The effects of different sensory augmentation on weight-shifting balance exercises in Parkinson's disease and healthy elderly people: a proof-of-concept study.

BACKGROUND: Earlier versions of biofeedback systems for balance-related applications were intended primarily to provide "alarm" signals about body tilt rather than to guide rehabilitation exercise motion. Additionally, there have been few attempts to evaluate guidance modalities for balance rehabilitation exercises. The purpose of this proof-of-concept study is to evaluate the effects of guidance modalities during common dynamic weight-shifting exercises used in clinical settings. METHODS: A motion guidance system providing visual biofeedback, vibrotactile biofeedback, or both, was used during weight-shifting exercises. Eleven people with idiopathic Parkinson's disease (PD) and nine healthy elderly people participated. Each participant wore a six-degree-of-freedom inertial measurement unit (IMU) located near the sacrum and four linear vibrating actuators (Tactors) attached to the skin over the front, back, and right and left sides of the abdomen. The IMU measured angular displacements and velocities of body tilt in anterior-posterior (A/P) and medial-lateral (M/L) directions. Participants were instructed to follow a slow moving target by shifting their weight in either the A/P or M/L direction up to 90 % of their limits of stability (LOS). Real-time position error was provided to participants in one of three sensory modalities: visual, vibrotactile, or both. Participants performed 5 trials for each biofeedback modality and movement direction (A/P and M/L) for a total of 30 trials in a random order. To characterize performance, position error was defined as the average absolute difference between the target and participant movements in degrees. RESULTS: Simultaneous delivery of visual and vibrotactile biofeedback resulted in significantly lower position error compared to either visual or vibrotactile biofeedback alone regardless of the movement direction for both participant cohorts. The pairwise comparisons were not significantly different between visual and vibrotactile biofeedback. CONCLUSION: The study is the first attempt to assess the effects of guidance modalities on common balance rehabilitation exercises in people with PD and healthy elderly people. The results suggest that combined visual and vibrotactile biofeedback can improve volitional responses during postural tracking tasks. Index Terms - sensory augmentation, weight-shifting balance exercise, guidance modality, vibrotactile biofeedback, visual biofeedback, Parkinson's disease.

The relationship between the hypnotic induction profile and the stanford hypnotic susceptibility scale, form C: revisited.

Hilgard's comment raises some important issues, although many of these have little to do with the primary purpose of the study under discussion. This purpose was to objectively examine the relationship between three conceptually and operationally different procedures for measuring hypnotic responsivity. Hilgard's concern over the magnitude of the correlation between the HIP and SHSS:C is unfounded. A cross-validated correlation of .66 was found between the HIP and SHSS:C in a new sample of 44 student volunteers. This demonstrates that the HIP correlates about the same with SHSS:C as the Harvard Group Scale of Hypnotic Susceptibility. Hilgard's conception of the Eye-Roll (ER) hypothesis is clarified. Evidence which utilizes all cases in the correlational analysis is presented in support of the ER hypothesis. Happily, we all agree on a new methodology which will be definitive in testing the validity of the ER hypothesis.

Strength and endurance adaptations to functional electrical stimulation leg cycle ergometry in spinal cord injury.

OBJECTIVES: To describe adaptations in power output, quadriceps muscle strength, and fatigability that occur during a 13-week regimen of Functional Electrical Stimulation Leg Cycle Ergometry (FES-LCE) in Spinal Cord Injury (SCI). To identify differences in outcomes between individuals with complete and incomplete motor impairment. DESIGN: Observational and longitudinal. SETTING: Rehabilitation and biomechanics research laboratory. PARTICIPANTS: Eleven (N = 11) individuals with SCI and no previous FES-LCE experience. INTERVENTION: 40 sessions of FES-LCE at a rate of three sessions per week. Continuous exercise was performed at a pedal cadence of 45 RPM against a constant resistance for up to 60 minutes. OUTCOME MEASURES: Mean power output was recorded for each session. Before and after the training regimen, each subject performed a fatigue test in which electrically stimulated knee extension torque and Fatigue Index were measured. RESULTS: Participants demonstrated significant increases in mean power output (9.0 to 20.3 W; p < 0.001), peak isometric knee extension torque (3.8 to 16.9 Nm; p = 0.006) and sustainable isometric knee extension torque (4.9 to 14.4 Nm; p = 0.001) after FES-LCE training (95% confidence intervals). Participants with incomplete motor impairment demonstrated a decrease in Fatigue Index (p = 0.021), and improved mean power output more than those with complete motor impairment (p = 0.037). CONCLUSIONS: Significant improvements in muscle conditioning and exercise performance are possible following the 13-week regimen of FES-LCE described in this article. Individuals with incomplete motor impairment experience greater improvements in mean power output than individuals with complete motor impairment.