Kayaking to Burn Calories: Horsepower and Cadence

[leong]

Say there is a constant 30-knot wind. You have a choice to paddle at maximum effort either:

1. With the wind

2. Against the wind

Question: Which exercise burns more calories per unit time?

Note the title includes a hint. You'll even burn some calories thinking about an answer to my brainteaser.

[Doug]

Just guessing here:

They will both burn the same amount of calories but you may stay cooler against the wind. Since you are by your description using maximum effort both upwind and downwind, the force used remains constant burning the same amount of calories.

Or perhaps against the wind your body may remain cooler having you retain fluids longer. I wonder if this in turn could slow your metabolism which would burn less calories.

Just thinking out loud here.

Leon you sucked me into this one. Haha!

Doug

[rfolster]

Leon, there is not enough information to answer the question! What about boat drag, wave height, kayaker's breakfast choice? Oh, never mind. I think I will stay clear of this one.

[leong]

Leon, there is not enough information to answer the question! What about boat drag, wave height, kayaker's breakfast choice? Oh, never mind. I think I will stay clear of this one.

He/she uses the same boat to go upwind or downwind so drag doesn't matter for this limited question. However, to eliminate the need for any calculations, assume the water is perfectly still (no waves or current). You got me on the breakfast though. It was one serving each of bran flakes, orange juice and skim milk.

[lhunt]

Going against the wind is less aerobic, more strength training. You have to pull harder at each stroke to move the paddle (actually the paddle is staying relatively still, it's harder to move you, but it comes to the same thing). Your cadence tends to go down when moving against the wind, too (unless you take shorter strokes).

Now, which burns more calories, aerobic vs. strength training? Hmmm..."Per unit time"... Well, you burn more calories in an hour of aerobic activity than an hour of strength training. But if you really pour on the juice going upwind you will still burn extra calories for an hour afterward trying to rebuild muscle, and having extra muscle makes you burn more calories per day even when you're not exercising. So if "per unit time" means calories you actually burn while paddling, it makes me vote for the downwinder. But for actually losing weight and keeping it off, I'd go the other way. Depending, of course, on those bran flakes.

Happily, if you went downwind you are probably going to have to go back upwind to get home, or vice versa, so you'll get both. Ain't life beautiful?

-Lisa

[Phil Allen]

At maximum (physiological) effort, up wind or downwind would be irrelevant (short of minor details like calories lost to heat from the difference in apparent wind speeds). Speed over ground on the other hand...

Phil

[Doug]

I don't think Leon knows the answer.

[leong]

I don't think Leon knows the answer.

Well, Leon thinks he knows the answer.

Here are two pretty good hints: The first hint is to help you understand why there is a difference between upwind and downwind for this quiz. The second hint shows by experiment that there actually is a difference.

Hint 1. Consider an automobile engine. If you look at a car’s horsepower curve you’ll see that the engine has a peak horsepower at some rpm value.

Hint 2. Wearing a heart rate monitor go and paddle as fast as you can first downwind and after a long rest (or the next day) paddle upwind. See how long it takes to get your heart rate up to its maximum. There will be a significant difference in time to get to your maximum heart rate. Actually you don’t even need to measure your heart rate. You’ll see the difference by how hard you’ll be huffing and puffing. Note that the higher the power (effort) the higher the heart rate.

Lisa said “Happily, if you went downwind you are probably going to have to go back upwind to get home, or vice versa, so you'll get both.”

Even assuming that the exercise value is equivalent upwind or downwind (which it's not), you won’t get the same workout if you don’t use maximum effort to get back to your starting point. Say the exercise period is 10 minutes by definition. If you choose to go downwind at maximum effort then you’d have to do a lot of work to get back to your starting point against the wind, right. But the other way you get a free ride to your starting point with the wind at your back, right. So it’s not symmetrical.

Gotta go now, my kayak is waiting patiently.

[lhunt]

So it’s not symmetrical

No, of course not. It's just nice to get some of each.

Here's my thought: Take it to an extreme. Imagine paddling against such a high wind that you can barely move your paddle (this wind is pushing you backwards). If that's hard to imagine, try imagining sitting on a stationary kayak-shaped rock in the middle of a river facing downstream with such a high current that it's hard (but possible) to move the paddle against it. Now take a few strokes. Are you limited by heart rate/breathing or by muscle strength? On the other hand, turn around and face upstream and "paddle". Are you limited by heart rate/breathing, or by your ability to turn the paddle around fast enough?

It's similar to comparing weight lifting against using the elliptical machine at the gym. Or maybe it's more similar to using the elliptical machine at a moderate level vs. a very high (slow) level. Or pedaling a bicycle up a very steep hill vs. going on the flat, vs. going downhill. At some point the exercise is too "hard" (you can't get any cadence, and are just straining your muscles anaerobically), or too "easy" (you are limited by your ability to make the motions fast enough, such as when bicycling down a very steep hill - just can't get your legs to move that fast). But if there is some resistance, you are going to get your heart and lungs working harder if your muscles are moving fast than if they are just straining against a heavy weight.

Kayaking, like most exercise, is part aerobic, part strength training. When you go upwind, the ratio of strength training to aerobic exercise goes up. I believe from experience that going against a stiff wind is less aerobic, and with a stiff wind is more. Maybe the tipping point isn't exactly in still air - maybe it's slightly one way or the other. That would depend on how muscly you are. I think a muscly guy would find the tipping point to be more upwind than me, because he can keep up his cadence better.

It's also harder to keep up with Leon in a stiff headwind, but that's another topic altogether!

