Influence of ankle loading on the relationship between temporal pressure and motor coordination during a whole-body paired task

• Published in: Experimental brain research Vol. 232; no. 10; pp. 3089 - 3099
• Main Authors: Yiou, Eric, Hussein, Tarek, LaRue, Jacques
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-10-2014; Springer; Springer Nature B.V
• Subjects: Adolescent; Adult; Analysis; Ankle; Ankle - physiology; Ankle Joint - physiology; Biological and medical sciences; Biomechanical Phenomena - physiology; Biomedical and Life Sciences; Biomedicine; Female; Fundamental and applied biological sciences. Psychology; Humans; Male; Mechanical properties; Motor ability; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Movement - physiology; Musculoskeletal Physiological Phenomena; Nervous system; Neurology; Neurosciences; Postural Balance - physiology; Posture; Posture - physiology; Pressure; Reaction Time; Research Article; Vertebrates: nervous system and sense organs; Young Adult; Loading; Leg flexion; Anticipatory postural adjustments; Motor coordination; Movement synchronization; Temporal pressure; Adaptation; Ankle; Lower limb; Synchronization; Postural fitting; Motor control
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/s00221-014-4003-0

We investigated whether ankle loading modifies the relationship between temporal pressure and motor coordination during a whole-body paired task. Eight young healthy adults standing in an erect posture performed multiple series of simultaneous rapid leg flexions paired with ipsilateral index finger extensions. They repeated the task ten times in three load conditions:
unloaded
,
loaded
(where additional 5-kg inertia was attached to the ankles), and
post
-
loaded
(immediately following the loaded condition). These conditions were conducted in two blocks of temporal pressure: self-initiated (SI) versus reaction time (RT). When participants were unloaded, the results showed that index finger extension preceded swing heel-off in RT, and conversely in SI. By contrast, when the participants were loaded, swing heel-off preceded index finger extension in both SI and RT, showing that loading modified the relationship between temporal pressure and movement synchronization in RT only. However, loading did not induce any increase in the error of synchronization. Furthermore, in both the
unloaded
and
loaded
conditions, the duration of “anticipatory postural adjustments” (APA) was shorter when the temporal pressure was increased. Interestingly, the shorter APA duration was compensated by an increase in APA amplitude. Thus, loading did not modify the relationship between temporal pressure and anticipatory postural dynamics.
Post
-
loaded
and
unloaded
conditions produced the same results. These results show that the central nervous system optimally adapts the relationship between temporal pressure and motor coordination to transitory changes in the mechanical properties of the lower limbs, here due to ankle loading.