Tuesday, November 1, 2011

What determines our running speed?

I was listening to the Simon Gowen Triathlon Show podcast with Dave Scott, 6-time Ironman World Champion (Oct 27, 2011), last weekend on my long run. Dave was describing his marathon at a 6:02 pace as just a "bit more than aerobic" with a heart rate in the 140’s. Aerobic at 6:02!!

Later that day I spoke to a friend who just signed up for her second half-marathon and she was very nearly apologizing for the fact that she’d be running 10 minute-per-mile (mpm) pace. I reminded her that she would be putting forth a similar effort as compared to others racing their best at a 6 mpm pace or 8 mpm pace so how does that make it any less? There’s no sense comparing or despairing because there’s probably nothing in the world that would allow either one of us to run a marathon at a 6 mpm pace (short of a jet pack or moving sidewalk). The point is, we are each doing our unique best.

I've always wondered, does our running have a genetic “set point”? What are the limiting factors? How much can we boost our speed and how do we do so?

It seems we may have an individually determined range of speeds that would be difficult to exceed. In my own 3-1/2 year running “career” thus far, I saw quite a bit of improvement in the first year but the returns have become increasingly more difficult to get. I'm still getting some and I'll never ever stop trying for more! Yet I'm pretty consistent - my 5Ks are always around the same and heck my two marathons, a year apart, are within 30 seconds of one another! Why is that? What determines my speed or your speed?

I combed through the databases of peer-reviewed journal articles at our library and the best I could do was to identify some basic factors that may contribute to our running speed and potential ways to increase speed. I did not find the review articles I was hoping to read to get the big picture (please let me know if you have leads for this). So I have knit this together the best I could, keeping it short:

Factors in individual speed: 
  • Ratio of fast-twitch to slow-twitch muscle fibers 
  • Amount of force that can be exerted on the ground 
  • Amount of time foot is in contact with the ground 
  • Stride rate (cadence)
  • Length of stride 
  • Individual biomechanics – limb length, muscle insertions 
  • Energy systems 

Possible ways to boost speed: 
  • Improve running form or running ‘economy’, body position, arms 
  • Speedwork 
  • Plyometrics
  • Parachutes (i did not make this up)
  • Increase cadence
  • Strength training 
  • Core strength 
  • Flexibility 
  • Decrease bodyfat (less mass to propel) 
  • Footware – lighter shoes, shoes that encourage midfoot strike 

Naturally things like general levels of fitness and endurance, nutrition, and recovery are major factors. The mental aspects - ability to tolerate pain, to focus, to self-manage – can’t be discounted either.

I’ve been training for the Richmond Marathon (November 12) and my coach and I have been tracking my pace and normalized graded pace on long runs to hone in on a race strategy. I thought about it some and figured on my best ever day I could go at MOST maybe 2% faster (about 10 seconds per mile) racing as compared to my "race-paced" training. Maybe. On the flipside, if things go bad, I could go a heck of a lot slower too…30%? 50%? So there's a tiny upside and a huge downside!

Honestly, I’d be tickled to hit the same kinds of paces I have dialed in on in training. It's always a bit of a crap shoot though from mile 20 onward!

Weyand et al (2010) garnered quite a bit of attention last year theorizing that based on muscle contraction speeds, humans could be capable of speeds up to 35 or 40 miles per hour. How’s that for perspective?!

Regardless of the whys and wherefores, I will never stop trying to eek out every little bit of speed I can. It's all part of the fun and the madness!

(Comments WELCOME....I am no expert on this....)

References

Murgia, C. (2008). Separating Fact from Fiction: Increasing Running Speed. Journal of Physical Education, Recreation & Dance 79(8).

Weyand, P. G. , Sandell, R. F., Prime, D. N. L., and Bundle, M. W. (2010). The biological limits to running speed are imposed from the ground up. Journal of Applied Physiology.

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