As to calories, I have a feeling that the difference is there. But because the calorie difference between aerobic and anaerobic is pretty minor, the difference when paddling upwind vs. downwind is even more minor, because it's a blend of both types of exercise.

-Lisa

[leong]

No, of course not. It's just nice to get some of each.

Here's my thought: Take it to an extreme. Imagine paddling against such a high wind that you can barely move your paddle (this wind is pushing you backwards). If that's hard to imagine, try imagining sitting on a stationary kayak-shaped rock in the middle of a river facing downstream with such a high current that it's hard (but possible) to move the paddle against it. Now take a few strokes. Are you limited by heart rate/breathing or by muscle strength? On the other hand, turn around and face upstream and "paddle". Are you limited by heart rate/breathing, or by your ability to turn the paddle around fast enough?

It's similar to comparing weight lifting against using the elliptical machine at the gym. Or maybe it's more similar to using the elliptical machine at a moderate level vs. a very high (slow) level. Or pedaling a bicycle up a very steep hill vs. going on the flat, vs. going downhill. At some point the exercise is too "hard" (you can't get any cadence, and are just straining your muscles anaerobically), or too "easy" (you are limited by your ability to make the motions fast enough, such as when bicycling down a very steep hill - just can't get your legs to move that fast). But if there is some resistance, you are going to get your heart and lungs working harder if your muscles are moving fast than if they are just straining against a heavy weight.

Kayaking, like most exercise, is part aerobic, part strength training. When you go upwind, the ratio of strength training to aerobic exercise goes up. I believe from experience that going against a stiff wind is less aerobic, and with a stiff wind is more. Maybe the tipping point isn't exactly in still air - maybe it's slightly one way or the other. That would depend on how muscly you are. I think a muscly guy would find the tipping point to be more upwind than me, because he can keep up his cadence better.

It's also harder to keep up with Leon in a stiff headwind, but that's another topic altogether!

As to calories, I have a feeling that the difference is there. But because the calorie difference between aerobic and anaerobic is pretty minor, the difference when paddling upwind vs. downwind is even more minor, because it's a blend of both types of exercise.

-Lisa

In the first case you discussed (wind is so strong you can barely move your paddle) the physics of the problem is that your maximum power output is close to 0 because power equals force * speed and the speed is close to 0. Think of it this way: Instead of paddling just hold on to a buoy so your boat won't move. No work is being done and therefore the output power is 0. On the other hand, there is some internal work going on inside your body, it’s necessary for your muscles to generate the force to hold onto the buoy.

Nevertheless, with the possible exception of your last statement, in this and your previous post you got the answer right; i.e. you'll burn more calories going downwind at your maximum speed (effort) than going upwind at your maximum speed (effort). Your reasons are not wrong, but they don't address the heart of the matter. So the following is what I think is the correct answer followed by some additional explanations:

The greater is the power output to move a kayak the greater will be the body’s internal calories burned. I think this is obvious. And the maximum power output that you can generate at a very low cadence (the case of going into the wind) is less than the maximum power output you can generate at a higher cadence (going downwind). That’s the answer. Some explanations follow:

An internal combustion engine’s maximum power curve starts at 0 at an rpm of 0 and hits a peak maximum power at some engine rpm. Analogously, your paddling maximum output power vs. paddle cadence also hits a peak at some cadence. At 0 cadence, the maximum output power is 0. As you increase the cadence your maximum output power increases until the peak maximum output power is reached. Call that cadence the optimal cadence. Of course, above the optimal cadence, your maximum output power is less than the peak maximum power. I don’t know where the optimal cadence is for kayaking, but I assume it occurs at a speed faster than you can paddle. Going upwind your paddle cadence is low so your maximum output power is lower than it would be for going downwind where the cadence is higher and closer to the optimum cadence.

Regarding your bicycle example, you are right. But, again, a little more clarifying physics. Say you have a one-speed bike. At the optimal pedal cadence, your maximum output power peaks. Going uphill as fast as you can you probably won’t be able to reach that optimal cadence, so your maximum power will be below the peak maximum power. But going downhill as fast as you can your cadence might be faster than the optimal cadence. But if you had an infinite set of gear ratio choices you could change to a gear ratio that maximized your fastest speed. Then you would be pedaling at the optimal cadence and your output power would be at its peak. And that is one reason why bicycles have variable gear ratios; i.e. to allow you to maximize your speed. Obviously the other reason is to allow your cadence to stay relatively steady and at about the same level of effort, whether or not you’re trying to maximize your speed.

>>Lisa said, “But because the calorie difference between aerobic and anaerobic is pretty minor, the difference when paddling upwind vs. downwind is even more minor, because it's a blend of both types of exercise.”

Well, my analysis is for output power and for that I’m sure I’m right. It’s possible that due to inefficiency, the input calories burned per unit of time are much more than the equivalent output power in units of calories per unit time. However, I looked up this site http://www.nutristra...oriesburned.htm that has a table of calories burned for various exercises. They don’t include vigorous kayaking but they do include vigorous canoeing (which is comparable, I think). Here are the results comparing vigorous weight lifting to vigorous canoeing for a 180 pound person for one hour of exercise:

Weight lifting = 490 calories per hour

Canoeing = 981 calories per hour

You might argue that the weight lifting is not continuous so it’s probably too low per minute of actual exercise.

However, I’m fairly certain that I’m right about the answer to the quiz. That’s because I re-tested today paddling with and against a 17-knot wind. I was much more winded paddling downwind at my maximum effort than upwind. I think this implies more calories burned per unit time going downwind. I didn’t have my heart monitor for a more objective result.

