What Are The Differences Between Cycling Muscles Vs Running Muscles?

Ever wonder how Ironman triathletes can cycle for 112 miles and then run a marathon afterwards? The only explanation is that they are super-human. Right? How else would their legs be able to do both sports. Yes, they are partly super-human, but there are fundamental differences in how the legs are used for running and cycling.

Cycling and running both use all the muscles of the legs. But they engage our muscles in different ways. Running provides a more balanced approach where-as cycling hits certain leg muscles much harder than others.

This partly explains why cycling and running can work well together. So to understand how exactly the two sports differ, let's first take a look at all the different muscle groups as well as how they are involved in each sport.

The Muscle Groups

The primary muscles that work while running and cycling are:

• The quadriceps (the muscles in the front of your thighs that extend our leg at the knee joint)
• The hamstrings (the muscles in the back of your thighs that flex our leg at the knee joint - ie bringing in your ankles to your butt)
• Hip Flexors (the muscles at the top of the thigh that..well flex our leg at the hip joint - think bringing your knees in to your chest)
• Glutes (the muscles in your hips and butt that extend our leg at the hip joint)
• Calves (the muscles in the back of your lower legs that flex our foot at the back of the ankle)
• The tibialis anterior muscle (muscle in the front of the lower legs that flexes our foot at the front of the ankle)

Note: both cycling and running use our core muscles groups including our back and abdominal muscles for stabilization

How Running Uses Our Muscles

Let’s look at how these muscles enable us to run:

The running stroke for one of the legs can be divided into different phases.

• Initial Contact. The leg hits the ground in front of you. The quads are used to balance out the forces of your knee flexing as your body moves forward over the leg.
• Mid Stance. You extend your hip (using your glutes) to continue to propel your body over your leg. The Calves work to stabilize the force over your foot.
• Take Off. Your body continues to move over your leg and your leg extends.
• Initial Swing. You flex your knee (using your hamstrings) to get your leg ready to swing forward.
• Mid Swing. You flex your hips to (using your hip flexors) to swing your leg forward. The tibialis anterior muscle flexes to bring your foot up and prevent you from tripping.
• Terminal Swing. You extend you knee and foot a little (using your quads and calves again) to get ready for initial contact again.

While running uses all the leg muscles, a lot of the movements of the leg are coordinated by our hips: the glutes and the hip flexors.

Let's Take A Look At What Happens To Our Muscles During Cycling

There are two main phases as you cycle the pedals in a circle. There is a Power Phase and a Recovery Phase.

This is what happens in a single revolution of the pedals:

• Start of the Power Phase. This occurs from 12 o'clock or the top of the pedal stroke to about 3 o’clock. The hip extends (using your glutes) to start pushing the pedal down
• Middle of the Power Phase. This occurs from 3 o'clock to 5 o'clock. This is where the knee is extended (using the quads) to continue to push the pedal down. This is the strongest part of the pedal stroke.
• End of the Power Phase. From 5 o’clock to 6 o’clock or the bottom of the pedal stroke. This phase uses the calves to stabilize the force generated from the upper legs to the pedals (it keeps your foot on the pedal or keeps the force efficient on the pedals if you are using clipless pedals - and clipless pedals are awesome if you are serious about cycling)
• Start of the Recovery Phase. From 6 o’clock to 8 o’clock. Essentially, the reverse happens from the power phase. Instead of the calves, the tibialis anterior muscle groups are used.
• Middle of the Recovery Phase. From 8 o’clock to 10 o’clock. The opposite of the quads, the hamstrings, are used to flex the knee.
• End of the Recovery Phase. From 10 o’clock back up to 12 o’clock. The opposite of the glutes, the hip flexors complete the cycle.

As you can tell from the names of the phases, certain muscle groups are used a lot more in cycling.

So What's The Difference

The biggest difference between cycling and running is that cycling has a much more dominant power portion of the activity. The downstroke on the pedal generates the most power on a bike. Thus, the muscles used in that portion of the activity get used more.

Running on the other-hand, has a much more balanced usage of all the muscles in the leg.

The quadriceps are used more for cycling.

• In cycling, the quadriceps is the major muscles used to generate power.
• During running, these muscles control the flexion and extension of the leg. They are used for stabilization as well as some power generation.

The hip muscles: the glutes and hip flexors are used a lot more during running

• These muscles generate much of the power for running by allowing us to pick up our legs and swing them forward
• The glutes are used during cycling to to transition into the power phase. The hip flexors don't require a ton of work in cycling.

Hamstrings are used more in running than cycling

• In cycling, most of the power is on the downstroke of the pedal using the quadriceps. The hamstrings are used during the recovery phase but to a much lesser degree.
• In running, the hamstrings have more of a role to actively swing the leg forward. Without their use, the legs would just drag behind; that wouldn't get you very far.

Muscle Build Up

Because of the focus for a few muscle groups, cyclists can end up with massive legs!!

_{Just look at those quads!!; image by www.Roth-Foto.de, CC BY-SA 3.0 DE, via Wikimedia Commons}

Cyclists really get a reputation for having tree trunk sized legs. And that reputation is pretty justified.

Runners develop a much much more balanced lean muscle mass on their legs.

_{Runner with lean legs; Fernando Frazão/Agência Brasil, CC BY 3.0 BR, via Wikimedia Commons}

Combining Running And Cycling Training Together

As many triathletes have experienced, there are benefits to combining both running and cycling into your workouts.

Despite working the same muscles, the muscles are worked differently. This allows you to cross-train very effectively. You avoid over-tiring your muscles out.

Triathletes have figured this out to a science. There are even specific bicycles for triathletes. Not only are those bikes more aero with special handlebars (which you can modify your own bike with), but the bikes also push the bicycle seat forward more. By pushing the bicycle seat more forward over the pedals, the pedal stroke works the glutes less and works the quads more. This keeps the glutes fresh for running after finishing the cycling portion of the race. Triathletes have really figured out the way to exploit the subtle differences between the muscles used for cycling and for running.

Summary

Even though cycling and running engage most of the same muscle groups, the two activities work those muscles very differently. Cycling hits certain muscles harder than other groups while running provides much more balance to all the muscle groups. But luckily both will give you nice strong and fit legs.