Discussion: Running vs Biking workouts

I have always thought that you have to do twice as much biking as running to get the same amount of aerobic conditioning. This does not mean 1 hour of orienteering, just a usual run workout. Example is 2 hours of biking = 1 hour of running.
Anybody have any comments on this.

I think it's probably closer to 3:1. Professional marathoners run about 10 hours a week whereas pro cyclists ride 25-30. The two groups have comperable VO2max numbers.

If you look at any of the widely-published Metabolic Equivalent Tables, running sub 7:30's and biking at race pace are almost equivalent:

For an hour of each, and percentage compared with running:
Running.........................24 545.....100%
Biking.............................21 818......89%
Orienteering-walking.....16 364......67%
Sitting..............................1 818........7%

Of course this is not a measurement of aerobic conditioning. But there has to be some relationship between metabolism and heart rate. So I'd think aerobic conditioning from fast biking could be very beneficial...certainly better than 2:1 or 3:1.

And biking becomes the only option when injury, overuse or age prevents one from running sub 7:30 miles.

A 2:1 ratio usually seemed to be about right for me though this is a general conditioning feeling and not specific to aerobic conditioning. The more I get in shape for cycling the difference becomes greater than double.

When cycling, the arms are much more at rest and I'd guess that fewer muscle groups are involved all around. The two therefore aren't really ever equivalent for general conditioning and the earlier AP discussions about specificity training go into that.

But what if it is junk cycling :)

I read long ago, and use as an equivalent, that you burn 40% as many calories per mile bicycling than running.
I think cyclists, and skiers and rowers, put in more hours because they can, it's so much easier on your body parts to roll or glide than jump from foot to foot (running).

I know that cycling up Blue Hill is harder than running, I have to haul an extra 25 lbs of bike with me, and it only takes a bit less time, and that's only because I can shift up a gear on the one flattish part and gain more speed than I can running.

I can only offer anecdotal evidence but when I'm running a 10 k on relatively flat terrain my heart rate will go in to the 150 range. During the bike portion of a triathlon on relatively flat terrain my heart rate does not go much over 135 to 140. That may say something about my biking ability but I'm typically taking 2 minutes to go 1 km. While running it takes me about 5 minutes to go that same kilometre. On trhe bike I'm going 2 1/2 times the speed with about 90% of the cardio effort.
The work to run 1 km seems to be much more than just twice the the work needed to bike 1 km. Therefore the amount of biking distance needed to get the same amount of aerobic conditioning as running would seem to be much greater than twice.
Anyway isn't it all about how long one keeps the heart rate in a target zone no matter what the exercise is?

According to NASA, the best excercise is rebounding and it is 68-percent more effective than running. When I run at AP intensity 4 my HR is about 180. So while rebounding my HR would be about 300. Not big deal for astronauts for sure, but I might not survive it.

I dont do too much biking in my training, although i would like to; but from experience, the times I´ve trained and measured my heart rate during Biking, most of it doesnt make it to intensity 1. I think some of it has to do with the downhills, that since you are sitting there, it doesnt amount to much at the point, but often at a flat course I feel that the limiting factor is the legs, and not the breathing or heart like it usually feels during running.

Like coach said, bikers as swimmers, who seems like they train 5 hours a day, has the posibility to train more, without being injured. I even felt the same thing when i was skiing during my ITBS problems, that it never was a problem.

Btw. can biking cause damaging effects to running, such as buildup of different muscles or other things?

For me I think it is 1:2.5 since I have so much more running in my legs versus any other sport. Because of my inexperience with biking this will stay at this ratio and when I become more fit at biking this will move to 1:2.

Thank you, attackpoint, for involving a ton numbers and ratios, a sweet table, and NASA, in a discussion about running and biking.

The discussion (particularly Eric and Clark's submissions) suggests that it's likely between 1:1:25 (clark's number's short range) and 1:2.5 (based on what is needed to compete at the highest levels) depending on exertion and ability. Fair summary?

Fair enough. A note to those who'd like to keep HR up on the downhills: replace the freewheel with a fixed cog. Downhills will quickly become the most productive part of the workout: high HR and technique with almost no taxing of skeletal muscles - pretty much ideal.