As a runner and Exercise Physiologist, I at times feel conflicted. I have trained for and completed Ultra-Marathons myself, and also helped coordinate the training plans for clients undertaking similar and more extreme goals than mine.
As a runner, I love the training, the planning, the dedication, the achievement- all of it. But as an Exercise Physiologist, my role in Allied Health is to prescribe exercise to enrich the health of my clients. Am I actually doing the opposite for the ultra-runners I train? Am I the equivalent of a Dietician helping their client’s to compete in a pie-eating contest?
In recent years researchers in my field have cast their scrutinous eye at the Ultra-running community. Ultra-running has evolved from a beyond-the-fringe subculture of self-flagellating weirdos to a legitimate, world-wide sport that attracts a broad cross-section of society. New evidence indicates this may not be an entirely great thing.
Ultramarathon Running and Bone Mineral Density
A recent study published in the International Journal of Applied Exercise (Düz, S., & Arik, M. 2020) compared the bone mineral density of middle-aged male ultramarathoners (UM) (aged 44-56y) to active (AM) and sedentary (C) peers. The average weekly running volume for the UM group was 104.29km, compared to the AM group which was 61.5km.
Analysis of bone mineral density (BMD) showed that the UM group had lower BMD at the lumbar spine, femoral neck and hip compared to the AM group. The total bone mineral density of the UM group was even actually lower than that of the sedentary control group. This indicates that the ultramarathon men in this study are at more risk of osteopenia and osteoporosis than men who do nothing! Bear in mind that impact exercise is recommended for maintaining and improving bone mineral density. This study indicates that there may be a threshold in which the overall stress of the training volumes that many ultramarathoners endure may be beyond what is healthy for their bones.
How do I reconcile this?
Firstly, I strongly advocate that all runners regularly undertake resistance training sessions. The main reasons I advocate this are for performance benefits, as well as improving soft-tissue resilience (for injury prevention). But for high-volume runners, I can add attenuation of bone-mineral loss to this list.
Secondly, I would challenge the need for super-high weekly running volumes for all but the absolute elite level ultramarathoners. High mileage is essential for elite performance in Ultramarathoning. But if your aim is to just complete the race, rather than win the race, is the cost of this high mileage really worth it? I have helped many runners achieve great outcomes in 50+km events with weekly training volumes of ‘only’ 50-60km per week. This would put them into the ‘active’ group of the study I referenced, which showed significantly higher BMD scores than the ultramarathoners and sedentary group.
For those aiming for events much longer than 50km, it is prudent to question the overall health impact of such a goal.
Düz, S., & Arik, M. (2020). The Effect of Ultramarathon Running on Bone Mineral Density in Male Athletes. International Journal of Applied Exercise Physiology, 9(5), 100-108.