PS

My prior post was just before going paddling. Ironically this post is just before going pedaling (I like to ride at night).

PPS

Muscly = muscular, right?

[rfolster]

Leon, I have three issues with your thought process:

In the first case you discussed (wind is so strong you can barely move your paddle) the physics of the problem is that your maximum power output is close to 0 because power equals force * speed and the speed is close to 0. Think of it this way: Instead of paddling just hold on to a buoy so your boat won't move. No work is being done and therefore the output power is 0. On the other hand, there is some internal work going on inside your body, it’s necessary for your muscles to generate the force to hold onto the buoy.

If your equation of power = force * speed is correct, then a car revving it's engine to hold its position on a steep hill is not using any power?

However, I’m fairly certain that I’m right about the answer to the quiz. That’s because I re-tested today paddling with and against a 17-knot wind. I was much more winded paddling downwind at my maximum effort than upwind. I think this implies more calories burned per unit time going downwind. I didn’t have my heart monitor for a more objective result.

Are you certain you applied your MAXIMUM EFFORT in each instance? I think that there may be a human-error mental trick at play. When paddling with the wind, we can all agree that there is a reduced effort to move the boat, so we can concentrate on paddling with a strong cadence, which provides not only a high aerobic workout, but a positive emotional reward of distance-to-effort ratio. When paddling against a strong head wind, there is a very strong negative emotion regarding the lack of distance-to-effort ratio, and can tend to reduce your cadence in order to "just push the boat along". Now Leon, please do not take this as any type of insult to your paddling abilities since I know for a fact that you can paddle circles around me, backwards, with your eyes closed, using one hand, and...well, you get the point.

I would like to offer everyone a challenging, and I must point out - DANGEROUS - (please bring plenty of spotters with you) exercise if you dare. Find yourself a strong headwind, and paddle for the purpose of paddling EFFORT alone, and not distance or control. The point is to put your absolute maximum effort into it. The reason I say that this is dangerous is that, if you do this correctly, you will not be paying as much attention to your stability or direction into the wind and you should have several spotters to help you if you get into trouble. I think if you do this, you will find yourself huffing and puffing much sooner than if you were paddling with the wind.

My final point is the misconception that this is solely a difference of upwind horsepower verses downwind cadence. If you want to discuss pure calorie burn, you must use BOTH repetition and resistance for a maximum calorie burn. There has been a recent explosion in resistance-type gym equipment that is designed to provide this exact type of workout because they have found that merely getting your heart rate up is not enough to burn the maximum amount of calories. Maybe this analogy will help:

Paddling downwind = running on a treadmill

Paddling upwind (low cadence) = lifting weights

Paddling upwind (MAX cadence) = running on an incline-trainer type of equipment

I originally thought that, paddling at MAXIMUM EFFORT should be equal for both upwind and downwind (based on your typical physics equations that maximum should be equal across the board), but I think that you can never truly reach your maximum effort paddling downwind since you have a low-resistance situation. Let's really max out the example and paddle with a 100 knot wind (scientific example only with no wind-wave results). I don't know exactly how fast you would get pushed, but let's just say you get pushed 30 knots. Can anyone in this club paddle at a 30 knot cadence? Once you put the paddle into the water, your boat will just be "pushed" past it faster than you can pull through the stroke.

In conclusion, my answer is to get BOTH horsepower and cadence, I would choose to paddle into the wind.

[lhunt]

I was referencing this article (OK, it's for women, but I think the basic concept holds for all). Mostly the part that says: "Calorie for calorie, cardio has a slight advantage. You'll burn 8 to 10 calories a minute hoisting weights, compared with 10 to 12 calories a minute running or cycling" Now, that's a pretty small difference for two very different activities. And we are talking here about one activity that is pretty similar (going upwind or down). The article goes on to point out, though, that building muscle burns as many calories in the long run.

Another frame of reference is using the elliptical machine at the gym with a heart monitor. There is an optimum setting, as you say - an optimum cadence. Too heavy and I can't get to max. That's understood. But too light, same problem, even if there is some resistance. That's harder to understand. There is biochemistry involved, along with your basic physics.

But I think we're mostly in agreement.

The point is to put your absolute maximum effort into it... I think if you do this, you will find yourself huffing and puffing much sooner than if you were paddling with the wind.

Actually this happens all the time in races, and in workouts on the river. I'm pretty sure on this point: I huff and puff more going downwind, definitely, though abs and legs burn more going upwind. Heart monitor proves it. This is true even when the current counteracts the wind; that is, even when I end up going the same speed over ground in both directions (which presumably removes most of the psychological component).

-Lisa

[leong]

Leon, I have three issues with your thought process:

If your equation of power = force * speed is correct, then a car revving it's engine to hold its position on a steep hill is not using any power?

Rob,

I’ll only address your first point here (the others points later) plus one general point.

I’m talking about output power as opposed to input power. When a car is not moving on a hill there is no output power at all! You could just as easily have used the parking brakes to hold the car’s position on a steep hill. The fact that you’re inefficiently using the engine to hold position doesn’t change the output power. Consider two cars idling on a flat road going nowhere. In both cases the output power would be 0; however, there would be two input powers, perhaps different (one car wasting more gas than the other).

