Introduction

Running is a widely accessible type of exercise that many individuals like to practice. Since it is so accessible, many are starting to run, with or without a coach. Despite the large number of health benefits, many novice runners tend to get injured along the course of their training. The reported injury rates range from 2.5 to 33 injuries per 1000 hours of running exposure, with the latter being the risk for novice runners. As this is a considerable high risk, effective programs are necessary for preventing running-related injuries. Several risk-reducing programs have been developed, however, the evidence on novice runners is scarce. There is a consensus that preventative training should incorporate strengthening. This study aimed to compare two different methods of strength training and compare them to a control intervention.

Methods

This three-arm randomized controlled trial aimed to study two strengthening programs for preventing running-related injuries. Novice recreational female and male runners were eligible when they were between 18-55 years and engaged in long-distance running as their primary form of exercise. They were considered novices when they had been running for less than 2 years and for less than 20km per week. However, they could run 20 minutes or 3 km continuously. In the previous 3 months they had not sustained any injury from running.

The participants were included and randomly assigned to one of three groups:

• Hip and Core Exercise Group
• Ankle and Foot Exercise Group
• Control Group performing static stretching

The intervention period lasted for 24 weeks and included supervised group strengthening and running training 2 times a week. These sessions were supplemented by independent home exercises performed once or twice per week.

Each training session started with a 5-minute general warm-up including running drills which was the same in every group. After the warm-up, the groups did their assigned strengthening which can be seen in the table here.

The sessions lasted for 20-35 minutes after which the participants did their outdoor running training sessions of 30-75 minutes. Progressions were made when the required number of repetitions and sets was properly achieved using good technique as rated by the supervising physiotherapist.

All three running groups followed the same running program that an experienced endurance coach and exercise physiologist designed. The program gradually increased in duration and level of difficulty and alternated between different types of running exercises such as running, brisk walking, Nordic walking, uphill and downhill running/walking, running intervals, and running coordination exercises. Two technique-focused training sessions were held during the intervention.

The primary outcome was the incidence of running-related lower extremity injuries, monitored through weekly questionnaires.

Results

325 participants were included in the study, with the majority of them being female (> 70%). Their characteristics were comparable at baseline. The ankle and foot group had slightly higher lower extremity injuries/complaints over the past year compared to the subjects in the other groups.

310 running-related injuries were registered, of which 283 were lower extremity injuries. The majority of these injuries (245, 87%) were overuse injuries. All groups had the same amount of running exposure hours. There was also no difference in the number of completed training sessions across the groups.

Considering the number of injuries, 75 were registered in the hip and core group, corresponding to 17.2 injuries per 1000 hours of running. In the ankle and foot group, 114 injuries were sustained per 1000 hours. 94 injuries per 1000 hours occurred in the control group.

A significantly lower incidence rate was found for the hip and core group for preventing running-related injuries compared to the control group (HR 0.66, 95% CI 0.45-0.97). This led to a significantly lower incidence rate of time-loss injuries in the hip and core group (HR 0.65, 95% CI 0.42-0.99) when compared to the control group.

When the division was made between acute and overuse injuries, the following was found:

Overuse injuries: The hip and core group had a 39% lower average weekly prevalence of overuse injuries (PRR 0.61; 95% CI 0.39 to 0.96) and a 52% lower prevalence of substantial overuse injuries (PRR 0.48; 95% CI 0.27 to 0.90) compared to the control group. No significant difference was observed between the ankle and foot group and control group in the prevalence of LE overuse injuries (PRR 0.83; 95%CI 0.55 to 1.25).

Acute injuries: There was no significant difference in the incidence rate of acute LE injuries between the hip and core and control group (HR 2.08, 95%CI 0.64 to 6.75). The ankle and foot group had a higher incidence of acute injuries compared to the control group (HR 3.60; 95% CI 1.20 to 10.86).

