June 2009

“Bike Fit for Physical Therapists” class

dscn0018_4I just returned from a “Bike Fit for Physical Therapists” class in Seattle, WA and learned a GREAT deal about cycling biomechanics, bike fit, and our roll in cycling rehab, injury prevention, and performance.  Erik Moen, PT led the seminar via power point and lab sessions.  I will be posting more blogs on cycling, bike fit, and biomechanics, but this one piece caught my eye.  It is based on the research of Jeff Broker, PhD who does mostly biomechanical research of cycling as an expert witness in bike accident cases. 

Some of what I am about to share with you is already common knowledge to most of us in the cycling world.  However, it doesn’t hurt to “drive it home.”

Here’s Broker’s Top 10 Things Known about Pedaling through research with my additional information applied to cycling injuries:

10.  As cadence increases, peak pedal forces decrease.  So, the faster you pedal, the less force on your joints!  Save those knees.  Increase your cadence.

9.  As power levels increase, peak pedal forces increase.  Makes sense, right?  As you increase resistance, you increase force on the pedal.

8.  Cyclists DO NOT pedal in circles.  In reality, we don’t.  Though it’s good to try!  See below.

7.  Cyclists DO NOT pull up in the upstroke.  This is an interesting one.  What they have found is that as we transition on the backstroke to the upstroke, the weight of the leg creates resistance so in actuality, we are not really creating more force on the pedal during the upstroke to propel us forward.  The upstroke does not contribute to biking faster.  However, we still tell people to “pull” up on the upstroke to keep the knee in alignment as well as lessen the resistance of the weight of the leg.

6.  Power flow profiles expose regions of passive pedaling.  This is the dead spot usually at the top of the stroke.  Trunk angle (the lean of your trunk in relation to horizontal) can influence how “dead” the stroke is at the top, by changing the function of your muscles in the transition from upstroke to downstroke.  Triathletes usually have a bigger dead spot since they are in the aero position more.  In turn, this means they cannot spread out the force through the entire pedal stroke.  Meaning, they will have a smaller area to create the same force as someone who is more upright.  Yes, this means they are set up to be more of a masher.  

5.  Body positioning affects force profiles.  See above.

4.  Body positioning affects joint moment patterns.  Again, by changing the trunk angle or any other angle in cycling biomechanics, you can apply more force to any given joint.  

3.  “Ineffective forces are fundamental to the coupled pedaling motion.”  This refers to the weight of the leg on the back part of the stroke.

2.  Pedaling mechanics can be modified.  This is good for us.  Via bike fit, stretching, rehab, strengthening, practice of pedal stroke.

1.  A “masher” can be the World Road Race Champion!  He is referring to Lance Armstrong in 1993, Oslo, Norway.  Lance was a big masher (maybe from his triathlon days just before becoming a professional cyclist?) until he meticulously worked on his pedal stroke to increasing cadence and spreading the force to more of the bottom, top, and upstroke.

 

While much of what is stated above can help with energy preservation and cycling performance, we as sports medicine providers can use this information to “fit” the patient to the bike (via flexibility, mobility, and strengthening) as well as fit the bike to the patient.   This is what separates us from the bike shop bike fitters.  Health practitioners who do bike fits have the unique ability to fit both the athlete and the bike to create an optimal position on the bike for performance and injury prevention.  

 

Press Play Analysis offers Bike Fit, biomechanics, and rehabilitation services to cyclists.  Call 510-883-1126 or email drjess@pressplayanalysis.com for more information.

 

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