Multi-segment foot landing kinematics in subjects with chronic ankle instability

Hip Strength as an Intrinsic Risk Factor for Lateral Ankle Sprains in Youth Soccer Players: A 3-Season Prospective Study

BACKGROUND

Numerous epidemiological studies have emphasized the burden of lateral ankle sprains in youth soccer players. However, no prospective study has identified intrinsic physical and modifiable risk factors for these injuries in this particular population. Although injury prevention programs in soccer incorporate proximal hip and core stability exercises, it is striking that the relationship between impaired proximal hip function and ankle sprains has not yet been prospectively investigated in youth soccer players.

HYPOTHESIS

This prospective study aimed to examine whether hip muscle strength is a risk factor for sustaining a lateral ankle sprain in youth soccer players. We hypothesized that decreased hip muscle strength would predispose youth soccer players to an increased risk of lateral ankle sprains.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

This study included a total of 133 male youth soccer players (age divisions U11-U17) for analysis. At the beginning of the season, anthropometric characteristics were collected and hip muscle strength was assessed using a handheld dynamometer. Injury registration was performed by the team medical staff during 3 consecutive seasons. A principal-component, multivariate Cox regression analysis was performed to identify potential risk factors for sustaining a lateral ankle sprain.

RESULTS

Twelve participants (18% of all reported injuries) sustained a lateral ankle sprain (0.36 per 1000 athletic-exposure hours). After adjustment for body size dependencies and other hip muscle forces, an increase in hip muscle extension force was associated with a significant decrease in the hazard of the injury (hazard ratio, 0.3; 95% confidence interval, 0.1-0.9; P = .028). No other study variable could be identified as a risk factor for lateral ankle sprains.

CONCLUSION

Reduced hip extension muscle strength is an independent risk factor for lateral ankle sprains in male youth soccer players. Other hip muscle strength outcomes were not identified as risk factors. Replication in larger samples with more injured cases is warranted to further ascertain the importance of this risk factor.

Altered Vertical Ground Reaction Forces in Participants With Chronic Ankle Instability While Running

CONTEXT

Altered gait kinetics may increase the risk of long-term injuries in participants with chronic ankle instability (CAI). Vertical ground reaction forces (vGRFs) can provide insight into how body loading is altered.

OBJECTIVE

To compare the components of vGRFs while running in participants with or without CAI.

DESIGN

Cohort study.

SETTING

University biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty-four experienced, college-aged runners. Groups were categorized by the presence (CAI group) or absence (control group) of CAI through self-reported questionnaires.

INTERVENTION(S)

After a warm-up period, all participants ran on an instrumented treadmill for 5 minutes at 3.3 m/s. Data were collected during the last 30 seconds. Five continuous trials of heel-to-toe running were identified per participant and averaged for statistical analysis.

MAIN OUTCOME MEASURE(S)

The dependent variables were impact peak force (N/body weight [BW]), active peak force (N/BW), time to impact peak force (milliseconds), time to active peak force (milliseconds), and average loading rate ([N/BW]/s).

RESULTS

A difference was found between groups (P = .002). The CAI group had higher impact peak forces (P = .001) and active peak forces (P = .002) compared with the control group. The CAI group also had an increased loading rate (P = .001) and a shorter time to reach the active peak force (P = .001) compared with the control group. No difference was seen between groups in the time to reach the impact peak force (P = .952).

CONCLUSIONS

Participants with CAI produced altered vGRFs and loading rates while running. Altered loading rates could predispose individuals with CAI to stress-related injuries and repetitive sprains.