My general point is that, everything else being equal, increasing the output power supplied by an engine (or person) almost certainly increases the input power required to cause the output power and therefore the gasoline (or calories) burned. So if your maximum output power going downwind is greater than your maximum output power going upwind then doesn’t it stand to reason that the two input powers have the same order relationship? If the wind is so strong that you can’t make any headway then you have 0 output power; in fact, just drop an anchor, drink a beer and you’ll do just as well as you would by paddling. And to boot, your input power will be 0 as well.

- Leon

[leong]

I was referencing this article (OK, it's for women, but I think the basic concept holds for all). Mostly the part that says: "Calorie for calorie, cardio has a slight advantage. You'll burn 8 to 10 calories a minute hoisting weights, compared with 10 to 12 calories a minute running or cycling" Now, that's a pretty small difference for two very different activities. And we are talking here about one activity that is pretty similar (going upwind or down). The article goes on to point out, though, that building muscle burns as many calories in the long run.

Another frame of reference is using the elliptical machine at the gym with a heart monitor. There is an optimum setting, as you say - an optimum cadence. Too heavy and I can't get to max. That's understood. But too light, same problem, even if there is some resistance. That's harder to understand. There is biochemistry involved, along with your basic physics.

But I think we're mostly in agreement.

Actually this happens all the time in races, and in workouts on the river. I'm pretty sure on this point: I huff and puff more going downwind, definitely, though abs and legs burn more going upwind. Heart monitor proves it. This is true even when the current counteracts the wind; that is, even when I end up going the same speed over ground in both directions (which presumably removes most of the psychological component).

-Lisa

I didn’t read the article you referenced but I think that a 20% (10C to 12C) to 25% (8C to 10C) advantage of cardio over weight lifting is more than a slight advantage. Also, it’s not clear that the article is addressing a maximum effort in either case.

Do you agree that if the wind is so strong that you can’t make any headway at all (just hold the kayak in one position) your output work (power) is 0? And as I told Rob, in that case just drop an anchor or hold on to a buoy and your input work will go to 0 as well. Compare this to paddling as fast as you can going downwind (say going at 10 knots). Don’t you think the second case will require more input power as well as output power?

In your elliptical example you say, “Too heavy and I can't get to max. That's understood. But too light, same problem, even if there is some resistance. That's harder to understand.”

I covered this earlier in my bicycle example. I don’t think that it’s hard to understand. If you can’t pedal fast enough to reach the optimal cadence than you won’t maximize your output power or speed. In the case of a bicycle, though, there might be a gear ratio available that will allow you to pedal at the optimal cadence.

I think that you responded backward to Rob’s statements, “The point is to put your absolute maximum effort into it... I think if you do this, you will find yourself huffing and puffing much sooner than if you were paddling with the wind.”. That is, you agreed to the opposite of your own premise.

One final point. Without specialized measuring equipment, I can’t prove that you burn more calories at maximum effort paddling downwind than paddling upwind. But I can prove analytically that your output power is greater. And I do know (from cycling friends that use power meters on their bicycles) that pedaling at maximum effort down a hill tends to use more power than pedaling up a hill, but, of course, this doesn’t address input power or calories burned.

Anyway, except for some background music and notation I think we both agree.

Respectfully,

Your training partner whose stuck in 80 degree weather today (but I can’t paddle … going to visit friends)

[lhunt]

Your training partner whose stuck in 80 degree weather today (but I can’t paddle … going to visit friends)

Yeah, well, we can't paddle, either - it's snowing here.

I think that you responded backward to Rob’s statements, “The point is to put your absolute maximum effort into it... I think if you do this, you will find yourself huffing and puffing much sooner than if you were paddling with the wind.”. That is, you agreed to the opposite of your own premise.

I don't see it; I meant to disagree (respectfully :-) ) with Rob.

I covered this earlier in my bicycle example.

OK, if you say so. I thought your bicycling example was only if there was no load on the pedals because the bike had no gear for it. I'm talking about using a machine where there is some resistance, but low enough to require a higher than optimum cadence. You did say there is an optimum cadence, and I agree. The question is, if it is pure physics, why isn't a very high cadence with low resistance not optimum?

[rfolster]

I’m talking about output power as opposed to input power. When a car is not moving on a hill there is no output power at all! You could just as easily have used the parking brakes to hold the car’s position on a steep hill. The fact that you’re inefficiently using the engine to hold position doesn’t change the output power. Consider two cars idling on a flat road going nowhere. In both cases the output power would be 0; however, there would be two input powers, perhaps different (one car wasting more gas than the other).

Let's back up for a second. I thought the discussions all along was regarding burining calories (input power) and not the speed of the boat (output power).

[leong]

Leon, I have three issues with your thought process:

If your equation of power = force * speed is correct, then a car revving it's engine to hold its position on a steep hill is not using any power?

Are you certain you applied your MAXIMUM EFFORT in each instance? I think that there may be a human-error mental trick at play. When paddling with the wind, we can all agree that there is a reduced effort to move the boat, so we can concentrate on paddling with a strong cadence, which provides not only a high aerobic workout, but a positive emotional reward of distance-to-effort ratio. When paddling against a strong head wind, there is a very strong negative emotion regarding the lack of distance-to-effort ratio, and can tend to reduce your cadence in order to "just push the boat along". Now Leon, please do not take this as any type of insult to your paddling abilities since I know for a fact that you can paddle circles around me, backwards, with your eyes closed, using one hand, and...well, you get the point.

