Can we predict running injuries?
In the movie Minority Report by Steven Spielberg, the scenario is set in the near future where mutants can predict crimes before they happen. Criminals are arrested before they can even commit any unlawful act, which brings the crime rate down to zero!
This fantasy of being able to predict events beforehand has always existed and running is no exception to the rule. Several research teams from across the world have already tried to determine which factors predict running injuries. With little success thus far.
A recent prospective study published in the American Journal of Sports Medicine aimed to identify risk factors for running injuries over a two-year periodin a cohort of recreational runners.
In order to participate in the study, runners had to be aged between 18 and 60, run at least 5 miles a week and be injury free since at least six months. The research team considered a number of potential risk factors for injury in their analyses. During the 2nd and 4th weeks, they collected information about weight, height, sex, footwear, previous injuries, medications, training loads, running experience, hamstrings and quadriceps flexibility, ankle range of motion, Q-angle, plantar arch height as well as muscle strength at the hip, knee and ankle. In addition, runners were invited to fill out psychosocial questionnaires assessing their anxiety, pain levels, life satisfaction and health status. Their running technique was also analyzed using a three-dimensional motion capture system. Finally, knee stiffness was defined as the ratio between quadriceps force and changes in knee flexion angle during the first half of the stance phase of running. Thus, greater knee stiffness was characterized by a combination of greater quadriceps eccentric force and small changes in knee flexion angle after foot landing.
A total of 300 runners participated in the study, among which 252 remained in the study over the two-year period. They were contacted on a regular basis by the authors to determine whether they had sustained a recent injury.
What were the main findings?
A majority (66%) of runners sustained at least one injury during those two years. Given that only 27% of women remained injury free compared with 38% of men, being a woman was identified as a risk factor for injury. Interestingly, most variables considered initially were not found to be significant risk factors. In fact, injured runners reported significantly worse mental health-related quality of life and more negative emotions (assessed using the SF-12 questionnaire.It also appeared that greater knee stiffness significantly increased the risk of injury. Researchers found out that weekly training loads were linked to the level of stress reported by runners. Finally, runners who sustained fewer injuries either ran fewer miles than injured runners or reported lower stress levels.
What can we learn?
This study confirms what other studies had previously reported (and what The Running Clinic had been teaching for a long time): running biomechanics are overestimated when it comes to predicting running injuries. Runners with a pronounced dynamic knee valgus, greater hip adduction or static Q angle, lesser muscle strength or flexibility or with flat or cavus feet generally don’t sustain more injuries than other runners. Psychological factors should be further considered in runners’ follow-up as they seem to impact the risk of injury. In their paper, the authors recommend that runners reduce their stride length (increase step rate/cadence) to decrease knee stiffness.
On the other hand, limitations of this study did not allow the authors to determine the influence of several other potential risk factors. For example, although running mileage was monitored, acute changes in training loads weren’t considered. This could have been interesting since changes in running mileage from one week to another are often more relevant than the actual mileage. Furthermore, the authors did not clearly define the criteria for “minimalist” or “maximalist” shoes. Consequently, determining the real influence of shoe type on the risk of injury becomes more difficult. Step rate and changes in footwear were not assessed either.
In conclusion, despite this additional well-conducted study, many factors can influence the risk of developing a running injury. However, there is still a long way to go before actually predicting and preventing running injuries. Maybe we should ask Steven Spielberg to look into it.
Article reference: Messier SP, Martin DF, Mihalko SL et al. A 2-Year Prospective Cohort Study of Overuse Running Injuries: The Runners and Injury Longitudinal Study (TRAILS). Am J Sports Med. 2018; 1:363546518773755. doi: 10.1177/0363546518773755.