Dynamic Postural Stability Index Research Articles

Balance Control During the Delivery Stride in Competitive Older Age Lawn Bowlers

This project assessed dynamic balance and stability in aged lawn bowlers during the delivery stride. Participants were divided into two groups: aged 65 years or less (n = 14) and aged over 65 years (n = 16). Standard balance-based center of pressure (CoP) and ground reaction force variables were recorded and a Dynamic Postural Stability Index (DPSI) was used for calculating during ten deliveries. None of the balance variables correlated significantly with age although years of bowling experience correlated with DPSI scores (r = -.42, P = .019). The over 65 group had significantly greater variance in the mediolateral CoP movements, with no other significant differences in balance or postural stability variables between groups. Analysis of covariance indicated that the DPSI data were influenced significantly by bowling experience regardless of age group. It was concluded that in older aged lawn bowlers, playing experience rather than age is a key determinant of balance control during the lawn bowls delivery action.

The Addition of Body Amor Diminishes Dynamic Postural Stability in Military Soldiers

Poor postural stability has been identified as a risk factor for lower extremity musculoskeletal injury. The additional weight of body armor carried by Soldiers alters static postural stability and may predispose Soldiers to lower extremity musculoskeletal injuries. However, static postural stability tasks poorly replicate the dynamic military environment, which places considerable stress on the postural control system during tactical training and combat. Therefore, the purpose of this study was to examine the effects of body armor on dynamic postural stability during single-leg jump landings. Thirty-six 101st Airborne Division (Air Assault) Soldiers performed single-leg jump landings in the anterior direction with and without wearing body armor. The dynamic postural stability index and the individual stability indices (medial-lateral stability index, anterior-posterior stability index, and vertical stability index) were calculated for each condition. Paired sample t-tests were performed to determine differences between conditions. Significant differences existed for the medial-lateral stability index, anterior-posterior stability index, vertical stability index, and dynamic postural stability index (p < 0.05). The addition of body armor resulted in diminished dynamic postural stability, which may result in increased lower extremity injuries. Training programs should address the altered dynamic postural stability while wearing body armor in attempts to promote adaptations that will result in safer performance during dynamic tasks.

Discriminating Between Copers and People With Chronic Ankle Instability

Differences in various outcome measures have been identified between people who have sprained their ankles but have no residual symptoms (copers) and people with chronic ankle instability (CAI). However, the diagnostic utility of the reported outcome measures has rarely been determined. Identifying outcome measures capable of predicting who is less likely to develop CAI could improve rehabilitation protocols and increase the efficiency of these measures. To determine the diagnostic utility and cutoff scores of perceptual, mechanical, and sensorimotor outcome measures between copers and people with CAI by using receiver operating characteristic curves. Case-control study. Sports medicine research laboratory. Twenty-four copers (12 men, 12 women; age = 20.8 ± 1.5 years, height = 173 ± 11 cm, mass = 78 ± 27 kg) and 24 people with CAI (12 men, 12 women; age = 21.7 ± 2.8 years, height = 175 ± 13 cm, mass = 71 ± 13 kg) participated. Self-reported disability questionnaires, radiographic images, and a single-legged hop stabilization test. Perceptual outcomes included scores on the Foot and Ankle Disability Index (FADI), FADI-Sport, and a self-report questionnaire of ankle function. Mechanically, talar position was quantified by measuring the distance from the anterior tibia to the anterior talus in the sagittal plane. Sensorimotor outcomes were the dynamic postural stability index and directional indices, which were calculated during a single-legged hop stabilization task. Perceptual outcomes demonstrated diagnostic accuracy (range, 0.79-0.91), with 95% confidence intervals ranging from 0.65 to 1.00. Sensorimotor outcomes also were able to discriminate between copers and people with CAI but with less accuracy (range, 0.69-0.70), with 95% confidence intervals ranging from 0.37 to 0.86. The mechanical outcome demonstrated poor diagnostic accuracy (0.52). The greatest diagnostic utility scores were achieved by the self-assessed disability questionnaires, which indicated that perceptual outcomes had the greatest ability to accurately predict people who became copers after their initial injuries. However, the diversity of outcome measures that discriminated between copers and people with CAI indicated that the causal mechanism of CAI is probably multifactorial.

