Cycling vs Running for Time-limited Base?

Hey all,

If you are on a limited time budget, with say 6 hours per week available on average, would your cycling fitness be better spent building base while cycling or running? I’m curious here because runners typically train less volume than cyclists because of the impact but runners still get very fit. For this scenario, I am thinking of only running for base season (3-4 months in the winter, block one) and then transitioning to some long intervals on the bike with Z1 training through running (two months, block 2) before going to hard intervals and only cycling (block three in the summer)

Here is my background and rationale:
I am primarily a cyclist, mostly riding mountain bikes with friends, road/gravel for fitness, and cyclocross races in the fall. I am relatively new to running but have picked up the pace since the pandemic began since most of our local trails were shut down and then they became too busy for a while. I want to train more just to see how far I can push myself, especially with cyclocross since I am usually toward the front of the pack when riding MTB with friends. Most of my rides are under 2 hours and rarely go over 3, and I ride 3-5 times a week and average 7 hours per week in the summer. I live in Canada where winters can get cold enough that my best gloves and sock/shoe covers can’t keep me warm enough if I try to do base training outside, and I don’t have the mental fortitude or backside to do big rides on a trainer indoors either.
The past few years I have taken many different approaches to off season base training, from doing interval-heavy plans on Sufferfest to hill repeats to more traditional Z1 (in a three zone model) base building via commuting. Through learning more about running and training I find that runs are much more taxing (and generate more TSS). That has me thinking, would I be more aerobically fit, even on the bike, doing running ‘base’ instead of cycling at this low time commitment? Or, is the specificity of training high enough that my running ‘base’ would be useless for my cycling training?

There was just an episode on this with Chris Carmichael. Worth a listen to.

Personally, I don’t think anyone who isn’t a very good runner can actually do “easy” while running without all but walking… My Z1 HR is 127… I cannot run at any speed for more than a couple minutes before crossing that.

That being said, running is a great way to add a little bit to your training volume. I can go out with my kid on the bike and run with her, or a quick 20min at lunch or before the day starts if I wake up too late for a bike ride before work (anything less than 40min doesn’t feel like enough for a ride).

I fully agree with @smashsquatch

@masjo16, have you tried online group rides with your friends and a voice audio connection?

@smashsquatch the recent Carmichael episode did have me thinking about this more! I have used the Time-Crunched Cyclist book for training plans over winter and summer before too.

I should also note that I too find it difficult to run at Z1, so end up doing mostly Z2 for this as well. For some reason, I can do a 45 minute run in Z2 and finish feeling fine and even do four of those in a week, but if I did 3x15min Z2 intervals on the bike I feel thrashed even after one day.

To further elaborate my thought, in a different theoretical way: if sub-elite runners (equivalent to Cat1 cyclist) only train for, say, 10 hours a week, but the same Cat 1 cyclist would train for 16 hours a week, would 6/10 running hours make me more fit (at least from a base training perspective) than 6/16 cycling hours? To go even further, if running base fitness only translates to cycling base fitness at 75%, does that still work out better for me as a cyclist since it’s still 45% of the hours vs 37.5%?

I know as Carmichael said on the podcast these things aren’t necessarily linear (e.g. you can’t take an elite training plan and just cut it in half) and I agree with that. My thought is that 6 hours of running gets me closer to an elite level than 6 hours of cycling, so would that be more beneficial?

@kjeldbontenbal I have done this, but I only have one friend that really puts in any consistent time on the trainer, and our sessions would max out around 1.5 hours due to commitments on either end from both of us.

Runners don’t train less because it makes them more fit, they train less because they have to due to impact of running on their bodies.

That being said, running has more cross over with cycling than cycling with running; due to needs of improving white tissue to be efficient.

Personally I find that running more often (4-6 days a week… Even for 20min) will improve me more for the sport than more frequent cycling does for cycling. I find this is because I’m less sore running 6 easy times a week at 20min each than 2x60min. With cycling I find that I’m not even sore if I did 6x40min at easy paces, but sessions long than an hour (even easy) can leave me feeling sore (when I’m only training 6-8hr / wk).

That’s why for my triathlon training I almost never do intensity while running… Just strides and the occasional tempo run when feeling great.

This tells me your zones are off or you really need to get that on-bike strength.

I think in the end, with limited time (relative to endurance sports) you should focus on the sport that aligns with your goals. If you’re just looking for general fitness, then doing a little bit of everything is the way to go!

