System In Healthy Subjects Research Articles

The effects of noradrenergic stimulation on the human motor system in healthy subjects

In this study, we investigated the effects of noradrenergic stimulation on the human motor system in healthy subjects assessing both changes in motor performance and changes in neural activity using functional magnetic resonance imaging (fMRI). Evidence from both animal and patient studies suggested that noradrenergic stimulation may enhance motor recovery after brain lesions (e.g., stroke). Furthermore, it was demonstrated that stimulating the motor system with noradrenaline (NA) enhancing drugs may also increase corticomotor excitability in healthy subjects. However, the mechanisms underlying the beneficial effects of noradrenaline on mammalian motor system are still poorly understood, especially in humans. To investigate this issue, we combined several motor behavioral tasks with different complexity such as finger tapping and visuomotor coordination tasks and an fMRI test with a joystick task to assess the effects of noradrenaline on behavior and neural activity. Reboxetine, a selective noradrenaline reuptake inhibitor (SNRI), was used as a noradrenergic stimulant with a double-blinded and placebo-controlled protocol in this study. The motor behavioral results showed that especially visuomotor abilities but not simple motor performance were improved after administration of 8mg Reboxetine compared to placebo. The fMRI results displayed that under Reboxetine neural activity was increased in visual cortex, in predominantly right-hemispheric motor areas, in the right thalamus, in the bilateral putamen and in the right intraparietal areas. In conclusion, our results suggest that noradrenergic stimulation has specific effects on motor behavior which is accompanied by stronger activation in visuomotor information processing areas. The specific effects on motor behavior and neural activity of noradrenergic stimulation in motor recovery of stroke patients will be further investigated to assess its medical usage in neurological rehabilitation.

Changes of skin characteristics during and after local Parafango therapy as used in physiotherapy

In physiotherapy, fango (mud) application is a frequently used heat therapy. The main therapeutic effects are due to the elevated temperature of the different tissues with a significant redistribution of blood towards the heated area. This may influence several cardiovascular parameters. There is only limited information on the effect of fango application on skin characteristics. It was the aim of the present study to evaluate the effects of fango application on skin temperature, perfusion of the microcirculation and skin colour. At the same time, cardiovascular parameters such as heart rate, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were recorded. Eighteen healthy subjects (age 23.7+/-3.8 years) entered the study. The skin characteristics and cardiovascular parameters were measured before, during and after a 21-min fango application at 44.5 degrees C. Skin temperature and perfusion of the microcirculation increased significantly during fango application: from 35.5+/-0.4 degrees C to 44.3+/-1.2 degrees C for skin temperature and from 23.2+/-8.8 to 197+/-41 p.u. for the skin microcirculation. These two parameters remained elevated during the fango application and decreased slowly to baseline values within 21 min after fango removal. Skin colour (CIELAB, a(*) parameter) increased from 11.0+/-2.5 to 17.9+/-1.9 when comparing pre- with post-treatment values. At the end of the measuring period, the a(*) parameter did not return to baseline values (15.8+/-2.1). Heart rate increased with 8 bpm during the fango therapy and returned to baseline within 3 min after removal of the fango. SBP and DBP varied slightly during the fango application. They returned to baseline values within 21 min after fango removal. The skin parameters indicate a transient temperature effect with an increased perfusion of the microcirculation and a flooding of the superficial capacitance system. The cardiovascular parameters were only slightly influenced and remained in the physiological range. Fango application seems not to be too demanding for the cardiovascular system in healthy subjects.

Changes in nonlinear characteristics of heart rate variability under functional load on the cardiovascular system in healthy subjects and coronary heart disease patients

Some nonlinear characteristics of heart rate variability in the course of functional tests with physical exercise are described. Two groups of volunteers participated in the tests: a control group of 32 healthy subjects (group 1) and a group of 35 coronary heart disease (CHD) patients (group 2). Two series of experiments were performed for each group. An active orthostatic test (AOT) was used in the first series, and a gradually growing physical load on a bicycle ergometer (bicycle ergometer test, BET), in the second series. Along with statistical indices of heart rate (the mean RR interval and standard deviation), nonlinear indices of heart rate were estimated: the correlation dimensionality (D2) and approximate entropy (ApEn). Trends of the changes in nonlinear indices of heart rate have been found. The D2 and ApEn decreased in both groups of subjects during the AOT and BET under the maximum load. However, the groups of healthy subjects and CHD patients differed in the reactivity of indices, the amplitude of changes in nonlinear indices being narrower in the latter group than in group 1. Differently directed shifts in standard deviation (SDNN) and nonlinear indices have been found. Thus, the data obtained with the use of nonlinear heart rate characteristics show that heart rate under physical load is more multivariate and diverse in healthy subjects at rest and the amplitude of changes during the AOT and BET is greater than in CHD patients, which is a result of the specific autonomic control of heart activity in cardiovascular pathologies.

