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Kyung-Min Kim, Joo-Sung Kim and Dustin R. Grooms

Context: Patients with somatosensory deficits have been found to rely more on visual feedback for postural control. However, current balance tests may be limited in identifying increased visual dependence (sensory reweighting to the visual system), as options are typically limited to eyes open or closed conditions with no progressions between. Objective: To assess the capability of stroboscopic glasses to induce sensory reweighting of visual input during single-leg balance. Design:Descriptive Setting: Laboratory Participants: 18 healthy subjects without vision or balance disorders or lower extremity injury history (9 females; age = 22.1 ± 2.1 y; height = 169.8 ± 8.5 cm; mass = 66.5 ± 10.6 kg) participated. Interventions: Subjects performed 3 trials of unipedal stance for 10 s with eyes open (EO) and closed (EC), and with stroboscopic vision (SV) that was completed with specialized eyewear that intermittently cycled between opaque and transparent for 100 ms at a time. Balance tasks were performed on firm and foam surfaces, with the order randomized. Main Outcome Measures: Ten center-of-pressure parameters were computed. Results: Separate ANOVAs with repeated measures found significant differences between the 3 visual conditions on both firm (P-values =< .001) and foam (P-values =< .001 to .005) surfaces for all measures. For trials on firm surface, almost all measures showed that balance with SV was significantly impaired relative to EO, but less impaired than EC. On the foam surface, almost all postural stability measures demonstrated significant impairments with SV compared with EO, but the impairment with SV was similar to EC. Conclusions:SV impairment of single-leg balance was large on the firm surface, but not to the same degree as EC. However, the foam surface disruption to somatosensory processing and sensory reweighting to vision lead to greater disruptive effects of SV to the same level as EC. This indicates that when the somatosensory system is perturbed even a moderate decrease in visual feedback (SV) may induce an EC level impairment to postural control during single-leg stance.

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Kyung-Min Kim, Christopher D. Ingersoll and Jay Hertel

Context:

Focal ankle-joint cooling (FAJC) has been shown to increase Hoffmann (H) reflex amplitudes of select leg muscles while subjects lie prone, but it is unknown whether the neurophysiological cooling effects persist in standing.

Objective:

To assess the effects of FAJC on H-reflexes of the soleus and fibularis longus during 3 body positions (prone, bipedal, and unipedal stances) in individuals with and without chronic ankle instability (CAI).

Design:

Crossover.

Setting:

Laboratory.

Participants:

15 young adults with CAI (9 male, 6 female) and 15 healthy controls.

Intervention:

All subjects received both FAJC and sham treatments on separate days in a randomized order. FAJC was accomplished by applying a 1.5-L plastic bag filled with crushed ice to the ankle for 20 min. Sham treatment involved room-temperature candy corn.

Main Outcome Measures:

Maximum amplitudes of H-reflexes and motor (M) waves were recorded while subjects lay prone and then stood in quiet bipedal and unipedal stances before and immediately after each treatment. Primary outcome measures were Hmax:Mmax ratios for the soleus and fibularis longus. Three-factor (group × treatment condition × time) repeated-measures ANOVAs and Fisher LSD tests were performed for statistical analyses.

Results:

Significant interactions of treatment condition by time for prone Hmax:Mmax ratios were found in the soleus (P = .001) and fibularis longus (P = .003). In both muscles, prone Hmax:Mmax ratios moderately increased after FAJC but not after sham treatment. The CAI and healthy groups responded similarly to FAJC. In contrast, there were no significant interactions or main effects in the bipedal and unipedal stances in either muscle (P > .05).

Conclusions:

FAJC moderately increased H-reflex amplitudes of the soleus and fibularis longus while subjects were prone but not during bipedal or unipedal standing. These results were not different between groups with and without CAI.