An examination, correlation, and comparison of static and dynamic measures of postural stability in healthy, physically active adults

ObjectiveTo examine the relationship and differences between static and dynamic postural stability in healthy, physically active adults. DesignDescriptive laboratory study. SettingResearch laboratory. ParticipantsTen females (age: 21.6 ± 1.2 yrs, mass: 60.8 ± 7.6 kg, height: 165.0 ± 5.0 cm) and ten males (age: 25.1 ± 3.0 yrs, mass: 73.9 ± 8.7 kg, height: 173.5 ± 9.0 cm). Main outcome measuresStatic postural stability was measured during a single-leg standing task (standard deviation of the ground reaction forces). Dynamic postural stability was measured during a single-leg landing task using the Dynamic Postural Stability Index. Pearson’s r-coefficients were calculated to examine relationships between the two tests and a one-way ANOVA was calculated to examine potential differences in test scores (p < 0.05). ResultsNone of the Pearson’s r-coefficients achieved statistical significance. The one-way ANOVA and post hoc comparisons demonstrated that dynamic postural stability scores were significantly higher than static postural stability scores. ConclusionsA lack of a correlation between static and dynamic measures and increase in difficulty during dynamic measures indicates differences in the type and magnitude of challenge imposed by the different postural stability tasks. The more challenging dynamic measures of postural stability may be more suitable for prospective studies examining risk of ankle and knee injury in healthy, physically active individuals.

Dynamic postural stability in gaelic football players during a single leg drop-landing, a comparison of ankle tape and lace-up brace

BackgroundAnkle inversion injuries commonly occur during landing from a jump. Both ankle braces and taping are methods used to prevent ankle injuries during sport.ObjectiveTo determine whether an ankle tape or...

Landing Impact, Hip Kinematics, and Hip Strength Predict Dynamic Postural Stability in Army 101st Airborne

Postural instability contributes to unintentional lower extremity musculoskeletal injury. It is unclear if reported contributors to knee injury influence dynamic postural stability. PURPOSE: To determine if peak vertical ground reaction force (vGRF), sagittal and frontal plane knee and hip kinematics at initial contact, knee flexor/extensor strength, and hip abductor/adductor strength significantly predict dynamic postural stability index (DPSI). METHODS: Thirty nine male Army 101st Airborne (Air Assault) soldiers participated (26.3±5.6 yrs, 176.9±8.5 cm, 81.0±17.7 kg). Three dimensional kinematic and ground reaction forces (GRFs) were captured with a motion capture system interfaced with a force plate. Subjects performed a double-leg forward jump over a 12" hurdle with a single-leg landing on a force plate positioned at a distance of 40% subject height. Subjects landed on the dominant limb, stabilized as quickly as possible, and maintained single-leg balance with hands at the waist. DPSI was calculated using three dimensional GRFs from the first three seconds following initial contact. Isokinetic knee strength at 60o/sec and side-lying isometric hip strength at 10o hip abduction were tested using a multi-mode dynamometer. Strength and peak vGRF were normalized to % body weight. A stepwise multiple linear regression was performed to determine if the independent variables significantly predicted DPSI. The F probability for variable entry of.05, F probability for variable removal of.10, and alpha level of.05 for model significance was set a priori. RESULTS: Significant predictors in the linear regression model of DPSI include peak vGRF, hip abduction strength, and hip flexion/extension angle at initial contact (p <.001; R2 =.88; respective b=.0001, -.0013,.0018; constant=.0141). CONCLUSIONS: Dynamic postural stability for soldiers of the Army 101st Airborne (Air Assault) may be optimized by decreasing landing impact, increasing hip abduction strength, and increasing hip flexion at initial contact during landing tasks. Current injury prevention strategies targeting the significant knee injury contributors may concurrently benefit dynamic postural stability. Investigations are warranted to assess effects of training targeting the hip on dynamic postural stability.

Dynamic postural control but not mechanical stability differs among those with and without chronic ankle instability

The purpose of this investigation was to compare dynamic postural control and mechanical ankle stability among patients with and without chronic ankle instability (CAI) and controls. Seventy-two subjects were divided equally into three groups: uninjured controls, people with previous ankle injury but without CAI, and people with CAI. Subjects completed a single-leg hop-stabilization task, and then had an anterior drawer test and lateral ankle radiograph performed bilaterally. The dynamic postural stability index was calculated from the ground reaction forces of the single-leg hop-stabilization task. Ankle joint stiffness (N/m) was measured with an instrumented arthrometer during the anterior drawer test, and fibula position was assessed from the radiographic image. Patients with previous ankle injuries but without CAI demonstrated higher frontal plane dynamic postural stability scores than both the uninjured control and CAI groups (P<0.01). Patients with and without CAI had significantly higher sagittal plane dynamic postural stability scores (P<0.01) and increased ankle joint stiffness (P=0.045) relative to the control group. The increased frontal plane dynamic postural control may represent a component of a coping mechanism that limits recurrent sprains and the development of CAI. Mechanical stability alterations are speculated to result from the initial ankle trauma.

