The Masters Runner: Part 2 - What Hurts?

In Part 1 we’ve identified the main differences between younger runners and Masters runners. In Part 2, let’s look at the most common running-related injuries in Masters runners (and talk about one that isn’t actually as common as popular belief).

Most of our modern knowledge about running injury prevalence in Masters runners has been from two survey-based studies over ten years ago. 34% (981 total runners) and 62% (179 total runners) in the studies were >40 and considered Masters runners. The takeaway from both shows that the most common locations of injury are at the level of the knee, ankle, and foot. Masters runners see a higher incidence of Achilles tendinopathy, plantar fasciiopathy, hamstring strains/tendinopathies, and calf muscle strains than their younger runner counterparts. That’s a lot of injuries from the knee down, and that will be particularly relevant when we talk about what to do about it.

Clearly, there are some problems with comparing injuries in younger and older runners. Are these differences seen because of physiological changes or changes in training habits (see previous post)? Are the changes in training habits a result of physiological changes?? Total running volume per week seems to not be significant for injury rate, but the frequency of training does (training 6-7x per week shows higher injury rates than 1-3x per week). Knowing that older athletes have more exercise-induced muscle damage at equivalent workbouts (presumably meaning more recovery time is needed), this could be a matter of physiology influencing training habits.

Going back to the specific injuries, we see a lot more injuries in the lower limb in the Masters runner. In Part 1, I referenced the study where Masters and younger runners were matched for training volume and intensity. The main difference seen is power production at the ankle, moreso in Masters runners training at lower intensities. This seems to fit the general trend: less power in the ankle (specifically in the calf), more injuries in the calf, ankle, and foot. Would we fix everything with heavy seated calf raises? It would confirm my biases, but it isn’t that simple. There isn't any experimental evidence to say that strengthening the lower limb is protective against injury in Masters runners, but it certainly makes sense in theory. If we improve capacity in the area of the body seemingly most prone to injury, we expand its "envelope of function" and it can tolerate more loading until the point of failure.

Something I haven’t mentioned yet is osteoarthritis (OA), a pathology commonly associated with the aging process. That seems to be because it’s not actually very prominent in the Masters runner. In one of the survey studies is it mentioned and its rate is nearly 40 times less than Achilles tendinopathy, the most common injury noted. In the past few years, there’s been some notable findings about OA and running. A systematic review and meta-analysis two years ago found the association of OA prevalence and recreational runners (3.5%) was much lower than non-running controls (10.58%) and competitive runners (13.3% and defined as elite, international-level competitors). That said, the findings from a review like this might just be showing that individuals who develop OA then stop running and fall into the non-running category. Interpreting running as protective from this study would be a form of survivorship bias.

In the same year, a narrative review proposing why running doesn’t seem to initiate OA presented two mechanisms. The first is that cumulative load may be more influential on OA development than peak loading, and the cumulative demands of running are fairly low compared to other activities more associated with OA development (think sitting in a deep squat for long periods like many physical labor jobs). The second mechanism is that joint cartilage is conditioned to tolerate more loading over time with a certain moderate amount of load. These two mechanisms don’t necessarily have to be interrelated, but they do explain the majority of the bell curve between no running and extremely high volumes/intensities.

What about running in the presence of OA? Clinically, many of the runners I see think of OA as the tombstone in their running career. Interestingly, a recent cohort study has shown that self-selected running does not appear to influence the progression of knee OA on radiograph or by subjective symptom response after a four year follow-up. Unfortunately the study can’t tell us what the optimal dosage (volume, intensity) of running is with knee OA, but we can use “self-selected running” as our guide for now. Somewhere in my head there’s an entire separate blog post dedicated to evidence on running after total joint replacement which may or may not be coming soon.

Anyhow, that’s what hurts (and doesn’t hurt as much) in the Masters runner. Questions? Self-selected comments?

Dr. Jason Tuori, PT, DPT, CSCS


References/cool running readings:

1. Knobloch K, Yoon U, Vogt PM. Acute and overuse injuries correlated to hours of training in master running athletes. Foot Ankle Int. 2008;29:671–676.
2. McKean KA, Manson NA, Stanish WD. Musculoskeletal injury in the masters runners. Clin J Sport Med. 2006;16: 149–154. 
3. Alentorn-Geli E, Samuelsson K, Musahl V, et al. The association of recreational and competitive running with hip and knee osteoarthritis: a systematic review and meta-analysis. J Orthop Sports Phys Ther. 2017;47:373–390. 
4. Miller RH. Joint loading in runners does not initiate knee osteoarthritis. Exerc Sport Sci Rev. 2017;45:87–95. 
5. Lo GH, Musa SM, Driban JB, et al. Running does not increase symptoms or structural progression in people with knee osteoarthritis: data from the osteoarthritis initiative. Clin Rheumatol. 2018.