Questions and thoughts

The hip and core training effectively reduced overuse injuries compared to people in the control group. However, this finding was not seen for acute lower extremity injuries. The authors indicated that the majority (95%) of the acute injuries were located in the hip/groin/thigh or calf and nearly all of them were sustained during interval or uphill/downhill running. This should be taken into account when extrapolating these procedures to clinical practice.

When looking at the raw data, you can easily observe the difference between the injury incidence between the two intervention arms. At one glance, you can see that

• The ankle and foot group sustained more injuries to the hip and groin region
• The anterior and posterior thigh were more affected in the ankle and foot group
• Regarding shin injuries, both groups had the same occurrence
• Maybe surprisingly, the ankle and foot group sustained more ankle injuries
• Time-loss injuries were more often suffered in the ankle and foot group
• When there were injuries with time loss, injuries that caused more than a week of time loss were more frequent in the ankle and foot group

This could indicate that the more demanding exercises affecting the hip and core were better in reducing the injury risk in these novice runners and thus preventing running-related injuries. That seems logical when we observe the nature of the interventions. In the hip and core group exercises such as deadlifts, (Nordic) hamstring curls, lunges, squats, planks and Copenhagen adductor exercises were completed. On the other hand in the ankle and foot group, the load seems much lower when the exercises of single leg balance, inversion and eversion, toe lifts, heel walks, and toe walks were performed. Is the ankle and foot group inferior? I think it was mostly too low a load.

The study highlights the importance of a physiotherapist-guided exercise program. While the findings are promising for novice recreational runners, the study’s generalizability is limited. The majority of participants were female, and the results may not apply to more experienced runners or different populations. Further research should explore the effectiveness of these programs in diverse groups and settings.

Physiotherapists can apply the findings by incorporating hip and core strengthening exercises into training programs for novice runners. This approach can particularly reduce the risk of overuse injuries, enhancing the safety and sustainability of running as a form of exercise. The simplicity and low cost of the program, which requires minimal equipment, make it feasible for broad implementation.

Talk nerdy to me

The sample size was based on research evidence from a pilot study. There were no substantial harms observed related to the interventions of the study. The hip and core exercise program that preceded the running sessions seems feasible, given the high retention rate of participants. The hip and core strengthening showed beneficial effects in preventing running-related injuries, particularly overuse injuries. For acute injuries, the hip and core exercise program did not show a beneficial effect. The foot and ankle program did not achieve protective effects compared to the control group for overuse injuries and for acute injuries there was even a higher injury incidence. Yet here we must keep in mind that this RCT was designed to study the risk of overuse injuries of the lower extremities. As such, the findings on the acute injuries are merely preliminary.

Compared to other studies, this RCT used a solid design (3-arms) where the interventions had a gradual progression of the resistance and levels of exercise. The exercises were instructed to feel heavy and to be performed until fatigue but ensuring good technique. The authors acknowledge that the ankle and foot program could have been less demanding compared to the hip and core exercise program. They think the people in the foot and ankle group were less familiar with the exercises, since they required activation of the foot muscles and isometric exercises, compared to more common dynamic lunges and squats in the hip and core group.

A possible limitation was the high heterogeneity of the participants and their fitness levels. For some, the training loads may have been high, while for others it could have been too low.

Take home messages

This study provides robust evidence supporting the efficacy of hip and core-focused training in preventing running-related injuries among novice runners. The lack of effectiveness of the ankle and foot-focused program in reducing overuse injuries and its association with higher acute injury rates suggest that such exercises may require careful integration with other training components to be beneficial. If you want to assess someone’s running injury risk, we refer you to our research review we published on this topic!

Reference

Leppänen M, Viiala J, Kaikkonen P, Tokola K, Vasankari T, Nigg BM, Krosshaug T, Werthner P, Parkkari J, Pasanen K. Hip and core exercise programme prevents running-related overuse injuries in adult novice recreational runners: a three-arm randomised controlled trial (Run RCT). Br J Sports Med. 2024 May 9:bjsports-2023-107926. doi: 10.1136/bjsports-2023-107926. Epub ahead of print. PMID: 38724071.