Kisi S1, Kimura Y1, Fujiwara K1
1Sumiya Orthopaedic Hospital, Rehabilitation, Wakayama, Japan
Background: Quantitative dynamic balance assessment is a method to evaluate sport athletes' physical functions. Kimura et al. analyzed plantar center-of-pressure (COP) trajectories when landing on one leg in drop-jump tests, and established a method for early body sway measurement from the perspective of lower extremity injury prevention. However, to our knowledge, there have been no reports comparing dynamic balance on the injured and healthy sides, with a view to helping athletes return to sports after a foot injury.
Purpose: To develop assessment/rehabilitation indices for the prevention of chronic and recurrent lower leg injuries among sport athletes, we analyzed plantar COP trajectories after drop-jump landing on one leg, and compared the foot function on the injured and healthy sides.
Methods: Subjects was Ten female athletes (mean age: 15.5±2.3; height: 158.3±5.3 cm; weight: 51.3±8.8 kg; and foot length: 22.7±1.2 cm) who received consultation in our facility due to stress fractures/shin splints of the lower leg. At the time of the study, pain due to basic movements was absent. The athletes had already resumed their training to return to sports. Their consent was obtained after explaining the study objective to them.
The athletes jumped off a platform with a height of 20 cm, and landed on a force plate on one leg. After landing, they maintained a static posture on one leg for 8 seconds. They performed the drop-jump landing task 10 times to adopt values from the last 5 successful landings. Through data analysis, the peak vertical ground reaction force (Fz) at landing and COP trajectory lengths at 20 to 200 ms and at 200 ms to 5 s after landing on the injured and healthy sides were calculated for comparison (the ground reaction force and trajectory length were normalized by the weight and foot length, respectively). Statistic processing was performed using the Wilcoxon signed-rank test, with the significance level set at 5%.
Results: The mean peak Fz and COP trajectory lengths at 20 to 200 ms and at 200 ms to 5 s after landing on the injured and healthy sides were as follows: injured: 448.6±83.0%BW, 73.3±11.2%, and 234.6±57.8%; and healthy: 410.2±85. 8%BW, 62.92±10.2%, and 232.3±58.5%, respectively. The peak Fz and COP trajectory length after 20 m to 200 ms were significantly greater/longer on the injured side (p 0.05). The COP trajectory length after 200 ms to 5 s did not markedly vary between the 2 sides.
Conclusion(s): Dynamic balance in the early stages after landing was poorer on the injured side, suggesting more marked impact stress on the vertical component of the force. As there were no significant differences in the COP trajectory length after 20 ms to 5 s between the 2 sides, it may be important to assess the dynamic balance of the foot immediately after landing as an index for returning to sports.
Implications: The results of the present study suggest the usefulness of assessing dynamic balance at 20 to 200 ms after drop-jump landing on one leg (feed-forward function) as an index for returning to sports after an injury.
Keywords: Sport Athletes, Dynamic Balance, Lower leg Injury
Funding acknowledgements: The present work was supported by the sumiya orthopedic hospital Research facility.
Purpose: To develop assessment/rehabilitation indices for the prevention of chronic and recurrent lower leg injuries among sport athletes, we analyzed plantar COP trajectories after drop-jump landing on one leg, and compared the foot function on the injured and healthy sides.
Methods: Subjects was Ten female athletes (mean age: 15.5±2.3; height: 158.3±5.3 cm; weight: 51.3±8.8 kg; and foot length: 22.7±1.2 cm) who received consultation in our facility due to stress fractures/shin splints of the lower leg. At the time of the study, pain due to basic movements was absent. The athletes had already resumed their training to return to sports. Their consent was obtained after explaining the study objective to them.
The athletes jumped off a platform with a height of 20 cm, and landed on a force plate on one leg. After landing, they maintained a static posture on one leg for 8 seconds. They performed the drop-jump landing task 10 times to adopt values from the last 5 successful landings. Through data analysis, the peak vertical ground reaction force (Fz) at landing and COP trajectory lengths at 20 to 200 ms and at 200 ms to 5 s after landing on the injured and healthy sides were calculated for comparison (the ground reaction force and trajectory length were normalized by the weight and foot length, respectively). Statistic processing was performed using the Wilcoxon signed-rank test, with the significance level set at 5%.
Results: The mean peak Fz and COP trajectory lengths at 20 to 200 ms and at 200 ms to 5 s after landing on the injured and healthy sides were as follows: injured: 448.6±83.0%BW, 73.3±11.2%, and 234.6±57.8%; and healthy: 410.2±85. 8%BW, 62.92±10.2%, and 232.3±58.5%, respectively. The peak Fz and COP trajectory length after 20 m to 200 ms were significantly greater/longer on the injured side (p 0.05). The COP trajectory length after 200 ms to 5 s did not markedly vary between the 2 sides.
Conclusion(s): Dynamic balance in the early stages after landing was poorer on the injured side, suggesting more marked impact stress on the vertical component of the force. As there were no significant differences in the COP trajectory length after 20 ms to 5 s between the 2 sides, it may be important to assess the dynamic balance of the foot immediately after landing as an index for returning to sports.
Implications: The results of the present study suggest the usefulness of assessing dynamic balance at 20 to 200 ms after drop-jump landing on one leg (feed-forward function) as an index for returning to sports after an injury.
Keywords: Sport Athletes, Dynamic Balance, Lower leg Injury
Funding acknowledgements: The present work was supported by the sumiya orthopedic hospital Research facility.
Topic: Sport & sports injuries; Orthopaedics; Pain & pain management
Ethics approval required: Yes
Institution: Sumiya Orthopaedic Hospital
Ethics committee: medical ethics committee of Sumiya Orthopedic Hospital
Ethics number: Rinsei01601205
All authors, affiliations and abstracts have been published as submitted.
