I've heard exercise and resistance/strength training increases the density, but doesn't increase mass. So basically, experimentally or theoretically possible at least, can modern science do this/is it feasible?

Density is just how "packed" the current bone is on the micro-level -- i.e., doesn't affect total mass potential. Filling or adding "density" is just like putting water in a fixed-size bucket until it fills. By "adding mass" I want the bone's bucket to be able to hold more density, i.e., a larger potential of density along with an overall greater weight to the bones themselves. I can't find any evidence that this is possible with long and flat bones alike, AKA the spine, leg and arm bones, clavicles and etc. -- or any bone.

I've heard facial bones are more malleable, but their bone mass cannot change with diet/training either.

So to make this as easy to understand as possible: Can bone mass in an adult be significantly changed somehow? Can I make my whole skeletal set heavier somehow, rather than just dense? Like for example, say I am considered "small framed." Rather than just density, could I make my frame bigger? Could I make my entire frame base more robust through some possible bio/drugs/etc. means?

And since I know someone will come along and claim this is a "medical/personal question," explain to me how this would be possible to ask in a non-medical/personal way then to enlighten me. Go ahead.


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  • $\begingroup$ Bone mass probably does vary with bone density, and it's the volume of the space that the bone occupies that doesn't change much due to exercise and resistance/strength training, at least in the short run. But I could be wrong... $\endgroup$ – uhoh Apr 28 at 4:27
  • 1
    $\begingroup$ Density = mass/volume. If volume stays the same and density increases, mass would also increase. $\endgroup$ – MelaGo Apr 28 at 21:33
  • $\begingroup$ @MelaGo My assumption would be that it's a limitation on volume in which density can take place. You can't "out-volume" the potential of the bone, which is my argument the whole "density vs. mass" simplification -- i.e., you can add as much density to the given volume/genetic/epigenetic/adult size/etc., but cannot really make the bones bigger in any significant way such as a smaller frame to a medium/large one. $\endgroup$ – Waste Of Time Apr 29 at 3:44
  • $\begingroup$ @WasteOfTime, your entire question can be clear enough if you just ask if exercise can make someone's bones bigger in the sense of a bigger frame. There's a lot of unnecessary confusion by mentioning mass and density. $\endgroup$ – Jan Apr 30 at 12:09

If you search for
- bone growth training
- bone hypertrophy athletics,
- bone diameter increase,
- bone strengh hunter gatherer,
on google, you will find more articles than I could possibly summarise:

stimulation of longitudinal bone growth and widening of the joint space (cartilage hypertrophy) occur. The possibility of bony hypertrophy as a result of athletic training, especially with regard to increases in of bone density and bone diameter, should lead to incorporation of sports medical considerations into the prophylaxis and therapy of osteoporosis.



I have slender bones and it was the gain of muscle which helped me to balance my physique.

  • $\begingroup$ Gaining muscle != making any significant difference of skeletal bone mass/shape/volume/etc. If anything, muscle can at best hide some smaller frame along with fat if you have the natural genetic potential for decent musculature (unlikely with a small skeletal frame). $\endgroup$ – Waste Of Time Apr 29 at 3:46
  • $\begingroup$ When you are 15-18 your bones grow a lot faster than what your musculature can adapt for. I found myself with hands and arms which were 30 percent longer in the space of a few years, so they would basically flap about and I didn't know why they had lost their agility. In that sense, you get used to your physique as it adapts. $\endgroup$ – com.prehensible Apr 29 at 10:46
  • $\begingroup$ I've found the opposite -- good muscle strength, but frame not good enough (on my body/my experience). A smaller skeletal frame overall is a death sentence when it comes to your ability to play brutal contact sports, as you're more susceptible and injury prone, along with generally having less physical potential due to bone shape/etc. There is a reason why most pro athletes don't have very frail/narrow/small bones/etc. $\endgroup$ – Waste Of Time Apr 29 at 16:53
  • $\begingroup$ I mean nobody will believe this guy plays in the NFL just by virtue of his body frame alone: discourse-cdn-sjc1.com/tnation/uploads/default/optimized/3X/f/8/… And no amount of muscle building will improve such a small body/skeleton shape/etc. that's always vulnerable. This is what I mean when I talk about skeletal mass, as it's the overall structure that can't be changed in any significant way vs. just merely adding some density/etc. that won't really do much if the guy in the photo above wanted to play organized contact sports. $\endgroup$ – Waste Of Time Apr 29 at 16:57

In short, yes, you can increase your bone mass by increasing both the bone density and thickness, but the increase may not be as great as you expect.

The body frame consists of the length and thickness of your bones, and is mainly genetically determined. After age about 20, you cannot increase your bone length further, but you can increase the bone thickness by few millimeters by regular heavy exercise. In this study in tennis players, the bones in their main arms were thicker by 2 mm at most compared to the weaker arms.

The bone mass also increases with bone density, which means more collagen fiber in your bones or, as you compared, more water in a glass. Bone density is 95% determined at the age about 20, when your bones stop to grow. Your bone mass probably reaches the peak between age 25 and 30 (OrthoInfo).

Until your bones still grow, you can somewhat increase your bone density by consuming enough calcium and vitamin D and by being regularly physically active (PubMed, 2015). Please note, that consuming excessive amounts of calcium or vitamin D will note further increase your bone density.

After your bones stop to grow, you can maintain your bone density, again, by sufficient calcium intake and regular physical activity (PubMed, 2008).

  • $\begingroup$ Wouldn't the thickness be attributed to just the most density built possible? They use the arms a lot so it's obvious the bones would be a little more dense there in their dominant arm/etc. This doesn't really mean an overall change in bone mass, other than just the same bone structure becoming more ossified/calcified/etc. I mean the actual bone didn't really "grow" or change in any significant way. The same bone shape/size/etc. that was/were genetically determined for the most part just became more dense by a super-tiny bit (2mm isn't even noticeable without like a DEXA scan or etc. maybe). $\endgroup$ – Waste Of Time Apr 29 at 15:47
  • $\begingroup$ I mean it's obvious sports and exercise make anyone's bones more dense, but this doesn't really make a real change in the overall bone mass/volume that is comparing, say, a small-framed man's skeleton to a large-framed man's. The bones may get stronger and as dense as possible, but do not really gain mass/noticeable thickness/size in any way that one could compare like an untrained individual's muscle mass to that of a multi-year weightlifter (on average). So no, this seems more like repeated use adds (very insignificant) density to bones, which is known -- but no real change in frame/size. $\endgroup$ – Waste Of Time Apr 29 at 15:51
  • $\begingroup$ They DID observe an increased diameter (thickness) of the arm bones but this was relatively small, so I said you may be disappointed. This bone growth doesn't really change your look and it certainly doesn't make your frame larger. It's not even nearly comparable with muscle mass increase. Looking only at bones you would barely notice the increase. You asked for a scientific evidence and that's it. $\endgroup$ – Jan Apr 29 at 16:00
  • $\begingroup$ I'm not discrediting your post or the source you gave -- both are valid/"okay" as far as info and sourcing/answering goes. What I am just adding on to is the fact that this doesn't and cannot make any significance in overall skeletal base/mass/frame by adding density itself. So it's meaningless in that regard, but still valid in general. Basically this confirms that it is indeed impossible to make any significant change to your overall skeletal frame from exercise at least, as evidence shows negligible results over long durations. $\endgroup$ – Waste Of Time Apr 29 at 16:49

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