How to Protect Your Bones as You Age – Part 1
Written by Mario Buchs, Certified Endurance Coach, Ultrarunner & Leadership Performance Practitioner
Mario Buchs is a certified endurance coach, ultrarunner and leadership performance practitioner who brings decades of experience across business, sport and human performance. He writes about resilience, leadership, mindset and what it takes to perform at your best, without losing the human in performance.
Around the end of July or the beginning of August 2020, I started feeling pain in my lower back while running. Like many runners, my first instinct was to brush it off. We tell ourselves that it is probably muscular. Maybe we have done a few too many kilometres. Maybe the training load has increased. Maybe we just need to warm up properly. Of course, we keep running. After all, surely if we ignore it long enough, it will go away? It rarely works that way.
At the time, I was training for my first race covering 100 miles, the Tarawera Miler in Rotorua, New Zealand, which was scheduled for February 2021. My training was building towards around 100 kilometres a week, so when things started to hurt, it was easy to convince myself that it was simply the soreness that comes with increasing mileage.
Initially, I thought the pain was muscular, so I went to see my trusted physiotherapist. He had me jump and hop on one leg. No pain. But as soon as I ran, the pain returned. This time, it didn't disappear when the run finished. In fact, it became worse afterward. That was when I knew this was something different.
We decided to get a magnetic resonance imaging (MRI) scan. The result was something I had never even heard of before: a stress fracture in my sacrum. I was stunned.
I was told that sacral stress fractures can occur in athletes involved in high volumes of training, including ultra runners and Australian Football League (AFL) players. I was referred to a sports doctor who specialised in these types of injuries, and the initial plan was relatively simple: stop loading the bone and give it time to heal. At least six weeks. Then another MRI scan to see whether the bone oedema, essentially the hazy area inside the bone that indicates the body's response to the injury, had settled.
That sounded straightforward. Until someone told an ultra runner to walk and ride a bike to stay fit. There was a problem with that advice.
When an ultra runner hears the word walking, we don't necessarily hear "take it easy." We hear: "Go for a bushwalk." So that's more or less what I did.
Six weeks later, I went back for another MRI scan. The fracture hadn't healed. The pain was still there. It was nowhere near as bad as it had been initially. At its worst, I could hardly move. But the bone hadn't recovered as expected.
The reason became clear. I had simply done too much exercise that loaded the bone. I hadn't given the bone the opportunity to properly heal.
That was a difficult realisation, both physically and mentally. I had to become much more aggressive with my recovery and drastically reduce the amount of walking and cycling I was doing until the next MRI scan.
That was probably my first major lesson about injury and recovery: Recovery actually means recovery. Not "I'll just do a little bit." Not "I'll walk instead." Not "I'll ride to keep my fitness up." Certainly not "It feels a bit better, so I'll see how it goes."
I also learned something else that has stayed with me ever since: listen carefully to the advice of your specialists and make sure you understand exactly what they mean. A walk for an AFL player and a walk for an ultra runner might mean two completely different things. Sometimes doing less is actually doing more.
Four years later, it happened again
After that first stress fracture, I thought I had learned my lesson. The following years were some of the best of my running life. In particular, 2022 and 2023 were fantastic. I completed several ultramarathons ranging from 72 kilometres all the way up to 240 kilometres, and I felt fit, strong and healthy.
So when I entered the Ultra Trail du Mont Blanc (UTMB) Finals event in Chamonix, France, I was excited rather than concerned. The race was a mountain ultra covering 174 kilometres with around 10,000 metres of elevation, taking runners around the Mont Blanc massif through France, Italy and Switzerland. Entries were decided by lottery, and in January 2024, I found out that my name had been pulled out of the hat. I was in.
Training for a race like that meant preparing for serious volume and, particularly, elevation. In February, during my first major training block, I headed to the Victorian Alps for a mini training camp. I was running trails, climbing, descending and putting in the work needed for the mountains.
The following weekend, I was training on trail stairs. I felt strong. I felt fit. Then the pain came back. That familiar pain in my lower back. But this time, it was on the other side. I knew immediately that something wasn't right.
After what had happened in 2020, I wasn't prepared to simply wait and see. The pain didn't settle over the following days, so I contacted the same sports doctor and was referred for another MRI. The result stopped me in my tracks. Another stress fracture in my sacrum. This time, on the opposite side. Four years after the first one.
Emotionally, this was very different. The first fracture had been a lesson in recovery. This one was a warning. I had to ask myself a much bigger question: Why was this happening again?
I wasn't prepared to accept that recurring stress fractures were simply part of being an ultra runner. Something else could be going on. If there was, I wanted to find out what it was.
That was when the investigation really began. Blood tests. Dual energy X-ray absorptiometry (DEXA) scans. X-rays. Ultrasounds. Eventually, an appointment with an endocrinologist.