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Brandon Warner, Kyung-Min Kim, Joseph M. Hart and Susan Saliba

Context:

Quadriceps function improves after application of focal joint cooling or transcutaneous electrical nerve stimulation to the knee in patients with arthrogenic muscle inhibition (AMI), yet it is not known whether superficial heat is able to produce a similar effect.

Objective:

To determine quadriceps function after superficial heat to the knee joint in individuals with AMI.

Design:

Single blinded randomized crossover.

Setting:

Laboratory.

Patients:

12 subjects (4 female, 8 males; 25.6 ± 7.7 y, 177.2 ± 12.7 cm, 78.4 ± 18.2 kg) with a history of knee-joint pathology and AMI, determined with a quadriceps central activation ratio (CAR) of <90%.

Intervention:

3 treatment conditions for 15 min on separate days: superficial heat using a cervical moist-heat pack (77°C), sham using a cervical moist pack (room temperature at about 24°C), and control (no treatment). All subjects received all treatment conditions in a randomized order.

Main Outcome Measures:

Central activation ratio and knee-extension torque during maximal voluntary isometric contraction with the knee flexed to 60° were collected at pre, immediately post, 30 min post, and 45 min posttreatment. Skin temperature of the quadriceps and knee and room temperature were also recorded at the same time points.

Results:

Three (treatment conditions) by 4 (time) repeated ANOVAs found that there were no significant interactions or main effects in either CAR or knee-extension torque (all P > .05). Skin-temperature 1-way ANOVAs revealed that the skin temperature in the knee during superficial heat was significantly higher than other treatment conditions at all time points (P < .05).

Conclusions:

Superficial heat to the knee joint using a cervical moist-heat pack did not influence quadriceps function in individuals with AMI in the quadriceps.

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Samuel F. Jazzo, Daniel Scribner, Stephanie Shay and Kyung-Min Kim

Clinical Scenario: Osteochondral lesions (OCLs) of the talus can result from ankle sprains which are the most common injury in the physically active. Recently, platelet-rich plasma (PRP) has been used to develop an innovate treatment for OCLs of the talus. Clinical Question: Do PRP injections improve self-reported pain and ankle function in patients with OCL of the talus? Summary of Key Findings: 3 randomized controlled trials were included. One of the studies compared a single dose of PRP to a single dose of hyaluronic acid (HA) or saline when added as an adjunct to microfracture surgery. Another study compared a group receiving a single dose of PRP after microfracture surgery to a group that only received microfracture surgery. The last study compared a series of 3 PRP injections to a series of 3 HA injections. In all 3 studies PRP appeared to be more effective in pain and function outcomes than comparison treatments. The superior outcomes of PRP were demonstrated at times as short as 4 weeks and as long as 25 months. Clinical Bottom Line: There is moderate to strong evidence that PRP produces favorable, short-term, pain and function results compared to HA, saline, and/or microfracture surgery alone. Strength of Recommendation: Level 2.

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Kyung-Min Kim, Joo-Sung Kim, Jeonghoon Oh and Dustin R. Grooms

Context: The sensory organization test (SOT) is a standard for quantifying sensory dependence via sway-referenced conditions (sway-referenced support and sway-referenced vision [SRV]). However, the SOT is limited to expensive equipment. Thus, a practical version of the SOT is more commonly employed—the clinical test for sensory integration in balance; however, it fails to induce postural instability to the level of SRV. Objective: Determine if Stroboscopic vision (SV), characterized by intermittent visual blocking, may provide an alternative to the SRV for assessing postural stability. Design: Descriptive laboratory study. Setting: Research laboratory. Participants: Eighteen participants (9 males, 9 females; age = 22.1 [2.1] y, height = 169.8 [8.5] cm, weight = 66.5 [10.6] kg). Intervention: Participants completed the SOT conditions, and then repeated SOT conditions 2 and 5 with SV created by specialized eyewear. Main Outcome Measures: A repeated-measures analysis of variance was completed on the time-to-boundary metrics of center-of-pressure excursion in the anteroposterior and mediolateral directions in order to determine the difference between the full-vision, SV, and SRV conditions. Results: Postural stability with either SRV or SV was significantly worse than with full vision (P < .05), with no significant difference between SV and SRV (P > .05). Limits of agreement analysis revealed similar effects of SV and SRV except for unstable surface mediolateral time-to-boundary. Conclusions: In general, SV was found to induce a degree of postural instability similar to that induced by SRV, indicating that SV could be a portable and relatively inexpensive alternative for the assessment of sensory dependence and reweighting.

