I came across this about a 73 lifter which I found fascinating.
In short, a 73 year old had a bone density Z score of 5. A score of 2 would put him in the top 99 percent. But the most interesting point is that he started at age 55.
Did Lifting Damage His Bones?
Any exercise would help but there does seem to be something special about very heavy loads in forcing the body to adapt. Learning to deadlift and starting double KB work with the Giant in my 40s had a big effect on my on how I thought about strength. I did not go through a bodybuilding phase in my youth.
Declining bone density is a critical health problem in the elderly, power movements and heavy loads (for that individual) should be retained as much as is feasible.
I have my own story here, impressive enough I think, without being quite as "over the top" as the one in the post above. (5.2?? 5 standard deviations?? Seems a bit much. But Z-score probably exaggerates the difference more than his T-score would.)
I had a DEXA scan for bone mineral density in September this year.
As I understand it, T score is compared to a healthy young adult, and Z score is compared to people your own age.
My results:
Left Femur Neck: 1.104 gm/cm2, T: 0.5, Z: 1.2
Left Total Hip: 1.123 gm/cm2, T: 0.9, Z: 1.2
L2-L4 vertebral bodies:
1.403 gm/cm2, T:1.5, Z: 1.8
Left Radius 33%: .879 gm/cm2, T: 0.0, Z: 0.6
So by the conversion to percentile charts, this puts me at
96th percentile for bone mineral density in the lumbar spine as compared with others my age/gender, and 93rd percentile when compared with younger people. Pretty awesome! Especially int he lumbar spine.
I wondered, is this good genetics? My sister and mother had also recently had theirs tested. Results reported a little differently, but I think are still comparable. Their scores are good, but more in the "normal - good" range.
Sister's: lumbar spine: 1.111 g/cm2,
T: -0.6
Mother's: L-spine total L1, L2, L3, and L4 AP lumbar spine is 0.994 g/cm2,
T: -0.5, Z: 1.7
Since my mother and sister both exercise but do very little heavy lifting,
I give the credit to my strength training. However, in the interest of full disclosure, I'm also on
HRT estrogen, where they are not. We are all post-menopause. I am almost 56 yrs old, my sister is 58, and mother 78. So the HRT may also have some positive effect. Also, I take
creatine supplement, and I a few studies have seen an improvement from that as well.
I have had some correspondence with a researcher who has looked at masters weightlifters compared with runners. They published a paper with their findings:
Bone Mineral Density and Muscle Mass in Masters Olympic Weightlifters and Runners; Kayleigh R. Erickson, Gregory J. Grosicki, Mara Mercado, and Bryan L. Riemann. Their findings are aligned with my own experience. From the paper, "While there was no significant difference between exercise groups for the femur T scores (p = .098), the OWL participants had significantly higher lumbar (p = .008), radius (p < .001), and total body (p = .008) T scores, as well as significantly greater lean body mass (p = .021)." In the conclusion, "In summary, midlife incorporation of an explosive, power-focused resistance training program (Olympic weightlifting) appears to provide substantial benefits for musculoskeletal health."
I am glad the message is getting out there.
Lifting is good for bone health! 
