WFR #1: Countering the Bounce | Wed 26th Nov, 7:30pm | Prospect Park Weekly Form Run

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When: Every Wednesday at 7:30 p.m. (run leaves at 7:37 abouts).

Where: Find The Big Red Pointer(TM) (center of the map, click here).

Distance: A single figure 8 lap of Prospect Park, ~4.6139 miles.

Optional Distance Sub-group: 3 miles or less if that's helpful (please let Run Leaders know).

Today's Direction: Left as you face the park at startup.

Pace: Welcome to all. Fun.

AQI: We're monitoring Air Quality Index here and have been asked to not run if the local index exceeds 125.

New Stuff:

I dragged this week's bubble ("HeadBob") to the top of the topics hierarchy and gave it a good shake. The result was this diagram. "BendedKnee", "ShortStrides", "ArmSwing", "ForwardTilt", and "HeadPosture". all support "HeadBob" (or the lack of it!). All those components, to "HeadBob", support "GroundContact" reduction.

Just in case you'd like to explore, here's a pretty QR Code for Week #19:

Towards the end of Week #19 Notes (below "The Mantra"TM) there are links to all the WFR weekly topics.

This week's focus: Bounce. Well, Less Bounce (efficiency, injury prevention, endurance)

TL:DR: Avoid this head-bob at all costs.

The bobbing-head dilemma: Efficient running is about maximizing forward motion. Head bobbing is as likely to cause injury as a loud breaking foot strike (hardly). Why aim for zero bounce? In a marathon, an extra 1.6 inches of bounce with each step equates to one extra mile traveled vertically across the marathon distance.

How does this work?

(Please ignore the following if it is too much detail. Who knew running was so complicated!)

When you stride, your bounce is tied to what your Center of Mass is doing. WRT "Bounce", your running gait has two distinct phases (1) one foot in contact with the ground and (2) no feet in contact with the ground. When a foot is in contact with the ground it is pushing against the ground to (a) keep you up and (b) give you forward motion. The (1)(a) component delivers energy into your bounce and all of that energy is measurable at your Center of Mass (somewhere near your abdomen). Once you enter phase (2) (no feet in contact with the ground), your Center of Mass is ballistic (describing a parabola) and, oh-no, more bounce.

In phase (1) (one foot in contact with the ground), by bending your knee as you stride, concertinaing your leg, you can absorb your Center of Mass' downward momentum and send it back upwards again for phase (2). It would seem there would be little you can do to absorb your Center of Mass' upward momentum, since there's nothing much to concertina above your abdomen. What could you possibly use to absorb your head bounce while you're ballistic?

Turns out that that's where your arms come in. As your Center of Mass is going up, your arm-swing (a different week's focus), absorbs and stores some upward momentum, flattening the rise of your upper body (and your connected head), re-vectoring some of that energy forward (as your arms both go up at the same time (working with your currently engaged foot) and both your arms come down at the same time, cushioning your foot impact). Additionally, if your shoulders remain perpendicular to your direction of travel, your arm-swing counters spine torsion. Who knew that arm-swing was so important (but that's a story for another week).

Aside:

We have some new running metrics on Apple Watches (v9.0 or higher). We're (still) "running" some group experiments to see how those metrics line up with our weekly forms.

Another Aside:
Keeping an eye on your head-bounce is easier during winter. You can see your head-bounce in your shadow projected in front of you as you pass a working street light. Try it with and without arm-swing to see the difference. Yaay, at last, there's a use for Night Time Winter Running - perhaps we'll also find a use for Spring!

Yet Another Aside:

Every now and again an article shows up that provides a counter point that, on the face of it provides an interesting technique spoiler. Here is an article, which, on the face of it, says "Don't worry about the Head Bob" (or "Bounce").

I'm not going to pick apart the analysis (which I'm happy to do offline), rather I'll step past that and make the point that Hellen Obiri (the subject of the article) has so much power in her stride that despite her amazing use of arm swing, that fully counters her torso torsion, she might not have the additional arm muscle mass required to further reduce her Phase 2 (see above) vertical body motion.

To put it simply, she has Short Stride, High Turnover (Cadence), Front Foot Landing, Forward Tilt, Tall Running, Arm Swing, Shoulders Back, all down. With so much thigh-power in her stride, there is simply nowhere else to put that extra push in her stride. i.e. Without more arm mass to redirect excess vertical component into horizontal speed, she's storing the extra force in upwards motion, which gravity gives back to her on the way down. (BTW, I don't agree she is actually exhibiting high vertical bounce, but that's another story).

The "spoiler" in the article is the claim that bounce reduction is unimportant by assuming that we (non-elite runners) don't have to try to reduce the bounce on our path to becoming elite. If you find you actually have power to spare, please, put it wherever you're comfortable spending it (in a non-damaging way). At that point, you've made it!

Related WFR Topics:
"Bended Knee" #2 (bubbles), "Short Strides" #3 (bubbles), "Arm Swing" #4 (bubbles), "Ground Contact Time" #7 (bubbles), "Forward Tilt" #8 (bubbles), "Head Posture/Gaze" #10 (bubbles).

Reading Bubble Diagrams:

Bubbles in the pictures are individually linked to the most recent notes. They are now no longer pictures (hooray), they're auto-generated scalable vector drawings.

Topics are related to each other. Some more or less directly than others. Bubble Diagrams (e.g. this week's topic bubble diagram) illustrate how they are related. Bubbles nearest the top are more directly related to this week's topic. The path to the top illustrates a chain of related topics. Topic bubbles are expanded once in their highest position (most closely related to this week's topic) and are colored blue (or colored black if this is a topic's only appearance). Duplicated bubbles are colored green, which is no less important than a blue colored bubble at the same vertical distance from the root.

Lines that join topic bubbles have been colored. Blue connecting lines illustrate a child topic (lower) supported by its parent topic (upper... think waterfall). Purple connecting lines illustrate the child topic supporting its parent topic. Black connecting lines indicate bi-directional (mutual) topic support. Lightly colored connecting lines indicate topics that are pulled out of the way, as the level they occupy is too crowded. One day 3D (AV) will allow us to walk through bubble diagrams (like tinkling mobiles hanging from your ceilings) and currently lightly-connected bubbles will just be viewable at a different angle (by spinning the view) and not colored differently. One Day... ahhh... One Day.

📢 ANNOUNCEMENTS 📢

 

After a decade of gripes about the google group and some beta testing on what works (threaded conversations, a few dedicated channels) and doesn't work (not using real names!) with Discord last year, the club is starting the process of transferring updates and discussion to an app purpose built for running clubs called Heylo. We have been testing it amongst the coordinators and run leaders for a few months and are now ready to invite the rest of the club in. Please join -  https://www.heylo.com/invite/16fd83bd-91aa-468d-9cb6-c817a98e219f

📢 Weekly Daddy 

Q: Why did the turkey cross the road twice?

A: To prove he wasn't a chicken!