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VO2 running vs cycling
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I'm trying to understand something about my personal physiology and how to become a faster triathlete. This week I did two VO2 Max workouts, one running one cycling. Comparing the running vs cycling: the workouts were "hard" in very different ways, and I'm trying to understand why.

Running -- I ran 8 x 1K repeats on the track on 3 min jogging recoveries, each 1K a few seconds faster than the last. The first couple at 6:00/mile pace were fairly easy/sustainable, but the last couple (5:40/mile) were decently challenging. By the last 200m of each 1K, I was breathing quite hard, almost feeling short of air. But there wasn't really any muscle fatigue to speak of.

Cycling -- I did 5 x 5K repeats on an outdoor cycling track on 3 min recoveries, all 5 were within a few seconds and watts of each other (~8 min and a mere 230 watts which is ~105% of my FTP), all by perceived exertion. My legs burned, more and more each 5K. I felt deep muscle fatigue and power dropped slightly through each interval (vs my running where pace was rock steady). My breathing was never hard, barely above my ventilatory threshold really. My heart and lungs never felt like I was working.

It feels to me a bit like my "muscles" are my performance limiter on the bike, and my VO2 max intervals don't take me anywhere near by VO2 max in terms of cardio-pulmonary stress. Put another way, if you did two VO2 max tests on me, one on a treadmill and another on a bike, I suspect you'd get wildly different values. Right?

I'd much appreciate help better understanding what's going on here from a physiological perspective, as well as an pointers on how to remedy (notably, become a stronger cyclist which is my triathlon Achilles heel).
Last edited by: wintershade: May 3, 19 14:13
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Re: VO2 running vs cycling [wintershade] [ In reply to ]
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You're simply less fit on the bike. More time in the saddle will bring them closer on par with each other. Lots and lots of base miles in your future...
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Re: VO2 running vs cycling [indianacyclist] [ In reply to ]
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8 minutes isn’t a good VO2 workout despite having a contribution. It’s more supra threshold. I think I have the term right.

VO2 is pursuit time/distance or less for a workout. So 4min and less.

I do 2 to 3 minutes usually. 8 is way too long.
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Re: VO2 running vs cycling [wintershade] [ In reply to ]
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8 mins at 105% isn't a vo2 workout. It's a fairly boring threshold workout (in that you should probably go longer than 8 minutes).
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Re: VO2 running vs cycling [rubik] [ In reply to ]
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I guess this makes sense. Kind of apples an oranges to compare 3:30-3:45 1K run intervals with 8:00 5K bike intervals.

That being said, I think the difference in how taxed my heart/lungs would have felt had I bike 4 minute max effort intervals would be largely the same. In fact, I think the effect of reaching leg jello but heart/lungs barely working would have just happened even faster. I guess my point is I don’t know that it even physically possible for me to get that “gasping for air so can’t go faster” sensation on the bike; my legs just fill with lactic acid and turn to jelly before I get even close.

Do I just need more “saddle time” base miles this winter, lots of long rides? Or more higher intensity stuff and low cadence strength hills, to build strength/power enough to make my heart work harder?
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Re: VO2 running vs cycling [wintershade] [ In reply to ]
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do a 1 mile TT running, 5k TT cycling after a deep warm up (on different days) and those are good starting VO2 paces for you. Then start repeats say 3-7 (depends on ability to maintain intensity) x 2-3 mins or so at the pace you determined in the tests. Eventually you can get up to 3-5 x 8 minute efforts, which is pretty hard. Experienced athletes can get up to 2 miles or 8k cycling distance at that effort for VO2 tests. However, time would be better spent to generally ride more and put in the miles, and don't fear the inclines (unless you plan on sticking to sprint/olympic stuff). Climb a lot. Climb fast, climb slow, climb steady. Embrace the hills and your cycling fitness will catch up.

As far as the physiology is concerned, your numbers may be different, but not "wildly" necessarily. In fact, it is unlikely they would ever be the same for any person because of the different muscular recruitments and environmental factors required for each sport. Also, cycling is more "resistive" in nature, especially if you have a slower cadence, so you can feel muscle fatigue in a different way than you would running. Without getting too deep, there are many things that play into your fatigue and performance between the two. I would hazard a guess that you likely need to work on your generally volume for cycling as well as mechanics and skills for both cycling (your apparent limiter) and running (most stressful on the body, so improved technique never hurts).