I would like to offer everyone a challenging, and I must point out - DANGEROUS - (please bring plenty of spotters with you) exercise if you dare. Find yourself a strong headwind, and paddle for the purpose of paddling EFFORT alone, and not distance or control. The point is to put your absolute maximum effort into it. The reason I say that this is dangerous is that, if you do this correctly, you will not be paying as much attention to your stability or direction into the wind and you should have several spotters to help you if you get into trouble. I think if you do this, you will find yourself huffing and puffing much sooner than if you were paddling with the wind.

My final point is the misconception that this is solely a difference of upwind horsepower verses downwind cadence. If you want to discuss pure calorie burn, you must use BOTH repetition and resistance for a maximum calorie burn. There has been a recent explosion in resistance-type gym equipment that is designed to provide this exact type of workout because they have found that merely getting your heart rate up is not enough to burn the maximum amount of calories. Maybe this analogy will help:

Paddling downwind = running on a treadmill

Paddling upwind (low cadence) = lifting weights

Paddling upwind (MAX cadence) = running on an incline-trainer type of equipment

I originally thought that, paddling at MAXIMUM EFFORT should be equal for both upwind and downwind (based on your typical physics equations that maximum should be equal across the board), but I think that you can never truly reach your maximum effort paddling downwind since you have a low-resistance situation. Let's really max out the example and paddle with a 100 knot wind (scientific example only with no wind-wave results). I don't know exactly how fast you would get pushed, but let's just say you get pushed 30 knots. Can anyone in this club paddle at a 30 knot cadence? Once you put the paddle into the water, your boat will just be "pushed" past it faster than you can pull through the stroke.

In conclusion, my answer is to get BOTH horsepower and cadence, I would choose to paddle into the wind.

Now back to your other points:

“Are you certain you applied your MAXIMUM EFFORT in each instance?”

No, but I’m never completely certain about anything. However, I work out in my kayak almost every day and it’s usually windy where I am. If there’s any difference in my effort I think I try harder on the upwind runs. That’s because going downwind in a 20-knot wind I probably hold back a little because of the fear of broaching and capsizing (which happened at least twice last year). Yet, even with a sub-maximum downwind effort I huff and puff more than on the upwind section (and a heart monitor is consistent with this … my rate goes up higher and faster going downwind). After all of this experimental evidence I analyzed the physics of the situation and the results were consistent with my experimental results. Nevertheless, both my experiments and analytic approach could be erroneous. Also, I could be wrong assuming that more power output implies more power input and that in turn implies more calories burned. The physiology thing may be behind my knowledge. I think an exercise stress testing facility could prove or disprove my conclusions.

“I think that there may be a human-error mental trick at play. When paddling with the wind, we can all agree that there is a reduced effort to move the boat, so we can concentrate on paddling with a strong cadence, which provides not only a high aerobic workout, but a positive emotional reward of distance-to-effort ratio.”

See my prior comments.

“Paddling downwind = running on a treadmill

Paddling upwind (low cadence) = lifting weights

Paddling upwind (MAX cadence) = running on an incline-trainer type of equipment”

I think that the much higher cadence (closer to the optimal cadence that maximizes power) for the first exercise above more than makes up for the increased resistance of the second and third exercises.

“Let's really max out the example and paddle with a 100 knot wind (scientific example only with no wind-wave results). I don't know exactly how fast you would get pushed, but let's just say you get pushed 30 knots. Can anyone in this club paddle at a 30 knot cadence? Once you put the paddle into the water, your boat will just be "pushed" past it faster than you can pull through the stroke.”

Yes, that’s very true. But, in this extreme example, you wouldn’t be able to paddle upwind either. Your paddle would be pulled out of your hand. But at reasonable wind speeds you can paddle at the optimal cadence going downwind.

- Leon

[leong]

Yeah, well, we can't paddle, either - it's snowing here.

I don't see it; I meant to disagree (respectfully :-) ) with Rob.

OK, if you say so. I thought your bicycling example was only if there was no load on the pedals because the bike had no gear for it. I'm talking about using a machine where there is some resistance, but low enough to require a higher than optimum cadence. You did say there is an optimum cadence, and I agree. The question is, if it is pure physics, why isn't a very high cadence with low resistance not optimum?

“I don't see it; I meant to disagree (respectfully :-) ) with Rob.”

Ah, I see it. You were implicitly agreeing to “absolute maximum effort”, not Rob’s conclusion. Okay then. Please don’t break my other leg.

“You did say there is an optimum cadence, and I agree. The question is, if it is pure physics, why isn't a very high cadence with low resistance not optimum?”

At a very low cadence the maximum power of a human is very low. As the cadence increases the maximum power increases until the optimal cadence is reached. At the optimal cadence the human’s maximum power is at its peak. When you increase the cadence above the optimal cadence the maximum power gets smaller. There’s only one peak for the power curve. So once you find the peak it corresponds to a single value of cadence (the optimal cadence). And that peak power implies the force the human can apply, since power = force (resistance) * speed (and speed is proportional to cadence … I don’t want to get into rotational motion here). So, there is only one pair (cadence, resistance) that is optimal.

Here’s a picture of a typical power curve:

http://www.google.co...29,r:0,s:0,i:86

This is from a cycling article but it’s similar for paddling a kayak.

- Leon

PS

BTW, in my other brain teaser “Kayak Resistance and Speed”, where the question was “How fast will you be able to sprint with the faster kayak?”, I purposely disregarded the power curve for a human. So, the purportedly “correct” answer in my table is slightly wrong. But it’s not far from correct and I didn’t want to add a subtle complication to that quiz.

[leong]

Let's back up for a second. I thought the discussions all along was regarding burining calories (input power) and not the speed of the boat (output power).

