Runners think they’ve got the impact box ticked.
It’s the one group I often see after a DEXA. They don’t have to be convinced to complete weight-bearing exercise, why should they? They’ve been pounding the pavement on every run they go on. So their question to me is, “Why is my bone density low? When all I've done is run for years?”
Here’s the study that explains it.
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Piasecki and colleagues, published in Archives of Osteoporosis in 2018, comparing 3 groups of older people:
38 master sprinters
149 master endurance runners
59 people who weren’t athletes at all
After adjusting for sex, age, height, body composition and jump power, the sprinters’ hip bone density was found to be significantly higher.
10% more than the endurance runners
14% more than the non-athletes
Interestingly, there was found to be no statistical difference between endurance runners and non-athletes.
Decades of distance running, and at the hip they looked similar to people who didn’t train.
As the majority of you reading this are female, it is important to note that this study was made up of mostly men. The point of sharing this is showing what kind of loading bone adapts to. Endurance running does not stress the bone cells enough to cause adaptation, but sprinting absolutely gets closer to the signal needed and experienced through weight training.
Know a woman who’s been told her bones are “just ageing”? Send her this.
Restack it and another few hundred women see it who otherwise wouldn’t.
Bone doesn’t respond to how many times you load it. It responds to how hard and how fast you load it.
Robling and colleagues showed this beautifully in 2002 (in an animal study). Take 360 loading cycles a day. Deliver them all in one go, and you get one result. Split the identical 360 cycles into four bouts of 90, separated by rest, and the bone response almost doubles.
Same total load. Different packaging. Nearly twice the bone development.
The mechanism is that bone cells get overloaded by signal, leading them to being unable to adapt any further at that time. Between 4 to 8 hours of rest restores nearly all of that sensitivity. (Remember this as a mechanism rather than prescription.)
Which tells you what an hour of steady running looks like from your femur’s point of view. Not ten thousand opportunities. But about 4 minutes of BONE adaptation followed by a great LUNG and HEART exercise.
I wrote about this a fortnight ago as the 40-rep ceiling. Distance running is that ceiling, hit early and then run past for another fifty minutes.
Sprinting is very different to endurance running, as the strain magnitude is much higher and the rate of loading is much quicker. Bone notices force applied quickly.
A 2021 study of high-level endurance runners found that female runners had about 4% higher leg bone density than female non-athletes. Real, positive difference. However, at the lumbar spine there was no advantage at all.
Running stimulates the bones in your legs. Your spine gets minimal stimulus, because running doesn’t compress it in any way it isn’t already compressed by standing up or walking.
And the spine is where a lot of osteoporotic fractures occur.
There’s a detail in that same study worth noting. The male runners had lumbar spine density 9% lower than male non-athletes, and the authors raised reduced energy availability as a likely explanation. Running lots while restricting your eating, leading to reduced energy availability, is a bone-loss protocol.
Most of the evidence on low energy availability comes from younger athletes, so I’d be careful bringing this past menopause (but I have seen this clinically being the case). If you’re running five times a week, in a deficit, trying to keep your weight down, you’re not in a bone-building situation no matter how much impact work you’re doing.
I’m not telling you to stop running. Running is good for your heart, your head, your metabolic health and your life expectancy, and none of that is in dispute.
I love running and run multiple times a week, I would be gutted if someone told me I should never run again.
I’m telling you it isn’t a bone program, and that you need to consider one alongside it.
A 2025 meta-analysis of 40 studies covering 2,230 postmenopausal women aged 50 to 60 found that combined training programs significantly improved bone density at both the femoral neck and the lumbar spine.
Combined beats either one alone, and it’s in the right population for once.
Two sessions a week that aren’t running, which include progressive resistance work heavy enough that you’re struggling to complete the last few repetitions. Including something axial or weight bearing through the spine, because running will never give you that. With impact that’s about height and landing rate rather than accumulated steps.
Not two sets of bodyweight squats after your long run. That’s a cool-down, and it’s why most runners’ strength work does nothing.
Which is Thursday’s piece, the eight-week program I have built to sit around your running.
If you’ve got a running friend who’s proud of never having set foot in a gym, this is the one to send her. She’s earned the cardiovascular fitness. She probably hasn’t earned the femoral neck she thinks she has, and there’s still time to fix that.
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