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Srikant Vallabhajosula publishes articles in three journals


Assistant Professor Srikant Vallabhajosula in the Department of Physical Therapy Education recently published three articles.

1. Biomechanical analyses of stair-climbing while dual-tasking. (from Journal of Biomechanics)

Stair-climbing while doing a concurrent task like talking or holding an object is a common activity of daily living which poses high risk for falls. While biomechanical analyses of overground walking during dual-tasking have been studied extensively, little is known on the biomechanics of stair-climbing while dual-tasking. We sought to determine the impact of performing a concurrent cognitive or motor task during stair-climbing. We hypothesized that a concurrent cognitive task will have a greater impact on stair climbing performance compared to a concurrent motor task and that this impact will be greater on a higher-level step. Ten healthy young adults performed 10 trials of stair-climbing each under four conditions: stair ascending only, stair ascending and performing subtraction of serial sevens from a three-digit number, stair ascending and carrying an empty opaque box and stair ascending, performing subtraction of serial sevens from a random three-digit number and carrying an empty opaque box. Kinematics (lower extremity joint angles and minimum toe clearance) and kinetics (ground reaction forces and joint moments and powers) data were collected. We found that a concurrent cognitive task impacted kinetics but not kinematics of stair-climbing. The effect of dual-tasking during stair ascent also seemed to vary based on the different phases of stair ascent stance and seem to have greater impact as one climbs higher. Overall, the results of the current study suggest that the association between the executive functioning and motor task (like gait) becomes stronger as the level of complexity of the motor task increases.

2. Low-frequency versus high-frequency subthalamic nucleus deep brain stimulation on postural control and gait in Parkinson's disease: a quantitative study (from Brain Stimulation).



High frequency stimulation (HFS) of the subthalamic nucleus (STN-DBS) has been shown to have little impact on postural control and gait improvements in Parkinson's disease (PD). There is a lack of consensus and quantitative evidence to suggest that stimulating STN at a lower frequency (LFS) as compared to HFS will be superior in improving symptoms.


To determine if postural control and gait characteristics of persons with PD improve at an LFS (60 Hz) compared to HFS (>100 Hz). We hypothesized that persons with PD would perform better on postural control and gait measures at LFS.


Nineteen participants with bilateral STN-DBS underwent UPDRS, static and dynamic postural control using gait initiation, and gait evaluations in three stimulation conditions (baseline voltage stable across conditions: OFF, LFS of 60 Hz, and HFS of >100 Hz). Additionally 10/19 participants were also stimulated at 30 Hz and 60 Hz and at higher voltages. A one-way ANOVA was performed to compare the conditions.


Total UPDRS-III score, step length and velocity during gait initiation, and gait speed significantly improved during 60 Hz and >100 Hz conditions when compared to the OFF condition (P < 0.05). There were no significant differences between 60 Hz and >100 Hz conditions. Using LFS at higher voltage showed no improvement over >100 Hz condition.


The positive effects of both LFS and HFS on postural control and gait were similar and clinical changes were relatively small. LFS may not help improve postural control, and gait particularly for persons with PD who do not develop gait-related disorders after HFS.

3. Tai chi intervention improves dynamic postural control during gait initiation in older adults: a pilot study. (FROM JOURNAL of applied biomechanics)


Tai Chi intervention has been shown to be beneficial for balance improvement. The current study examined the effectiveness of Tai Chi to improve the dynamic postural control among older adults with mobility disability. Six sedentary older adults with mobility disability participated in a 16-week Tai Chi intervention consisting of one hour sessions three times a week. Dynamic postural control was assessed pre- and post intervention as participants initiated gait in four stepping conditions: forward; 45° medially, with the stepping leg crossing over the other leg; 45° and 90° laterally. The center of pressure (CoP) displacement, velocity, and its maximum separation distance from the center of mass in the anteroposterior, mediolateral, and resultant directions were analyzed. Results showed that in the postural phase, Tai Chi increased the CoP mediolateral excursions in the medial (13%) and forward (28%) conditions, and resultant CoP center of mass distance in the medial (9%) and forward (19%) conditions. In the locomotion phase, the CoP mediolateral displacement and velocity significantly increased after the Tai Chi intervention (both by > 100% in the two lateral conditions). These results suggest that through alteration in CoP movement characteristics, Tai Chi intervention might improve the dynamic postural control during gait initiation among older adults.


Jennifer Medlin,
4/30/2015 4:20 PM