E205 ストレスならびに行動特性と眼・耳などの感覚器や自律神経系の症状の関係(VDT作業,一般演題:口演,地方の時代の産業保健,第79回日本産業衛生学会)

E205 ストレスならびに行動特性と眼・耳などの感覚器や自律神経系の症状の関係(VDT作業,一般演題:口演,地方の時代の産業保健,第79回日本産業衛生学会)

Effects of pure ethanol and alcopops on glucose, insulin, and the insulin-like growth factor system in healthy subjects

Introduction Alcohol induces disturbances in insulin-like growth factor-I (IGF-I) and IGF binding protein-1 (IGFBP-1) levels. The aim of the present study was to compare pure ethanol and alcopop effects on total and free IGF-I, IGFBP-1, IGF-I:IGFBP-1 complex, insulin and plasma glucose levels in healthy subjects. Methods Five males and seven females (21–51 years) consumed pure ethanol and alcopops with identical alcohol content in a cross-over design after 6 h fasting. Blood samples were obtained for determination of serum ethanol and plasma glucose at 0, 30, 60, 90, 120 and 180 min. Serum total and free IGF-I, IGFBP-1, IGF-I:IGFBP-1 complex, and insulin were measured at 0, 60 and 180 min. Results Area under the curve for serum ethanol concentration was significantly less following alcopop compared to pure ethanol (1124 ± 201 vs. 1691 ± 359 mmol/L h, P < 0.01). Serum insulin and glucose levels were unchanged by ethanol while alcopop intake was followed by a transient increase in glucose and insulin levels ( P < 0.05). Pure ethanol and alcopop reduced free IGF-I levels by the end of the study period ( P = 0.05). IGFBP-1 and the IGF-I:IGFBP-1 complex increased following ethanol intake ( P < 0.05) while only a small transient IGFBP-1 increase was observed following alcopop intake. No change in total IGF-I was observed. Conclusion Both drinks resulted in reduced free IGF-I levels, however, only pure ethanol increased IGFBP-1 and the IGF-I:IGFBP-1 complex. Alcopop intake was associated with a transient increase in IGFBP-1 and unchanged IGF-I:IGFBP-1 complex levels probably due to marked changes in insulin and glucose levels.

Effect of a new angiotensin converting enzyme inhibitor MK 421 and its lysine analogue on the components of the renin system in healthy subjects

1 MK 421 and its lysine analogue are two new inhibitors of angiotensin converting enzyme. Ten mg of both compounds were each given p.o. to 12 normotensive volunteers to determine their effect on the various components of the renin angiotensin aldosterone system. 2 Plasma converting enzyme activity decreased to very low levels within 3 to 4 h to recover only slowly over the next 72 h. Plasma angiotensin II and aldosterone also fell but returned to baseline within 24 h, whereas plasma renin activity rose reflecting the low angiotensin II levels. 3 There was a close correlation between both angiotensin II and aldosterone levels and the logarithm of plasma converting enzyme activity demonstrating that angiotensin II and aldosterone fell only when converting enzyme activity was reduced to very low levels. 4 Mean hourly urinary sodium excretion increased markedly 6 to 10 h post-drug, while blood pressure decreased slightly. Both drugs were well tolerated. 5 Thus 10 mg of MK 421 or its lysine analogue given orally are effective and long acting angiotensin converting enzyme inhibitors.

