This is obviously very individual so its only my experience. I got away with a surprising amount less cycling, but still had to get a bit of targeted bike efforts in. I was a very strong swim biker at the time though and my running needed by far the most development. I had some great fitness after this with regard to my own personal levels.

Ultimately the experience made me realize I was getting stronger with less volume in certain activities while I targeted others and it hammered home why I'm the kind of athlete that needed a coach. ;)

a different way to answer this one

i found that with triathlete...the best way to get them to run very fast or a PB at the marathon distance wasnt in completly cutting bike and swim but keeping some of it in the program for active recovery and loosing up session as part of a run focus.

in this kind of structure...i found the lost in FTP to be perhaps 10% over a 2-3 months period and when we get back to bike focus, the FTP would come back very quickly within weeks.

but going 100% running with no bike or swimming wasn't optimal for running performance in most cases. it s amazing how a little bit of swim and bike conditionning can add to the load while keeping injury risk a little lower.

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Jonathan Caron / Professional Coach / ironman champions / age group world champions
Jonnyo Coaching
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There's a few questions in here.

1-How soon after the marathon do you need to be fast at cycling again? Doing a 3 month marathon build in the fall is unlikely to affect FTP in the spring if cycling is brought back for the winter.

2-What's the baseline? Are you a pro cyclist with zero running experience? Or are you going from 5h/w SBR to 10h/w running? I've seen people boost their FTP just by running because their cycling training was so little and at such a low intensity. Just global fitness gains. But it depends on where you're starting.

3-It would make sense to taper off the cycling through the run block. Start off around 70/30 and finish at 100/0. Should help with injury risk too.

My story isn’t quite what you’re asking about as it’s long term versus short term, but I came from a decade plus higher level racing career into triathlon and have lost a massive amount of cycling fitness. I typically averaged around 9 hours a week in the 7 to 11 hour range for most of the year with an ftp of 4.6ish, 20 min power around 5w/kg, 5 min power of 5.8 w/kg and 1 min power of 10 w/kg At peak form each season, usually winning 1-5 bike races a year.

My first year of triathlon I cut back to about 5 hours a week as i added in 2 hours of swimming and 2-3 of running while continuing to race crits. Ftp and one minute power seemed to take the biggest hit early on and all of the sudden I couldn’t close things down in the last few minutes of a race like before.

By year two ftp was down to about 3.95, 5 min down to 5.2, and 1 min to about 7.9 w/kg. Year three even worse.

I have found that my if I do a bigger block of riding (say 7-8 hours) I get some fairly immediate gains, so I wouldn’t be surprised if I could get closerish to those initial power values with cycling only, but swim and run training just kill all of my higher end stuff (because I can’t and don’t really ever train it). I’m definitely not seeing any positive crossover from one sport to the next.

The only plus is that the loss of fitness has made aero gains a necessity, so I’m still doing similar speeds at almost 30 watts less than the first year.

I’ve given up bike racing completely as I have no hope of being competitive at current cycling levels.

Iirc, Stephen Seiler had data to show that there is roughly a 2/3 cross-over between cycling and running. So, 3 hours of cycling = 2 hrs of running and vice versa.

Your experiences coaching aligns well with my own personal experience, and that of my good runner friends. Given the high degree of cross-over, the aerobic benefits couple well with the decreased "running load"... Allowing for recovery from the pounding of high volume running, while still maintaing (or even building) some aerobic fitness.

I have a friend who is a very good marathoner... Completing 10-12 per year, at sub-3hr pace as a 58 Yo male. He does 2-3 50 mile rides a week coupled with about 40mpw running. Obviously, the devil is in the details of making that work. But, it certainly, can and does... When done right.

My n=1 experience is that I can substantially cut back on cycling for a run focus with little/no loss in ftp over a 6 week period, if run volume / intensity is increased. I've done that many times with great success. Rotating focus periods of 6-8 weeks is a staple of my triathlon training during the off/early season.

what are run times? Before and after?

My open run times are basically the same from the beginning of triathlon to now, mid 18s 5k and mid 39s 10k. In a triathlon anything from barely sub 20 to 22 5k and 42-45 10k depending on how badly I execute the bike. But I've run sub 17/mid 35s in the past in my early 30s when I only ran and was doing 50-60 mpw.