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@smashsquatch I probably should take another test to determine my zones, maybe I’ve been too hard on myself!

I know that runners can’t train past a certain point because of impact, but I agree that doing a 30 minute run feels like I did some significant exercise, but doing even 45 minutes on the bike feels short.
I suppose if the running is doing more whole body stress, it may be the way to go for ‘base’ season, since I have a finite number of hours and doing them while running will get me more of a full body workout then cycling for the same amount of time.

Don’t forget about specificity. Cracking the heart rate up will not magically make you a better cyclist. If that were true, just watch a few few horror movies :smiley:
You need to train your cycling muscles at the cycling contraction frequency.

The only useful thing of doing other sports is to improve cardiovascular fitness (stroke volume, breathing). A well trained heart is worth nothing without ‘cycling legs’.


Absolutely @kjeldbontenbal! My thought was to run for base training during the colder months, and then transition to a mix of cycling/running during the build phase in spring to get that specificity back.

If I understand right, base training is all about building up an aerobic base, so why not do that in a modality that can elicit additional adaptations (e.g. concentric muscular contraction, more core/stability required) at the same time?

Because base is also about type I and type IIA fibers. With running, you train other muscles groups than with cycling. Your cardiovascular fitness will be good, but you cannot put it to good use because you lack well developed oxidative fibers in the muscles you need for cycling.

Running is ‘back of the leg’, cycling is ‘front of the leg’.

What is your goal? General fitness? Some cycling event? If it’s the first, your plan sounds awesome. If it’s the second, I would suggest you make sure you work in some cycling throughout… Especially if your zones are correct and the following occurs

I think this is an oversimplification. On one of the episodes, I believe was Seiler, they talk about data about translatability of various sports to cycling. Swimming didnt have much impact but running did cross over to cycling. Perhaps this isnt so surprising as running does develop quad and gluteal muscle groups.

The challenge you might have in switching to running is that pace there will be influenced not only by CV fitness and muscular endurance, but running economy is another major factor in determining efficiency. Getting your tendon, ligament and muscular stiffness optimized for efficient energy transfer will only come from running or perhaps with strength training.

From my own personal experience, it has taken time to get to the point where I can bring my running fitness closer in line with cycling fitness which I believe is due to this musculoskeletal adaption that needs to happen. I can definitely run for an hour and half at a very reasonable/stable Z2 run but it took time.

I started mixing some running in last fall when I got mentally tired of riding my bike every day. I’ve found that running works good for recovery after an intense day of cycling, probably because different muscles are used. To keep your heart rate down, shorten your stride but keep your cadence up to 180 steps per minute (90 for each foot), which is similar to an average cycling cadence. If your heart rate goes over target, keep shortening your stride, stay light on the front of your feet, which should land below the hips. Just run in place a bit to get the feeling down. Some benefits of running vs cycling are the stress it places on your bones and tendons. Done right, much running energy is returned by elastic recoil in the tendons.

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my n=1 : I started running 1-2 days a week to add some extra aerobic volume (zone 1 in 3 zone system) when I became pretty time limited. It is pretty easy to sneak in a 30-40 minute run here and there.

I have no background as a runner and am primarily a cyclist. My cycling doesn’t suffer in the base or general prep phase, if anything I feel like the extra aerobic volume helps quite a bit, plus some additional bone density never hurts as cyclists.

If you have having trouble keeping your heart rate down: try alternating run/walk, eg. 1 min run, 1 min walk, and decrease the walk interval as you get more fit. You might feel silly initially, but that’s not the point. After a few weeks of this you’ll probably have your walk interval quite short like 10 seconds and keep heart rate low. This I found also helps prevent soreness the next day coming from cycling.

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Great input here everyone!
I think I may have overcomplicated my initial post and so things are getting away from my initial thoughts. If I only have a certain, limited amount of time to train - say 5 hours per week, not including strength training and yoga - what is the best use of my time to develop my aerobic engine? Running or cycling?

Part of my thought here is, if running can elicit a greater response with less training hours, but the crossover from running to cycling is not 1:1 but say 70%, I may still come out ahead by doing the majority of my aerobic build through running. Some of this is probably compounded by the fact that most non-elite runners would probably end up running in Z2 (three zone model) and may elicit gains that way.
I have heard/read some other studies noting that runners train less but seem to have similar or greater V02Max values than cyclists - I know this is caveated by the impact/upright nature of running but it’s an interesting thought. Our bodies were built to run before cycling, so maybe that is where part of this comes from.

