Limits...
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

GEV and NGEV averaged across ID and movement phases for the physical demand conditions.Vertical bars denote standard error of the mean. Note that the statistical analysis was performed on the log transformed GEV (GEVT) and NGEV (NGEVT).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4430491&req=5

pone.0127017.g004: GEV and NGEV averaged across ID and movement phases for the physical demand conditions.Vertical bars denote standard error of the mean. Note that the statistical analysis was performed on the log transformed GEV (GEVT) and NGEV (NGEVT).

Mentions: The main effect for variability showed that the amount of GEV was significantly larger than NGEV during all phases and at the end-point of the reaching movement (Tables 4 and 5). This finding implies that the end-effector position was a controlled variable during reaching [9]. The significant main effect for phase during movement demonstrated that the average amount of variability ((GEVT + NGEVT)/2) in elemental variables was largest during 26–75% of the reaching movement (Table 4). As illustrated in Fig 4 the main effect of physical demand shows that GEV and NGEV proportionally increase with increasing physical demands (Fig 4). This finding and the results from the analysis on VRatioT demonstrate that the stabilizing effect of motor flexibility was maintained despite increases in NGEV and GEV with increasing physical demands (Fig 5; Tables 2 and 3). In other words, although the variability measures GEV and NGEV increased with increasing resistance to the reaching movement their relative values did not change.


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)

GEV and NGEV averaged across ID and movement phases for the physical demand conditions.Vertical bars denote standard error of the mean. Note that the statistical analysis was performed on the log transformed GEV (GEVT) and NGEV (NGEVT).
© Copyright Policy
Related In: Results  -  Collection

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

pone.0127017.g004: GEV and NGEV averaged across ID and movement phases for the physical demand conditions.Vertical bars denote standard error of the mean. Note that the statistical analysis was performed on the log transformed GEV (GEVT) and NGEV (NGEVT).
Mentions: The main effect for variability showed that the amount of GEV was significantly larger than NGEV during all phases and at the end-point of the reaching movement (Tables 4 and 5). This finding implies that the end-effector position was a controlled variable during reaching [9]. The significant main effect for phase during movement demonstrated that the average amount of variability ((GEVT + NGEVT)/2) in elemental variables was largest during 26–75% of the reaching movement (Table 4). As illustrated in Fig 4 the main effect of physical demand shows that GEV and NGEV proportionally increase with increasing physical demands (Fig 4). This finding and the results from the analysis on VRatioT demonstrate that the stabilizing effect of motor flexibility was maintained despite increases in NGEV and GEV with increasing physical demands (Fig 5; Tables 2 and 3). In other words, although the variability measures GEV and NGEV increased with increasing resistance to the reaching movement their relative values did not change.

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