Chanki Kim

Study Objective: This study investigated the effects of chronic ankle instability (CAI) on axial (neck and trunk) and lower-extremity joint kinematics during a side cutting jump to identify compensatory strategies across the kinetic chain. Methods: Twenty-seven male adults in their 20s participated, including fourteen with CAI and thirteen healthy controls. CAI was defined as a Cumberland Ankle Instability Tool-Korean version (CAIT-K) score ≤ 24 and an Identification of Functional Ankle Instability-Korean version (IdFAI-K) score ≥ 11. Participants performed side cutting jumps on a force plate while three-dimensional joint kinematics were captured using a 14-camera motion system (100 Hz). Eighteen joint angles from the upper body to the ankle were analyzed. Group differences across the movement phase (initial contact to 1 s post-landing) were assessed using Statistical Parametric Mapping (SPM1D) with Bonferroni correction (α = 0.00085). Results: Compared with controls, the CAI group showed smaller neck motions across all planes, which may suggest a potential reliance on visual stabilization. Trunk flexion and rotation were greater, which is consistent with a potential mechanism for impact absorption. At the pelvis and hip, CAI participants displayed increased anterior tilt, greater flexion and internal rotation, and reduced abduction. Notably, at the knee, flexion was significantly greater during the 1.7–32.8% phase (peak d = 1.06, large effect size) with smaller valgus and rotational angles. At the distal level, the ankle showed a significant increase in eversion during the 3.4–15.5% phase (d = 0.00–0.28) and external rotation during the 5.2–13.8% phase (d = 0.28–0.48), representing a compensatory pronation-bias strategy. Conclusions: CAI alters not only ankle function but also global coordination during side cutting jumps, reflecting multi-joint compensatory mechanisms to stabilize posture and modulate kinematic forces. Compensatory strategies involving visual fixation, trunk modulation, and proximal joint adjustments highlight the need for an integrated kinetic chain approach in CAI evaluation and rehabilitation.

Study Objective: This study aimed to examine the effects of a short-term (three times a week for a total of four weeks) low-load elastic exercise program on sarcopenia-related parameters and the contractile properties of the vastus lateralis in twenty older adult women. Methods: All participants underwent assessments for sarcopenia-related parameters, including body composition, strength, and functional performance. Tensiomyography was utilized to evaluate the contractile properties of the vastus lateralis. A paired samples t-test was employed to compare pre-and post-exercise intervention measurements. Results: Except for body weight, all parameters associated with sarcopenia showed a significant difference following low-load elastic exercise program (p < 0.05). Tensiomyography of the vastus lateralis indicated a considerable increase in contraction time after low-load elastic exercise program (p < 0.05); however, there were no significant differences in maximum radial displacement or velocity of contraction. Conclusions: Our findings suggest that a short-term low-load elastic exercise program may be associated with improvements in sarcopenia–related indicators, including muscle strength and muscle contraction characteristics, in older adults, while being time-efficient.

Objective: The purpose of this study was to compare the contractile properties of posterior chain muscles and isokinetic trunk strength in females with or without non-specific chronic low back pain (NSCLBP). Method: All participants (control group: n = 22, NSCLBP group: n = 22) were assessed using tensiomyography to evaluate the contractile properties of the posterior chain muscles, and all participants were also assessed for isokinetic trunk strength. An independent t-test was performed to compare the tensiomyography variables and isokinetic trunk strength test results between group. Results: Result of tensiomyography, we found that the contraction time significant differences in the maximal radial muscle displacement, and velocity of contraction between groups in erector spinae. Semitendinosus revealed significant differences in all variables between groups. Additionally, the isokinetic trunk strength test revealed significant differences in all variables between groups. Conclusion: These findings suggest that due to the characteristics of NSCLBP, such as increased muscle stiffness, fat infiltration, and muscle fatigue, kinesiophobia, physical deconditioning syndrome, the posterior chain muscles of the NSCLBP group showed higher muscle stiffness and slower contraction speed than the control group. Also in the NSCLBP group, trunk isokinetic muscle strength was lower than in the control group, and flexor and extensor muscles were unbalanced.

This study examined the erector spinae contractile properties, trunk isokinetic strength, and differences in acute muscle fatigue response after exercise in young females with and without non-specific chronic low back pain (NSCLBP). This study evaluated participants using tensiomyography and isokinetic trunk strength tests. An independent t-test compared the control group and the NSCLBP group, while a two-way mixed ANOVA analyzed differences in the erector spinae’s acute muscle fatigue response before and after exercise within and between groups. The results of the tensiomyography indicated that the NSCLBP group exhibited significantly lower Dm and Vc (p < 0.05) compared to the control group, while Tc showed no significant difference between groups. Significant differences in all variables were observed between the groups in the isokinetic trunk strength test (p < 0.05). Furthermore, the two-way mixed ANOVA revealed significant group main effects in Dm and Vc of the erector spinae (p < 0.05). This study found that non-specific chronic low back pain is linked to a decrease in Dm, Vc, and trunk isokinetic strength in both extensor and flexor muscles. It suggests that future research should further investigate the acute muscle fatigue response in individuals with and without NSCLBP.

Background. This study investigated the effects of lower limb movements on dynamic postural stability (DPS) during drop landing in adult women with patellofemoral pain syndrome (PFPS). Methods. Thirty-eight adult women were recruited and divided into two groups, the PFPS group and the control group. The study participants performed a single-leg drop landing from a 30 cm box, and their lower limb movements and DPS were measured. Differences between groups were examined using independent sample -tests. In addition, stepwise multiple linear regression was used to examine the kinematic parameters that contribute to the DPS. Results. The PFPS group had significantly lower hip flexion, internal rotation, knee flexion, ankle external rotation, pelvic oblique, tilt, rotation, and higher hip abduction, knee valgus, and ankle plantarflexion. In terms of DPS, the PFPS group had a significantly higher anteroposterior and a lower mediolateral than that of the control group. In the control group, regression analysis revealed a controlled anteroposterior using knee flexion, while the PFPS group controlled mediolateral through ankle plantarflexion. Conclusions. Patients with PFPS experienced more shock on their knee joint during landing than patients in the control group with greater anteroposterior instability and lower mediolateral instability.