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Rebecca J. Bedard, Kyung-Min Kim, Terry L. Grindstaff and Joseph M. Hart

Objective:

To compare active hamstring stiffness in female subjects with and without a history of low back pain (LBP) after a standardized 20-min aerobic-exercise session.

Design:

Case control.

Setting:

Laboratory.

Participants:

12 women with a history of recurrent episodes of LBP (age = 22.4 ± 2.1 y, mass = 67.1 ± 11.8 kg, height = 167.9 ± 8 cm) and 12 matched healthy women (age = 21.7 ± 1.7 y, mass = 61.4 ± 8.8 kg, height = 165.6 ± 7.3 cm). LBP subjects reported an average 6.5 ± 4.7 on the Oswestry Disability Index.

Interventions:

Participants walked at a self-selected speed (minimum 3.0 miles/h) for 20 min. The treadmill incline was raised 1% grade per minute for the first 15 min. During the last 5 min, participants adjusted the incline of the treadmill so they would maintain a moderate level of perceived exertion through the end of the exercise protocol.

Main Outcome Measures:

During session 1, active hamstring stiffness, hamstring and quadriceps isometric strength, and concurrently collected electromyographic activity were recorded before and immediately after the exercise protocol. For session 2, subjects returned 48–72 h after exercise for repeat measure of active hamstring stiffness.

Results:

Hamstring active stiffness (Nm/rad) taken immediately postexercise was not significantly different between groups. However, individuals with a history of recurrent LBP episodes presented significantly increased hamstring stiffness 48–72 h postexercise compared with controls. For other outcomes, there was no group difference.

Conclusions:

Women with a history of recurrent LBP episodes presented greater active hamstring stiffness 48–72 h after aerobic exercise.

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Jinah Kim, Sung Cheol Lee, Youngmin Chun, Hyung-Pil Jun, Jeffrey G. Seegmiller, Kyung Min Kim and Sae Yong Lee

Context: Clinically, it has been suggested that increased activation of intrinsic foot muscles may alter the demand of extrinsic muscle activity surrounding the ankle joint in patients with stage II posterior tibial tendon dysfunction. However, there is limited empirical evidence supporting this notion. Objective: The purpose of this study was to investigate the effects of a 4-week short-foot exercise (SFE) on biomechanical factors in patients with stage II posterior tibial tendon dysfunction. Design: Single-group pretest–posttest. Setting: University laboratory. Participants: Fifteen subjects (8 males and 7 females) with stage II posterior tibial tendon dysfunction who had pain in posterior tibial tendon, pronated foot deformity (foot posture index ≥+6), and flexible foot deformity (navicular drop ≥10 mm) were voluntarily recruited. Intervention: All subjects completed a 4-week SFE program (15 repetitions × 5 sets/d and 3 d/wk) of 4 stages (standing with feedback, sitting, double-leg, and one-leg standing position). Main Outcome Measures: Ankle joint kinematics and kinetics and tibialis anterior and fibularis longus muscle activation (% maximum voluntary isometric contraction) during gait were measured before and after SFE program. Cohen d effect size (ES [95% confidence intervals]) was calculated. Results: During the first rocker, tibialis anterior activation decreased at peak plantarflexion (ES = 0.75 [0.01 to 1.49]) and inversion (ES = 0.77 [0.03 to 1.51]) angle. During the second rocker, peak dorsiflexion angle (ES = 0.77 [0.03 to 1.51]) and tibialis anterior activation at peak eversion (ES = 1.57 [0.76 to 2.39]) reduced. During the third rocker, the peak abduction angle (ES = 0.80 [0.06 to 1.54]) and tibialis anterior and fibularis longus activation at peak plantarflexion (ES = 1.34 [0.54 to 2.13]; ES = 1.99 [1.11 to 2.86]) and abduction (ES = 1.29 [0.50 to 2.08]; ES = 1.67 [0.84 to 2.50]) decreased. Conclusions: Our 4-week SFE program may have positive effects on changing muscle activation patterns for tibialis anterior and fibularis longus muscles, although it could not influence their structural deformity and ankle joint moment. It could produce a potential benefit of decreased tibialis posterior activation.

