Recep OZDEMIR | University of Miami, Medical School (original) (raw)

Papers by Recep OZDEMIR

challenging postural conditions presumably related to corti-cal representations of changing senso... more challenging postural conditions presumably related to corti-cal representations of changing sensory conditions in pos-tural tasks. Theta rhythms, on the other hand, were more responsive to cognitive task difficulty in both groups, with more pronounced increases in younger subjects which may underlie neural correlates of high-level cognitive computations including encoding and retrieval. Gamma oscillations also increased in the elderly primarily over central and central-parietal cortices during challenging postural tasks, indicating increased allocation of attentional sources to postural tasks.

Gait & Posture, 2013

To better understand sensorimotor posture control differences between blind and sighted individua... more To better understand sensorimotor posture control differences between blind and sighted individuals, we examined the role of ankle joint proprioception and ankle muscle strength on postural control in healthy blind (n=13, 25-58 years) and age-and sex-matched sighted (n=15, 20-65 years) volunteers. We measured ankle joint proprioceptive acuity and isokinetic muscle strength in plantarflexion and dorsiflexion using an isokinetic dynamometer. We also assessed postural control performance during quiet bipedal stance with and without sudden postural perturbations, and during quiet unipedal stance. We found that while our blind subjects exhibited significantly better proprioceptive acuity than our sighted subjects their postural control performance was significantly poorer than that of the sighted group with eyes open, and no different from that of the sighted group with eyes closed suggesting that their superior proprioceptive acuity does not translate to improved balance control.

2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2014

Stroke remains a leading cause of disability, limiting independent ambulation in survivors, and c... more Stroke remains a leading cause of disability, limiting independent ambulation in survivors, and consequently affecting quality of life (QOL). Recent technological advances in neural interfacing with robotic rehabilitation devices are promising in the context of gait rehabilitation. Here, the X1, NASA's powered robotic lower limb exoskeleton, is introduced as a potential diagnostic, assistive, and therapeutic tool for stroke rehabilitation. Additionally, the feasibility of decoding lower limb joint kinematics and kinetics during walking with the X1 from scalp electroencephalographic (EEG) signals -the first step towards the development of a brain-machine interface (BMI) system to the X1 exoskeleton -is demonstrated.

Türkiye Fiziksel Tıp ve Rehabilitasyon Dergisi, 2013

The primary purpose of the present study was to examine differences in balance performance betwee... more The primary purpose of the present study was to examine differences in balance performance between the dominant and nondominant legs during dynamic balance tasks in healthy individuals with no regular exercise backgrounds. As a secondary purpose, gender differences in single-leg stance were also investigated. Material and Methods: Twenty-one men and 24 women participated in this study. Single-leg balance performance was evaluated by the Biodex Stability System SD. All subjects were tested at level 1 for 20 sec, and 1-minute rest intervals were provided among 6 trials for each leg. Results: According to the results, there was no multivariate effect of leg dominance on any stability index, indicating symmetry between limbs in terms of balance performance. Mean comparisons showed that women had significantly better balance scores than men on overall (p<0.05), antero-posterior (p<0.05), and medio-lateral (p<0.05) stability indexes. Conclusion: Functional symmetry exists between the dominant and nondominant leg in all stability indexes of balance performance of sedentary individuals. Female subjects swayed less than males on both the dominant and the nondominant leg measurements in all directions (overall, antero-posterior, and medio-lateral directions).

Journal of Visualized Experiments, 2013

Recent studies support the involvement of supraspinal networks in control of bipedal human walkin... more Recent studies support the involvement of supraspinal networks in control of bipedal human walking. Part of this evidence encompasses studies, including our previous work, demonstrating that gait kinematics and limb coordination during treadmill walking can be inferred from the scalp electroencephalogram (EEG) with reasonably high decoding accuracies. These results provide impetus for development of non-invasive brain-machine-interface (BMI) systems for use in restoration and/or augmentation of gait- a primary goal of rehabilitation research. To date, studies examining EEG decoding of activity during gait have been limited to treadmill walking in a controlled environment. However, to be practically viable a BMI system must be applicable for use in everyday locomotor tasks such as over ground walking and turning. Here, we present a novel protocol for non-invasive collection of brain activity (EEG), muscle activity (electromyography (EMG)), and whole-body kinematic data (head, torso, and limb trajectories) during both treadmill and over ground walking tasks. By collecting these data in the uncontrolled environment insight can be gained regarding the feasibility of decoding unconstrained gait and surface EMG from scalp EEG.

