Gains and Brains: a lil crown

Hi! Megan here. Sorry for the late newsie, Saturday was Carl's birthday, so we took some time to celebrate. With cake, even. Bloody lovely to celebrate such a legend. Many Happy Returns, friend!

Back in the days before I cut women’s magazines out of my life, I can remember knowing that an hour on the treadmill burned the equivalent calories of a Moro bar. 

Now, divested of diet culture, and all it entails, I have some questions about that, even if they are 20 years too late. 

• When you say “an hour on the treadmill,” what do you mean. cos sometimes I get on there, and amble my way through a you tube cooking video and call it a day. That’s very different to the sprints some people are doing. 
• “Also: surely I, a person who weighs more than average, burn more calories walking than the waif you have illustrated this intense body-shaming exercise with?”
• WHAT IN THE FALSE EQUIVALENCE? 

As I said in last week’s newsletter, it has taken me years to learn that food is not a reward for moving my body and exercise isn’t a punishment for eating “bad” foods. 

So, it drives me a little bit nuts that the way my Oura ring is set up to track my activity is calories burned. 

I love my ring. The sleep tracking has made a significant difference to my life, as has the stress and recovery tracking. I do find it fascinating that we’ve created a world where we can collect all this data about ourselves. But how we’re supposed to use that data is often pretty oblique. I try to focus on the trends - have I been sleeping more overall? Is my HRV higher or lower this week? Is it yelling at me to stand up because I have been sitting for three hours straight?

I could probably stop looking at the activity goal, because I have enough ways to assess how much I am doing. My goals are in absolutely no way calorie related. They are “am I getting stronger” and “are my delts getting bigger” and “are men running screaming from me because I make them insecure?” 

But here’s the thing. The Oura app gives you a little crown if you achieve a certain score and I am enough of a people pleaser to want that. 

So, I try to ignore the calorie count and just focus on the lil crown.

But while I have been rehabbing this knee issue, I have noticed something. I went to the pool and walked up and down for 90 minutes. I took some pauses to frolic in the water, and used the floaty dumbbells to do lateral raises (Surprisingly hard!) and chest press. When I told my ring that’s what I had been doing, it said I had burned 700 calories. 

A 45 minute boxing class where I sat on a box to protect my leg was 412. But my last two 30-minute strength training sessions, where I was out of breath and at least as sweaty, were 120 and 122 calories. 

This makes no sense to me. I definitely rest between sets, but 400 calories worth?

Ultimately, it probably doesn’t matter. The things that I am tracking is data a ring can’t give me. How does my body feel? Can I go up a plate in my squat? The numbers are helpful, but they don’t tell the full story. And yet…I have questions. 

I figure not everyone has a ring, but everyone has put their hands on the pads on a treadmill and wondered what the readout is saying. 

So, Carl, over to you. Is my ring inherently biased against resistance training and we should ignore it, and do the exercise that feels good? Or is there something Oura knows that I don’t. 

Oh, and while I am at it, it also shows me that I spent - for my core session this week, for example, 18 minutes in zone 2 and 7 in zone 3. What does that mean, and why does it matter? 

And are these things people should care about? 

Carl here, ah yes the eternal question: are wearables genuinely helpful tools, or just another metric we feel obliged to manage? And perhaps more importantly, do they reinforce our internal cues about how our bodies feel, or do they slowly train us to ignore those cues and defer to the algorithm?

My feeling is that it’s a little bit of both.

Wearable devices such as the Oura Ring are good at collecting physiological data. They can measure things like heart rate, heart rate variability (HRV), sleep stages, and movement patterns with reasonable accuracy. Where things become more complicated is when that raw data is translated into estimates of calories burned or training load, because those numbers rely heavily on predictive algorithms rather than direct measurement.

Calorie estimation is where things start to get fuzzy.

A large body of research has shown that consumer wearables often produce substantial errors when estimating energy expenditure. In some cases, devices can misestimate calories burned by 20 to 50 percent depending on the activity (Shcherbina et al., 2017; Fuller et al., 2020). These estimates are typically based on movement data and heart rate, but neither of these perfectly reflects the true metabolic cost of an activity.

