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Catching a ball at the right time and place: individual factors matter.

Cesqui B, d'Avella A, Portone A, Lacquaniti F - PLoS ONE (2012)

Bottom Line: Inter-individual variability was observed in several kinematic parameters, such as wrist trajectory, wrist velocity profile, timing and spatial distribution of the impact point, upper limb posture, trunk motion, and submovement decomposition.Individual idiosyncratic behaviors were consistent across different ball flight time conditions and across two experimental sessions carried out at one year distance.These results highlight the importance of a systematic characterization of individual factors in the study of interceptive tasks.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy.

ABSTRACT
Intercepting a moving object requires accurate spatio-temporal control. Several studies have investigated how the CNS copes with such a challenging task, focusing on the nature of the information used to extract target motion parameters and on the identification of general control strategies. In the present study we provide evidence that the right time and place of the collision is not univocally specified by the CNS for a given target motion; instead, different but equally successful solutions can be adopted by different subjects when task constraints are loose. We characterized arm kinematics of fourteen subjects and performed a detailed analysis on a subset of six subjects who showed comparable success rates when asked to catch a flying ball in three dimensional space. Balls were projected by an actuated launching apparatus in order to obtain different arrival flight time and height conditions. Inter-individual variability was observed in several kinematic parameters, such as wrist trajectory, wrist velocity profile, timing and spatial distribution of the impact point, upper limb posture, trunk motion, and submovement decomposition. Individual idiosyncratic behaviors were consistent across different ball flight time conditions and across two experimental sessions carried out at one year distance. These results highlight the importance of a systematic characterization of individual factors in the study of interceptive tasks.

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Inter-individual differences in wrist velocity at maximum speed, minimum speed, and impact.Wrist velocity components (mean ± SE; SE are reported only when number of trials per block was larger than 2) in the sagittal plane (x, anterior-posterior axis; z vertical axis) for each one of the three flight time conditions (T, indicated by different marker shapes) are illustrated separately for the two different arrival heights (first row: high, second row: low). Subject color coding is the same as in Figure 2.
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pone-0031770-g003: Inter-individual differences in wrist velocity at maximum speed, minimum speed, and impact.Wrist velocity components (mean ± SE; SE are reported only when number of trials per block was larger than 2) in the sagittal plane (x, anterior-posterior axis; z vertical axis) for each one of the three flight time conditions (T, indicated by different marker shapes) are illustrated separately for the two different arrival heights (first row: high, second row: low). Subject color coding is the same as in Figure 2.

Mentions: Individual kinematic features were quantified by monitoring the components of the wrist velocity in the sagittal plane at three different instants: the time of the first speed peak, the time of the first speed trough, if present, and the time of impact. Inter-subject variability increased getting closer to IT, as highlighted by the progressively broader distribution of velocity components (Figure 3). However, subject-specific characteristics were present since the beginning (AIClmm<AIClm for all x-z velocity components, vx and vz, at the three time instants of interest, see Table 1). For low launches (bottom panels of Figure 3), S1 and S2 presented higher values of vx and vz at the time of peak wrist speed, and lower values at the time of minimum speed with respect to the other participants. S1 (dark green) presented a segmented motion, and decelerated to almost 0 velocity before the final downward displacement of the hand, as indicated by the small vx and vz in correspondence of the first minimum of the wrist speed. S2 (light blue) showed instead higher vx both in correspondence of the peak and the trough of the speed profile, probably due to his tendency to move smoothly further toward the approaching target. S6 (orange) instead began to manifest its strategy in correspondence of the first minimum of the speed profile, when he moved at higher velocity than the rest of population. The analysis of the wrist velocity at IT showed that subjects caught the ball with very different horizontal and vertical components (third column of Figure 3). In low launches both S1 and S2 presented a large negative vz due to the downward motion before the impact. Differently from S1, S2 moved toward the ball with also a higher vx. S3 (light green), S4 (red), and S5 (dark blue) impacted the ball with a low velocity both along the x and z axis. In particular, S5 showed a negative vx, i.e. he moved slightly backward at impact, S3 instead stopped on the ball, and S4 tended to move toward the ball with a positive vx. Finally, S6 showed very high positive vx and vz due to the final forward and upward motion aimed at catching the ball from below.


Catching a ball at the right time and place: individual factors matter.

