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Physical Demand but Not Dexterity Is Associated with Motor Flexibility during Rapid Reaching in Healthy Young Adults.

Greve C, Hortobàgyi T, Bongers RM - PLoS ONE (2015)

Bottom Line: Here we examine how dexterity demand and physical demand affect flexibility in joint coordination and end-effector kinematics when healthy young adults perform an upper extremity reaching task.Our results demonstrate a proportional increase in stabilizing and de-stabilizing variability without a change in the ratio of the two variability components as physical demands increase.Our findings have practical implications for improving the effectiveness of movement therapy in a wide range of patient groups, maintaining upper extremity function in old adults, and for maximizing athletic performance.

View Article: PubMed Central - PubMed

Affiliation: Center for Human Movement Science, University of Groningen, University Medical Center Groningen, Groningen, The Netherland.

ABSTRACT
Healthy humans are able to place light and heavy objects in small and large target locations with remarkable accuracy. Here we examine how dexterity demand and physical demand affect flexibility in joint coordination and end-effector kinematics when healthy young adults perform an upper extremity reaching task. We manipulated dexterity demand by changing target size and physical demand by increasing external resistance to reaching. Uncontrolled manifold analysis was used to decompose variability in joint coordination patterns into variability stabilizing the end-effector and variability de-stabilizing the end-effector during reaching. Our results demonstrate a proportional increase in stabilizing and de-stabilizing variability without a change in the ratio of the two variability components as physical demands increase. We interpret this finding in the context of previous studies showing that sensorimotor noise increases with increasing physical demands. We propose that the larger de-stabilizing variability as a function of physical demand originated from larger sensorimotor noise in the neuromuscular system. The larger stabilizing variability with larger physical demands is a strategy employed by the neuromuscular system to counter the de-stabilizing variability so that performance stability is maintained. Our findings have practical implications for improving the effectiveness of movement therapy in a wide range of patient groups, maintaining upper extremity function in old adults, and for maximizing athletic performance.

No MeSH data available.


Related in: MedlinePlus

Log transformed VRatio (VRatioT) and VRatioPerm (VRatioPermT) averaged across ID and movement phases for all physical demand conditions.Vertical bars denote standard error of the mean.
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pone.0127017.g007: Log transformed VRatio (VRatioT) and VRatioPerm (VRatioPermT) averaged across ID and movement phases for all physical demand conditions.Vertical bars denote standard error of the mean.

Mentions: In order to determine whether UCM effects originated from multi-joint covariation or individual joint variability we performed a repeated measures ANOVA on ratio components (VRatioT and VRatioPermT) with phase, dexterity demand and physical demand as within subjects factor. The analysis during movement revealed a significant main effect for Ratio component and phases and significant two-way interaction effects between ratio component and phases and between ratio component and physical demand (Table 6). Figs 6 and 7 show that VRatioT was larger than VRatioPermT during all phases and physical demands indicating that UCM effects largely originated from multi-joint covariation and not from individual joint variability.


Physical Demand but Not Dexterity Is Associated with Motor Flexibility during Rapid Reaching in Healthy Young Adults.

Greve C, Hortobàgyi T, Bongers RM - PLoS ONE (2015)

Log transformed VRatio (VRatioT) and VRatioPerm (VRatioPermT) averaged across ID and movement phases for all physical demand conditions.Vertical bars denote standard error of the mean.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4430491&req=5

pone.0127017.g007: Log transformed VRatio (VRatioT) and VRatioPerm (VRatioPermT) averaged across ID and movement phases for all physical demand conditions.Vertical bars denote standard error of the mean.
Mentions: In order to determine whether UCM effects originated from multi-joint covariation or individual joint variability we performed a repeated measures ANOVA on ratio components (VRatioT and VRatioPermT) with phase, dexterity demand and physical demand as within subjects factor. The analysis during movement revealed a significant main effect for Ratio component and phases and significant two-way interaction effects between ratio component and phases and between ratio component and physical demand (Table 6). Figs 6 and 7 show that VRatioT was larger than VRatioPermT during all phases and physical demands indicating that UCM effects largely originated from multi-joint covariation and not from individual joint variability.

Bottom Line: Here we examine how dexterity demand and physical demand affect flexibility in joint coordination and end-effector kinematics when healthy young adults perform an upper extremity reaching task.Our results demonstrate a proportional increase in stabilizing and de-stabilizing variability without a change in the ratio of the two variability components as physical demands increase.Our findings have practical implications for improving the effectiveness of movement therapy in a wide range of patient groups, maintaining upper extremity function in old adults, and for maximizing athletic performance.

View Article: PubMed Central - PubMed

Affiliation: Center for Human Movement Science, University of Groningen, University Medical Center Groningen, Groningen, The Netherland.

ABSTRACT
Healthy humans are able to place light and heavy objects in small and large target locations with remarkable accuracy. Here we examine how dexterity demand and physical demand affect flexibility in joint coordination and end-effector kinematics when healthy young adults perform an upper extremity reaching task. We manipulated dexterity demand by changing target size and physical demand by increasing external resistance to reaching. Uncontrolled manifold analysis was used to decompose variability in joint coordination patterns into variability stabilizing the end-effector and variability de-stabilizing the end-effector during reaching. Our results demonstrate a proportional increase in stabilizing and de-stabilizing variability without a change in the ratio of the two variability components as physical demands increase. We interpret this finding in the context of previous studies showing that sensorimotor noise increases with increasing physical demands. We propose that the larger de-stabilizing variability as a function of physical demand originated from larger sensorimotor noise in the neuromuscular system. The larger stabilizing variability with larger physical demands is a strategy employed by the neuromuscular system to counter the de-stabilizing variability so that performance stability is maintained. Our findings have practical implications for improving the effectiveness of movement therapy in a wide range of patient groups, maintaining upper extremity function in old adults, and for maximizing athletic performance.

No MeSH data available.


Related in: MedlinePlus