Right or wrong, my assumption is that increasing the output power also increases the input power and the calories burned.

[lhunt]

Right or wrong, my assumption is that increasing the output power also increases the input power and the calories burned.

Um... then I don't think you can use the example of a car with the emergency brake on, can you? I think that mixes in too many other concepts (Isn't that the dynamic energy of going up the hill turned into the potential energy of the stopped car or something like that?) Certainly the car with the emergency brake on isn't burning any gas, but I don't think that has anything to do with the discussion. The car trying to stay still by revving the engine is burning gas, and a person trying to keep the kayak moving but being pushed back by the wind is also burning calories.

The guy paddling like mad to stand still is actually moving - his hands are moving, anyway (and more of him, if he has a good stroke :-) ) So he is definitely burning calories to keep his paddle moving against resistance. I'm saying he isn't working as aerobically because he has to slow his movements when pulling the paddle through the water. That's because the muscles involved can't take in enough oxygen locally to do the deed. The blood vessels aren't getting it there fast enough or the muscle cells aren't taking it up fast enough, or whatever. The heart and lungs are therefore not limiting him - his muscles are limiting him. Breathing harder doesn't help because there's a local logjam in oxygen transport. This situation results from the water feeling "thicker" (because the boat can't move forward to relieve some of the resistance). The paddler feels it as the burn of muscle fatigue. I think I understand all of this as being a good reason why it's hard to reach maximum heart/lung efficiency when paddling upwind. This guy is getting a great workout, making his muscles a little bigger with every stroke, but he's not working his heart and lungs quite as much.

Now, if you talk about downwind, you get different limitations. Rob talked about paddling downwind in such a fast wind that you can't paddle fast enough. No, you're not going to get a very high heart rate doing that, either. Any time your cadence has to increase beyond some optimal level, you'll fall off on your aerobics, and it will make more sense to "coast". I believe this, but cannot really explain it. Leon, I don't think you have explained it very well, either (yet), although it seems to be obvious to you that it happens. I bet it has something to do with the recovery time in the muscles - they contract by sliding the muscle fibers one over the other, and they have to slide back (relax) before they can contract again. Since the muscles aren't working very hard when the paddle is in the water, the resulting sum of oxygen usage is reduced, and because there is a limitation on turnaround time, the paddler can't make up for it by moving faster. Or something like that.

Of course, in both cases, if the guy keeps paddling at the lower or higher cadence, he probably can train his muscles to increase the range. And when paddling against the wind, it is possible, as Leon has often reminded me, to take a shorter stroke so as to increase the cadence. That gets you into the little rest period while you switch sides more frequently, spreading the anaerobic load a little. I'm pretty bad at it, though.

In any case, we're basically believing the conventional wisdom that if your heart and lungs aren't working as hard as possible for the given exercise and duration that you aren't burning as many calories during the exercise time as you would be otherwise. OK, probably so, I guess - after all, the heart and lungs themselves can burn calories if they are working hard. As I said, I think the difference is pretty slight. The difference given between weight lifting and running is much bigger, because when weightlifting you are usually only exercising one muscle at a time, sometimes pretty small ones, like triceps, which can't consume much oxygen at the best of times. But when paddling you're exercising core and upper body, and, if you are paddling knees up, legs. So I just think the difference would be pretty small.

Anyway, those are my thoughts about it, for what it's worth!

-Lisa

[leong]

Um... then I don't think you can use the example of a car with the emergency brake on, can you? I think that mixes in too many other concepts (Isn't that the dynamic energy of going up the hill turned into the potential energy of the stopped car or something like that?) Certainly the car with the emergency brake on isn't burning any gas, but I don't think that has anything to do with the discussion. The car trying to stay still by revving the engine is burning gas, and a person trying to keep the kayak moving but being pushed back by the wind is also burning calories.

The guy paddling like mad to stand still is actually moving - his hands are moving, anyway (and more of him, if he has a good stroke :-) ) So he is definitely burning calories to keep his paddle moving against resistance. I'm saying he isn't working as aerobically because he has to slow his movements when pulling the paddle through the water. That's because the muscles involved can't take in enough oxygen locally to do the deed. The blood vessels aren't getting it there fast enough or the muscle cells aren't taking it up fast enough, or whatever. The heart and lungs are therefore not limiting him - his muscles are limiting him. Breathing harder doesn't help because there's a local logjam in oxygen transport. This situation results from the water feeling "thicker" (because the boat can't move forward to relieve some of the resistance). The paddler feels it as the burn of muscle fatigue. I think I understand all of this as being a good reason why it's hard to reach maximum heart/lung efficiency when paddling upwind. This guy is getting a great workout, making his muscles a little bigger with every stroke, but he's not working his heart and lungs quite as much.

Now, if you talk about downwind, you get different limitations. Rob talked about paddling downwind in such a fast wind that you can't paddle fast enough. No, you're not going to get a very high heart rate doing that, either. Any time your cadence has to increase beyond some optimal level, you'll fall off on your aerobics, and it will make more sense to "coast". I believe this, but cannot really explain it. Leon, I don't think you have explained it very well, either (yet), although it seems to be obvious to you that it happens. I bet it has something to do with the recovery time in the muscles - they contract by sliding the muscle fibers one over the other, and they have to slide back (relax) before they can contract again. Since the muscles aren't working very hard when the paddle is in the water, the resulting sum of oxygen usage is reduced, and because there is a limitation on turnaround time, the paddler can't make up for it by moving faster. Or something like that.

