Hey there SYSTM crew! This week we are going to chat about muscle activity during the pedal cycle. To begin, please check out this figure of the primary muscles involved. Review the nine muscles with a red star- can you locate and palpate them on your own body?
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This should be interesting…
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I’m reading this over a coffee at lunch. Homework done, but I did get a few strange looks when palpating my gluteus maximus.
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Best if you don’t use both hands at the same time 
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Found them all. What is the name of the ‘goose foot’ tendon that connects at the interior knee joint. I wrecked that with a bad cleat adjustment. I’m thinking it is what connects the vastus medialis to the actual joint. Is is not the patellar tendon extending from the vastus lateralis.
Just be glad I did not give you adductors…
The goosefoot tendon is actually 3 joined tendons; gracilis, semitendinosus, and sartoris.
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How about a QUICK QUIZ with some FUN FACTS related to these muscles. Understanding the unique qualities will help us appreciate their function when cycling!
The answer to each of the following questions is one of the starred muscles in yesterday’s post.
- What is the largest muscle in the human body?
- What is the strongest muscle in the human leg?
- Which muscle of the hip, thigh, and shank can be active for the longest amount of time without fatiguing?
- Which muscle causes low back pain when it is fatigued and tight?
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1.gluteus maximus
2.rectus femoris
3.gastrocnemius
4.biceps femoris.
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Not confident in these answers but giving it a try:
- Gluteus Maximus
- Soleus
- Rectus Femoris
- Biceps Femoris and Semimembranosus (hamstrings)
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- Gluteus maximus
- Rectus femoris
- Long head of biceps femoris
- Vastus lateralis
@ut-och-cykla, @JSampson, @TTDragon
ALL of you are close- but no one has ALL four correct yet…
Anyone else want to try for 100%?
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- Gluteus max
- Rectus femoris
- Anterior tibialis
- Semitendinosus
??!!
@JSampson @ut-och-cykla @TTDragon @Christine-B AWESOME JOB!
Thank you for your critical thinking and intelligent responses!
Here are the answers.
- The largest muscle in terms of total mass is the gluteus maximus.
- The strongest muscle in the leg is the rectus femoris.
- The muscle with the greatest percentage of oxidative fibers and slow motor units between the hip and the ankle is the soleus. (The primary muscle that supports body weight during standing.)
- The muscle(s) that cause(s) back pain is biceps femoris and/or semimembranosus (hamstrings).
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OK! Next step in our goal of learning more about typical muscle activity during cycling is to check out this figure from Cycling Anatomy by Dr. Shannon Sovndal. The circle is a full pedal stroke, the colored bars are each a single muscle and the location of the colored bar on the pedal stroke is when the muscle is active.
Does this make sense? Are you surprised by any aspect?
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I got into cycling properly when challenged to do LEJOG. It gave me bad knees! So…a few years later when challenged to another end to end (Dover - Cape Wrath) I thought it best to make a real effort and nail a better pedal technique in the hope of saving my knees.
My calves grew…and my shins ached.
Now I see why…they were getting no help what so ever from any other muscle!! 
Btw: the knees survived and I got faster👍
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Also, I am surprised the glutes aren’t used more on the up stroke…
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Right! The upstroke is all about recovery for that leg!
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A few definitions to keep us all on the same page!
Pedal Cycle:
- two main phases of the pedal cycle; the power phase and the recovery phase
- power phase = portion of pedal cycle from top to bottom
- recovery phase = portion of pedal cycle from bottom to top
- the power phase is where the majority of force is generated, and the majority of muscle activity is initiated
Joint Power:
- joint power is generally used to assess the contribution of the different joints to the crank power output
- 40% hip, 40% knee, 15% ankle and 5% trunk/upper limbs (hip transfer)
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I hope we are leading to: how to produce the idea pedal stroke!