Journal of Sports Science …, Jan 1, 2012

Although there are many studies demonstrating increased trunk activation under unstable condition... more Although there are many studies demonstrating increased trunk activation under unstable conditions, it is not known whether this increased activation would translate into meaningful trunk strength with a prolonged training program. Additionally, while balance-training programs have been shown to improve stability, their effect on specific joint proprioception is not clear. Thus the objective of this study was to examine training adaptations associated with a 10-week instability-training program. Participants were tested pre-and post-training for trunk extension and flexion strength and knee proprioception. Forty-three participants participated in either a 10-week (3 days per week) instability-training program using Swiss balls and body weight as resistance or a control group (n = 17). The trained group increased (p < 0.05) trunk extension peak torque/body weight (23.6%) and total work output (20.1%) from pre-to post-training while the control group decreased by 6.8% and 6.7% respectively. The exercise group increased their trunk flexion peak torque/body weight ratios by 18.1% while the control group decreased by 0.4%. Knee proprioception (combined right and left joint repositioning) improved 44.7% from pre-to post-training (p = 0.0006) and persisted (21.5%) for 9 months post-training. In addition there was a side interaction with the position sense of the right knee at 9 months showing 32.1% (p = 0.03) less deviation from the reference angle than the right knee during pre-testing. An instability-training program using Swiss balls with body weight as resistance can provide prolonged improvements in joint proprioception and core strength in previously untrained individuals performing this novel training stress which would contribute to general health.

International Journal of Human …, Jan 1, 2010

The purpose of the present study was to investigate effects of both local and general physical fa... more The purpose of the present study was to investigate effects of both local and general physical fatigue on visual simple and visual choice reaction time of elite level athletes. 15 male and 3 female national Muay-Thai athletes (M age = 21.55, SD= 3.47) who participated at least 5 training sessions per week volunteered to participate present study. Subjects were asked to perform Wingate anaerobic test on a mechanically braked cycle ergometer (834 E, Monark) to induce general fatigue. Hand grip dynamometer was used for resistance exercises to induce local fatigue. Simple, two-choice and three-choice visual reaction times were measured at resting, after local and general physical fatigue conditions both on right and left hands, respectively. The results of repeated measure ANOVAs yielded that compared to resting conditions simple reaction time significantly increased after inducing the local and general physical fatigue on both hands. On the other hand, although two-choice and threechoice reaction time mean scores increased from resting to both general and local physical fatigue conditions, these increments were not statistically different among measurements. It was concluded that both dynamic and resistance exercise induced fatigue may seems to lengthen only simple reaction time and did not affect decision making processes of elite level Muay-Thai athletes.

International Journal of …, Jan 1, 2010

Journal of Sports Science …, Jan 1, 2011

The purpose of this study was to determine if Pilates exercise could improve dynamic balance, fle... more The purpose of this study was to determine if Pilates exercise could improve dynamic balance, flexibility, reaction time and muscle strength in order to reduce the number of falls among older women. 60 female volunteers over the age of 65 from a residential home in Ankara participated in this study. Participants joined a 12-week series of 1-hour Pilates sessions three times per week. Dynamic balance, flexibility, reaction time and muscle strength were measured before and after the program. The number of falls before and during the 12-week period was also recorded. Dynamic balance, flexibility, reaction time and muscle strength improved (p < 0.05) in the exercise group when compared to the non-exercise group. In conclusion, Pilates exercises are effective in improving dynamic balance, flexibility, reaction time, and muscle strength as well as decreasing the propensity to fall in older women.