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In JoVE (1)
Other Publications (11)
- Journal of Vascular Surgery : Official Publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter
- Clinical Science (London, England : 1979)
- Clinical Biochemistry
- NeuroImage
- Stress (Amsterdam, Netherlands)
- Physiology & Behavior
- Physiology & Behavior
- BMC Physiology
- Journal of Sports Sciences
- Journal of Science and Medicine in Sport / Sports Medicine Australia
- Medicine and Science in Sports and Exercise
Articles by Christopher D. Askew in JoVE
JoVE Neuroscience
Coherence between Brain Cortical Function and Neurocognitive Performance during Changed Gravity Conditions
1Institute of Movement and Neurosciences, German Sport University Cologne, 2Deptartment of Surgical Skills, University of Toronto, 3School of Human Movement Studies, Institute of Health and Biomedical Innovation, Queensland University of Technology, 4Brain Products GmbH, Scientific Support, Gilching, Germany
The effect of weightlessness and hypergravity on both hemodynamic and electrophysiological processes in the brain is going to be followed during parabolic flight by EEG and NIRS techniques. A feasibility study of a more complex experiment, which is planned to carry out during medium- and long-term space flight.
Other articles by Christopher D. Askew on PubMed
Skeletal Muscle Phenotype is Associated with Exercise Tolerance in Patients with Peripheral Arterial Disease
To better understand the association between skeletal muscle and exercise intolerance in peripheral arterial disease (PAD), we assessed treadmill-walking performance and gastrocnemius muscle phenotype in healthy control subjects and in patients with PAD. We hypothesized that gastrocnemius muscle characteristics would be altered in PAD compared with control subjects and that exercise tolerance in patients PAD would be related to muscle phenotype.
Effect of Training on the Response of Plasma Vascular Endothelial Growth Factor to Exercise in Patients with Peripheral Arterial Disease
Expansion of the capillary network, or angiogenesis, occurs following endurance training. This process, which is reliant on the presence of VEGF (vascular endothelial growth factor), is an adaptation to a chronic mismatch between oxygen demand and supply. Patients with IC (intermittent claudication) experience pain during exercise associated with an inadequate oxygen delivery to the muscles. Therefore the aims of the present study were to examine the plasma VEGF response to acute exercise, and to establish whether exercise training alters this response in patients with IC. In Part A, blood was collected from patients with IC (n=18) before and after (+20 and +60 min post-exercise) a maximal walking test to determine the plasma VEGF response to acute exercise. VEGF was present in the plasma of patients (45.11+/-29.96 pg/ml) and was unchanged in response to acute exercise. Part B was a training study to determine whether exercise training altered the VEGF response to acute exercise. Patients were randomly assigned to a treatment group (TMT; n=7) that completed 6 weeks of high-intensity treadmill training, or to a control group (CON; n=6). All patients completed a maximal walking test before and after the intervention, with blood samples drawn as for Part A. Training had no effect on plasma VEGF at rest or in response to acute exercise, despite a significant increase in maximal walking time in the TMT group (915+/-533 to 1206+/-500 s; P=0.009) following the intervention. The absence of a change in plasma VEGF may reflect altered VEGF binding at the endothelium, although this cannot be confirmed by the present data.
Stress Hormone Stability: Processing of Blood Samples Collected During Parabolic Flight. A Pre-flight Comparison of Different Protocols
Compare different protocols for blood processing to be used during parabolic flights.
