local 'box' and committed myself for a couple of months.  I'm just two weeks into it, and it has been 'interesting'.  There are a bunch of new skills to learn.  I've considered myself pretty athletic - I'm ok at softball, golf, and tennis, and I swim.  But it's been years since I did a chin-up, and I've never done any weight training.  And despite being comfortable with running, I lack a lot of flexibility/mobility that CrossFit demands.  So I'm trying to ease into it, hoping that working at things that I'm not good at will wind up benefiting me in life (and running).

I've actually been impressed with my CrossFit coaches' emphasis on form and that they share my interest in not getting injured.  I hope this turns out to be a good addition to my routine.  Articles like this one do scare me though ...

looking both ways

2012 was a good running year for me.  Looking back at my log, I ran a little over 900 miles in the first half of the year leading up to the Comrades run in South Africa in June.  I'm actually surprised to see that I ran another 1,000 miles in the second half of the year because I haven't been running very often since the JFK 50 miler in November.  It seems I've been taking December off from running (along with the first couple weeks in January) in recent years.  I think that's been a good thing, allowing me to rest up and start dreaming big again.

Looking forward, I've started thinking about doing a 24 hour run.  I paced a runner for a couple of loops last year at the 24 Hour Adventure Trail Run at Prince William Forest Park down near Quantico, VA. It's a nice place to run, and the race management and support seemed fantastic (the race's web-site is here). I haven't signed up yet, but now I better do it ...

Run strong in the new year.  Keep your feet under you!

JFK 50 mile

Yesterday was the 50th running of the JFK 50 mile race.  I laced up my shoes and went to the starting line in Boonsboro for the seventh time, going for my fifth finish.  It was a great day for the race, and I made it in 11:39.  That's slower than I had hoped for, but pretty consistent with my previous attempts. I've been faster and slower over different parts of the course each year, but I guess it all averages out over the day.

I had a minor foot problem early on the course.  Right at the top of the switchbacks dropping off the ridge down on to the canal I kicked a rock, hard, with my big left toe.  Not too long after that I decided it was going to be fine.  Sometime in the next hour though I was thinking there was something wrong with my shoe, that maybe I had a hole in the sole that was keeping my sock wet.  Then I noticed that my shoe was getting a little red. I thought that can't be good.

there is not supposed to be any red

I thought I might have torn my toenail, but since it was feeling ok to run, I didn't see any use in stopping to look.  The sock sticking to the bottom of my foot was causing a blister though (I hardly ever get blisters on my feet) but all in all it wasn't really a problem.  After the run of course I got to clean it up.  Surprisingly, the toenail is ok but it seems I kicked the rock hard enough to cut the the front of my toe.

Trail running gear lesson learned:  I thought the Trance II's I've been wearing on the roads would make me 'faster' on the tow path, but my Cascadia trail shoes might have saved my toe.

stuff from other places ...

I occasionally read the "I of the Tiger" blog. The author is definitely NOT politically correct, but he is provocative. I like his latest note about Spelman college giving up on most of its athletic teams, and putting the money into trying to improve every student's fitness (not just the athletes). Here's a quote:

"What Spelman is doing is acknowledging that fitness is not a competition. It is not something you do in order to prepare to compete in sports (and which can safely be ignored by those who aren't competitive athletes). It is not something that you do for a few weeks a year when you want a sexy Spring Break beach body. It is not something that requires fancy personal trainers or fancy fad workouts or fancy equipment. It is not something only for other people. And it is not an optional, unimportant elective.

Fitness is what you do so you can move your body and not have diabetes. Okay?"

Can I get an amen?

His blog can be found at:  http://gawker.com/i-of-the-tiger/

Groundhog Fall 50K

My friend and neighbor Jenny and I went up to Punxsutawney PA last weekend to run the Groundhog Fall 50K.  We had a great time.

I love this race for some reason. This was the seventh time we've made the trip up.  It's a well organized race that holds true to trail-running ideals.  The course isn't really that hard, but apparently for someone of my abilities it's a real challenge!  Even though I now know my way around the course I'm always humbled by the runners who remember it as a 50 Mile run, and remember horses on the course as well ... so I'm not that old.  This year there was some hard rain during the run, and I decided to get rid of my waist pack/water bottle and shirt, and just run aid-station to aid-station and enjoy it.  I met a first-time 50K runner named Staci who turned out to be a great running companion  for the second half of the race.  If you are reading this Staci - hi! - it was good running with you - and hope your feet are good.

Here are some photos Mary took:

Mike at the start

Here is Jenny a couple of miles from the finish ...

Jenny - approaching Adrian aid station on the way back

and me, just at the finish ...

Mike - happy to finish Punxsutawney 50K 2012

On the long drive (~5 hours) home after the race, we don't need much of an excuse to stop the car and stretch our legs.  Jenny treated us all to ice cream at our first stop (and took this picture of me and Mary - I like it).

Mary - the best crew chief in ultra-running today