Matt Leu, M.S. Kinesiology
San Pedro Fit Works, Los Angeles, CA
Endurance Athlete and Coach
Consistency/time=results
Last edited by: ironmatt85: May 3, 19 20:56
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Re: VO2 running vs cycling [wintershade] [ In reply to ]
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wintershade wrote:
Do I just need more “saddle time” base miles this winter, lots of long rides? Or more higher intensity stuff and low cadence strength hills, to build strength/power enough to make my heart work harder?

Yes, build that base. If you have lots of hours to throw it then long rides are great. If you're more time limited then look at sweet spot training.

I had the same issue as you in reverse for a while - lots of bike fitness but when I started running my legs weren't strong enough to keep up with the aerobic engine I'd built on the bike. Burning and heavy legs (and injuries if I pushed too hard) were limiting me well before my heart and lungs were. Took quite a while to build up the running miles to get things more in balance. Good news is that with cycling being a non impact sport you should be able to ramp up the volume more quickly.
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Re: VO2 running vs cycling [rubik] [ In reply to ]
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I agree that it’s not VO2 but disagree that 40’ total of TH work isn’t a good workout with real benefits
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Re: VO2 running vs cycling [DFW_Tri] [ In reply to ]
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I agree, 5X8' is one of my standard Threshold workouts.
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Re: VO2 running vs cycling [DFW_Tri] [ In reply to ]
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Longer as in longer intervals. I don't like 8 minute stuff if only 105%, but whatever gets you going.
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Re: VO2 running vs cycling [wintershade] [ In reply to ]
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What is your cadence on the bike and are you measuring hr? Spinning at 95 plus will generally stress your aerobic system more for the desired . Everyone's suprathreshold abilities are different, but you should be getting in the 90 to 95% of max hr in the second half of your intervals especially if they are longer than 2-3 minutes.
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Re: VO2 running vs cycling [Bioteknik] [ In reply to ]
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Thanks guys for responses so far, and @Ironmatt much appreciate the advice.

To answer the question about my HR and cadence
Bike: HR average - 145-147 bpm average for each interval, with max HR value of 152. So pretty low. Average cadence was ~85, but it varied a bit more from 80-low 90s depending on wind direction (outdoor oval track).
Run: Average HR was 160-165 (crept up for faster intervals) with a max value of 182 (near end of last two fastest intervals).

I can never seem to get my HR up on the bike. Did a hellacious ride today with a 2K ft climb with some 14-16% pitches. Max HR was 160 with some prolonged stretches climbing at 300+ watts (which is a big number for my chicken legs)!
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Re: VO2 running vs cycling [wintershade] [ In reply to ]
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wintershade wrote:
I'm trying to understand something about my personal physiology and how to become a faster triathlete. This week I did two VO2 Max workouts, one running one cycling. Comparing the running vs cycling: the workouts were "hard" in very different ways, and I'm trying to understand why.

Running -- I ran 8 x 1K repeats on the track on 3 min jogging recoveries, each 1K a few seconds faster than the last. The first couple at 6:00/mile pace were fairly easy/sustainable, but the last couple (5:40/mile) were decently challenging. By the last 200m of each 1K, I was breathing quite hard, almost feeling short of air. But there wasn't really any muscle fatigue to speak of.

Cycling -- I did 5 x 5K repeats on an outdoor cycling track on 3 min recoveries, all 5 were within a few seconds and watts of each other (~8 min and a mere 230 watts which is ~105% of my FTP), all by perceived exertion. My legs burned, more and more each 5K. I felt deep muscle fatigue and power dropped slightly through each interval (vs my running where pace was rock steady). My breathing was never hard, barely above my ventilatory threshold really. My heart and lungs never felt like I was working.

It feels to me a bit like my "muscles" are my performance limiter on the bike, and my VO2 max intervals don't take me anywhere near by VO2 max in terms of cardio-pulmonary stress. Put another way, if you did two VO2 max tests on me, one on a treadmill and another on a bike, I suspect you'd get wildly different values. Right?