I went from bike racing to running to bike racing to triathlon, so always had decent starting points (48 min 10k off the couch, 38 min a year later, etc), but I never did well relative to what I did with a pure focus on that specific sport. Which makes sense, I guess.

All that to say, maybe it's just me, but I simply have never had success with the notion of aerobic abilities transferring. The specific nature of each event has always led to me needing very specific and lengthy preparation to be successful (even within sports, i.e. a road race versus a crit, 5k versus half, etc).

this can be tough to quantify as you are much older. but many bike racers I see dont lose fitness as rapidly as a runner can.

I have twice tested FTP after blocks of no riding; once in my mid-40s when I was coaching HS running and not riding much at all, and once this past winter/spring.

For the first I broke my toe and was going stir crazy so I dusted off my bike and did a max effort for like 40 minutes. I was shocked how close to my former FTP I was.

This past winter weather was miserable and I don't do indoor cycling so I rode near zero and ran more than I have in a decade. When I tested FTP mid-March I was right back where I was in the fall when prepping for my end of season race.

The big however to this is my performance in a duathlon in April. I faded very hard about one hour in (19 or so minutes of the first run and 40 minutes of riding) and my second run was a painful shuffle.

So my theory is that while your ftp as a training number might not suffer a bunch, you have almost no cycling endurance to support it so it is really a meaningless number. I suspect in both cases if I had done an actual full-hour effort rather than estimate from 40-minute efforts, my number would have dropped drastically.

So if you are just trying to do a ten-mile TT after no riding but lots of running, you may be fine, but an actually tri/duathlon of an hour or longer is going to be rough.

I’m going to look up this reference to Seiler, that could be something to work off if it has some foundation to it.

Going through the replies and it’s really up in the air. Seems to be little correlation between experiences. I was thinking maybe it was a case that the less fit you were then the more cross cover gains you might make - and the more fit you were, the steeper the losses would be. Perhaps even some theoretical middle ground where you wouldn’t lose or gain fitness.

Possibly that’s just not even remotely the case and it’s way more complex judging by the personal experiences!

Thought it through and don’t want to risk any severe losses so going to keep doing Z1 polarised type long efforts and use that to build fitness for the running as I cant handle as much running volume as I’d like. Thought that was an astute comment up top (on phone and really bad at multi quoting so haven’t even tried!).

I do still want to try a period of maybe 4 weeks where I don’t ride at all and test at both ends but will wait until I can handle a lot of running volume and running speed work together to give it a proper shot.

https://forum.slowtwitch.com/...en%20seiler#p7084621

I don't find the experiences above that different. Cdw seems the most "different". But, even that isn't 180 degrees out.

Nothing above is saying that you won't lose some sport specific fitness, if you focus on another sport. But, its not as bad as you might think, and it can be managed with just a little bit of activity in that de-emphasized sport (as little as 1x per week). There will still be a need to rebuilt some after a return to balanced training. But, for triathlon the question is really can you build better overall triathlon performance through focus blocks vs continuous balanced training? Or for single sport, can you gain some benefit from "cross-training"?

For single sport that question is based on: can you do more single sport, or not? For running, if the mechanical load of running limits weekly run volume, the perhaps cycling can fill that volume gap and improve overall aerobic fitness (once the run volume is maximized, but time is still available and recovery isn't compromised).

Again, at the end of the focus, there will always be a need to return to balanced, multi-sport, race specific training to maximize multisport performance.

Sort of. Consistent and tough training in running can help you maintain and improve your cycling fitness to some extent. While running and cycling are different activities that engage different muscle groups and movement patterns, they both involve cardiovascular endurance and aerobic capacity. Running is a great cardiovascular exercise that can help increase your heart rate, lung capacity, and overall cardiovascular endurance. This improved cardiovascular fitness can benefit your cycling performance by allowing your heart and lungs to deliver more oxygen to your muscles during cycling. Both running and cycling primarily rely on the aerobic energy system. Running can help improve your aerobic capacity, which translates to better endurance during cycling. Also, running places different stresses on your leg muscles compared to cycling. Running helps develop strength and endurance in your leg muscles in a slightly different way, which can complement your cycling training. Stronger leg muscles can contribute to improved cycling power and efficiency.

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Ryan
http://www.SetThePaceTriathlon.com
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