July 29, 2015 cburnham

Myth of Pedaling Circles

How many times have you read an article in your favorite cycling magazine about how the key to your cycling success lies in pedaling better circles?  It seems every spring and early summer we start seeing articles explaining the benefits of pedaling circles and if you are concerned with performance you need to stop mashing the pedaling to increase efficiency.  Usually included in these articles are some fancy one leg-pedaling drills that not only help you improve your pedaling, but also show you how weak and inefficient you pedal your bike.  Surely professional cyclists and triathletes must pedal perfectly round circles….not really.  The reality is that the fitter the athlete, the more they mash on the pedals.  Pedaling circles is just a myth and trying to do it may actually be hurting you.

“It appears that ‘elite-national class’ cyclists have the ability to generate higher ‘down-stroke power.’  Compared with group 2 (amateur group), group 1(elite group) also produced higher peak torques and vertical forces during the down-stroke even when cycling at the same absolute work rate as group 2.”- Physiological and bio-mechanical factors associated with elite endurance cycling performance. Coyle EF et. al.  1991

Wait a second, how can that be when we have products like Computrainer showing fancy graphs that my spin isn’t perfect and Power Cranks to help me fix my spin?  Marketing has never lied to me before, how could this happen?!

Power Cranks

This is a pretty common conversation I have had with athletes over the last several years.  With power meters dropping in price and providing more data, the question of how to best pedal a bike has come up over and over again.  There is so much miss information on this that I think it is important to put out what science has said on the myth of pedaling circles.

Pioneer has some of the best pedaling metrics in the market.  This is a good example of data from elite athletes in national level events.

Pioneer has some of the best pedaling metrics in the market. This is a good example of data from elite athletes in national level events.

Before we dig deeper into the studies, I think it would be beneficial to go over a bit of biomechanics and physiology.  Cycling is essentially looking at hip and knee extension and flexion as you pedal. Extension in cycling is essentially pushing down, while flexion is the upward phase of the pedal stroke.  There are other smaller muscles and joints involved but to keep this somewhat simple we will just look at the knee and hip. Extension in the hip and knee primarily uses the gluteus maximus, hamstrings, and quadriceps.  Flexion in the knee and hip primarily involves the hip flexors (psoas, iliopsoas) and rectus femoris.  Before we go any further, it is pretty obvious that the extension muscles are quite a bit physically bigger than the flexion muscles.  If we also think about how we use those muscles most of the time, extension is used to push against gravity while we really only use the flexion muscles to lift up our leg.  The amount of force to lift our bodies is always going to be more than it takes to lift our leg and this is the first blow against the myth of pedaling circles.  Unless you have very weak extensors, it is impossible for the muscles responsible for flexion (pulling up on the pedals) to produce equal force as the extensors.  That would be required to provide meaningful power to the pedal stroke since in pedaling both legs are connected through the crank and bottom bracket.  As your left leg pushes down it in effect lifts your right leg as well.  At best, all you can really do is lift the weight of your leg on the upstroke.  Metabolically speaking, there is no difference in your left flexors lifting the leg or your right extensors pushing the left leg up as long as you aren’t still actively pushing down with your left leg.  We are moving the same mass the same amount so the energy cost is exactly the same.

Yep, his hip flexors are totally bigger than his quads...

Yep, his hip flexors are totally bigger than his quads…

Even though it is the same metabolic cost, pulling up on the pedal stroke can still be problematic.  The primary hip flexors, psoas and iliopsoas, originate on the transverse process and body of the T12 – L5 vertebrae.  Essentially the pull on your lower back.  If you are using the muscles extensively they can start to fatigue your lower back and lead to a lordotic curve in your lumbar spine.  This is often a cause of lower back pain in cyclist and triathletes.  Furthermore, if you are a triathlete that is fatiguing the hip flexors on the bike by trying to pedal circles it will be even harder to lift your legs up on the run which can have a huge impact on performance, getting full hip extension, and maintain proper posture.  In extreme cases, pulling up on the pedals can even lead to an impingement on the iliac artery leading to numbness and a loss of power.  Even if you aren’t a triathlete, over activation of hip flexors and the resulting tightness of the muscle group can result in anterior pelvic tilt, lordotic back, and lower back pain.  Not of that is athletic, powerful, or attractive.  Seriously, anterior pelvic tilt does not bring sexy back.

Anterior Pelvic Tilt

When we look at the independent studies down on cycling bio-mechanics the picture is pretty clear.  Pedaling circles results in impaired performance, loss of efficiency, and potentially increases the risk of injury. In a literature review by Simon A Jobson, et. al. (Gross efficiency and cycling performance: a brief review. 2012) it was concluded that  “‘pedalling in circles’ allows pedaling to become mechanically more effective, this technique does not result in short-term improvements in gross efficiency.”  In another study by Korff T, et. al. (Effect of pedaling technique on mechanical effectiveness and efficiency in cyclists.) they found that “When the participants were instructed to pull on the pedal during the upstroke, mechanical effectiveness was greater (index of force effectiveness=62.4+/-9.8%) and gross efficiency was lower (gross efficiency=19.0+/-0.7%).”  What really matters is gross efficiency since that is the net result of your physiological energy propelling the bicycle.

Bottom line, pulling up on your pedal stroke and trying to achieve the perfect pedal stroke or circle spin scan will not increase performance.  In fact, it is more likely to see a decrease in performance by working on mechanical efficiency since the best way to achieve the perfect circular pedal stroke is to push down easier.  If you push down easier, the extensor muscles will produce a similar torque to the flexion muscles and hence produce a better mechanical efficiency but who wants to go slower.  I would rather give up mechanical efficiency and just go faster.  How about  you?

Sea Otter CX