What Happens to the Brain in Weightlessness? A First Approach by EEG Tomography
Basic changes in environmental conditions are fundamental to understanding brain cortical mechanisms. Several studies have reported impairment of central nervous processes during weightlessness. There is ongoing debate as to whether these impairments are attributable to primary physiological effects or secondary psychological effects of the weightlessness environment. This study evaluates the physiological effects of changed gravity conditions on brain cortical activity. In a first experiment, EEG activity of seven participants was recorded at normal, increased and zero gravity during a parabolic flight. Additionally an EEG under normal gravity conditions preflight was recorded. In a second experiment, 24 participants were exposed to a supine, seated and 9 degree head-down tilt position while EEG was recorded. Data were analysed using low resolution brain electromagnetic tomography (LORETA). Beta-2 EEG activity (18-35 Hz) was found to be increased in the right superior frontal gyrus under normal gravity conditions inflight. By exposure to weightlessness a distinct inhibition of this activity within the same areas could be noticed. As the tilt experiment showed changes in the left inferior temporal gyrus in supine and tilted positions we conclude that the observed changes under weightlessness are not explainable by hemodynamic changes but rather reflect emotional processes related to the experience of weightlessness. These findings suggest that weightlessness has a major impact on electro cortical activity and may affect central nervous and adaptation processes.
The Effect of Parabolic Flight on Perceived Physical, Motivational and Psychological State in Men and Women: Correlation with Neuroendocrine Stress Parameters and Electrocortical Activity
Previous findings of decreased mental and perceptual motor performance during parabolic flights have been attributed mainly to the primary effects of weightlessness rather than the accompanying effects of stress and altered mood. Although recent studies have alluded to the possible negative effects of stress on performance, there has been no attempt to investigate this during parabolic flights. Over a period of 3 years, 27 human participants (male n = 18, mean age +/- SD 34.67 +/- 7.59 years; female n = 9, 36.22 +/- 9.92 years) were recruited with the aim to evaluate if, and to what extent, parabolic flights are accompanied by changes in mood. Furthermore, the relationships between mood and physiological markers of stress and arousal, namely circulating stress hormones (ACTH, cortisol, epinephrine, norepinephrine, prolactin and brain activity (EEG)) were investigated. A strong and significant correlation was found between circulating stress hormone concentrations and perceived physical state, motivational state (MOT) and psychological strain (PSYCHO), whereas no interaction between mood and EEG or EEG and stress hormone concentrations was observed. Therefore, two different stress responses appear to be present during parabolic flight. The first seems to be characterised by general cortical arousal, whereas the second seems to evolve from the adrenomedullary system. It is likely that both these mechanisms have different effects on mental and perceptual motor performance, which require further investigation and should to be taken into account when interpreting previous weightlessness research.
EEG Activity and Mood in Health Orientated Runners After Different Exercise Intensities
An increasing number of studies within the recent years connected physical exercise with changes in brain cortical activity. Most of this data (1) refers to aerobic exercise and (2) does not correlate to psychological parameters although it is well known that exercise has a positive effect on mood. In times where health activities play a major role it is increasingly necessary to connect somato-physiological and somatopsychological components of physical activity. This study aimed to find changes in EEG activity and mood after low, preferred and high intensity running. EEG and actual state of mood were recorded before and after exercise. Results showed an effect for the preferred and high intensity velocity in both, EEG and mood. As only the higher frequency areas N18 Hz showed persisting decreases post-exercise we concluded that this might be a sign of outlasting effects of exercise on brain cortical activity which may have influences on general well-being. We could also show that there is a clear relationship between EEG activity and mood reflecting a basic principle of cortical excitation.
Changes in Brain Cortical Activity Measured by EEG Are Related to Individual Exercise Preferences
Exercise is well known to result in changes of brain cortical activity measured by EEG. The aim of this study was (1) to localise exercise induced changes in brain cortical activity using a distributed source localisation algorithm and (2) to show that the effects of exercise are linked to participants' physical exercise preferences. Electrocortical activity (5 min) and metabolical parameters (heart rate, lactate, peak oxygen uptake) of eleven recreational runners were recorded before and after incremental treadmill, arm crank and bicycle ergometry. Electroencephalographic activity was localised using standardised low resolution brain electromagnetic tomography (sLORETA). Results revealed an increase in frontal alpha activity immediately post exercise whereas increases after bike exercise were found to be localised in parietal regions. All three kinds of exercise resulted in an increase of beta activity in Brodmann area 7. Fifteen and thirty minutes post exercise a specific activation pattern (decrease in frontal brain activity-increase in occipital regions) was noticeable for treadmill and bike but not arm crank exercise. We conclude that specific brain activation patterns are linked to different kinds of exercise and participants' physical exercise preferences.
