Background
Assessing and understanding the control of the ankle during multidirectional jump landings in athletes with chronic ankle instability (CAI) would help health professionals develop ...interventions to reduce the risk of recurrent injuries. The aim of this study was to investigate the angle, angular velocity, and movements of the ankle joint, and the muscle activity of peroneus longus (PL), tibialis anterior (TA), and gastrocnemius (GAS) muscles during multidirectional landings in athletes with CAI.
Methods
Nineteen athletes with CAI (≤25 Cumberland Ankle Instability Tool–Thai Score) participated. A Vicon Nexus motion analysis system synchronously collected data with an AMTI force plate and surface electromyography (EMG) to capture kinematics, kinetics, and muscle activity, respectively. Participants were asked to perform single-leg jump-landing tests in forward (0°), 30° diagonal, 60° diagonal, and lateral (90°) directions. Ankle joint kinematics, kinetics, and muscle activity of PL, TA, and GAS were analyzed. Repeated measure ANOVA (analysis of variance) and Friedman tests were used to analyze the main effects of the jump-landing direction.
Results
Athletes with CAI exhibited significant differences in ankle angles, angular velocities, ankle movements, and average muscle activity of GAS between directions. Greatest average EMG of GAS muscle was observed during landing in the lateral direction compared with the forward and 30° diagonal directions.
Conclusion
Lateral and diagonal direction movements showed the greatest risks associated with recurrent ankle sprains. Impairments of neuromuscular control in both pre-landing and landing phases were observed in athletes with CAI when considered alongside previously published data.
Level of Evidence:
Laboratory-based observational study
Purpose: Ankle sprain is one of the most common sports injuries and many people suffer from chronic ankle instability after ankle sprains. Changes in the function of the lower limbs following chronic ...ankle instability make a person susceptible to re-injury of ankle sprains. This is a systematic review of studies that investigated the kinematic changes of the lower limbs in people with chronic ankle instability during unilateral jump landing tasks. Methods: Articles in English were searched in Google Scholar, Science Direct, PubMed, Scopus, ProQuest, and Cochrane Library databases without a time limit until 2021 with keywords related to “chronic ankle instability,” “kinematics,” and “single-leg jump-landing.” The inclusion criteria included the subjects being male and female with ankle instability and the type of single-leg jump-landing task. The modified checklist of Downs and Black (1998) was used to evaluate the quality of the studies. Results: Based on the inclusion and exclusion criteria and the study quality review, 15 articles out of 762 studies, which investigated the kinematics of the lower limbs in the performance of unilateral jump landing, were comprehensively examined. Conclusion: According to the findings of this study, individuals with chronic ankle instability showed kinematic changes in the lower limbs during various unilateral jump landing tasks. These changes are possible factors for the recurrence of ankle sprain injury. The findings show the necessity of developing and creating a rehabilitation program that comprehensively considers the kinematic changes.
This study aimed to investigate the developmental characteristics of the double- and single-leg countermovement jump (CMJ) and rebound jump (RJ) in elementary and junior high school students. A total ...of 823 students (401 boys and 422 girls) aged 7 to 15 years performed the CMJ, RJ, single-leg CMJ (SCMJ), and single-leg RJ (SRJ). To evaluate jumping ability, we measured the jumping height and RJ-index for the CMJ and SCMJ and for the RJ and SRJ, respectively. The main results obtained were as follows: 1) In boys, both the CMJ and SCMJ jumping heights and the RJ and SRJ indices were shown to develop with age. 2) In girls, the developmental characteristics of both CMJ and RJ ability differed between single-leg and doubleleg. 3) In both sexes, the ground contact time in the SRJ increased significantly after age 9—10 years (p < 0.01). 4) Regarding the CMJ jump height, a significant correlation was found between the CMJ and SCMJ in both sexes (p < 0.01). For the RJ-index, a significant correlation was found between the RJ and the SRJ in both sexes (p < 0.01). 5) The number of boys and girls with a SRJ type may increase after junior high school, and the number of girls with a RJ type may decrease after junior high school. Our findings indicate that the developmental process of double- and single-leg jumping in elementary and junior high school students is similar in boys but different in girls. Comparison between double- and single-leg jumping ability showed that the CMJ had a high coefficient of determination, while the RJ had a lower value. Additionally, the number of boys and girls with a SRJ type may increase after junior high school. Therefore, especially when evaluating performance of the RJ, it is necessary to measure the performance of the double-leg and that of the single-leg.
