Rowing For Distance Versus Rowing For Calories

Rowing For Distance Versus Rowing For Calories You’re at the competition. The final WOD is announced. It’s rowing followed by Fran (21-15-9 95# thrust...
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Rowing For Distance Versus Rowing For Calories You’re at the competition. The final WOD is announced. It’s rowing followed by Fran (21-15-9 95# thrusters, pullups). What’s your plan? Like so much in life the answer is “it depends.” In this case, it depends on whether you’re rowing for distance (e.g., 500m) or rowing for energy (e.g., 25 calories). It also depends on how long it’s going to take to row versus how long it’s going to take you to do Fran. To whet your appetite, here are some sample race results. Pace Per 500m

Time To Row 500 meters

Calories

2:30

150 seconds

10

2:20

140 seconds

11

2:10

130 seconds

13

2:00

120 seconds

15

1:50

110 seconds

19

1:40

100 seconds

23

Pace Per 500m

Time To Row 25 Calories

Meters

2:30

385 seconds

1250

2:20

318 seconds

1137

2:10

255 seconds

958

2:00

216 seconds

900

1:50

174 seconds

625

1:40

114 seconds

544

In a 500m race, if you row at 2:30/500 and I row at 2:20/500 I’m going to get off the rower 10 seconds ahead of you. If you row at 2:10/500 and I row at 1:50/500 I’m going to get off the rower 20 seconds ahead of you. In a 25 calorie race, if you row at 2:30/500 and I row at 2:20/500 I’m going to get off the rower 53 seconds ahead of you.

If you row at 2:10/500 and I row at 1:50/500 I’m going to get off the rower 81 seconds ahead of you. The value of rowing at 2:20/500 instead of at 2:30/500 when rowing for 25 calories is a 55 second advantage in the race. The value of rowing at 2:20/500 instead of 2:30/500 for 500m is only a 10 second advantage in the race. That’s a 45 second difference. When rowing for calories it’s probably worth it, when rowing for distance it probably isn’t. After reading this article you’ll know that if you’re rowing for distance you probably won’t go to the redline and that if you’re rowing for calories you might. Why? Because going faster only reduces the time it takes to go a certain distance a little bit while going faster reduces the time it takes to count a given number of calories by a lot. This happens because the relationship between speed and distance is linear and the relationship between speed and calories is exponential. In plain English, the payoff for going faster is small when rowing for distance but is enormous when rowing for calories. Why? It has to do with drag. Linear Versus Exponential As you row faster, the distance you cover in a certain amount of time increases linearly. The line in the distance per minute graph is pretty much a straight line. There’s a one to one return.

However, as you row faster, the calories you count in a certain amount of time increases exponentially, which is much faster than linearly. The line in the second graph has a big bend in it, right at about two minutes per 500m. There’s an eight for one return.

How Is This Possible? Distance measures how far you’ve gone. How far you’ve gone depends on how fast you’ve gone for how long. When you go faster you go farther in any given period of time. Calories measures how much energy you’ve put into the system. When you go faster, you put more energy into the rower in any given period of time. When you go faster, the distance you go increases linearly (e.g., one for one) but the energy you put into the system increases exponentially (e.g., eight for one). We all understand that if we want to get off the rower first that we have to row faster than the other competitors. But, is rowing faster always worth it? And if it’s worth it, by how much? After you read this article you’ll understand the difference, and then you’ll be able to plan your strategy for competition WODs that include either rowing for distance or rowing for calories.

What Does The Rower Measure? The rower measures three things: how many times you made the flywheel go around, how long you’ve been rowing, and the rate at which the flywheel slows down. Counting the number of times the flywheel went around measures distance. Dividing how far you went by how long it took you to get there gives you your pace. We are all comfortable with distance and time. We can all figure out how many hours it’s going to take us to drive from Cleveland to Cincinnati (200 miles) if we average 50mph or if we average 100mph. What we never figure out is how much gas it takes at 50mph vs. 100mph. It takes a lot more than twice as much gas to go 100mph than it does to go 50mph. The same thing happens with calories. It takes a lot more calories to go just a little faster. We’re not so comfortable with energy expenditure. We know when we’re working hard and we know when we’re working easy, but unlike distance, speed, and time, energy isn’t a unit we deal with every day. On the rower, energy expenditure is measured by the rate at which the flywheel slows down. Measuring how quickly the flywheel slows down measures how much energy has been dissipated, which can be converted to Watts and then to calories. To measure how quickly the flywheel is slowing down, the rower checks how fast the flywheel is spinning at different times. The flywheel slows down primarily due to drag produced by air resistance. While the distance equation is simple (e.g., distance = how many times the flywheel went around), the calorie equation is more complicated and depends on how many Watts you are producing. The Watts equation may be close to Watts = 2.8 divided by pace3.

