COP Sway Research Articles

지면반력장비의 정밀성, 신뢰도와 장비설치.사용 환경의 영향

Ground reaction force (GRF) measures are one of the most commonly used in biomechanical study. GRF system is very useful educational tool to explain and demonstrate the Newton`s law of universal gravitation and laws of motion as well. However, accuracy, intra- and inter- force platform measures` consistency, reliability, noise, and the effect of platform mounting to GRF measures were not clearly viewed. The aim of this study was to examine the above. GRFs of a plastic dummy and two subjects` quiet upright standing were collected at four university laboratories eight force platforms. The types of platforms, analysis programs, and platform set-up were various. Three 100s-trials were conducted with sampling frequency of 100 Hz. First two trials` vertical component of GRFs, Fz, and CoP sway ranges of mid-60s-portion of 100s trials were analyzed by the paired t-tests and one-way ANOVA. Six of eight platforms` 1st and 2nd trial dummy Fz were statistically different (p

Sling Exercise Training Improves Balance, Kicking Velocity, and Torso Stabilisation Strength in Elite Soccer Players

PURPOSE: To determine the impact of a Sling Exercise Training (SET) core stability program on postural balance, kicking velocity, functional strength, and back pain in nationally elite level soccer players. METHODS: 12 Norwegian 1st division soccer players completed 8 wk × 2 d.wk−1 SET training with a main focus on the trunk and hip area. Each training session, athletes performed 8 different highly unstable, closed kinetic chain exercises in adjustable slings. Exercise difficulty was progressed by increasing the resistance arm and degree of instability. 4 of the training group athletes had suffered extended periods of low back pain. 9 players of similar performance level served as a control group. RESULTS: Balance: Mean one-legged eyes-closed COP sway velocity moment decreased 45 % in the worst leg (p <0.01) and 18% in the best leg (p = 0.113). The mean difference in velocity moment between the legs was reduced from 51% to 3% (p=0.001). No change in balance performance was observed in the control group. Kicking: Ball velocity during one-step I maximal velocity kicking (preferred leg) increased significantly Kl in the training group (3.5%,) compared to controls (−2.3 %, p = I 0.04). Torso functional strength: The 4 subjects with chronic low B back pain all reported that pain was reduced after training. The training group, and particularly chronic low back pain subjects, significantly improved in a clinical test of pelvic rotational stability (p <0.01, see picture of test condition). CONCLUSIONS: This unique functional stability training program involving movements performed in unstable slings clearly improved static balance. Chronic back pain subjects also reported strongly reduced back pain. In addition, a small but significant improvement in kicking performance was observed. To our knowledge this is the first study to demonstrate a direct performance enhancing effect of a core stability training program. Functional strength training in slings appears to be an effective modality for enhancing neuromuscular control and joint stability.Figure

The Influence of FAI on Proprioception, Balance Control and Lower Extremities Muscle EMG Activity

1330 Functional Ankle Instability (FAI) is a clinical syndrome associated with periarticular muscle weakness and repeated episodes of giving way. Freemann described FAI is a feeling of giving way which will impaire proprioception and postural stability. However, recent studies (Bernier, Perrin & Rijke, 1997; Isakov & Mizrahi, 1997) showed FAI did not affect postural sway or balance control. Otherwise, none of any study examined the influence of FAI on proprioception function, body center of pressure sway and EMG activity altogether. PURPOSE: To analyze the influence and relationship of FAI on propriception function, balance control and lower extrenities EMG activity. METHODS: Twenty-three college-aged healthy students recruited as subjects: 10 subjects with FAI and 13 subjects with normal ankle. AMTI force platform, Biodex isokinetic dynameter and Dasylab EMG recorder were used to collect the ankle active/passive reposition sense, the mean radius of Romberg standing body COP sway, and the four lower limbs muscle (rectus femoris, biceps femoris long head, gastrocnemius lateral head, tibialis anterior) iEMG activity. Descriptive statistics and independent t-test were used to analyze the data and the significant level was set at .05. RESULTS: 1. FAI subjects had significantly poor proprioception and balance control ability, especially in eye-closed situation. 2. FAI Poor proprioception would induce larger range of muscle EMG activity, particular in tibialis anterior, but only found significantly difference in right biceps femoris and gastrocnemius lateral under eye-closed situation. CONCLUSION: Proprioception had close relationship with balance control. FAI will truthly inpaired the proprioception and balance control, induced abnormal lower extremities EMG activities. This study also founded the tibialis anterior played an important role on postural control. More research are needed to examine and clarify if EMG activity could be used as an index of balance ability, especially recovery from ankle injury. Supported by NSC-91-2413-H-179-008, Taiwan, R.O.C.

