24 Comments
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CMFasulo's avatar

Must be why rucking is so successful! The science behind it all. It's more than burning calories. The mystery is solved. I love it.

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Nick Norwitz MD PhD's avatar

How dare you… the mystery is never full solved… that’s what makes science the gift that keeps on giving!

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Eshani King's avatar

Very interesting indeed! Thank you. My handbag weighs a ton and I keep meaning to clear it out. I now won't bother!

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Nick Norwitz MD PhD's avatar

“Rock on!” (Or rocks in … to the bag)

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Mark Fickler's avatar

Why do overweight people remain overweight? They are loading their bones

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Nick Norwitz MD PhD's avatar

Weight isn't regulated by one lever. Environmental + genetic factors can "conspire" to shift any individuals weight set "range" (not a point, a range). We talk about macronutrient shifts, insulin resistance, etc. That gravity might be a lever is fascinating, isn't it?

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Mark Fickler's avatar

I see. Perhaps the gradual shift of gaining weight is accepted by the brain while a 10% load triggers the bone gage response

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Nick Norwitz MD PhD's avatar

Not sure it’s about gradual vs immediate. Rather I think it’s that Gravity is just one lever - and probably not the most powerful in a real world setting.

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Mark Fickler's avatar

Got it

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Chris Moore's avatar

My understanding is running is essentially jumping from one leg to the other this applies a large compressive force on that leg. Daniel Lieberman at Harvard has spoken about this being exactly the amount of force needed to promote new bone growth. I wonder if that is a reason why runners are notably skinny. Is running doing the same thing?

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Nick Norwitz MD PhD's avatar

I had a similar thought, but I don’t think the gravitational/compression forces are spread over long enough duration for the gravity to play a very significant role in so far as your body won’t be “tricked” into thinking it’s heavier. However, it’s a good thought because the evolutionary logic is you want to be lean enough to be agile. It’s possible the brain could adjust the threshold on the gravitostat if it learns it needs to be moving around more as signaled by high mileage running. Make sense? Just a hypothesis.

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Manjunath Markandaya's avatar

You inspired me to get back to Rucking! Doing it as I was reading this article! Thanks Nick! Can you at some point do some deep dives into peptides like SLU- PP332 and 5Amino1MQ? Also what are your thoughts on carb cycling for those on a keto diet? Say eating carbs once a week? Any upside or what are the downsides?

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Nick Norwitz MD PhD's avatar

Glad you liked the letter! Here are thoughts on carb cycling: The What, How, Why… and WOW of Carb Cycling

https://youtu.be/1DboMQ9PBIM

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Manjunath Markandaya's avatar

Thanks Nick!

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Nick Norwitz MD PhD's avatar

Welcome!

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Jared's avatar

Great content, Nick! I think about how expensive healthcare is and how we need to try and leverage effective and affordable intervention's, this could be low hanging fruit to help people! I also think (and maybe this is my cynic in me) that possibly effective and inexpensive interventions like this don't get the proper attention as compared to pharmaceutical interventions (to clarify, I am not against pharmacy). Do you have similar sentiment? How do we change the culture in medicine in that sense?

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Filip Ainouz's avatar

Fascinating! Last autumn I had the impression that I got leaner running hill intervals every Monday for about two months. I have since then had a theory that the body makes some adaptations. May this be it then?

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Nick Norwitz MD PhD's avatar

Body absolutely makes adaptations. And hill runs are killer! Nice work.

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Maura Santangelo's avatar

loved this one, I am going to get a weighted vest....and of course we have always known that bone responds to loads or so I am reminded by my orthopod husband. I expect that they will discover more nuance in the follow up studies. At a minimum: Do you have to keep increasing the weight in the vest? or time of weating? would it work with a controlled low calorie diet as in teh study? etc etc

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Nick Norwitz MD PhD's avatar

Glad you liked the letter. For sure, many more answers to unpack! That's the fun part!

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Howard W Newkirk's avatar

Any idea if this will work with those of us over 80 with sarcopenia?

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Nick Norwitz MD PhD's avatar

I see no reason why not.

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adam's avatar

maybe after the first 6 months, your body thinks you lost weight, so now your appetite is lower?

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Nick Norwitz MD PhD's avatar

If I had to guess it has something to do with the epigenetic changes in osteocytes and the general slow turnover of bones. I wish they’d had intermediate follow-up points so we could see if there were a waning effect and - if so - when it kicked in.

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