Cesqui B, d'Avella A, Portone A, Lacquaniti F - PLoS ONE (2012)

Inter-individual differences in wrist velocity at maximum speed, minimum speed, and impact.Wrist velocity components (mean ± SE; SE are reported only when number of trials per block was larger than 2) in the sagittal plane (x, anterior-posterior axis; z vertical axis) for each one of the three flight time conditions (T, indicated by different marker shapes) are illustrated separately for the two different arrival heights (first row: high, second row: low). Subject color coding is the same as in Figure 2.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3285177&req=5

pone-0031770-g003: Inter-individual differences in wrist velocity at maximum speed, minimum speed, and impact.Wrist velocity components (mean ± SE; SE are reported only when number of trials per block was larger than 2) in the sagittal plane (x, anterior-posterior axis; z vertical axis) for each one of the three flight time conditions (T, indicated by different marker shapes) are illustrated separately for the two different arrival heights (first row: high, second row: low). Subject color coding is the same as in Figure 2.
Mentions: Individual kinematic features were quantified by monitoring the components of the wrist velocity in the sagittal plane at three different instants: the time of the first speed peak, the time of the first speed trough, if present, and the time of impact. Inter-subject variability increased getting closer to IT, as highlighted by the progressively broader distribution of velocity components (Figure 3). However, subject-specific characteristics were present since the beginning (AIClmm<AIClm for all x-z velocity components, vx and vz, at the three time instants of interest, see Table 1). For low launches (bottom panels of Figure 3), S1 and S2 presented higher values of vx and vz at the time of peak wrist speed, and lower values at the time of minimum speed with respect to the other participants. S1 (dark green) presented a segmented motion, and decelerated to almost 0 velocity before the final downward displacement of the hand, as indicated by the small vx and vz in correspondence of the first minimum of the wrist speed. S2 (light blue) showed instead higher vx both in correspondence of the peak and the trough of the speed profile, probably due to his tendency to move smoothly further toward the approaching target. S6 (orange) instead began to manifest its strategy in correspondence of the first minimum of the speed profile, when he moved at higher velocity than the rest of population. The analysis of the wrist velocity at IT showed that subjects caught the ball with very different horizontal and vertical components (third column of Figure 3). In low launches both S1 and S2 presented a large negative vz due to the downward motion before the impact. Differently from S1, S2 moved toward the ball with also a higher vx. S3 (light green), S4 (red), and S5 (dark blue) impacted the ball with a low velocity both along the x and z axis. In particular, S5 showed a negative vx, i.e. he moved slightly backward at impact, S3 instead stopped on the ball, and S4 tended to move toward the ball with a positive vx. Finally, S6 showed very high positive vx and vz due to the final forward and upward motion aimed at catching the ball from below.

Bottom Line: Inter-individual variability was observed in several kinematic parameters, such as wrist trajectory, wrist velocity profile, timing and spatial distribution of the impact point, upper limb posture, trunk motion, and submovement decomposition.Individual idiosyncratic behaviors were consistent across different ball flight time conditions and across two experimental sessions carried out at one year distance.These results highlight the importance of a systematic characterization of individual factors in the study of interceptive tasks.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, Italy.

ABSTRACT
Intercepting a moving object requires accurate spatio-temporal control. Several studies have investigated how the CNS copes with such a challenging task, focusing on the nature of the information used to extract target motion parameters and on the identification of general control strategies. In the present study we provide evidence that the right time and place of the collision is not univocally specified by the CNS for a given target motion; instead, different but equally successful solutions can be adopted by different subjects when task constraints are loose. We characterized arm kinematics of fourteen subjects and performed a detailed analysis on a subset of six subjects who showed comparable success rates when asked to catch a flying ball in three dimensional space. Balls were projected by an actuated launching apparatus in order to obtain different arrival flight time and height conditions. Inter-individual variability was observed in several kinematic parameters, such as wrist trajectory, wrist velocity profile, timing and spatial distribution of the impact point, upper limb posture, trunk motion, and submovement decomposition. Individual idiosyncratic behaviors were consistent across different ball flight time conditions and across two experimental sessions carried out at one year distance. These results highlight the importance of a systematic characterization of individual factors in the study of interceptive tasks.

Show MeSH
Related in: MedlinePlus