I recently started downloading my trail running and biking sessions onto my computer using a Polar 720i. ( its pretty interesting )

I noticed my heart beat can be in the 170 to 180 range for long peiods of time (20 minutes) when I run compared to when I bike, where it rarely gets over 170. Once in a while if I do a hard hill I can get it as high as 185 but it no where near for as long as I can when I run. The weird part is I feely equally tired/exhausted doing both

The only things I can think of are that I can coast for moments when I bike; there are natural traffic obstacles that prevent me from biking hard for extend periods of time and that running just involves more muscles in my body.

Any thoughts?

Thanks,

George

Try this question on a triathlon forum. Triathletes are well aware that your running HR > your biking HR > your swimming HR. As for the why, I've got no idea. They all hurt me.

Didnt realize thats just the way it was. Thanks.

George

I would only comment that at the same perceived exertion, heart rate is greater on the run than on the bike than on the swim. I think part of his has to do with body postion, Upright on the run, sitting on the bike and prone on the swim.

I find I can maintain a higher heart rate --171-172-- on the bike longer than I can on the run.

Also larger muscles are involved with running -- all very well documented.

_________________
John979

as has been mentioned in the above posts, HR does differ between the 3 dicsplines in triathlon

running definitely elicits higher HR than cycling. it's not so much that running uses larger muscles - both running and cycling use your glutes, quads, calves & they don't change in size ) - it's got more to do more with the physiological cost of propulsion due to the type of work you're doing. keep in mind also that when running, you are using your arms a hell of a lot more than when cycling - so there's more physiological stress as well.

for example - you have to work harder to run 100 metres when cycling then running, and you have to work even harder when swimming. a simple look at the respective times over this distance across all disciplines will show this

the differences vary but at the top level (ie elite triathletes) they are not vastly different as top pros will sit at high HR for the enitre race.

Also when swimming your HR is limited by how hard you can go, which is limited by how fast you can tilt your head to the side and breathe.

_________________
Cannondale is quite simply the best

I'm sorry but that's incorrect....

if you watch elite sprinters, they might only breathe 3-4 times during a 50m sprint. this mean they're not going hard because they aren't breathing? of course not. so backstrokers who have their head out of the water the whole time and can breathe work harder? asboulutely not....

the smaller musculature involved and the difference in body position contribute to lower HR....HOWEVER, top swimmers will still sit on very high HR...eg, Keiren Perkins, former 1500m world record holder sat on high 160's on his WR swim....

I was reffering to long distance swimming such as the swim leg of the ironman, or any swim event that takes more than 5 minutes

_________________
Cannondale is quite simply the best

The HRM is a tool.

You body is the ultimate device you must listen too..

_________________
"Ride it like you've just stolen it!"

I run and bike.

Running I have a hard time keeping my HR below 150.
Biking I have a hard time keeping it over 150.

Cycling is much easier than running. I guess there are not free rides in running.

Here's my take on it:

1) Running is the highest because a) you cannot coast, and b) you are supporting your body weight, not the bike, or the water.

2) Cycling middle road because you still have to support your body, yet to a much smaller degree, but provide more brute power than cycling. Also, you do not use your arms as in running. Case in point: my legs have grown slightly larger since switching from running to cycling.

3) Swimming is the lowest because the water supports your body weight. You just have to provide the motor. Also, the water cools your body, which naturally slows the heart rate, as the body does not need to pump blood to the skin/external layers in an effort to cool itself.

Incorrect I am afraid - research on water polo players and swimmers shows that their sweat rates can be similar to those of land based sports. Your core temperature certainly increases and blood to the peripheries (including skin) is vital to keep you cool....

This more likely due to the fact that when you are running there is a large force when your leg stikes the pavement, causing eccentric contraction of your muscles (ie the muscles are contracting but lengthening at the same time - as opposed to a concentric contraction like when you push off with your leg).
Eccentric contraction of the muscle causes greater "damage" to the muscle fibres. Remember that when you train, you are actually fatiguing and damaging your musles and then you rest and they recover usually stronger than they were before. Eccentric contractions can also performed with weight training to cause additional stress to the muscle.

Anyway, this stress causes greater destruction of the muscle tissue and is the main reason why elite marathon runners can "only" race marathons 3-4 times per year, whereas elite cyclists can race long road races many more times per season.

_________________
You can't be a real country unless you have a beer and an airline. It helps if you have some kind of a football team, or some nuclear weapons, but at the very least you need a beer.
-- Frank Zappa

The contact with the water certainly aids regulation of body temperature but the body temp will still rise, and sweat glands cant tell whether your skin is already wet or not...


The difference in HR is pretty much only due to the muscle mass involved with each activity.

Running has the highest muscle involvement of all sports, AFAIK the only sport that comes close is rowing. Running is also a full weight bearing activity.

Cycling uses many muscle groups, but not as many and not as intensely as running. It is also not really a weight bearing exercise (no matter how sore your arse may get after 100km!). Coasting is the perfect example of this.

Swimming uses much fewer muscle groups/muscle mass. The bodyweight is virtually completely supported during swimming. Think about muscle size in your arms compared to muscle size in your legs.

**edit: cross country skiing is equal to or greater than running. (Sorry, this sport doesn't cross my mind too much coming from Australia!)

_________________
You can't be a real country unless you have a beer and an airline. It helps if you have some kind of a football team, or some nuclear weapons, but at the very least you need a beer.
-- Frank Zappa