Ipsi- and contralateral exteroceptive EMG modulation in uni- and bilaterally activated thenar muscles

Objective The cutaneous silent period (CSP) is a spinal inhibitory reflex mediated by A-δ fibers. The exact underlying neural pathway, however, is unknown. This study was undertaken to investigate whether the neural circuitry mediating CSPs is wired unilaterally or whether there is evidence of influence from or upon the contralateral side. Methods Fifteen healthy subjects underwent bilateral CSP testing following unilateral nociceptive digit II stimulation. Surface electromyographic (EMG) recordings were obtained bilaterally from thenar muscles following unilateral recurrent nociceptive digit II stimulation while activating the ipsilateral or the contralateral or both thenar muscles against resistance. Results Nociceptive digit II stimulation evoked consistent CSPs in ipsilateral thenar muscles during voluntary contraction, while there was no consistent influence on EMG activity in contralateral thenar muscles at rest. Furthermore, nociceptive digit II stimulation did neither consistently affect EMG activity in ipsilateral thenar muscles at rest nor in contralateral thenar muscles during voluntary contraction. Finally, there was no significant difference between any CSP parameters obtained during unilateral versus bilateral muscle contraction. Occasional late excitatory EMG activity in relaxed or contracted thenar muscles resembled startle reflexes, which seem to contribute to the post-inhibition EMG-rebound. Conclusions The present findings are consistent with unilateral wiring of the spinal circuitry mediating CSPs. Significance The essential lack of a crossed inhibitory influence of nociceptive digit II stimulation underscores the utility of CSP testing in the assessment of the A-δ fiber system in healthy subjects and patients with various pathologies.

Time-related heart autonomic balance characteristics in healthy subjects

Changes of the heart autonomic balance between morning (8–9 h) and afternoon (14–15 h) measurements were studied in 22 healthy subjects. The selection of these two daytime periods was substantiated by the established higher risk of cardiovascular incidents in the morning and the relative balance of the vegetative nervous system in the afternoon hours. The changes were analysed by RR-variability indices from ECG recordings in the resting state and with vegetative nervous system stimulation by the handgrip test and Valsalva manoeuvre. It was shown that there were no significant differences between the morning and afternoon values of the respective indices, between morning and afternoon handgrip tests and between morning and afternoon Valsalva manoeuvres. However, there were significant differences in comparison of the index values between resting state and handgrip test and resting state and Valsalva manoeuvre, both from morning and afternoon measurements. Moreover, the significantly differing indices were clustered in different groupings, when comparing resting state recordings with morning and afternoon stimulation tests. For this reason, the authors introduced an indicator for time-related autonomic balance changes. The indicator evaluates the power of each RR-variability index to respond to changes in the autonomic control, in comparisons between resting state and stimulation data in the morning and afternoon measurements. These evaluations showed low power of the frequency-domain indices to respond to time-related autonomic balance changes in stimulation, with respect to the resting state. The time-domain indices have considerably higher power to react to relative morning and afternoon changes in the two vegetative nervous system components. Based on the estimations of the RR-variability indices obtained by the introduced indicator, a profile was constructed to represent time-related heart autonomic balance changes in healthy subjects. It was established that in spite of the relative stability of the vegetative nervous system in healthy subjects, hypersympatheticotonia and relatively lower parasympathetic tone were present in the risky morning hours.

Functional imaging studies of dopamine system and cognition in normal aging and Parkinson's disease

Modern functional imaging methods, such as positron emission tomography (PET) and single photon emission computed tomography (SPECT), provide non-invasive, quantitative tools for the direct measurement of neurotransmitter function in the living human brain. The dopamine system has been of key interest; first, because it has a prominant role in several cognitive and motor processes, and secondly because the tracers currently available for the dopamine system enable an effective investigation of various pre, post- and intra-synaptic processes. Recent functional imaging findings indicate that certain cognitive deficits associated with both normal aging and Parkinson's disease are modulated by changes in the brain dopamine system. This review covers the literature related to age-associated phenomena in the dopamine system studied with in vivo imaging. In particular, the focus is on describing and discussing the relationships between aging, cognition and the dopaminergic system in healthy subjects and in patients with Parkinson's disease.

Neutral substrates for postural balance in humans

In order to investigate the neural substrates in the intact human brain, healthy volunteers underwent positron emission tomography (PET) with [ 15O]H 2O while they were adopting several postures: lying, sitting passively (reclining) and standing in different manners. Compared with the supine posture, statistical parametric mapping (SPM) showed that bipedal standing with eyes open activated the cerebellar anterior lobe and the visual cortex, and standing on one foot activated the anterior vermis, ipsilateral to the weight-bearing side. Bipedal standing further activated the vermis in comparison with the sitting posture, indicating that passive sitting might have been insufficient to evoke significant neuronal activation in the postural control system in healthy subjects. Standing in tandem was accompanied by activation within the visual association cortex, anterior and posterior vermis as well as the midbrain. Standing with eyes closed activated the prefrontal cortex (Brodmann area (BA): 8/9). These results confirmed that the cerebellar vermis efferent system plays an important role in human postural control and suggested that the visual association cortex may subserve regulating postural balance while standing.

