0.05) with the higher value of all COP parameters (COP path length PF = 2.54 ± 0.61 and NF = 2.43 ± 0.37; COP velocity PF = 0.127 ± 0.306 and NF = 0.121 ± 0.185; 95% CEA PF = 0.0235 ± 0.0076 and NF = 0.022 ± 0.115) in PF group than NF group. Conclusions: Limited number of participants demonstrated no significant differences in COP parameters among hamstring injury with normal foot and pronated foot. Even though this study did not find the differences in a single leg standing, the PF group tends to have higher sway parameters which mean that hamstring injured leg with pronated foot may impair postural control ability in comparison to injured leg with normal foot. Clinical Relevance: This study provided a new insight for clinical rehabilitation and prevention of hamstring strain injury by considering the foot posture and balance ability of the athlete in the training program.' />
Background and Purpose: It is unclear how hamstring injuries combined with foot pronation influence static postural stability among athletes with prior hamstring strains. This study aimed to investigate the differences in postural stability during a single-leg standing in athletes with hamstring strains with and without pronated foot. Methods: Ten hamstring injured legs (5 injuries with-and 5 injuries without pronated foot) were analyzed according to their injury history and foot posture. Foot posture was classified according to the foot posture index scale (FPI-6). Participant were requested to perform a single-leg standing with eye-open on the Zebris force plate in 25 second. The main outcomes were center of pressure (COP) path length, COP velocity, and the 95% of confidence ellipse area (95% CEA). Independent T-test and Mann-Whitney U test was performed to analyze the differences in the main outcomes between the two groups. Results: There were no differences in participants' characteristics (age pronated foot [PF] = 24.6 ± 4.9, normal foot [NF] = 26.2 ± 5.3; weight PF = 71.2 ± 4.9 and NF = 69.6 ± 71.2; height PF = 1.73 ± 0.05 and NF = 1.76 ± 0.89). This study revealed no significant differences of all COP outcomes between two groups (p > 0.05) with the higher value of all COP parameters (COP path length PF = 2.54 ± 0.61 and NF = 2.43 ± 0.37; COP velocity PF = 0.127 ± 0.306 and NF = 0.121 ± 0.185; 95% CEA PF = 0.0235 ± 0.0076 and NF = 0.022 ± 0.115) in PF group than NF group. Conclusions: Limited number of participants demonstrated no significant differences in COP parameters among hamstring injury with normal foot and pronated foot. Even though this study did not find the differences in a single leg standing, the PF group tends to have higher sway parameters which mean that hamstring injured leg with pronated foot may impair postural control ability in comparison to injured leg with normal foot. Clinical Relevance: This study provided a new insight for clinical rehabilitation and prevention of hamstring strain injury by considering the foot posture and balance ability of the athlete in the training program.