CrossFit Competitions CrossFit competitions have two different types of rowing WODs: rowing for distance (e.g., 500m) and rowing for energy (e.g., 25 calories). In both cases, the person who rows fastest wins the race. Most competitors and coaches stop their analysis right there and figure they will simply go all out on the rower to finish first. But that may not always be the best idea, especially when the rowing is an early element in a WOD that includes other elements. The reason it may not be wise to go faster is that

going faster is harder. Going a lot faster is a lot harder. Going twice as fast is eight times as hard. If you’re going to invest the energy to go faster, you need to get an appropriate return on that investment. You don’t want to be the first off the rower but be so wrecked that you are unable to do burpees, or dubs, or pullups or wall ball shots or whatever else follows the rowing.

Distance And Time Are Linear We can all calculate that if we row at 4 minutes per 500m that it is going to take us 4 minutes to finish the 500m. We can also all calculate that if we row at 2 minutes per 500m that it is going to take us 2 minutes to finish the 500m. When we double our speed it takes exactly half as long to finish. We can also calculate that if we row at 1 minute per 500m (which would be super-human) that it is going to take us 1 minute to finish the 500m. Once again, when we double our speed we decrease our time by half. We’ve done this a thousand times in our cars, and too many times in SAT prep. If we go 100 miles at 10mph it takes 10 hours. If we go 100 miles at 25mph it takes 4 hours. If we go 100 miles at 50mph it takes 2 hours. If we go 100 miles at 100mph it takes 1 hour. We can even plot these and see the straight line. What we never check, unless we are a NASCAR crew chief, is how much gas we’re burning, which wouldn’t be a straight line. There is a linear relationship between going faster and taking less time. On a graph, as you go faster, the distance you cover goes up in a straight line at a gentle angle. This is illustrated in the following graph.

Energy And Time Are Exponential While we can easily calculate distance and miles per hour, few of us can calculate how many calories we are going to burn rowing at 4 minutes per 500m, 2 minutes per 500m, and 1 minute per 500m. Unlike distance, when we go twice as fast, we don’t burn twice as many calories. Instead, we burn nearly eight times as many calories. This is why your car gets great mileage at 25mph, okay mileage at 50mph, and abysmal mileage at 100mph. This is illustrated in the following graph.

The Erg (rower) Measures Watts The rower is actually called an ergometer. It measures Watts. It measures how much energy you’ve put into the system, along with how far you went and how long it took to get there. Looking at the data that the erg provides us shows that going faster burns more calories because going faster means you are work at a higher wattage. The extra wattage is needed to overcome the exponentially increasing drag. Watts and speed on the rower are illustrated in the following graph.

Sample Data If we experiment with the data the rower reveals to us, and compare it to the formulae that the rower uses, we get proof that there isn’t a one to one relationship between going faster and counting more calories. The equation for computing distance is simple. It’s speed x time. The rower measures how long you’ve been going and how fast you’ve been going and multiplies to find out how far you’ve gone. The rower may count how many times the flywheel went around in a second or may time how long it takes for the flywheel to go around each time. Regardless of how it samples, the rower knows how many times the flywheel went around and how long it took. The equation for computing calories isn’t simple. Concept2 says the formula for computing calories is based on 2.8/pace3. Others have reported different formulae. For example, Marinus van Holst reports 4.31*u2.75 while The Physics of Ergometers reports a lower number. What does all this mean? It means that you get a little payback in distance for going faster, but you get a big payback in calories for going faster. It also means that for a linear increase in speed you have to produce an exponential increase in Watts, and thus calories.

Lab Rat Data The following table shows some sample results. The data was collected from lab rats who rowed one minute intervals trying to stay as close to the pace per 500m as possible. The variations in the data are explained by the fact that it’s really hard to row a perfectly even pace. The data shows that distance increases one to one with speed, but calories increase much more than one to one with speed. Pace Per 500m (seconds)

Distance Covered In One Minute (meters)

Watts

Concept2 Predicted Watts

Calories Counted In One Minute

Calories Per Hour Reported

Predicted Time To Row 25 Calories (seconds)

240 220 211 203 200 190 189 180 172 170 162 160 152 143 142 140 130 125 123 120 115 112 111 104 100 98

125 135 141 148 149 152 149 159 174 175 185 185 197 208 211 210 229 239 243 249 254 267 270 286 291 308