Of course, in both cases, if the guy keeps paddling at the lower or higher cadence, he probably can train his muscles to increase the range. And when paddling against the wind, it is possible, as Leon has often reminded me, to take a shorter stroke so as to increase the cadence. That gets you into the little rest period while you switch sides more frequently, spreading the anaerobic load a little. I'm pretty bad at it, though.

In any case, we're basically believing the conventional wisdom that if your heart and lungs aren't working as hard as possible for the given exercise and duration that you aren't burning as many calories during the exercise time as you would be otherwise. OK, probably so, I guess - after all, the heart and lungs themselves can burn calories if they are working hard. As I said, I think the difference is pretty slight. The difference given between weight lifting and running is much bigger, because when weightlifting you are usually only exercising one muscle at a time, sometimes pretty small ones, like triceps, which can't consume much oxygen at the best of times. But when paddling you're exercising core and upper body, and, if you are paddling knees up, legs. So I just think the difference would be pretty small.

Anyway, those are my thoughts about it, for what it's worth!

-Lisa

I’m not sure where you disagree and agree with me.

>> “Um... then I don't think you can use the example of a car with the emergency brake on, can you? I think that mixes in too many other concepts (Isn't that the dynamic energy of going up the hill turned into the potential energy of the stopped car or something like that?)”

There's potential energy but it has no relevance to this discussion. I was using that example to just easily demonstrate that there is no external work performed unless the vehicle moves. I’ve been very careful not to mix output power with input power. But they surely are related. Your body needs to burn more calories (input power) as the output power increases. The ratio of output power to input power is a measure of efficiency. If your sitting in a kayak facing into a strong wind but keep it stationary somehow, then the efficiency is 0 (no output power and non-zero input power). By the way, you don’t have to move your arms to keep the kayak stationary in a strong wind. Just plant the paddle blade into the mud below you. Or if the water is extremely viscous just plant your blade into it and keep it stationary. The force on your arms will cause your body to burn calories, even though you are not doing any external work (zero output power).

Time for a simple thought experiment. Push on a block pinned to the ground with a force of 10 pounds. Clearly, there is no external work being done (the power is zero, although you are burning some calories to generate the force. Now unpin the block and continue pushing with a constant force of 10 pounds. The block will accelerate and eventually reach a constant velocity, say 2 feet per second. Now your external power is 20 foot-pounds/sec. Don’t you think that your internal power (calories burned per unit time) has increased because the external power has increased from 0 to 20 foot-pounds/sec.

I don’t think you’re using the proper definitions of aerobic and anaerobic.

While “aerobic” means “with oxygen,” anaerobic means “without air" or "without oxygen." Anaerobic exercise is short lasting (no more than about 2 minutes), high-intensity activity, where your body’s demand for oxygen exceeds the oxygen supply available. Anaerobic exercise relies on energy sources that are stored in the muscles and, unlike aerobic exercise, is not dependent on oxygen from (breathing) the air. Paddling against a very strong wind for a lot more than 2 minutes is not anaerobic. It's not like weight-lifting where there is a maximal short spurt of energy.

As I understand it, a short sprint downwind is just as anaerobic as a sprint upwind, probably more so because you can reach your peak power. But overall, anaerobic exercise burns fewer calories than does aerobic exercise and may be somewhat less beneficial for cardiovascular fitness. However, as you said, it is better at building strength and muscle mass and still benefits the heart and lungs. In the long run, increased muscle mass helps a person become leaner and manage his weight, because muscle uses large amounts of calories. But my brainteaser is concerned with the calories burned during the exercise, not days after when muscles are grown.

>>“Rob talked about paddling downwind in such a fast wind that you can't paddle fast enough. No, you're not going to get a very high heart rate doing that, either.”

Yes, I think you will get a high heart rate trying to match your cadence with the speed the boat is going by itself. This is a case of burning a lot of calories doing no useful work. You huff and puff swinging your arms widely at a high speed.

>>” In any case, we're basically believing the conventional wisdom that if your heart and lungs aren't working as hard as possible for the given exercise and duration that you aren't burning as many calories during the exercise time as you would be otherwise. OK, probably so, I guess - after all, the heart and lungs themselves can burn calories if they are working hard.”

I’m not sure I follow you here. If your heart is beating fast and you are burning a lot of oxygen it’s probably because one or more of your muscles is doing a lot of external work. I think that your misunderstanding is that a small force implies a small amount of work per unit time (power). This is clearly wrong. Pushing on the block (like in the example above) with only 2 pounds of force would require 0.5 horsepower if the block was moving at 100 miles per hour. And because of output/input efficiency the internal work (calories burned) would be quite a lot more.

>> Anyway, those are my thoughts about it, for what it's worth!

Must be worth a lot, you’re burning out my brain.

-Leon

[leong]

Now, if you talk about downwind, you get different limitations. Rob talked about paddling downwind in such a fast wind that you can't paddle fast enough. No, you're not going to get a very high heart rate doing that, either. Any time your cadence has to increase beyond some optimal level, you'll fall off on your aerobics, and it will make more sense to "coast". I believe this, but cannot really explain it. Leon, I don't think you have explained it very well, either (yet), although it seems to be obvious to you that it happens. I bet it has something to do with the recovery time in the muscles - they contract by sliding the muscle fibers one over the other, and they have to slide back (relax) before they can contract again. Since the muscles aren't working very hard when the paddle is in the water, the resulting sum of oxygen usage is reduced, and because there is a limitation on turnaround time, the paddler can't make up for it by moving faster. Or something like that.

