On-field testing environment and balance error scoring system performance during preseason screening of healthy collegiate baseball players

To determine if testing environment affects Balance Error Scoring System (BESS) scores in healthy collegiate baseball players. Experimental, randomized, repeated-measures design with a sample of convenience. Uncontrolled sideline and controlled locker room baseball environments. A total of 21 healthy collegiate baseball players (age = 20.1 +/- 1.4 years, height = 185.1 +/- 6.8 cm, mass = 86.3 +/- 9.5 kg) with no history of head injury within the last 12 months, no lower extremity injuries reported within the past 2 months that caused them to miss 1 or more days of practice or game time, and no history of otitis media, Parkinson disease, or Meniere disease. Participants performed the BESS test in 2 environments, controlled locker room and uncontrolled sideline, in 2 testing sessions 1 week apart during the baseball preseason. The BESS scores were evaluated for each of the 6 conditions and total score across the testing sessions. Separate, paired-samples t tests with Bonferroni adjustment (P < .008) were used to examine differences between testing environments for each BESS subcategory and total score. Cohen d tests were calculated to evaluate effect sizes and relative change. Significant group mean differences were found between testing environments for single-leg foam stance (P = .001), with higher scores reported for the uncontrolled sideline environment (7.33 +/- 2.11 errors) compared with the controlled clinical environment (5.19 +/- 2.16 errors). Medium to large effect sizes (0.53 to 1.03) were also found for single-leg foam, tandem foam, and total BESS scores, with relative increases (worse scores) of 30% to 44% in the sideline environment compared with the clinical environment. The BESS performance was impaired when participants were tested in a sideline environment compared with a clinical environment. Baseline testing for postural control using the BESS should be conducted in the setting or environment in which testing after injury will most likely be conducted.