I'd much appreciate help better understanding what's going on here from a physiological perspective, as well as an pointers on how to remedy (notably, become a stronger cyclist which is my triathlon Achilles heel).

I replied to a similar thread concerning the respective high-end performance limitations here, about half way down: https://forum.slowtwitch.com/...._P6873102/#p6873102
Let me know if you have any other questions.

---------------------------------------------------------------

https://connect.garmin.com/modern/profile/domingjm
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Re: VO2 running vs cycling [wintershade] [ In reply to ]
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I actually did two VO2 max tests, One on the bike and one on the run this year. I am a decently experienced runner and have just started cycling less than a year ago. My scores were wildly different.

69 on the run
56-ish on the bike

I am interested in testing again next year with a lot more miles in the saddle. I always find the tests to be helpful on how to focus training for the next 6-12 months.
Last edited by: ruckustrx11: May 6, 19 14:34
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Re: VO2 running vs cycling [domingjm] [ In reply to ]
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im trying to see if i can square the lower heart rate when tired with the less muscle utilized cycling (vs. running or xc skiing) -
if you are going as hard as you can go and the heart rate is not your limiter -- what is? is it the oxygen you can get your lungs to use to fuel the muscles aerobically so you don't reach anaerobic failure as quickly?

the bicep curls seem to me to be an anaerobic activity - i'd compare a 10 second max sprint when rested on the bike where the hr might not get within 15-20 beats of max, to a 10 second sprint at the end of fast leadout of several laps (where i can get very close to max hr).

when tired i feel i can still hit close to best anaerobic efforts (1 minute and less), but aerobic efforts seem to be much harder to match my best. does the running max hr vs. cycling max hr explanation address this (or is there a better explanation)?

thanks for all the thoughts already!
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Re: VO2 running vs cycling [fredericknorton] [ In reply to ]
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Yeah, the examples I provided in the other thread represent the average physiological situation for the different muscle groups recruited for a maximal aerobic output (~2 to 5 minutes). A three minute activity to volitional failure, regardless of the muscle that's producing the work (or the exercise performed), is accomplished by nearly 100% aerobic machinery. But that doesn't mean that your heart is challenged to any extent whatsoever. The local metabolic environment is what shuts the liberation of ATP off in the examples of smaller quantities of muscle mass; bicep curls here are a useful example, which I'm using as an "extreme" cycling exercise. There's some debate as to what, precisely, produces that local fatigue, but inorganic phosphate, which is a product of ATP hydrolysis, is one example of a contender.

Regarding systemic fatigue (e.g., last set of intervals) or a local DOMS-like state in running vs cycling (I think that's what you're asking), if you were able to sever sensory feedback from the muscle, my guess is that your cycling performance would improve more than your running performance purely as a result of the perception of pain, but I don't have any literature to back that up. And in that example, you have to consider how much more work you're asking the sore and fatigued quads and glutes to do during cycling than during running.

In general, I think the answer to the questions you're asking is dominantly answered by the examples I provided above, which ultimately is determined by the quantity of active muscle mass that's being asked to generate a given amount of work.

And FYI, in humans, unless there is underlying pathology (e.g., diaphragm atrophy or scarring of the lungs), ventilation does not limit performance. With horses it's the opposite situation; their VO2 max is limited by ventilation, not cardiac output.


fredericknorton wrote:
im trying to see if i can square the lower heart rate when tired with the less muscle utilized cycling (vs. running or xc skiing) -
if you are going as hard as you can go and the heart rate is not your limiter -- what is? is it the oxygen you can get your lungs to use to fuel the muscles aerobically so you don't reach anaerobic failure as quickly?

the bicep curls seem to me to be an anaerobic activity - i'd compare a 10 second max sprint when rested on the bike where the hr might not get within 15-20 beats of max, to a 10 second sprint at the end of fast leadout of several laps (where i can get very close to max hr).

when tired i feel i can still hit close to best anaerobic efforts (1 minute and less), but aerobic efforts seem to be much harder to match my best. does the running max hr vs. cycling max hr explanation address this (or is there a better explanation)?

thanks for all the thoughts already!

---------------------------------------------------------------

https://connect.garmin.com/modern/profile/domingjm
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