The velocity of the center of gravity of the pivot leg and the ground reaction force of the stride leg during windmill pitching are critical for ball speed. The aim of this study was to investigate ...jump ability in relation to the velocity of the center of gravity of the pivot leg and the ground reaction force of the stride leg. Seven female softball pitchers performed windmill pitching and various jump tests: countermovement jump, standing long jump (SLJ), rebound jump (RJ), and one-step approach single-leg vertical jump (AVJ). The results obtained were as follows. 1） No significant relationship between the ball speed during windmill pitching and jump ability was observed in any of the jump tests. 2） The velocity of the center of gravity of the pivot leg was significantly correlated with SLJ and RJ ability. 3） The vertical and horizontal negative impulses (ground reaction force) during windmill pitching were significantly correlated with those in the AVJ. These results demonstrated that the velocity of the center of gravity of the pivot leg and the ground reaction force of the stride leg—which, as demonstrated in previous studies, are crucial in determining the ball speed during windmill pitching—were correlated with jump ability. Moreover, the relationship between jump ability and the velocity of the center of gravity of the pivot leg and that between jump ability and the ground reaction force of the stride leg differed.
Background and Objectives: Asymmetries between the lower limbs were evaluated by both researchers and practitioners as they seem to be related to the occurrence of injuries and the effect on ...performance. The purposes of this study were to (a) detect asymmetries of the lower limbs using a unilateral jump (single-leg countermovement jump (SLCMJ)) and 505 agility test, and (b) examine asymmetry effects on fitness (acceleration, speed, squat jump, Illinois agility test), in U16 youth male soccer players. Materials and Methods: Twenty U16 soccer players performed an SLCMJ and a 505 test to calculate the asymmetry index. They also performed the above fitness tests. The difference between the lower limbs was tested using the paired samples t-test (dominant vs. non-dominant). The correlations between the asymmetries of the lower extremities with the performance indicators were tested using the Pearson’s correlation test. The level of significance was set at p < 0.05. Results: The lower limbs differed significantly in the SLCMJ and 505 tests (p < 0.05). The only correlation was between the asymmetry in SLCMJ and performance in SJ (r = −0.641, p = 0.002). Asymmetries did not affect performance on most fitness tests. Conclusions: The two asymmetry tests identified asymmetries in different limbs. This indicates the variability in asymmetries and the need for specialized tests depending on the kinematic chain. The asymmetries observed should be eliminated using individualized training programs so that athletes are protected from injuries and from the possible negative impact on performance. Also, the detection of asymmetries in developmental age offers a greater time period for their elimination before the athlete enters professional sports.
The aim of this study was to determine the effect of plyometric exercises in single leg jump and depth on explosive power and under shoot. This study used 18 basketball players. The results showed a ...significant influence between before and after training in group I plyometric single leg jump to increase power and under shoot results, in group II depth jump was a significant effect between before and after training on increasing power and under shoot, whereas in group III the control had no significant effect on increasing power and under shooting. It can be concluded that the group I plyometric single leg jump and group II depth jump explosive power and under shoot both have a significant influence on basketball athletes.
Purpose The purpose of this study was to evaluate the relationship between malalignment and lower-extremity injury and to determine the optimal dynamic alignment of the lower extremity with wall ...squats. Subjects and Methods Healthy individuals from one therapy school were enrolled and assigned to a wall squat normal or abnormal group based on their forms during wall squats. The abnormal group was found to be more prone to lower-extremity injury on three-dimensional motion analysis. Eight students from each group were randomly chosen for the study. The effects of single-leg landing movements were assessed using three-dimensional motion analysis. Results In the sagittal plane, significant flexion of the hip and knee joints occurred 0.02 and 0.04 seconds after initial foot contact with the ground in the normal and abnormal groups, respectively. In the frontal plane, significant adduction of the hip joint occurred at 0.07 seconds in the abnormal group. Conclusion The abnormal group tended to display later flexion of the hip and knee joints and narrower hip, knee, and ankle range of motion than the normal group, suggesting that dynamic alignment of the lower extremity in the abnormal group likely made them susceptible to injury.
Purpose: This study aimed to investigate the effect of genu varum abnormality on the activity of the anterior leg calf muscle during single-leg jump-landing task. Methods: A total of 28 male ...students of Physical Education (Mean±SD age: 21.53±1.65 y, weight: 66.67±7.15 kg, height: 173.38±4.54 cm) were assigned into the genu varum (n=14) and normal knee (n=14) groups. Their level of activity of tibialis anterior muscle and ground reaction force were analyzed using an electromyography and force plate in single-leg jump-landing task. In order to analyze the data, the Independent t test was used at the significance level of P<0.05. In jump-landing task, the subjects were required to jump up to 50% of maximum vertical jump and land with one leg on the plate. Root-Mean Square (RMS) level of tibialis anterior muscle was calculated by MATLAB. Results: The study results showed no significant differences between genu varum and normal knee groups (P>0.05) in the mean scores of the tibialis anterior muscular activity before and after landing. Conclusion: In performing the jump-landing task, tibialis anterior muscular activity of the two groups was similar before and after floor contact. Therefore, activity of tibialis anterior muscle does not seem responsible for differences observed in the balance between people with genu varum and normal knee. In addition to biomechanical reasons, other muscles or muscle groups might responsible for weaker balance observed in people with genu varum.
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