I am not concerned about my cycling economy or form since I have been riding for 15+ years and have been doing some form of cycling training (at least for half the year) for 5 years or so. In addition, adding in peak power form won’t take nearly as long as building a base and I could do some sprint training for a few weeks to get that back.

I am coming off of a month or so without cycling, two months of running ~20km/week, and 2.5 months of strength training build up. I am doing a 10K race plan now, with 4 running workouts per week, 2 strength training workouts (more for maintenance, often doubled with runs) and two cycling workouts, one easy and one with threshold intervals. I have taken an FTP ramp test and I will repeat it again after the training plan ends and see where we end up!

As an interesting aside, my animal physiology friends note that the act of running, or even the thought of having to run, elicits an increase in heart rate in humans. It’s not totally clear why this is (priming the body for the effort? Stress?) but it could also contribute to a non-elite runner’s inability to run in Z1.

I didn’t know where to put this, but this thread seems to be about as good as any of the others. As someone who’s done pretty significant volume (700+ hours each of the the last two years) and not seen much improvement in power at threshold, I’ve been forced to think about the purpose of different intensities and incorporating different modalities into my training.

The attached image is the product of my thinking to this point. I have run several marathons and done half-ironman triathlons, so running at a higher volume is something I can do. I also have a C2 which I want to incorporate as well as I think it lends itself particularly well to high intensity work.

I’m certain I’ve done too much in the middle zone at times, and I think there is a chance I’ve not done enough work at high intensities - to the degree that cardiac output may now be a limiter.


  • I do believe there is a greater aerobic benefit per unit of time for running when compared to cycling. Low intensity aerobic work can be done here to the degree it can be handled.

  • The long ride is hard to replace even if you can run for 120 minutes. This should be a staple of your training if the bike is your focus. Once every two weeks at a minimum.

  • I am a big believer in @steveneal’s tempo and it’s ability to challenge Type IIA fibers to work aerobically; this should be a priority - especially for those who see large discrepancies between 5m and 60m power.

  • The rower may lend itself to aerobic capacity work more so than the other modalities. Running hard really beats you up so that’s out. You can do this on the bike, but the rower uses around 85% of the muscles in the body which (a) may allow for extended periods of time at VO2 Max intensities and (b) potentially train the body to shuttle lactate using muscles other than the legs.

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Probably want to change the label “ZONE 2” under intensity*. Interesting and informative scheme. :+1:

* or not :grin: since it’s your scheme and you can call it “fiddlesticks” :man_shrugging: Also occurs to me that it’s a variation on “Zone 2” in the 3-Zone model, in which case I can see the reasoning. Still potentially confusing given that there is Coggan Zone 2, ISM Zone 2, 3-Zone model Zone 2 (Seiler, etc), and others I’m leaving out for brevity.


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Thanks for the reply. I replaced the image with one identifying that middle area as “SEILER ZONE 2”. What’s interesting is I think @steveneal’s heart rate prescription for tempo is right in line with the top of the Norwegian Zone 1. I posted it in a other thread but I believe it’s 82% of HR Max.

I also looked back over a period of eight weeks leading up to Boston where I dropped around 8-10 lbs. I doubled exactly half of those 56 days. I know this is something runner’s do a lot but cyclists tend to shy away from but I’m adding this back in as well. With the multiple modalities it makes sense.


Everyone interested in this topic should read this article.

There are two headline results in the new study. The unsurprising one is that the runners were more efficient than the cyclists at running (with the triathletes somewhere in the middle). On average, the cyclists had to burn 21 percent more energy than the runners to maintain the required pace. That’s partly because the cyclists were a bit heavier on average, but even if you correct for weight, they were still 10 percent less efficient.

The more surprising headline, in contrast, is that the cyclists weren’t more efficient than the runners or triathletes at cycling. Statistically, all three groups were pretty much the same in the cycling test.

Personally I’d rework the priority. For me priority is about what do you do if you get a clash and you cannot do everything that week or block, what are your priority workouts and which get dropped? With so many classed as high priority, the priority won’t help you decide between them.

I tend to work priorities by training phase. For instance base phase then endurance will be that high priority workout. Early build high priority might be tempo. Late build it might be threshold and final weeks before main event I might make vo2 max priority.

Plus sometimes the priority is rest. If time limited as per title of this thread, then rest might get squeezed out, which can be absolutely the wrong priority.

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