Two dominant coordination constraints have been identified during isofrequency conditions in previous work: the egocentric constraint, i.e., simultaneous activation of homologous muscle groups, and the allocentric constraint, i.e., moving the segments in the same direction in extrinsic space. To verify their generalization, bimanual drawing movements were performed in different planes of motion (transverse, frontal, sagittal, frontal-transverse) according to the in-phase and anti-phase mode along the X- and Y-axes. Convergent findings were obtained across the transverse, frontal, and frontal-transverse planes. The in-phase mode along both axes was performed most accurately/consistently, whereas the anti-phase mode resulted in a deterioration of the coordination pattern and this effect was most pronounced when the latter mode was introduced with respect to both dimensions. For sagittal plane motions, the in-phase mode was again superior but the second most optimal configuration was the anti-phase mode along both axes. This finding was hypothesized to result from the familiarity with the pattern since it resembles cycling behavior. It illustrates how cognitive mapping is superimposed onto the dynamics of interlimb coordination. Overall, these results support the presence of both the egocentric and allocentric constraint during bimanual movement production.
Whereas previous bimanual coordination research has predominantly focused on the constraining role of timing, the present study addressed the role of spatial (i.e., directional) constraints during the simultaneous production of equilateral triangles with both upper limbs. In addition to coordination modes in which mirror-image and isodirectional movements were performed (compatible patterns), new modes were tested in which the left limb lagged with respect to the right by one triangle side (non-compatible patterns). This resulted in the experimental manipulation of directional compatibility between the limbs. In addition. triangles with either horizontal or vertical orientations were to be drawn in order to assess the role of static images on movement production. Results supported the important role of directional constraints in bimanual coordination. Furthermore, triangles in vertical orientations (with a vertical symmetry axis, i.e., one apex pointing up) were drawn more successfully than those in horizontal orientations (with a horizontal symmetry axis, i.e., one apex pointing left or right), suggesting that the static aspects of a geometric form may affect movement dynamics. Finally, evidence suggested that cognitive processes related to integration of the submovements into a unified plan mediate the performance of new coordination patterns. The implications of the present findings for clinical populations are discussed.
β-Thromboglobulin (β-TG) and platelet factor 4 (PF-4) are specific platelet proteins released during in vivo platelet activation. An increase in PF-4 after exercise- induced myocardial ischemia was reported by Green, L.H. et al.. This observation prompted us to measure β-TG and PF-4 in patients with chronic occlusive arterial disease of the lower limbs and to look for increments during treadmill exercise.
β-TG was measured using the Amersham test kit and PF-4 using the radioimmunoassay kit of Abbott Diagnostics Division. Plasma levels in 28 normal individuals ranged for β-TG from 7 to 39 ng/ml with a mean value of 21.0 ng/ml, for PF-4 from 1 to 19 ng/ml with a mean value of 6.0 ng/ml.
β-TG and PF-4 were measured in 59 patients with chronic peripheral arterial disease before and 5 min. after treadmill exercising till occurrence of claudication. Plasma levels of β-TG before treadmill exercising ranged from 24 to 260 ng/ml with a mean of 77.9 ng/ml, PF-4 levels ranged from 2 to 240 ng/ml with a mean of 30.4 ng/ml. These levels were significantly higher than those measured in normal individuals.After treadmill exercise β-TG levels showed a statistically significant increase to a mean value of 87.3 ng/ml but PF-4 did not rise significantly (mean value : 32.4 ng/ml). The supplementary increase of already elevated β-TG levels may be explained by enhanced in vivo platelet activation during treadmill exercising till occurrence of claudication. As the clearance of PF-4 from human plasma has been shown to be much faster than the clearance of β-TG increases in PF-4 levels may be more difficult to detect during dynamic explorations of the vascular system.
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