Calories to Meters Revisited

We’ve previously covered the topic of converting calories to meters across different cardio machines (rowing, biking, skierg, running), and our conclusion was that there is not a simple 1:1 conversion. Instead, coming from the CrossFit world, we used TIME as our common denominator.

More specifically, your power output maintained over a certain time period. And ultimately, it comes down to your proficiency with a specific modality. You may be a great runner, but not a great rower, in which case your 400m run equivalent may actually be less than 400m on the rower.

This week, we’re going to focus on the rower specifically, because I still get the question “how many meters is that?” when we’re rowing for calories. And, because I FINALLY have the equations from the founder of Concept 2 which explains WHY we can’t neatly convert from calories to meters.

Rowing for Meters

Before we dive in, I’m sure most of us can confirm the below anecdotally, and we frequently mention this during our whiteboard briefing – sometimes, it’s not worth it to kill yourself just to shave 10 seconds off your row time, as you’ll likely need to rest later on to make up for that energy expenditure. And now we can put some numbers to it to show you exactly why that’s true.

As it turns out, the relationship between power output and SPEED (pace /500m) on the rower is cubic, rather than linear:

This means that to double your speed, you need 2³ the power, which is EIGHT times the power. And, doubling your power only gets you ³√2 the speed, which is 1.26 times faster. The specific example given by the founder of the founder of Concept 2 is for a 1000m row test – to improve from a 4:20 1k to a 4:10 1k, you would need a 10 second, or 3.8% improvement. To do so, you would need to supply 12.5% more power. So, as we’ve all experienced, it DOES take a lot more effort to get a little improvement.

Why is this the case? Because the rower is designed to mimic a boat in water. Which makes sense, given that these machines were created to help rowers when they can’t get on the water. In any case, when moving on land, we encounter friction, which affects us linearly.

In water, we experience drag, which is proportional to the square of velocity. (If you’re interested, you can actually do a drag factor test on the rower to determine which damper setting most closely mimics the feel of water for you.)

In other words, to maintain a constant velocity (speed), our force output (power) must match the drag. As we just said, drag is proportional to the square of velocity, and power is force x velocity. By equating power and drag and moving terms to the same side of the equation, we get our cubic function.

If I didn’t lose you describing the math, you may be wondering how this information can help you. Good question! In practice it means that when rowing for meters, we need to be smart about how we pace. If rowing is the ONLY movement in your workout, you can determine your stroke rate and pace/500m, and modify accordingly.

In a mixed modality setting like a CrossFit WOD, it’s worth dialing back the row to save energy for your other movements. Those other movements do not have the same cubic relationship with power, which means pushing harder on them has a much clearer effect on time saved. Conversely, slacking off on those other movements will greatly impact your time. Gravity and friction scale linearly, not cubically.

Rowing for Calories

Now, keep in mind, all of the above ONLY applies to rowing for meters. When rowing for calories, it DOES pay to push harder. As noted in our first paragraph, there is no 1:1 correlation between calories and meters. And, if you push harder, you can row the same number of calories while racking up fewer meters. So, the harder you push, the less you row.

Why? Because like most cardio machines, the row erg is estimating how many calories you burn based on the work performed. The equation Concept 2 uses is below:

If math scares you, I’ll summarize – the assumption here is that your body burns 4 units of energy to generate 1 unit of work, for roughly a 4:1 energy to work ratio. It also takes into account your body’s normal energy consumption to just exist, which is estimated at 300 calories per hour (0.35 kJ per hour).

In other words, there is a roughly linear relationship between your power output and calories burned. Not to mention that since the background energy consumption is based on time, you burn fewer calories if it takes less time to do the work. Any way you slice it, it shows that when rowing for calories, you can treat the row like any other movement, where you are rewarded for your power output.

So, that was a very long-winded and math heavy way of getting to our ultimate strategy: when rowing for meters, be smart and pace yourself. It’s not a bad idea to coast a little bit to bring your heart rate down. When rowing for calories, you’re rewarded for harder effort, so don’t slack.

What about the fly wheel setting? It’s a matter of personal preference. As mentioned above, if you’re trying to simulate the feel of water, it’s not a bad idea to use drag factor test to determine the best damper setting for mimicking it. If you’re not training to row on water, I would equate the damper to gears on a bike. A higher gear requires more effort per rep, but allows you to move faster if you can sustain it.

Same with the damper – you’ll feel more resistance in a higher setting, but if you can sustain it, you’ll go faster (or burn more calories). So, it once again comes down to whether you’re rowing for meters or calories. More effort = more calories, so a higher damper setting might be beneficial here. Give the cubic relationship between power and speed, using too high a damper setting may be a waste of energy. So, play with different settings, and find what works best for you! See you in the gym.