Plasma ATP Concentration and Venous Oxygen Content in the Forearm During Dynamic Handgrip Exercise
It has been proposed that adenosine triphosphate (ATP) released from red blood cells (RBCs) may contribute to the tight coupling between blood flow and oxygen demand in contracting skeletal muscle. To determine whether ATP may contribute to the vasodilatory response to exercise in the forearm, we measured arterialised and venous plasma ATP concentration and venous oxygen content in 10 healthy young males at rest, and at 30 and 180 seconds during dynamic handgrip exercise at 45% of maximum voluntary contraction (MVC).
Exercise, Music, and the Brain: is There a Central Pattern Generator?
The frequency for movements along the longitudinal axis during running peaks at approximately 3 Hz. Other physiological systems (e.g. heart rate and brain cortical activity) are known to show a dominant frequency of ~3 Hz connected to exercise. As recent studies have proposed a clear correlation between musical tempo, mood, and performance output, we wished to ascertain whether peak locomotion frequency of ~3 Hz during running is synchronized with different intrinsic and extrinsic frequencies. Eighteen healthy regular runners performed three outdoor running sessions at different intensities. Oscillations along the longitudinal axis were recorded using an accelerometer (ActiBelt). Electrocortical activity was recorded using electroencephalography before and after exercise and analysed in the delta frequency range (2-4 Hz). In addition, the frequency spectra of the participants' favourite musical pieces were analysed. Data revealed a peak frequency at around 2.7 to 2.8 Hz for the vertical acceleration during running. Similar oscillation patterns were found for heart rate and musical pieces. Electroencephalographic delta activity increased after running. Results of this study give reason to speculate that a strong relationship exists between intrinsic and extrinsic oscillation patterns during exercise. A frequency of approximately 3 Hz seems to be dominant in different physiological systems and seems to be rated as pleasurable when choosing the appropriate music for exercising. This is in line with previous research showing that an adequate choice of music during exercise enhances performance output and mood.
Identifying Symmetry in Running Gait Using a Single Inertial Sensor
Running gait has been shown to alter due to changes in intensity. It was hypothesised that a sacral mounted single inertial sensor could identify the centre of mass (COM) vertical accelerations. This study aimed to validate this new technique against a criterion measure and to determine the influence of changes in running intensity on COM vertical acceleration and the symmetry of COM vertical acceleration between left and right steps. Ten athletes ran for 5min at their self-selected pace, plus 1km/h above and below this velocity. Validity of the single inertial sensor was determined by comparing COM vertical acceleration against that measured with a six-camera infrared system. Large correlation (r=0.96), a small typical error of estimate (1.84), and mean bias (0.02) were found between the two systems. The greatest magnitude in COM vertical acceleration occurred at the slowest running pace and decreased as pace increased. Sixty percent of the athletes exhibited asymmetry during at least one running pace; 30% were asymmetrical across all three velocities. While significant changes in COM vertical acceleration occurred between the different running velocities, this did not always result in a change in symmetry. This study found that a single inertial sensor can be used as a valid means of measuring COM vertical acceleration. This technique can detect changes in the COM vertical acceleration that may change with running velocity. Gait symmetry (using COM vertical acceleration) during running was also quantified using the inertial sensor.
Brain and Exercise: a First Approach Using Electrotomography
The impact of exercise on brain function has gained broad interest. Because hemodynamic and imaging studies are difficult to perform during and after exercise, electroencephalography (EEG) is often the method of choice. Within this study, we aimed 1) to extend prior work examining changes in scalp-recorded brain electrical activity associated with exercise and 2) to use a distributed source localization algorithm (standardized low-resolution brain electromagnetic tomography [sLORETA]) to model the probable neural sources of changes in EEG activity after exercise.
