The purpose of this study was to clarify changes in kinetic visual acuity in elite Japanese baseball players during training camp. Twenty fielders who belong to an elite amateur baseball team were divided into 2 groups: group A (n = 8) consisted of 8 regular players (ie, played every game) and group B consisted of 12 substitute players (ie. played 33% game in a year). Five healthy males participated in this study as the control group. Kinetic visual acuity, defined as the ability to see an object approach from ahead, was tested by the AS-4 C test. The kinetic visual acuity was measured 8 times during camp (every second day). The profile of mood status (POMS), reaction time, and bunt performance were measured at the same time to compare results with changes in kinetic visual acuity. There were no significant changes from baseline in group A in kinetic visual acuity; changes in group B were significantly worse than baseline on days 6 and 8 only (p < 0.05). Significant changes in subjective assessments, such as fatigue and vigor, occurred in both groups. However, kinetic visual acuity and the bunt performance in group A remained high even when subjective conditions were low (p < 0.05). Change in reaction time in group A, only results on day 8 were significantly longer than baseline. In group B, significant (P < 0.05) increases from baseline occurred on day 6 and day 8. This study, however, did not clarify the reason kinetic visual acuity and bunt performance did not decrease, despite increased fatigue. Results of this study indicate that kinetic visual acuity of elite baseball players during a winter-season training camp were maintained at a high level despite the fact that subjective conditions in the POMS were reduced.

The purposes of this study were to investigate the electromyographic (EMG) activities of the abdominal muscles during walking and to clarify abdominal muscle function. Twenty-eight healthy male volunteers (20.8 ± 2.5 years) participated in this study. Bipolar surface electrodes were placed on both sides of the rectus abdominis and the oblique abdominis muscles. The EMG and signals from foot switches during standing and walking were recorded and analyzed. The EMG raw data were rectified and averaged, and then the integrated EMG was normalized by the values obtained during maximum voluntary contractions (%MVC). The rectus abdominis muscles showed continuous activity (1.6% MVC) during walking. The oblique abdominis muscles showed two patterns during walking. One pattern was a continuous pattern (continuous group) and the other had a peak during the swing phase (the peak pattern group). The amount of activity of the oblique abdominis muscles during walking in the continuous pattern group was 10.1% MVC and that in the peak pattern group was 13.2% MVC. These data suggested that the abdominal muscles play almost no role in maintaining the standing posture and that the rectus abdominis muscles show a little continuous activity. This is because the movement of trunk flexion is very small during walking, when a man's center of gravity moves in thehorizontal plane. The oblique abdominis show two patterns. This is because the opposite rotation movement of trunk and pelvis.