The Influence of FAI on Proprioception, Balance Control and Lower Extremities Muscle EMG Activity

1330 Functional Ankle Instability (FAI) is a clinical syndrome associated with periarticular muscle weakness and repeated episodes of giving way. Freemann described FAI is a feeling of giving way which will impaire proprioception and postural stability. However, recent studies (Bernier, Perrin & Rijke, 1997; Isakov & Mizrahi, 1997) showed FAI did not affect postural sway or balance control. Otherwise, none of any study examined the influence of FAI on proprioception function, body center of pressure sway and EMG activity altogether. PURPOSE: To analyze the influence and relationship of FAI on propriception function, balance control and lower extrenities EMG activity. METHODS: Twenty-three college-aged healthy students recruited as subjects: 10 subjects with FAI and 13 subjects with normal ankle. AMTI force platform, Biodex isokinetic dynameter and Dasylab EMG recorder were used to collect the ankle active/passive reposition sense, the mean radius of Romberg standing body COP sway, and the four lower limbs muscle (rectus femoris, biceps femoris long head, gastrocnemius lateral head, tibialis anterior) iEMG activity. Descriptive statistics and independent t-test were used to analyze the data and the significant level was set at .05. RESULTS: 1. FAI subjects had significantly poor proprioception and balance control ability, especially in eye-closed situation. 2. FAI Poor proprioception would induce larger range of muscle EMG activity, particular in tibialis anterior, but only found significantly difference in right biceps femoris and gastrocnemius lateral under eye-closed situation. CONCLUSION: Proprioception had close relationship with balance control. FAI will truthly inpaired the proprioception and balance control, induced abnormal lower extremities EMG activities. This study also founded the tibialis anterior played an important role on postural control. More research are needed to examine and clarify if EMG activity could be used as an index of balance ability, especially recovery from ankle injury. Supported by NSC-91-2413-H-179-008, Taiwan, R.O.C.

New quantitative and qualitative measures on functional mobility prediction for stroke patients

The purpose of this study was to explore whether we could provide supportive laboratory evidence for clinical observations that a stroke patient has lost functional mobility/locomotion capability based on dynamic balance responses (centre of pressure, COP sway patterns) and motor control activities (EMG patterns) during the motor task of sit-to-stand. A computerized controlled dynamic postural control assessment system was developed and used in this study. Various dynamic balance indices were introduced and derived from COP sway patterns expressed in four domains (i.e. space, time, force, and frequency). Motor control was assessed by multi-channel surface electromyography of each side of the lower limb during the same motor task. The functional mobility capability was evaluated using a traditional FIM method. Fourteen stroke patients with right hemiplegia and nine healthy elderly were recruited as the experimental and control groups respectively. Muscle activity was recorded for quadriceps, hamstrings, anterior tibialis, and triceps surae muscles and used for analysis. Centre of pressure sway patterns and ground reaction forces were registered. All signals were synchronized at ‘seat-off. Surface electromyographic patterns of activities recorded during sit-to-stand and dynamic balance indices computed from centre of pressure sway patterns were categorized and compared with the functional mobility scores. The results show that both the motor control patterns and dynamic balance indices correlated well to the extent of mobility impairment evaluated using the traditional FIM method. An important conclusion for rehabilitation medicine is that the functional mobility capability of stroke patients may he quantified analytically using dynamic balance indices and visualized graphically through EMG motor patterns.