25 32 39 43 43 46 42 59 68 70 82 83 100 118 122 120 156 178 187 191 231 247 255 303 320 380

25.3 32.9 37.3 41.8 43.7 51.0 51.8 60 68.8 71.2 82.3 85.4 99.7 119.7 122.2 127.6 159.3 179.2 188.1 202.5 230.1 249.1 255.9 311.1 350 371.9

6 6 7 7 7 7 8 8 8 9 9 9 10 11 11 11 13 15 15 15 17 19 19 22 23 26

387 410 435 444 447 476 479 480 546 548 582 582 642 701 719 713 831 909 940 956 1110 1149 1178 1339 1343 1595

232.5 219.5 206.9 202.8 201.3 189.1 187.8 187.5 164.9 164.3 154.6 154.6 140.2 128.4 125.2 126.3 108.31 99.01 95.75 94.12 81.09 78.32 76.41 67.22 67.01 56.42

This graph shows the time it takes to row 500m versus the time it takes to row 25 calories. At a slow pace (e.g., 240 seconds per 500m), it takes about the same time to row 500m and 25 calories. At a faster pace (e.g., 152 seconds per 500m), rowing 25 calories takes a little less time than rowing 500m. At a much faster pace (e.g., 98 seconds per 500m), rowing 25 calories takes a LOT less time than rowing 500m. This is what confuses people. If the exact same guy goes the exact same distance in the exact same time, why are the calories different? It’s because of drag.

This difference can also be visualized by plotting distance vs. Watts. Distance increases in a straight line, Watts increase in an exponential curve.

Explanation How is the possible? It’s because of drag. Drag is really hard to explain. Something kinda sorta like drag is much easier to explain. Imagine you are on your bike. There are three different courses to ride. Each course is 500m. One course is flat, one course is uphill, and one course is downhill. Without doing any math or physics you can tell me which one you are going to be slowest on and which one you are going to go fastest on. You are also going to be able to tell me which one is going to be easiest and which is going to be hardest. You are likely going to be fastest and will likely use the least amount of energy going downhill. If you coasted the whole way you might even use no energy. You are likely going to be slowest and use the most amount of energy going uphill. Going flat and level is going to be somewhere in the middle. If you rode all three courses in exactly the same amount of time, you can predict that you would work hardest (count most calories) going uphill and you would work the

easiest (count fewest calories) going downhill. The difference in effort required here isn’t due to drag, it’s due to gravity, but it illustrates one reason why the exact same guy going the exact same distance on the exact same bike can burn different numbers of calories. Now imagine you are on your bike and there is one flat and level course. On one day there is no wind, on another day there is a tailwind, and on another day there is a headwind. Again, without doing any math or physics you can tell me that it is going to be easiest/fastest to ride with the tailwind pushing you along, hardest/slowest to ride into the headwind, and somewhere in the middle with no wind. You understand these things because you have experienced them and have felt them (and maybe even timed them and checked your power meter). In this case where the wind is different, the power meter will have an exponential curve in it for the same reason as for the rower, drag. People who ride bikes will tell you that it’s not just a little harder to go into the wind, it’s a lot harder. They’ll also tell you that you don’t get it all back when you ride with the wind at your back. That’s because of the exponential term in the drag equation. Conclusion In a competition, if you’ve got something to do after you get off the rower, it’s worth your while to do some strategizing. If you’re rowing for distance, you might want to weigh how much it’ll cost you to get off the rower first. You might want to consider if you’re going to be wrecked for whatever comes next. If you’re rowing for distance, it might not be worth it. If you’re rowing for calories, it might be worth it, because although you might be wrecked, you’ll have an enormous head start. I encourage you to do some experiments of your own so that you’ll know your best 500 time, what 90% of your 500 time feels like, and what 80% of your 500 time feels like. I also encourage you to do some experiments so that you’ll know your best 25 calorie time, what 90% of your 25 calorie time feels like, and what 80% of your 25 calorie time feels like. One extremely important experiment is to see how long it takes you to do 25 burpees and 50 dubs after rowing 500m at 100%, 90%, and 80%. You might be

surprised at which rowing pace is most efficient for the entire WOD. Another extremely important experiment is to see how long it takes you to do 25 burpees and 50 dubs after rowing 25 calories at 100%, 90%, and 80%. If you do these experiments and spend a little time to understand the difference between rowing for distance (meters) and rowing for energy (calories) you’ll have an advantage over everyone who doesn’t. I wonder what tomorrow’s WOD will be…