Elevated plasma fatty acid concentrations stimulate the cardiac autonomic nervous system in healthy subjects

Fatty acids have been shown to stimulate the sympathetic nervous system in rats. Power spectral analysis of heart rate variability (HRV) is a safe and useful tool with which to evaluate cardiac autonomic nervous system (ANS) activity. Whether changes in plasma fatty acid concentrations affect the sympathetic nervous system or HRV in humans is unknown. We investigated the possible changes in HRV after a significant increase in plasma fatty acid concentration. Subjects were randomly assigned to receive an infusion of lipid emulsion (10% triacylglycerol emulsion for 180 min) + heparin (a bolus of 200 U followed by 0.2 U*min(-)(1)*kg body wt(-)(1); n = 20) or 0.9% NaCl (for 180 min; n = 10). Lipid emulsion + heparin infusion was associated with a rise in plasma epinephrine and norepinephrine concentrations. The rise in plasma fatty acid concentration was associated with a significant decline in the RR interval (P: < 0.03) and in total power (P: < 0.03). Analysis of the different components of HRV showed that lipid emulsion + heparin infusion stimulated low- frequency (LF) components (P: < 0.03 at the second hour and P: < 0. 01 at the third hour) and inhibited high-frequency (HF) components (P: < 0.03 at the second and third hours). Consequently, the LF-HF ratio was significantly stimulated (P: < 0.03 at the second hour and P: < 0.01 at the third hour). Such results persisted, although attenuated, when the study was repeated in association with a propranolol infusion (n = 8). Elevated plasma fatty acid concentrations may stimulate cardiac autonomic nervous system activity.

Plasma Leptin Concentrations and Cardiac Autonomic Nervous System in Healthy Subjects with Different Body Weights

Plasma Leptin Concentrations and Cardiac Autonomic Nervous System in Healthy Subjects with Different Body Weights

Plasma leptin concentrations and cardiac autonomic nervous system in healthy subjects with different body weights.

Previous studies have shown that leptin stimulates sympathetic nervous system; heart rate variability (HRV) is a widely used technique for assessing the sympathovagal balance at the cardiac level. The aim of our study was to investigate a possible relationship between plasma leptin levels and the autonomic regulation using spectral analysis of HRV. In 120 healthy nonobese subjects the plasma leptin concentration was determined, and HRV was recorded at baseline and during tilt. All subjects were categorized in quartiles of plasma leptin concentration. Analysis of data showed a significant increase in body mass index, body fat, fasting plasma insulin, triglyceride concentration, and homeostatic model assessment values throughout the different quartiles of plasma leptin concentration. Concerning cardiovascular parameters, heart rate, arterial blood pressures, and RR intervals were not significantly different among the quartiles. Total power and high frequency (HF) in normalized units were significantly decreased, whereas low frequency (LF) normalized units was progressively increased from the first to the fourth quartile. Thus, the LF/HF ratio rose gradually and significantly from the lowest to the highest quartile. Such results were independent of the body fat estimate (P < 0.03 for the trend). The change in the LF/HF ratio was significantly enhanced during tilt (P < 0.001 vs. rest values for all quartiles); the effect was stronger in subjects in the fourth quartile of plasma leptin concentration (P < 0.005 for the trend). The latter parameter was also independent of body fat content and distribution (P < 0.01). Our study shows that increasing fasting plasma leptin concentrations are associated with a shift of the sympathovagal balance toward a progressive increase in sympathetic activation and an increased response to orthostatic stimulus in nonobese subjects with different body fat contents.

