Risk Factors for Overuse Injuries in Runners:

A Randomized Study of a Strength Training Program to Prevent Injuries in Runners of the New York City Marathon

BACKGROUND

Lower extremity overuse injuries are common among runners, especially first-time marathoners. Hip abductor and quadriceps strengthening is often recommended to reduce running-related injuries.

HYPOTHESIS

A 12-week strength training program would decrease the rate of overuse injuries resulting in marathon noncompletion and improve race finishing time.

STUDY DESIGN

Randomized trial.

LEVEL OF EVIDENCE

Level 2.

METHODS

Twelve weeks before the New York City Marathon, first-time marathon runners age 18 years and older were randomized into a strength training group or an observation group. The strength training group was instructed to perform a 10-minute program 3 times weekly using written and video instruction. This program targeted the quadriceps, hip abductor, and core muscle groups. Injuries were self-reported through biweekly surveys, with major injuries being those that resulted in marathon noncompletion and minor injuries being those that impaired training or race performance.

RESULTS

A total of 720 runners were enrolled (mean age, 35.9 ± 9.4 years; 69.4% female), of whom 583 runners started the marathon and 579 completed it. The incidence of major injury was 8.9% and minor injury was 48.5%. Fifty two of 64 major injuries were overuse, of which 20 were bone stress injuries. The incidence of overuse injury resulting in marathon noncompletion was 7.1% in the strength training group and 7.3% in the observation group (risk ratio, 0.97; 95% CI, 0.57-1.63; P = 0.90). The mean finishing time was 5 hours 1 ± 60 minutes in the strength training group and 4 hours 58 ± 55 minutes in the observation group (P = 0.35).

CONCLUSION

There is a high prevalence of injury among first-time marathon runners, but this self-directed strength training program did not decrease overuse injury incidence resulting in marathon noncompletion.

CLINICAL RELEVANCE

Prevention strategies such as strength training need to be developed and evaluated through clinical trials to reduce the high prevalence of overuse injuries in runners, especially for high-risk populations such as first-time marathon runners.

Influence of stride frequency and length on running mechanics: a systematic review

Context:

A high number of recreational runners sustain a running-related injury each year. To reduce injury risk, alterations in running form have been suggested. One simple strategy for running stride frequency or length has been commonly advocated.

Objective:

To characterize how running mechanics change when stride frequency and length are manipulated.

Data Sources:

In January 2012, a comprehensive search of PubMed, CINAHL Plus, SPORTDiscus, PEDro, and Cochrane was performed independently by 2 reviewers. A second search of the databases was repeated in June 2012 to ensure that no additional studies met the criteria after the initial search.

Study Selection:

Inclusion criteria for studies were an independent variable including manipulation of stride frequency or length at a constant speed with outcome measures of running kinematics or kinetics.

Study Design:

Systematic review.

Level of Evidence:

Level 3.

Data Extraction:

Two reviewers independently appraised each article using a modified version of the Quality Index, designed for assessing bias of nonrandomized studies.

Results:

Ten studies met the criteria for this review. There was consistent evidence that increased stride rate resulted in decreased center of mass vertical excursion, ground reaction force, shock attenuation, and energy absorbed at the hip, knee, and ankle joints. All but 1 study had a limited number of participants, with several methodological differences existing among studies (eg, overground and treadmill running, duration of test conditions). Although speed was held constant during testing, it was individually self-selected or fixed. Most studies used only male participants.

Conclusion:

Despite procedural differences among studies, an increased stride rate (reduced stride length) appears to reduce the magnitude of several key biomechanical factors associated with running injuries.

Dynamic balance performance and noncontact lower extremity injury in college football players: an initial study

Background:

Field expedient screening tools that can identify individuals at an elevated risk for injury are needed to minimize time loss in American football players. Previous research has suggested that poor dynamic balance may be associated with an elevated risk for injury in athletes; however, this has yet to be examined in college football players.

Hypothesis:

To determine if dynamic balance deficits are associated with an elevated risk of injury in collegiate football players. It was hypothesized that football players with lower performance and increased asymmetry in dynamic balance would be at an elevated risk for sustaining a noncontact lower extremity injury.

Study Design:

Prospective cohort study.

Methods:

Fifty-nine collegiate American football players volunteered for this study. Demographic information, injury history, and dynamic balance testing performance were collected, and noncontact lower extremity injuries were recorded over the course of the season. Receiver operator characteristic curves were calculated based on performance on the Star Excursion Balance Test (SEBT), including composite score and asymmetry, to determine the population-specific risk cut-off point. Relative risk was then calculated based on these variables, as well as previous injury.

Results:

A cut-off point of 89.6% composite score on the SEBT optimized the sensitivity (100%) and specificity (71.7%). A college football player who scored below 89.6% was 3.5 times more likely to get injured.

Conclusion:

Poor performance on the SEBT may be related to an increased risk for sustaining a noncontact lower extremity injury over the course of a competitive American football season.

Clinical Relevance:

College football players should be screened preseason using the SEBT to identify those at an elevated risk for injury based upon dynamic balance performance to implement injury mitigation strategies to this specific subgroup of athletes.

Chronic lower leg pain in athletes: a guide for the differential diagnosis, evaluation, and treatment

Context:

Chronic lower leg pain in athletes can be a frustrating problem for patients and a difficult diagnosis for clinicians. Myriad approaches have been suggested to evaluate these conditions. With the continued evolution of diagnostic studies, evidence-based guidance for a standard approach is unfortunately sparse.

Evidence Acquisition:

PubMed was searched from January 1980 to May 2011 to identify publications regarding chronic lower leg pain in athletes (excluding conditions related to the foot), including differential diagnosis, clinical presentation, physical examination, history, diagnostic workup, and treatment.

Results:

Leg pain in athletes can be caused by many conditions, with the most frequent being medial tibial stress syndrome; chronic exertional compartment syndrome, stress fracture, nerve entrapment, and popliteal artery entrapment syndrome are also considerations. Conservative management is the mainstay of care for the majority of causes of chronic lower leg pain; however, surgical intervention may be necessary.

Conclusion:

Chronic lower extremity pain in athletes includes a wide differential and can pose diagnostic dilemmas for clinicians.