Author(s): KUO, Y.L., CHENG, H., Institution: NATIONAL CHENG KUNG UNIVERSITY, Country: TAIWAN, Abstract-ID: 543

INTRODUCTION:
Athletes with a chief complaint of low back pain (LBP) are frequently observed with mobility restrictions in the thoracic spine and hip joint. These restrictions may contribute to compensatory hypermobility in the lumbar spine and subsequently leads to recurrent LBP. The objectives of this study were to: (1) investigate if there is a significant mobility difference in the thoracic spine and hip joint between baseball players with and without a history of LBP; (2) identify thoracic spine and hip mobility related predictors for batting velocity in baseball players.
METHODS:
Ten male adult baseball fielders with a history of LBP (age: 20.3±2.2 years; weight: 76.9±12.4 kg; height: 175.4±7.6 cm; baseball experience: 9.6±4.1 years) and 10-aged matched controls (age: 19.5±1.6 years; weight: 75.9±12.0 kg; height: 177.0±4.4 cm; baseball experience: 7.1±2.6 years) participated in this study. Joint mobility and muscle stiffness for the thoracic spine and hip joints were measured using a hand-held inclinometer and a MyotonPRO device, respectively. Batting velocity was measured using a 13-camera Vicon motion analysis system. Independent t-tests and multiple linear regressions were used to analyze the data between the LBP and control groups.
RESULTS:
The LBP group had a statistically significantly smaller internal rotation range in the lead hip (31.70±5.17 vs. 37.45±5.42, t = -2.427, p = 0.026) and significantly decreased iliotibial band flexibility in the pivot hip (7.80±3.57 vs. 12.80±3.21, t = -3.295, p = 0.004) compared to the control group. No significant between-group differences were found in thoracic spine mobility and muscle stiffness measurements (p > 0.05). Hip joint mobility statistically significantly predicted the linear batting velocity (F(12, 7) = 4.335, p = 0.030, R² = 0.881). Among all measurements for hip joint mobility, the internal rotation range (ß= -1.303, p = 0.034) and measurement of the FABER test (ß= -1.235, p = 0.023) in the pivot hip added statistically significantly to the prediction. Thoracic mobility, on the other hand, did not predict the linear batting velocity (F(6, 13) = 1.638, p = 0.214, R² = 0.431).
CONCLUSION:
Baseball players with a history of LBP showed mobility restriction in the hip joint but not in the thoracic spine compared to healthy controls. More emphasis should be placed on hip internal rotation mobility when treating or training baseball players to enhance batting performance.