Effects of a Wobble Board-Based Therapeutic Exergaming System for Balance Training on Dynamic Postural Stability and Intrinsic Motivation Levels

Randomized controlled trial. To compare the effects of wobble board exercises with and without feedback provided through integrating the wobble board movement into a computer game system, by comparing changes in postural stability and motivation. Therapeutic exergaming systems may offer a solution to poor adherence to postural control exercise regimes by improving motivation levels during exercise performance. Twenty-two healthy adults, randomly assigned to an exergaming group (n = 11) and a control group (n = 11), completed 12 exercise sessions. Dynamic postural stability was quantified at baseline and follow-up using the star excursion balance test and the dynamic postural stability index during a jump-landing task. Intrinsic motivation was measured at baseline using the Self-Motivation Inventory and at follow-up using the Intrinsic Motivation Inventory. Star excursion balance test scores showed a statistically significant (P<.008) improvement in the posteromedial and posterolateral direction for both groups. No within-group change for the dynamic postural stability index or between-group difference for star excursion balance test or dynamic postural stability index scores were observed. The "interest and enjoyment" category of the Intrinsic Motivation Inventory showed significantly higher scores (P<.001) in the exergaming group at follow-up, which was 1 of the 5 Intrinsic Motivation Inventory categories evaluated. The findings suggest that exercising with the therapeutic exergaming system showed similar improvements in dynamic postural stability and showed a greater level of interest and enjoyment when compared to a group doing similar balance training without the game system. Therapy, level 2b.

Gait Termination Control Strategies Are Altered in Chronic Ankle Instability Subjects

Despite the high incidence of chronic ankle instability (CAI), the underlying neurophysiologic mechanism is unknown. Evidence suggests that both feed-forward and feedback mechanisms may play a role. However, no investigation has examined both control mechanisms during the same movement task in the same cohort of CAI patients. To determine the neuromuscular and biomechanical control alterations present in CAI patients during planned (feed-forward) and unplanned (feedback) gait termination. Twenty subjects with CAI and 20 uninjured controls completed planned and unplanned gait termination protocols. Both tasks began with subjects walking at a self-selected speed across a 12-m walkway. Unplanned gait termination required subjects to stop during randomly selected trials on two adjacent force plates when cued. Planned gait termination required purposeful stopping on the force places. Propulsive and braking force magnitude and the dynamic postural stability index were calculated from the resulting ground reaction forces. In addition, muscle activity from the soleus, tibialis anterior, and gluteus medius was collected bilaterally. Both maximum propulsive (CAI = 99.8 +/- 40.8 N, control = 88.6 +/- 33.6 N) and braking (CAI = 207.1 +/- 80.9 N, control = 161.6 +/- 62.2 N) forces were significantly higher in the CAI group. The dynamic postural stability index revealed higher scores in the CAI group (0.24 +/- 0.03) compared with the control group (0.22 +/- 0.03). Muscle activation of the soleus and tibialis anterior differed during unplanned and planned gait termination between groups (P < 0.05) and between the limbs of the CAI group (P < 0.05). Altered biomechanical strategies during both planned and unplanned gait termination indicate that patients with CAI have alterations in feed-forward neuromuscular control and suggest the presence of feedback neuromuscular control deficits.

Dynamic Postural Stability in Copers and Individuals with Chronic Ankle Instability

