Background:​ A high body mass index and previous ankle sprains have been shown to increase the risk of sustaining noncontact inversion ankle sprains in high school football players.

Hypothesis:​ Stability pad balance training reduces the incidence of noncontact inversion ankle sprains in football players with increased risk.

Study Design:​ Cohort study;​ Level of evidence, 2.

Methods:​ Height, body mass, history of previous ankle sprains, and current ankle brace/tape use were documented at the beginning of preseason training in 2 high school varsity football teams for 3 consecutive years (175 player-seasons). Players were categorized as minimal risk, low risk, moderate risk, and high risk based on the history of previous ankle sprain and body mass index. Players in the low-, moderate-, and high-risk groups (ie, any player with a high body mass index and/or a previous ankle sprain) were placed on a balance training intervention on a foam stability pad. Players balanced for 5 minutes on each leg, 5 days per week, for 4 weeks in preseason and twice per week during the season. Postintervention injury incidence was compared with preintervention incidence (107 players-seasons) for players with increased risk.

Results:​ Injury incidence for players with increased risk was 2.2 injuries per 1000 exposures (95% confidence interval, 1.1–3.8) before the intervention and 0.5 (95% confidence interval, 0.2–1.3) after the intervention (<em>P</em> < .01). This represents a 77% reduction in injury incidence (95% confidence interval, 31%–92%).

Conclusion:​ The increased risk of a noncontact inversion ankle sprain associated with a high body mass index and a previous ankle sprain was eliminated by the balance training intervention.