The acquisition of a striking action is discussed from two perspectives: the informational/computational and dynamical systems. The former approach to motor learning is derived from a computer metaphor, placing much emphasis on the concept of a motor program/schema. The variability of the practice hypothesis, derived from Schmidt's schema theory, maintains that practicing a variety of movement outcomes within the same class of movement would be the most efficient way of establishing a particular schema. This preprogrammed control model proposes that accurate performance is the outcome of a well established motor program for that class of movement. In contrast, the continuous control model, derived from Gibson's theory of direct perception, proposes a funnel-like type of control which invokes the concept of compensatory variability during movement execution. That is, an initial wide ball-park action to solve a given motor problem would be followed by more appropriate actions, in terms of the process of attunement on the basis of perceptual information. In contrast to these two approaches, the dynamical systems approach to the learning of a new action pattern focuses on the concept of order-order transitions between different modes of a coordinative structure. Such a process is preceded by disorder-order transitions, in that the workspace must first be established and gradually developed as a self-organizing information system before it can function in this way. Although a dynamical systems approach could provide explanations for the learning and performance of complex human movements in terms of an open, non-equilibrium system, such a system is unable to account for the continuous abrupt switching of temporal input. In the present study, the basic coordinative structures in continuous and complex striking movements were examined from an extended dynamical systems perspective with a temporal input. The complex striking action was shown to be best explained by a fractal transition between two excited attractors. From the proposed theoretical framework, it is argued that a complex training condition achieves its superiority by exploiting the inertia of the trunk rotation movement produced by the preceding striking action. This suggests that a dynamical systems approach is not only able to describe complex human movement, but can also offer practical applications to motor learning in a real-world setting.

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We studied training exercises designed to improve the chest pass ability of basketball players, enabling them to pass the ball in as short a time as possible, as soon they catch a ball. The subjects were 25 male college basketball players, who performed rebound chest passes, catching four balls of varying weights (basketball (0.6kg), 1kg, 3kg, 5kg). When the ball landed on the player's chest, it was thrown immediately. Press chest passes without counteraction were also performed. The contact time of the hands and the height of the chest passes were examined. Furthermore, the relationship between a player's chest pass ability and bench press capacity was also examined as an index of strength. The results can be summarized as follows: (1) There was a tendency that for both the press and rebound chest pass, the height of the ball during the pass became increasingly lower, corresponding to an increase in ball weight (0.6kg, 1kg, 3kg, 5kg). In addition, the contact time of the rebound chest pass become longer as the ball weight increased. (2) There was no significant correlation between contact time and height in the rebound chest pass between the differently weighted balls. It was found that there are two independent skills throwing in a short time, and gaining a high ball speed for very effective passing. (3) A comparison of the nature of these two factors (contact time and height) was conducted between guard position players and other players. There was no significant difference in height, but contact time was significantly shorter for guard position players than for players in other positions. It was found that guard position players have superior ballistic power in the upper limbs, and better ability to execute a throw in a very a short time. (4) There was a significant correlation between contact time and height in the rebound chest pass, both when using the basketball and when using balls of different weight (1kg, 3kg and 5kg). However, there was no significant correlation between bench press capacity (used as an indicator of upper limb strength), and contact time and height in the rebound chest pass among the four different balls. This indicates that training with weighted balls (1kg, 3kg and 5kg) may be more directly effective than methods such as the bench press for improving chest pass ability in basketball. These findings are potentially useful for clarifying effective training exercises to improve the chest pass ability of basketball players, and appear to concur with the principles of plyometrics of the upper limbs.

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The ball size for table tennis was recently changed in the revision made to the international rules by the ITTF (International Table Tennis Federation), and the new ball has been in use for official games since October 2000. The new rules stipulate that the diameter of the ball should now be 40mm (an increase from 38mm), and the weight of the ball should be 2.7g (an increase from 2.5g). It is estimated that the style of play and game tactics will change to some extent as a result of the new ball. The purpose of this study was to compare the hitting properties of the new ball in comparison with the old one, in order to clarify the influence on play. The reduction ratio of ball speed from the shooting point to the receiving point was calculated using a ball-shooting machine and a speed measurement system. Initial velocities and ball spins were calculated using a golf-swing robot and a high-speed video camera system. The robot hit the balls with different hitting speeds and hitting angles by a racket attached to the robot arm. An all-around wooden bat pasted with a reverse-soft rubber sheet was used. Average rally times for the two kinds of ball were measured, and three kinds of basic shot-drive, chop and serve-were made in the rallies by skilled payers. The following results were obtained: (1) The initial speed of the new ball was 1-2% less, and the ball spin was 5-20% less than for the old ball. (2) No difference in the speed reduction ratio was observed between the new ball and the old one. (3) The average rally time for the new ball was 2-4% longer than for the old ball for drive and chop shots.

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It appears that certain factors, such as the movements of the leading forelimb and head of the horse, and the existence of the rider, influence a horse's jumping performance during show jumping. The purpose of the present study was to investigate the fundamental timing control of the horse's movement immediately before jumping and to consider the relationships between these factors. Video recordings (60 frames/s) were made using four 8-mm video cameras from 4 angles around a 100-cm-high fence. The 3-D coordinates were calculated using the direct linear transformation (DLT) method. The movements of the horse with and without the rider were compared and analyzed during a few strides before jumping. The subjects were two sound horses and two skilled student riders. The results are summarized as follows: 1) Upward movement of the horse's head immediately before jumping was still evident after the forelimbs had left the ground. This situation was different from that reported for galloping horses (Amano and Ishii, 1992). 2) Immediately before jumping, the horse took a position with a shorter stride between the forelimbs. This shorter stride probably contributes to the upward movement of the horse's head mentioned in 1), and to the more forward landing of the hindlimb before jumping. 3) In relation to this short stride of the forelimb before jumping, the horse increased the landing angle of the leading forelimb and decreased the take-off angle to change its forward velocity to a more upward velocity. 4) There was no significant difference between the ridden and non-ridden horses in the timing control of the vertical movement of the horse's head and the pre-jump velocity. This may be due to the ridden horse's control of its own movement by decreasing the take-off angle of the leading forelimb in order to jump the fence. However, more cases should be examined to clarify and quantify these influences.

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Participation in physical activity (including exercise and sports) is often recommended for elderly people to enhance physical, social and psychological health. Although physiological benefits of physical activity in elderly people have been consistently reported, psychological benefits have not been consistently reported. The purpose of this study was to examine the psychosocial relationship between exercise habits and subjective well-being, which is one of the positive components of psychological health for elderly adults, activities of daily living (ADL), social support, and self-rated health using data for 209 elderly rural residents over 65 years of age, living in their own home. The main results obtained from the analysis were as follows : 1. The main effects of exercise obtained from analysis of variance (ANOVA) were statistically significant for social autonomy factor of ADL, self-rated health, family support and subjective well-being in the "old-old" sample (75 years of age and over). 2. Results of covariance structure model analysis supported a psycho-sociological model (GFI = .933, AGFI = .892, CFI = .907, RMSEA = .075) in which exercise leads to a higher level of ADL and enhances both self-rated health and social support, which in turn can influence subjective well-being for elderly adults. 3. The findings indicate that the effects of exercise on subjective well-being imply indirect benefits in terms of intervening ADL, self-rated health and social support.

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