Effect of sensory stimulation (acupuncture) on sympathetic and parasympathetic activities in healthy subjects

It has been postulated that sensory stimulation (acupuncture) affects the cardiovascular system via the autonomic nervous system. Previously, skin temperature, thermography, plethysmography and blood pressure changes have been used in evaluation of sympathetic nerve activity following acupuncture. By using power spectral analysis, the low frequency and high frequency components of heart rate variability can be calculated reflecting the sympathetic and parasympathetic activity. The purpose of this study was to investigate to what extent acupuncture applied into the thenar muscle and into the cavum concha of the ear induced changes in the sympathetic and/or parasympathetic nervous system in healthy subjects. Materials and Methods. Twelve healthy volunteers, six men and six women, mean age 34.4 (range 23–48) participated in three balanced, randomly distributed sessions. At an individual initial visit the 12 volunteers were introduced to the needle sensation by having a needle inserted into the point LI 11. The needle sensation was evoked and the subject was trained to identify the characteristic needle sensation. The introduction was followed by three test sessions. Session A. A short acupuncture needle, (Seirin no 3, ∅0.20×15 mm) was inserted perpendicular into the earpoint, Lu 1, in the left inferior hemi-conchae. Session B. An acupuncture needle (Hwato, ∅0.30×30 mm) was inserted perpendicular into the Hegu point (LI 4) in the middle of the right dorsal thenar muscle. Session C. An acupuncture needle (Hwato, ∅0.30×30 mm) was inserted perpendicular superficially into the skin overlying the Hegu point on the left hand. Results. Stimulation of the ear induced a significant increase in the parasympathetic activity during the stimulation period of 25 min ( P<0.05) and during the post-stimulation period of 60 min ( P<0.05). No significant changes were observed in either the sympathetic activity, blood pressure or heart rate. Stimulation of the thenar muscle resulted in a significant increase in the sympathetic and the parasympathetic activity during the stimulation period ( P<0.01) and during the post-stimulation period ( P<0.01 and P<0.001, respectively). A significant decrease in the heart rate frequency ( P<0.05) at the end of the post-stimulation period was also demonstrated. The superficial needle insertion into the skin overlaying the right thenar muscle caused a pronounced balanced increase in both the sympathetic and parasympathetic activity during the post stimulation period of 60 min ( P<0.01) while no changes were observed during the stimulation period. Conclusion. It is indicated that sensory stimulation (acupunctura) in healthy persons is associated with changed activity in the sympathetic and parasympathetic nervous system depending on site of stimulation and period of observation.

Fibrinolytic Response to Venous Occlusion Compared to Physical Stress Test in Young Patients with Coronary Artery Disease

Venous occlusion (VO) and exercise stress (ES) are stimulators of the fibrinolytic system. Aim of this study was to answer which of both stimulation tests is more useful in patients with symptom-limited coronary artery disease (CAD) to evaluate possible defects in the fibrinolytic system. We investigated 20 patients (M/F = 15/5; mean age = 36.7 years) with angiographically proven CAD for their plasma levels of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-type-1 (PAI-1) at basal conditions as well as after VO and at maximal ES (standardised bicycle stress test) and compared the data to those obtained from 12 sex- and age-matched healthy controls (M/F = 9/3; mean age = 40.4 years). At basal conditions mean t-PA activity and t-PA antigen plasma levels were within the normal range and comparable between the two study groups. After both VO and maximal ES, mean t-PA activity and t-PA antigen levels increased significantly more in the control group as compared to the CAD group. Mean PAI-1 activity plasma levels were significantly higher in the CAD group at basal conditions before VO (patients 7.0 +/- 3.1; controls 3.9 +/- 3.9; IU/ml; p = 0.025) as well as before ES (patients 8.1 +/- 3.5; controls 4.3 +/- 3.8; IU/ml; p = 0.009). PAI-1 activity plasma levels showed a significant decrease for patients and controls only after VO, while PAI-1 activity was not significantly decreased in both study groups at maximal ES. The significantly higher increase in mean plasma levels of t-PA activity and t-PA antigen after VO compared to ES in both groups might be explained by the fact that CAD induced symptoms in the patients during ES thus permitting only 80% of their age, sex, and body mass index related optimal work load. VO and ES are applicable triggers of the endogenous fibrinolytic system in healthy subjects and patients who are not limited in their physical exercise. Standardised VO appears to be superior to ES as stimulation test of the endogenous fibrinolytic system in patients with symptomatic CAD.