Which brings us to your boxing versus strength training bout.

In this case, I feel the algorithm is probably pointing in roughly the right direction.

Activities like boxing tend to involve continuous movement, repeated strikes, footwork, and elevated heart rates for sustained periods of time. That means you are spending longer periods drawing on the aerobic energy system, which relies on oxygen to produce energy. When oxygen consumption rises, overall energy expenditure rises as well.

Resistance training often operates differently. During heavy lifting, the muscles rely more heavily on the anaerobic (meaning energy without oxygen,energy that's already stored in muscles) energy systems, particularly the phosphocreatine and glycolytic pathways. These systems produce energy quickly without requiring oxygen, but they do so for very short bursts that typically last seconds. Between sets, heart rate and oxygen consumption drop while you rest and recover.

So although strength training can feel incredibly demanding and leave you sweaty and breathless, the total continuous energy expenditure across the session is often lower than activities where movement is sustained for longer periods. Studies examining resistance training sessions generally show moderate calorie expenditure compared with steady state cardio or combat style conditioning sessions.

However, there is an important caveat.

Strength training has metabolic effects that extend beyond the workout itself. I call this the afterburner effect. The process of muscle repair, protein synthesis, and tissue remodelling requires energy, meaning that resistance training can increase post exercise oxygen consumption and metabolic activity for hours after the session. This phenomenon, often referred to as excess post exercise oxygen consumption (EPOC), is something most wearables struggle to capture accurately (LaForgia et al., 2006). Also lets consider the longer lasting metabolic benefits of muscle. Muscle mass is responsible for a reasonably large chunk of your daily energy expenditure, meaning the more muscle mass you have, the higher your resting metabolic rate. Therefore strength training will have a nice long term metabolic benefit!

So while your ring might show a smaller calorie burn during the session itself, it is not capturing the full physiological story.

Which brings us to the heart rate zones your ring reports.

When your app tells you that you spent 18 minutes in Zone 2 and 7 minutes in Zone 3, it is simply categorising your heart rate relative to your estimated maximum heart rate.

Very broadly speaking:

Zone 1 is very light activity and recoveryZone 2 is moderate aerobic work that is sustainableZone 3 is harder aerobic work where breathing becomes more noticeableZones 4 and 5 represent high intensity efforts approaching maximum capacity

These zones are used because different physiological adaptations occur at different intensities. For example, spending time in Zone 2 is strongly associated with improvements in aerobic efficiency and mitochondrial function, while higher zones tend to stress cardiovascular capacity more directly (Seiler and Tønnessen, 2009). This is probably why zone 2 has become all the rage recently! When you look at the literature though, all zones are important. For example the zones 3-5 are important for release of a brain chemical called Brain Derived Neurotrophic Factor (BDNF). This chemical makes our brain more plastic!

That said, whether people need to care deeply about these numbers depends largely on their goals.

For elite endurance athletes, heart rate zones can be very useful for structuring training. For the rest of us, they are often best treated as context rather than command. They can provide insight into how hard we are working, but they should not override our own perception of effort or our broader training goals.

This circles back to the point you made earlier.

The most meaningful indicators of progress in strength training are rarely captured by a wearable device. Things like whether you are getting stronger, whether you can add weight to the bar, whether you are recovering well enough to train consistently, and whether your body feels resilient and capable.

Those are the signals that tend to matter most.

Wearables can be useful tools for spotting trends in sleep, recovery, and activity patterns. But they are still estimating rather than measuring, and they cannot capture many of the adaptations that make resistance training so powerful for long term health.

So your instinct to pay more attention to how your body feels, and whether you can go up a plate on your squat, is probably a very sensible place to land. Note the data, see if it actually correlates with how you feel, but don't overinvest in it running your life! I personally like these devices for sleep scores, step count and HRV, but in terms of calorie counting, I think its got a way to go.

The little crown, however, is entirely between you and the algorithm.