The results showed bone mineral density in the osteopenic range. However, because I had sustained a fracture of the fragility type, my overall clinical picture was treated as osteoporosis. That was a confronting word to hear.
I was an endurance athlete who felt fit and strong. I was running huge distances. I was strength training. I was eating what I considered a healthy diet based on plants. Yet underneath all of that, there was a problem with my bones.
Medication was put on the table. I understood why. But I wanted to understand the why behind the problem before simply treating the number.
My approach wasn't to reject medication outright. It was to ask whether there were things I could change first, particularly around nutrition, training and recovery, and then objectively measure whether those changes were working.
So I went back to my nutritionist. We looked closely at my diet based on plants and made some deliberate changes, particularly increasing my intake of whole foods rich in calcium. Walnuts, figs, oranges and dried apricots became regular parts of my diet, alongside calcium supplementation.
This time, I did something else that I had failed to do properly in 2020. I rested. Properly. My endocrinologist gave me three months to make these changes before we reviewed things again.
It wasn't simply a matter of waiting to see how I felt. Before the follow-up appointment, I needed further urine and specialised blood testing to determine whether my bones were still under excessive metabolic stress despite the reduced training load.
If the results suggested there was still a problem, medication would become the next step. So I waited. Then came the results.
The news was encouraging. Even with around 60% of my normal training load restored, including running and strength training, the results came back looking very positive. For the moment, medication was off the table.
But I wasn't satisfied with simply getting a good result. I wanted to understand what had happened. Why had an athlete who felt strong and healthy developed two stress fractures?
Was it simply the amount of running? Was it age? Was it nutrition? Was it recovery? Was it strength training? Or was it a combination of all of these things?
That question became the beginning of a much bigger journey into bone health, ageing, strength, nutrition and longevity.
I wanted to know what was really happening to my bones
As a personal trainer and running coach, I already understood that strength training needed to become a bigger part of my approach.
Heavy compound movements such as squats and deadlifts provide a very different stimulus to the body than simply running more kilometres. I wanted to build strength, support my bones and, importantly, give my body another reason to maintain and potentially improve bone mineral density.
So I joined a gym that also happened to have a DEXA scanner. If you're wondering what a DEXA scan actually does, the simple explanation is this: it is an X-ray scan that uses a low dose of radiation to measure bone mineral density and can also provide information about body composition. It is commonly used to assess bone health and osteoporosis risk.
For me, however, the DEXA machine became much more than a diagnostic tool. It became a way of asking questions.
I was still an ultra runner. I had no intention of giving up the sport I loved. So rather than simply asking, "How do I get my bone density back up?" I started asking another question: What does ultra endurance running actually do to my bones?
I had spent years pushing my body to its limits. Hundreds of kilometres. Thousands of metres of elevation. Long periods of repetitive impact and enormous training loads. But what was happening beneath the surface? I decided to find out. Three races. Three sets of measurements.
My next three major races were going to provide a pretty good testing ground. In 2025, I lined up for:
Ultra Trail Australia 100 (UTA100), 100 kilometres with around 4,400 metres of elevation
Elephant Trail Race, 100 miles with around 9,000 metres of elevation
Coast to Kosci, 240 kilometres with around 5,500 metres of elevation
These weren't exactly laboratory conditions. They were real races that I had trained for and wanted to complete. That was important to me.
I wasn't interested in creating a perfect experiment where every variable could be controlled. I wanted to understand what was happening to my body in the real world of ultra endurance running.
So around each event, I used DEXA measurements to track what was happening. Before the race. Again, 2 to 4 days after the race. Once more 5 to 7 days into recovery, depending on the event.
Alongside bone mineral density, the scans also gave me information about lean mass, fat mass, body fat percentage and visceral adipose tissue.
I was essentially trying to capture a snapshot of my body before I asked it to do something extraordinary, immediately after that stress, and then again once recovery had started.
The question was simple: Would repeated ultra-endurance racing cause my bone density to decline? Or could I continue to run extreme distances while supporting my bones through strength training, nutrition and recovery?
I was about to find out. Keep an eye out for Part 2.
Read more from Mario Buchs
Mario Buchs, Certified Endurance Coach, Ultrarunner & Leadership Performance Practitioner
Mario Buchs is a certified endurance coach, ultrarunner and leadership performance practitioner whose career has spanned engineering, business, sport and human development. After more than two decades as a service engineer and business professional, working across technical, leadership, sales and training roles around the world, Mario discovered a passion for endurance sport and human performance. He has since completed 23 ultramarathons, including multiple 100-mile-plus events, and founded Healthetica Coaching and Forward Motion Leadership. Today, Mario brings the lessons of business, endurance, and life together to explore resilience, leadership, mindset, and what it really takes to unlock human potential.
