Jackie Hudson, Scholar

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Coordination Articles: Introductions

Movement analysts ranging from spectators and sportswriters, to teachers and coaches, to biomechanists and kinesiologists, to neuroscientists and roboticists believe that coordination is a desirable aspect of performance. Yet, there has been little coordination among movement analysts in the effort to understand and improve coordinated movement. Perhaps our disjointed activity is due in part to our diverse conceptions of coordination. If so, identifying and clarifying the various meanings of coordination may enable movement analysts to cooperate on the topic of coordination. Thus, the purpose of this paper is to ask and address a series of questions: What is meant by coordination? Are the meanings similar or different for professionals and non-professionals, for scholars and practitioners? Are the meanings complementary or contradictory for researchers in various fields? Is there a common thread of meaning that could be used as both a basis of communication as well as a basis for research? (Article in pdf)

Stair climbing has become a popular form of training for athletes as well as non-athletes. Considering that there are a plethora of devices for stair climbing, how does a person decide which apparatus to use? Aside from issues of practicality, much of the decision could be based on the principles of specificity of training. That is, for maximum transfer of benefits from one activity to another, the activities should be compatible in the usage of energy systems, muscle groups, and patterns of coordination. As for the first two criteria of specificity, the choice is simple: Almost all stair climbing devices are beneficial to the aerobic energy system and the leg extensor muscles. However, for the criterion of coordination, the choice may be more difficult. First, the reasons for exercising on stairs are diverse: They can range from cross-training for the serious athlete who wishes to gain a competitive advantage to reconditioning for the injured or elderly person who wishes to safely negotiate the staircase at home. Second, little is known about the patterns of coordination that are employed in leg extensor activities. To date, only jumping (Bobbert & van Ingen Schenau, 1988; Hudson, 1986) and speed skating (Koning et al., 1991) have been analyzed in terms of intersegmental coordination. From the data depicted in these studies, it appears that the thigh and shank operate with predominant simultaneity in both these tasks. That is, the thigh and shank both begin and end their propulsive phases at approximately the same times. Presuming a volleyball player wanted to reinforce a simultaneous pattern of coordination, do either stair machines or staircases afford this opportunity? Presuming a person with a hip replacement wanted to rehabilitate with a stair machine, do certain stair machines compare more favorably with staircases in terms of coordination? To gain insight into these and similar questions, the purpose of this study was to investigate patterns of intersegmental coordination in different modes of stair climbing. (Article in pdf)

There is general agreement that highly skilled throwers and strikers employ a sequential pattern of intersegmental coordination (Bunn, 1972; Kreighbaum & Barthels, 1990; Morehouse & Cooper, 1950). That is, "movements proceed from base to free end, from proximal to distal" (Kreighbaum & Barthels, p. 625) and "each [distal] segment comes forward as the movement of its proximal segment reaches its greatest angular velocity" (Kreighbaum & Barthels, p. 604). There is little agreement, however, concerning the coordination of less skilled throwers and strikers. According to Kreighbaum and Barthels, novice or immature performers typically display simultaneous or nearly simultaneous patterns of coordination (i.e., proximal and distal segments contribute to the movement at about the same time). In addition to the "optimal" sequential pattern of coordination, Morehouse and Cooper described two sub-optimal sequential patterns: the "early" pattern (i.e., distal segments initiate forward movement before proximal segments reach peak angular velocity) and the "late" pattern (i.e., distal segments initiate forward movement after proximal segments reach peak angular velocity). Further, Morehouse and Cooper stated that "hurrying the action is more detrimental to performance" (p. 125, 128) and "beginners usually have the fault of omitting some [segments]" (p. 128). Finally, Bunn (p. 42-43) hypothesized that "jerky movement instead of smooth rhythmic action" was associated with diminished effectiveness in throwing. Interestingly, none of these biomechanists addressed the contextual differences between throwing which is a closed skill (e.g., releasing a light object for high velocity) and striking which is an open skill (e.g., intercepting and propelling a light object for high velocity). Given that interception is a crucial component of many sports, the purpose of this study was to address the following questions: What pattern of coordination do smooth, sequential throwers exhibit in an unfamiliar interception task? How does this pattern of coordination change with practice? (Article in pdf)

Intersegmental coordination in complex, forceful movements has been discussed in the biomechanics teaching literature for many years. Until recently the presumption has been that the optimal pattern of coordination was sequentially timed (Morehouse & Cooper, 1950; Bunn, 1972). That is, the sequencing of segments was ordered from proximal to distal, and the timing of segments was arranged such that exactly one segment contributed positively to the movement at a given time. Deviations from optimal timing were described by Morehouse and Cooper in continuous terms ranging from "early" (i.e., overlaps in segmental contribution) to "late" (i.e., gaps in segmental contribution). Similarly, Bunn advised against "simultaneous" or "jerky" movements.

In 1981 Kreighbaum and Barthels suggested a different timing continuum with polar positions of simultaneous (i.e., all segments contribute concurrently) and sequential (i.e., each segment contributes serially). Also, they postulated that the position on the continuum for a particular performer and task would be related to contextual factors. For example, if the performer were a beginner or the task involved rectilinear movement, limited incorporation of segments, lever-like movement, or accuracy, the expected mode of timing would be simultaneous. If the performer were advanced and the task involved curvilinear movement, maximal incorporation of segments, wheel-axle movement, or velocity, the expected mode of timing would be sequential. Given the complexity of sports skills in terms of these contextual factors, it is not surprising that there are few empirical studies of context and coordination. Therefore, the purpose of this study was to explore the intersegmental coordination of beginning and advanced performers in a two-segment, lever-like task with velocity and accuracy demands. (Article in pdf)