Introducing an activity-based balance index for soccer players: A validity and reliability study

Objectives: The aim of this study was to evaluate the validity and reliability of introducing a new activity-based balance index using a triaxial accelerometer during activity. Methods: Twenty seven soccer players (age: 14.5 ± 0.4 years old, body mass: 58.3 ± 9.3 kg, height: 172 ± 8 cm) who participated in the national premier league were recruited. The participants were tested for their balance, activity, and skill in four tests: (I) one leg stance; (II) dynamic Y balance; (III) running; and (IV) dribbling slalom. The acceleration of the body was recorded using an accelerometer during those tests. By processing acceleration data, a new activity-based balance index (ABI) was calculated based on the velocity, acceleration, and position index of soccer players. Using intra-class correlation coefficients (ICC), reliability was calculated. Results: Reliability was high (ICC = 0.87-0.89; 95% CI = 0.77-0.93) in calculating ABI for the three activities performed in the tests. A significant positive correlation between ABI and both static and dynamic balance scores (r = 0.62, P = 0.002) was observed. Further-more, negative correlation was found significantly between ABI and dribbling scores (r =-0.61, P = 0.026) and Y Balance test (r = 0.6, P = 0.002). Conclusions: In conclusion, the introduced ABI demonstrates great potential to determine balance and skill scores based on accelerometer-based measures.