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Why Cycling Fitness Hardly Carries Over To Running & Vice Versa

It happens every year.  The mornings are brisker. The leaves turn from green to brown, and the cold weather gear comes out. As the seasons turn from summer to fall to winter, I find myself switching up my sport of choice until spring graces us with its presence.  This switch entails going from cycling as my sole sport to running exclusively for the next 4-6 months (fat and winter road biking are not my thing). One would think this would be a relatively easy transition as both sports are aerobic and fitness from one would translate over to the other without too much difficulty.  If this were true, we would see the world’s best cyclists also be the world’s best marathon runners which we all know is not possible.  Sorry, Chris Froom.

So why then it is so hard to go from cycling full time to running full time? This article will discuss the key differences between running and cycling and why fitness from one does not carry over fully to the other.  It will also provide practical solutions to make the transition easier from cycling to running and vice versa.

Key Difference #1: Cycling and Running Have Different Neuromuscular Recruitment Patterns

Why Cycling Fitness Hardly Carries Over To Running

Muscles are made up of three different fiber types. Type I, Type IIA, and Type IIx (If you want to read in-depth about muscle fibers types click here). Type 1 oxidative fibers contract slowly but are very fatigue resistant and are the ones that are mostly utilized during efforts below 40% of an individual’s VO2 max.  Type IIA contract faster than Type I and can produce more power but fatigue quicker.  These fibers are recruited in addition to type I as exercise intensity increases (40-75% VO2 Max) or during longer, more intense effort.  Last but not least, Type IIX fibers contract the fastest and can produce the most power but fatigue very quickly. Type IIx fibers are usually the last to be recruited during endurance exercise (75% of VO2 Max and higher) and come in to play during sprints or break away efforts.

Running, for the most part, relies on type I fibers to produce muscular contraction and hence locomotion while cycling, where more power is generated, will still rely on Type I fibers but there is also greater recruitment of type IIA and Type IIX fibers.  Ever wonder why you can ride 100 miles easily but barely make it a mile when you first start running.  It’s partly due to the underdevelopment of type I fibers and how they are recruited.

Key Difference #2: VO2 Max Is Sport Specific

Why Cycling Fitness Hardly Carries Over To Running

In an ideal world, VO2 Max would stay the same for cycling and running.  Unfortunately, this is not the case.  By strict definition, VO2 Max (maximal oxygen uptake) is the greatest amount of oxygen that can be used at the cellular level for the entire body and is calculated using a number of variables such as weight and the amount of muscle mass utilized during an activity.  For the purposes of this article, running involves more moving muscles than cycling.  While both involve the lower limbs, running involves more upper body musculature recruitment due to arm locomotion while the upper body in cycling is generally stationary. This is largely why VO2 Max will not be the same for cycling and running and why you might be gasping for air for the first few weeks of running.

Key Difference #3: Different Muscle Group Use

Why Cycling Fitness Hardly Carries Over To Running

Running movement is produced mainly through the contractions of the glutes, hamstrings, plantar flexors, shoulders, back and to some degree the quadriceps.  Cycling, on the other hand, is a quad dominant sport while also relying on the hip flexors to facilitate pedaling (and to some extent muscles mentioned for running minus upper body muscles). The point being as you transition from cycling to running the muscles that come in to play need time to adapt to the new motion and stress put upon them.  This is why you are often sore for the first two weeks of running, and your stride/running form feels very inefficient. This inefficient movement will also influence how difficult running feels and how much power you can produce.

Key Difference #4: Neuromuscular Fatigue

Why Cycling Fitness Hardly Carries Over To Running

Since the type of muscle contraction and potential muscle damage are different between cycling and running, the neuromuscular fatigue induced by prolonged exercise probably originates from different sites (central vs. peripheral) and leads to different levels of strength loss.  With running, the decrease in strength and time to fatigue is proportional to the amount of impact and the duration of the training session.  In cycling, where there is less impact, fatigue is more influenced by the amount of power generated and the rise in muscle acidity. 

As you move from cycling to running neuromuscular fatigue will occur more quickly in the beginning as the muscles learn to cope with a higher impact sport.  This can directly affect the amount of training sessions per week and recovery time needed between workouts.

 

Now that we know why cycling fitness hardly carries over to running fitness let’s explore two ways to make the transition easier.

Solution #1: Run Two Times A Week During The Cycling Season And Vice Versa

This one is a no-brainer and will make the transition from cycling to running and running to cycling much easier.  If possible squeeze in two running sessions a week during the cycling season.  My recommendations, one training session should be long and easy (45-60 minutes) while the other should be done at threshold pace (10-minute warm-up, 20 minutes at threshold, 5-minute cooldown).  Research has shown that this type of training plan can help you maintain running fitness.  These sessions could be performed on your off days from cycling or on an easy day.

The same principle can be applied making the switch back from running to cycling.  Do one long ride a week (2 hours at an easy pace) and one ride a week at threshold.

Solution #2: Get Your Butt In The Gym Two Times a Week

Why? So all the muscles you use for running and cycling are developed, strong, and can produce more power/force.  This doesn’t have to be anything fancy.  If you want to hit all the muscles used in running and cycling, perform squats, deadlifts, pull-ups,  bench press, and the shoulder press.  Keep the weight high, reps low, and rest between sets long so you don’t pack on too much muscle to your skinny frame.  Stronger muscle are also more fatigue resistant and efficient plus you’ll be the envy of your training partners when the short shorts and tank tops come out.

Solution #3: Become A Triathlete

That way you’ll never have to choose between running and cycling, and you’ll also get the cardio and strength benefits of swimming.

The Bottom Line

Let’s face it.  The transition from cycling exclusively to running exclusively can suck.  The difficulty arises from the differences in VO2 Max, muscle groups used, muscle fiber recruitment patterns, and different rates of neuromuscular fatigue.  If like me, you find yourself switching between the two as the seasons change you can make the transition easier by always including both in your weekly training schedule with an emphasis on training for the sports season you are in and going to the gym 2 times a week.

References:

Millet, G. P., Vleck, V. E., & Bentley, D. J. (2009). Physiological differences between cycling and running. Sports Medicine39(3), 179-206.



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