Central effects of acamprosate: Part 2. Acamprosate modifies the brain in-vivo proton magnetic resonance spectrum in healthy young male volunteers

Although acamprosate is a drug which is successfully used for therapy in maintaining alcohol abstinence following alcohol withdrawal in chronic alcoholism, little is understood about its mechanism of action in the central nervous system. Our objective was to assess the effects of acamprosate on the central nervous system in healthy subjects by dynamic proton magnetic resonance spectroscopy (MRS) measurements localized in brain tissue in vivo. Recordings were performed after intravenous administration of acamprosate or placebo to eight healthy male volunteers participating in a double-blind, randomized, cross-over, placebo-controlled study. The data were acquired using a spin-echo volume selective localized spectroscopy scheme on a 3-T whole body MRS system. Spectra obtained at baseline and at 20-min time intervals after the beginning of drug infusion were analyzed on the basis of five non-overlapping spectral integration regions. In the acamprosate-treated group, the median integral values in the regions for which N-acetylaspartate and glutamate are the main signal contributors showed decreases relative to placebo 20 min after the infusion began. Results suggest a central glutamatergic effect of acamprosate consistent with cerebral microdialysis glutamate measurements in vivo obtained from alcoholized rats treated with acamprosate (Part 1 of this study). This study is to our knowledge the first one describing a central effect of acamprosate in humans by MRS.

Electric versus magnetic transcranial stimulation of the trigeminal system in healthy subjects. Clinical applications in gnathology.

This investigation is focused on the analysis of the masseter responses evoked by means of magnetic and electric stimulation of the cortex and root of the trigeminal system of 20 healthy subjects. Moreover, in order to determine jaw elevation in centric occlusion, the analysis also focused on the motor response of the trigeminal bilateral roots evoked simultaneously using two stimulators. The masseter responses show a high level of symmetry in both latency and amplitude. The difference between the hinge axis in natural centric occlusion (CO) and in centric relation (CR) as determined by electric and magnetic transcranial stimulation is lesser than 2.5 mm. This is due to two main factors: (i) the response is evoked from the trigeminal motor neural pool involving all the masticatory muscles and hence simulating the natural 'muscular coactivation'; (ii) there is no manual manipulation to guide the jaw into the centric relation (CR). This method could be of some help for diagnosis in patients suffering from TMJ dysfunction who have lost stereognostic control over the jaw and display obvious signs of deviation during closure of the mandible.

Electric versus magnetic transcranial stimulation of the trigeminal system in healthy subjects. Clinical applications in gnathology

summary This investigation is focused on the analysis of the masseter responses evoked by means of magnetic and electric stimulation of the cortex and root of the trigeminal system of 20 healthy subjects. Moreover, in order to determine jaw elevation in centric occlusion, the analysis also focused on the motor response of the trigeminal bilateral roots evoked simultaneously using two stimulators. The masseter responses show a high level of symmetry in both latency and amplitude. The difference between the hinge axis in natural centric occlusion (CO) and in centric relation (CR) as determined by electric and magnetic transcranial stimulation is lesser than 2.5 mm. This is due to two main factors: (i) the response is evoked from the trigeminal motor neural pool involving all the masticatory muscles and hence simulating the natural ‘muscular coactivation’; (ii) there is no manual manipulation to guide the jaw into the centric relation (CR). This method could be of some help for diagnosis in patients suffering from TMJ dysfunction who have lost stereognostic control over the jaw and display obvious signs of deviation during closure of the mandible.

Treatment with recombinant human erythropoietin induces a moderate rise in hematocrit and thrombin antithrombin in healthy subjects

Recombinant human erythropoietin (EPO) therapy in uremic patients raises the hematocrit (Hct) and increases physical exercise capacity (1,2) and quality of life (1). In general, partial correction of anemia to subnormal levels in uremic patients has proven to be safe with few serious adverse effects apart from hypertension (3). Ever since the advent of EPO the prospect of abuse of the hormone by sportsmen has been subject to scrutiny. Both maximal oxygen uptake and endurance capacity are increased after EPO treatment in healthy subjects (4). Moreover, EPO treatment in healthy subjects has been found to induce an accentuated blood pressure reaction after submaximal exercise (5). Previous studies have shown that extreme physical exertion can predispose to an increased intravascular coagulation (6). Moreover there is a significantly increased risk of thrombosis in patients with myeloproliferative disorders, particularly in polycythemia vera (7). An enhanced risk of cardiovascular events may therefore arise should sportsmen abuse EPO as a blood doping agent. The aim of this study was to examine the effects of an EPO-induced increase in Hct on the coagulation system in healthy subjects.

The Effects of 3 Different Physical Exercise Programmes on the Musculo-Skeletal System of Healthy Subjects 55 Years of Age and Older

The Effects of 3 Different Physical Exercise Programmes on the Musculo-Skeletal System of Healthy Subjects 55 Years of Age and Older