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David Cruz-Díaz, Kyung-Min Kim, Fidel Hita-Contreras, Marco Bergamin, Agustin Aibar-Almazán and Antonio Martínez-Amat

Context: Tai Chi is a physical activity modality which is widely practiced over the world. The effectiveness of Tai Chi on postural control and balance has been described in older population, but until recently there are no studies that include patients with chronic ankle instability. Objectives: The aim of this study was to evaluate the effectiveness of 12 weeks of Tai Chi intervention on dynamic balance and self-reported instability in patients with chronic ankle instability. Study Design: A randomized controlled trial was carried out. Setting: University physical therapy facility. Participants: Fifty-two participants were allocated to an intervention group (n = 26) based on Tai Chi training or a control group (n = 26) who received no intervention. Intervention: The participants completed 12 weeks of Tai Chi intervention (1 h session/2 times per week) or no intervention in the control group. Main Outcome Measures: Outcome measures included postural control and self-reported instability feeling assessed by the Star Excursion Balance Test and the Cumberland Ankle Instability Tool, respectively. Results: There was observed significant improvement in all Star Excursion Balance Test reach distances (anterior [F = 6.26, P < .01]; posteromedial [F = 9.58, P < .01], and posterolateral [F = 8.42, P < .01]) in the Tai Chi group with no change in the control group (P < .01). The intervention group demonstrated significant improvement on self-reported instability feeling assessed by the Cumberland Ankle Instability Tool questionnaire (F = 21.36, P < .01). Conclusion: The obtained results suggested that 12 weeks of Tai Chi intervention have positive effects on postural control and self-reported instability feeling in patients with chronic ankle instability.

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In-Ho Jeon, Hemanshu Kochhar, Jong-Min Lee, Hee-Soo Kyung, Woo-Kie Min, Hwan-Sung Cho, Ho-Wug Wee, Dong-Joo Shin and Poong-Taek Kim

Context:

Wheelchair tennis has been identified as a high-risk sport for shoulder injury, so understanding shoulder pathology in these athletes is important.

Objective:

This study investigated the incidence and pattern of shoulder injuries in wheelchair tennis players using high-resolution ultrasonography.

Design:

Descriptive study.

Setting:

International Wheelchair Tennis Open.

Participants:

33 elite-level wheelchair tennis players.

Outcome Measures:

Wheelchair tennis players completed a self-administered questionnaire, and shoulders of each athlete were investigated using high-resolution ultrasonography (linear probe 7.5 MHz).

Results:

The most common pathology in the dominant shoulder was acromioclavicular pathology, in 21 players (63.6%). Full-thickness rotator-cuff tears involving the supraspinatus were found in 8 dominant shoulders and 6 nondominant shoulders. There were no correlations between identified shoulder pathology and the different variables studied, such as age, training time per day, length of wheelchair use, and length of career as a wheelchair tennis player.

Conclusion:

High prevalence of rotator-cuff and acromioclavicular pathology was found by ultrasonographic examination in the elite wheelchair tennis players in both dominant and nondominant shoulders. A high index of suspicion of these pathologies in wheelchair athletes is required.