Alex Hutchinson

The Explorer's Gene is out TODAY! Try before you buy: -excerpt in @TheAtlantic: theatlantic.com/science/archiv… -excerpt in @outsidemagazine: outsideonline.com/culture/books-… -newsletter interview with @DavidEpstein: davidepstein.substack.com/p/why-you-shou… -podcast with @richroll: richroll.com/podcast/alex-h…

Baking soda to counter the effects of altitude? A new study finds a 1.2% gain for 40K cycling at 1,800m. But that's actually no better than the same group found at sea level - so more evidence that it works, but nothing special about altitude. outsideonline.com/health/trainin…

Awesome - so glad to hear that you enjoyed it, Marc!

@HermanPontzer @cremieuxrecueil I meant a regression of Fig 3A (with resistance excluded). I'm not trying to argue that there's no compensation, just that the number in the abstract (represented by the blue line below) is inconsistent with the data it claims to represent.

@sweatscience @cremieuxrecueil Here’s the regression of compensation vs exercise load. Includes all data including resistance training (open symbols) w negative compensation, so it will underestimate aerobic

On @HermanPontzer energy compensation model: Per @sweatscience the figures are incorrect. "30% of your exercise energy are added to your metabolic expenditure" is a modelling error biased by low exercisers whose data isn't informative open.substack.com/pub/sweatscien… Thoughts? @cremieuxrecueil

@cremieuxrecueil FWIW, my take is that the high-leverage point exposes an inappropriate method of analysis (a weighted average of a bad secondary variable). Take it out and the number jumps from 31% to 55%, which is closer... but we should just be looking at the slope of the regression line.

@yzilber @HermanPontzer @sweatscience Pretty neat that the magnitude is so strongly driven by a high leverage point. Might check if this holds later.

Our 2nd monthly issue, "Biology's New Era," is live now on bigthink.com. In this issue, we explore the bleeding edge of biotech, as well as the scientists, writers, and philosophers whose efforts helped get us here. Some of what's inside: ⬤ Scientist-turned-writer Alex Hutchinson @sweatscience uses the legend of Secretariat to probe the limits of human athletic performance. ⬤ Futurist Peter Leyden examines how synthetic biology could help save Earth. ⬤ Astrophysicist Ethan Siegel @startswithabang challenges the leading theory of how life began. All that and much, much more. We hope you enjoy.

@_javierivero Glad you asked, Javier! :) outsideonline.com/health/wellnes…

@sweatscience Alex did I miss your list of top reads of 2025?

Thanks, Michael -- super to hear that you enjoyed it!

@davykevinp Point taken, my apologies.

For the record @sweatscience , we never indicated the constrained model was wrong. We indicated that our data were inconsistent with that model. Very different things.

A new study on an old question: does exercise actually burn (net) calories? Or do our bodies respond to exercise by cutting back on, e.g., immune function and cell repair, with potentially negative consequences at high levels? The evidence is... mixed. outsideonline.com/health/trainin…

“But it’s enough, for now, to know that when the moment of truth comes, science has confirmed what athletes have always intuited. There’s more in there, if you’re willing to believe it.” First book of the year down. Highly recommend the work from @sweatscience!

@dhammonia That's weird - I only skimmed the paper, but didn't see that message. I'll have to take another look. And no apologies needed, interesting to see that paper!

@sweatscience Thank you for indulging me. Now for the take I saw on IG: Carbon plates don't make you go faster! Better to do some exercises suggested in the paper which will increase Achilles Tendon response, etc..I didn't have access to the full text. So didn't validate. Apologies

Am assuming @sweatscience has received this paper pubmed.ncbi.nlm.nih.gov/41389728/ lots of times in the past month. Eagerly waiting for his take and not the random slop on IG which led me to it in the first place

@dhammonia [...] (NCP is "non carbon plate" and CP is "carbon plate." The two bars are unfatigued and fatigued.) The main point seems to be that the shoes shift load from the foot to the ankle, knee and hip. You could argue this isn't worse, just different: the body needs to adapt.

@dhammonia That said, they try: "The reduction in knee flexion moment is clinically relevant, reflecting a quadriceps-avoidance gait that redistributes loads and increases patellofemoral joint stress..." Here (below) is the key graph. I can't say it fills me with fear. [2/...]

@jem_arnold @MCRiddell1 Wow, that's a big overshoot! That's pretty satisfying to be too fit for the machine to handle. :)

@sweatscience @MCRiddell1 Or in this case, well beyond it. Their calibration device reports validation up to 6 L/min VO2. Kristian's 7.7 L value is nearly 30% above that. I don't know how you *can* validate up to that range. Break out the sled dog equipment?

Kristian Blummenfelt's apparent VO2max record of 101 (and why scientists are skeptical of his respiratory exchange ratio), bone health for cyclists, freediving physiology, and the trouble with a recent exercise/longevity study. My latest Substack: sweatscience.substack.com/p/the-vo2max-r…

@BigBoyBern80872 😆

@sweatscience I actually believe it because it’s hard to believe that somebody that fat could be as good as he is. Bro is such a fatso.

@MCRiddell1 Agreed! And yes, I've also heard that elite athletes are sometimes pushing the edge of the calibration range.

@sweatscience I was told by an experienced physiologist that the flow sensors in many of the systems cannot pick up the VE accurately at very high flow rates. ventilation rate is part of the Fick equation so it might have been a sensor or a flow rate issue. But who cares. It’s just a number

@benjtannen @BMJMedicine The data is straight from their supplementary data (first supplementary file, Table 5), which gives adjusted and unadjusted (except for age) all-cause mortality. Link to supp data is here: bmjmedicine.bmj.com/content/bmjmed…

@sweatscience @BMJMedicine Do you think you could provide the maths behind your charts with the two curves, what proportion of the variances gets taken away by the controlling

There's been a ton of discussion about the recent @BMJMedicine paper on exercise variety and longevity. I have some thoughts, including on why statistically adjusting for BMI, blood pressure, cholesterol, etc. creates the illusion of a plateau: outsideonline.com/health/trainin…

@benjtannen @BMJMedicine Thanks!

@sweatscience @BMJMedicine Great article Alex