Effects of simulated hypo-gravity on lower limb kinematic and electromyographic variables during anti-gravitational treadmill walking

Introduction: This study investigated kinematic and EMG changes in gait across simulated gravitational unloading levels between 100% and 20% of normal body weight. This study sought to identify if each level of unloading elicited consistent changes—particular to that percentage of normal body weight—or if the changes seen with unloading could be influenced by the previous level(s) of unloading.Methods: 15 healthy adult participants (26.3 ± 2.5 years; 53% female) walked in an Alter-G anti-gravity treadmill unloading system (mean speed: 1.49 ±0.37 mph) for 1 min each at 100%, 80%, 60%, 40% and 20% of normal body weight, before loading back to 100% in reverse order. Lower-body kinematic data were captured by inertial measurement units, and EMG data were collected from the rectus femoris, biceps femoris, medial gastrocnemius, and anterior tibialis. Data were compared across like levels of load using repeated measures ANOVA and statistical parametric mapping. Difference waveforms for adjacent levels were created to examine the rate of change between different unloading levels.Results: This study found hip, knee, and ankle kinematics as well as activity in the rectus femoris, and medial gastrocnemius were significantly different at the same level of unloading, having arrived from a higher, or lower level of unloading. There were no significant changes in the kinematic difference waveforms, however the waveform representing the change in EMG between 100% and 80% load was significantly different from all other levels.Discussion: This study found that body weight unloading from 100% to 20% elicited distinct responses in the medial gastrocnemius, as well as partly in the rectus femoris. Hip, knee, and ankle kinematics were also affected differentially by loading and unloading, especially at 40% of normal body weight. These findings suggest the previous level of gravitational load is an important factor to consider in determining kinematic and EMG responses to the current level during loading and unloading below standard g. Similarly, the rate of change in kinematics from 100% to 20% appears to be linear, while the rate of change in EMG was non-linear. This is of particular interest, as it suggests that kinematic and EMG measures decouple with unloading and may react to unloading uniquely

The function of methodology to changing gravitational load during treadmill walking

Adaption to long term sensory changes involves both the adaption of sensory receptors and the central nervous system allowing for reinterpretation of the new sensory feedback. Astronauts learn to function in microgravity after a period of adaptation during space flight. Similarly, patients with certain medical conditions can experience changing sensory input. Previous work has suggested that the pattern of leg movement and muscle electrical activity is a function of how the amount of loading is achieved in addition to the amount of body loading. The participants walked on the unloading treadmill while having electromyography (EMG) electrodes and Xsens sensors attached over muscles and body segments, respectively. One protocol consisted of reducing the participants’ weight by 20% every minute until they reached 20% of their actual weight and then increasing the weight by 20% every minute until actual weight was reached again. In another protocol, the participant underwent a similar procedure, but with a minute rest in which the treadmill was stopped between each changing weight load. Both protocols and loading and unloading conditions will be compared. This study will use statistical parametric mapping (SPM) to compare waveforms with spatiotemporal dimensionality unique to the individual. The EMG activity and the joint angles could present certain patterns at given weights depending upon the protocol used to reach that weight. This experiment could provide additional information associated with the patterns of adaptation to a changing sensory environment and could reveal how altering the protocol to reaching the same condition can impact adaptability.Biology and Biochemistry, Department ofHonors Colleg

Epidemiological Aspects of Giant Cell Arteritis

Giant cell arteritis (GCA) is a systemic vasculitis that affects medium-to-large-sized arteries, in which the inflammatory reaction destroys the artery wall with the fragmentation of the elastic lamina. Such phenomena can result in vision loss if not treated promptly. Other nonocular symptoms noted include GCA, headache, tenderness in the temporal area of the scalp, myalgias and arthralgias, fever, weight loss, and jaw claudication. Clinical suspicion is an essential pathway to the diagnosis of this disease. Thus, immediate Westergren sedimentation rate and C-reactive protein should be obtained. A temporal artery biopsy, however, remains the most definitive diagnostic tool. The incidence of GCA remarkably increases with each decade of age among those aged 50 years or over. Additionally, there have been notable differences among patients of different ethnicities. The epidemiological characteristics of GCA have been primarily researched in populations from the United States as well as several European countries with emphasis on the Caucasian population. In more recent years, a handful of studies have emerged from non-European countries regarding the epidemiology of GCA. The results of these findings are in parallel with previous observations, which presumed GCA to be more common in European and North American populations