Injury prevention programs that include balance training exercises reduce ankle injury rates among soccer players: a systematic review

Key Points

1. Balance training effectively reduces the risk of ankle sprain with a 36% risk reduction per 1000 hours of exposure.
2. The optimal exercise content is unclear, but it is likely to involve single leg balance challenges, progressed through liable surfaces and the introduction of explicit motor tasks (catching a ball, hop holds etc).
3. The large clinical effects associated with balance training are likely mediated by high levels of athlete compliance, sustained over a 6-month period.

BACKGROUND & OBJECTIVE

Ankle sprains are one of the most common acute injuries occurring in team sports such as soccer. Large cohorts of athletes do not fully recover after ankle sprain, developing chronic symptoms such as instability, pain, and recurrent injury. There is a need to develop effective strategies for the primary prevention of ankle sprains in soccer; it is also important that these can be easily implemented into clinical practice.

This systematic review and meta-analysis examined if injury prevention programs that include balance training exercises effectively reduce the incidence of ankle sprains among soccer players.

Large cohorts of athletes do not fully recover after ankle sprain, developing chronic symptoms such as instability and pain.

Clinicians should encourage a minimum of 2-3 balance training sessions each week.

METHODS

This review was prospectively registered, and its methods aligned with Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The search strategy was clear, and two authors independently examined four core databases (Cochrane, Web of Sci, Pubmed, PEDro).

Included studies were in the English language, used a randomized controlled design (RCTs), and involved soccer players (male or female) being allocated to either an injury prevention program that included balance training or a standard warm up program.

Data extraction was standardized and included: the intervention dosage, athlete adherence (to the intervention), playing exposure, and injury incidence. The main meta-analysis focused on the incidence rate ratio (IRR) – this statistic represented the injury incidence of the ‘balance group’ divided by the injury incidence of the ‘control group’. For context, IRRs of 1 represent a null finding, where the injury incidence is the same in each group.

RESULTS

• 9 large RCTs were included, with aggregate data from 9634 soccer players, recruited across 4 continents.

• The age demographic ranged from 7 to 35 years and the level of competition varied from youth, collegiate, up to first division players.

• The mean duration of balance training was 7 months (range 10 weeks to 12 months), and intervention adherence was high, with two-thirds of studies reporting figures >75%.

• An aggregate of 529 ankle sprains occurred over 775,606 exposure hours. 63% (333/529) of sprains occurred in the control groups, versus 37% (196/529) in the balance training groups.

• There was also clear effect in favour of balance training when the authors controlled for playing exposure, based on a pooled IRR of 0.64 (95% CI 0.54-0.77), equating to a risk reduction for ankle sprain of 36%. See Figure 1.

LIMITATIONS

• Although the review included almost 10,000 soccer players, there were not enough individual studies to undertake powerful subgroup analyses.

• 88% (8/9) of included studies used a cluster randomized design. Without a careful design, cluster trials can introduce a unique source of bias (known as identification/recruitment bias), whereby individuals are recruited into the study after the teams have been allocated to different interventions.

CLINICAL IMPLICATIONS

Multi-interventional programs that include balance training have been shown to be effective in the primary prevention of lower limb injuries in sport (1). In this well performed systematic review and meta-analysis, the authors provide further evidence for incorporating balance-based training into an athlete’s weekly training schedule.

A key strength of the review was that the authors analyzed injury incidence rates, rather than simply basing their conclusions on injury prevalence (numbers of participants with a sprain). By controlling for variations in playing exposure, their results provide a more accurate and powerful estimate of injury risk. The overall (pooled) effect across the 9 studies was large and clinically important, based on a 34% reduction in ankle sprain risk per 1000 playing hours. For context, a single professional player will accumulate around 300 hours of playing exposure each season (2).

Although the authors were not able to conclude a dose-dependent response for balance-based interventions, the consensus from available data is that clinicians should encourage a minimum of 2-3 balance training sessions each week. It is also likely that optimal risk reduction is achieved through high levels of athlete compliance, that is sustained over a prolonged period (average intervention duration was 7 months).

We know that even in professional sports, players’ adherence to effective injury preventative strategies (such as the Nordic hamstring curl) can be as low as 20% (3). It is therefore incumbent on clinicians (and coaching staff) to create an environment and team culture where athletes buy into key injury prevention strategies such as balance training.

+STUDY REFERENCE

Al Attar W, Khaledi E, Bakhsh J, Faude O, Ghulam H, Sanders R (2022) Injury prevention programs that include balance training exercises reduce ankle injury rates among soccer players: a systematic review. Journal of Physiotherapy, 68(3), 165-173.

SUPPORTING REFERENCE

1. Hubscher, M., Zech, A., Pfeifer, K., Hansel, F., Vogt, L. and Banzer, W., 2010. Neuromuscular Training for Sports Injury Prevention. Medicine & Science in Sports & Exercise, 42(3), pp.413-421.
2. Hagglund, M., M Walden., J Ekstrand., 2006. Previous injury as a risk factor for injury in elite football: a prospective study over two consecutive seasons. British Journal of Sports Medicine, 40(9), pp.767-772.
3. Bahr, R., Thorborg, K. and Ekstrand, J., 2015. Evidence-based hamstring injury prevention is not adopted by the majority of Champions League or Norwegian Premier League football teams: the Nordic Hamstring survey. British Journal of Sports Medicine, 49(22), pp.1466-1471.