Ankle sprains are the most common orthopedic injury in the United States and result in chronic ankle instability (AI) for 40−75% of patients. Interestingly, 25−60% can maintain high level activities (copers) and are thought to have a coping mechanism that limits the impairments seen in AI patients. Understanding the differences between copers and AI patients may elucidate the mechanisms of AI. PURPOSE: To determine if dynamic postural stability varies among copers, AI patients, and healthy controls. METHODS: Dynamic postural stability scores were assessed in 72 subjects (24 in each group) during a single leg hop stabilization protocol. Subjects started 70cm from a force plate and jumped off both legs to touch an overhead marker placed at 50% of their maximum vertical jump height before landing on the force plate with a single leg. Force data were collected at 200 Hz and normalized to the subject's body weight. Directional and composite scores were calculated using modified dynamic postural stability index formulas. These indices are created from the standard deviation fluctuations around a zero point. The medial/lateral stability index and anterior/ posterior stability index assess the standard deviation fluctuations from zero along the frontal (X) and sagittal (Y) axes of the force plate. The vertical stability index assesses the fluctuation from the subject's body weight along the Z-axis of the force plate. RESULTS: Group and limb means were analyzed with a 3 x 2 MANOVA that revealed a significant group effect [F(8,272)=6.226, p<0.001]. Further analysis revealed that copers (0.122±0.002) and AI patients (0.119±0.002) performed worse than healthy controls (0.106±0.002). Composite scores also revealed a reduction in performance for copers (0.296±0.003) and AI patients (0.292±0.003) compared to controls (0.282±0.003). However, in the sagittal plane copers (0.047±0.001) were significantly worse than AI (0.042±0.001) and controls (0.042±0.001). CONCLUSIONS: The results indicate that frontal plane dynamic postural stability is altered after acute ankle injury and that the copers' decreased performance in the sagittal plane may represent the hypothesized coping mechanism. Supported in part by the College of Health and Human Performance Opportunity Fund.

Dynamic Postural Stability Deficits in Subjects with Self-Reported Ankle Instability

A limited understanding of how functional ankle instability (FAI) affects dynamic postural stability exists because of a lack of reliable and valid measures. Therefore, the purpose of this investigation was to determine whether a new reliable index for dynamic postural stability could differentiate between those with stable ankles and those with FAI. Data were collected on 108 subjects (54 subjects with stable ankles (STABLE group); 54 subjects with functionally unstable ankles (FAI group)). Subjects performed a single-leg-hop stabilization maneuver in which they stood 70 cm from the center of a force plate, jumped off both legs, touched a designated marker placed at a height equivalent to 50% of their maximum vertical leap, and landed on a single leg. The dynamic postural stability index and directional stability indices (medial/lateral, anterior/posterior, and vertical) were calculated. The raw and normalized (to energy dissipated) indices were compared between groups. Significant differences were noted for the anterior/posterior stability index (FAI = 0.36 +/- 0.09, STABLE = 0.30 +/- 0.06). Similar results were seen for the vertical stability index (FAI = 0.73 +/- 0.17, STABLE = 0.61 +/- 0.13), the normalized dynamic postural stability index (FAI = 0.85 +/- 0.17, STABLE = 0.73 +/- 0.12), the normalized vertical stability index (FAI = 0.007 +/- 0.004, STABLE = 0.005 +/- 0.001), and the dynamic postural stability index (FAI = 0.008 +/- 0.003, STABLE = 0.006 +/- 0.001). These results indicate that the dynamic postural stability index is a sensitive measure of dynamic postural stability and is capable of detecting differences between individuals with stable ankles and individuals with functionally unstable ankles.

Gender and Limb Differences in Dynamic Postural Stability During Landing

To determine if gender and limb dominance affect dynamic postural stability and vertical ground reaction force data during jump landings. Secondary objective was to assess the reliability of the dynamic postural stability index (DPSI). A mixed model (2 genderx2 limb) repeated measures design was used to determine the effects of gender and limb dominance on dynamic postural stability. Subjects were required to perform a two-legged jump to a height equivalent of 50% of their maximum vertical leap, land on a single-leg and balance for three seconds. Sports Medicine Research Laboratory. Forty healthy subjects (20 men, 20 women) participated in this investigation. The DPSI and its directional components quantified dynamic postural stability during a single-leg jump landing. Normalized vertical ground reaction force data quantified energy absorption. DPSI values revealed that females had significantly different dynamic postural stability as compared to males in the vertical plane [T (78)=-4.2, P<0.01], and in the composite score (dynamic postural stability index) [T (78)=-6.3, P<0.01]. In addition, females had significantly higher peak vertical ground reaction forces [T (78)=-13, P=0.01] than males. The DPSI also showed excellent reliability (ICC=0.96), with a 95% confidence interval ranging from 0.94 to 0.97. The results indicate that females have higher dynamic postural stability scores in the vertical direction as well as the composite score. This suggests that females used different dynamic postural stability strategies than males. There were no side-to-side dynamic postural stability differences between healthy contralateral limbs.