-Lisa

I didn’t respond to this very well. Referring to the power curve, it’s possible that going downwind will push your cadence above the optimum cadence, and accordingly, your power will be below the peak on the other side. I think this is a pathological case of wind that’s too strong to paddle in. Nevertheless, in this case, the upwind paddle cadence will be even father to the left of the optimum cadence than it would be with reasonable wind speeds. I’m not certain, but my experience tells me that for winds no greater than 30 knots (the fastest that I’ve paddled in … yeah it’s scary) your maximum effort cadence will be below the optimal cadence for downwind and even more below for upwind.

Summarizing what I think most of us agree to:

1. For a given person there exists a kayak-paddling curve (maximum obtainable output power vs. cadence).

2. The greater your output power the more calories you burn.

3. The higher your efficiency the more output power you can generate for your calories burned per unit time (input power).

4. You can burn a lot of calories without generating output power (a case of 0 efficiency).

5. There are some subtle physiological differences between high force and high cadence, although output power probably predominates.

6. Output power = force * speed and speed is proportional to cadence.

7. For at least a range of wind speeds, you can generate more output power going downwind at maximum effort than upwind.

8. I believe that the statement above implies that you burn more calories going downwind at maximum effort than upwind. This is somewhat counterintuitive to many.

9. If you could change paddle size, length and stroke length you might be able to optimize your stroke to get closer to the optimal cadence. But, unlike gear ratios on a bicycle, these changes introduce other problems.

10. As Lisa mentioned, physiological aspects of the heart, lungs and muscles have some relevance to the problem. I don’t disagree but I think that optimal cadence is the main driver.

11. On my best days, and if Lisa is feeling under the weather, it’s possible I can beat her going against a strong wind. Oh, okay, at least give her and Ms. Sally Mustang a decent workout.

12. I can’t think of any other items right now.

[leong]

I would like to offer everyone a challenging, and I must point out - DANGEROUS - (please bring plenty of spotters with you) exercise if you dare. Find yourself a strong headwind, and paddle for the purpose of paddling EFFORT alone, and not distance or control. The point is to put your absolute maximum effort into it. The reason I say that this is dangerous is that, if you do this correctly, you will not be paying as much attention to your stability or direction into the wind and you should have several spotters to help you if you get into trouble. I think if you do this, you will find yourself huffing and puffing much sooner than if you were paddling with the wind.

Ha, ha speaking of the devil. Circumstances today compelled a similar, but unplanned, experiment. As I frequently do, I was paddling fast laps around Peanut Island for an afternoon workout. Then I noticed two women on a SOT kayak having trouble paddling against the strong current … they were trying to get back to their put-in (this is a fairly frequent occurrence in the channel between Peanut Island and the mainland).

I didn’t have my regular towline but I did have about 30-feet of ¼ inch line behind my seat. I used this line to tow them back to their launch point (only about a mile). I worked pretty hard. Between the drag of the SOT and the fairly swift current, my cadence was so low that it felt almost like an isometric exercise. As Lisa stated elsewhere in this thread, I was more limited by muscle fatigue than by oxygen debt doing the tow.

Unfortunately, I wasn’t using a heart rate monitor for accurate measurements. However, based on my own perception and breathing rate, I’m pretty sure that my heart rate went higher during the prior and later workout than during the tow.

BTW, I do have my wrist watch heart rate monitor down here with me. But I forgot to pack the associated chest strap transmitter before leaving MA. However, I’m pretty sure that my heart rate was lower while towing than while paddling during my workout. I almost want to buy another heart rate monitor system to do some experiments (unfortunately, the two sport stores I visited don’t sell the strap separately).

All and all, I think that towing would be a better experiment than paddling with and against the wind. In fact, I would restate the brainteaser as:

Which would burn more calories, an all–out effort towing another kayak or regular all-out paddling without towing? Almost everyone would vote for the tow, but based on my knowledge of cadence and the power curve I think it’s the other way around!

BTW, a good estimate for calories burned per hour can be calculated from:

60*(-55.0969 + .6309*HR + .0902*W + .2017*A)/4.184, for men

60*(-20.4022 + .4472*HR - .0573*W + .074*A)/4.184, for women

where HR is heart rate in beats per minute, W is weight in pounds and A is age in years. Both curves are linear with HR (straight lines).

Some heart rate monitors do this for you (or a similar calculation of their own).

-Leon

[lhunt]

Between the drag of the SOT and the fairly swift current, my cadence was so low that it felt almost like an isometric exercise.

Drag of the SOT I believe! But the current shouldn't have any effect on cadence...

BTW: here is one way to get a chest strap...

-Lisa

[leong]

Drag of the SOT I believe! But the current shouldn't have any effect on cadence...

BTW: here is one way to get a chest strap...

-Lisa

You belief is exactly right, of course. In fact, the current increased the cadence needed to make any headway.

I couldn't find the chest strap for my model or even my brand of monitor. I sent Sportline an email asking how I could get a replacement for the Duo 1025 HR monitor. No answer yet. I was hoping to try any brand in the store to see it worked with my unit. The cheap HR monitors like mine are so cheap it might be better to just buy a new one.

PS

A simple winter test to validate (or disprove) my theory is to set the resistance on an exercise bicycle to that value that allows a maximum effort cadence of 80 to 90 rpms (that’s the optimal cadence for cycling). Then spin at that cadence for about 5 minutes. Then, after a rest, increase the resistance by about 50% and spin again as fast as you can for 5 minutes. The average and maximum HR for each run should validate or invalidate my theory.