This study was designed to investigate the relationships between the tendencies toward Type A behavior pattern (TABP) and sports injuries. A total of 2164 (1631 males and 533 females) athletes from several colleges in Japan, volunteered for this study. They were divided into two groups ; an injury group and a non-injury group. KG's Daily Life Questionnaire was used to investigate the tendency of TABP. Our hypothesis was that Type A individuals showed higher occurrences of sports injury than Type B individuals. Most of the results in this study supported our hypothesis. To put it concretely, the injury group showed higher TABP tendency than the non-injury group. And the higher TABP score group showed higher occurrence of injury experiences than those of low score group. Therefore, there was a possibility that TABP tendency of athletes might be one of the informations to prevent sports injuries.
A balance test was given to middle-aged and elderly persons who are practicing Tai Chi Chuan for evaluating its effect on postural stability. The subjects were 34 (female : 34) healthy persons aged from 50 to 70 (mean : 63.2 ± 7.8years) . The Equitest System (Neuro Com Co. Ltd.) was used for the balance test. The Equitest System has several devices for evaluating postural balance both in a static and dynamic condition. The two tests used in this study-the Sensory Organization Test (SOT) and the Movement Coordination Test (MCT) -were performed to evaluate postural stability. The SOT consists of 3 static and 3 dynamic testing conditions, while the MCT evaluates postural response time against a shift board. The subjects were separated into 2 groups-beginner and skilled-for comparison between the two. The results of SOT showed that there were statistically significant differences of postural control in the dynamic condition between the two groups. But, there was no such difference seen in the static condition. For MCT, statistically significant differences were also observed between the two groups in the dynamic postural condition. The results of SOT and MCT suggest that skilled persons in Tai Chi Chuan acquire both highly developed dynamic balance and quick response in the disturbed condition. The results of the Cybex muscle strength test also suggests that the leg extensor develops muscle strength through long-term Tai Chi Chuan training.
We evaluated motor unit (MU) fatigue in the first dorsal interosseous muscle (FDI) using the collision principle. Eight healthy men exerted 70% (short-duration fatigue task: SDF task) and 30% (long-duration fatigue task: LDF task) maximum voluntary contraction of isometric abductions in the left FDI until exhausted. Before and after voluntary contractions, the ulnar nerve was stimulated at the wrist and elbow with supramaximal intensity, and a pair of M-waves was obtained. Fatiguerelated changes were studied in mean power frequency (MPF), averaged rectified value (ARV) calculated from surface EMG, and motor nerve conduction velocity (MCV) and distribution of motor nerve conduction velocity (DMCV) calculated from M-waves. The MPF of voluntary EMG decreased, whereas ARV increased significantly during SDF and LDF tasks, indicating fatigue had developed in the FDI. Endurance was significantly shorter in the SDF task than in the LDF task (p<0.01), whereas differences between tasks were not seen in MPF and ARV changes. Tasks did not affect MCV, but lower components in DMCV increased for both tasks. Increased lower components were larger in the LDF task than in the SDF task. The shift in DMCV indicated that fatigued MUs stopped activity and enduring MUs, which had lower axon conduction velocity, were activated selectively. These results suggest that the collision principle is applicable in evaluating motor unit fatigability.
This study was undertaken to examine the effects of electro-acupuncture with direct current on peripheral nerve regeneration. Fifty-five 7 month old male rats were used in the present study. Sciatic nerve of each rat was crushed at the thigh, then the subject were divided into four groups as Cathode distal group (n=15), Anode distal group (n=14), Sham group (n=13), and Control group (n=13) . In the Cathode distal group, an insulated acupuncture needle which was inserted at lcm distal to the injured site was used as cathodal electrode, while a needle inserted at lcm proximal to the lesion was used as anodal electrode. In the Anode distal group, the needle at lcm distal and pro. ximal to the lesion were used as the anodal and the cathodal electrodes respectively. In the Sham group, no electrical stimulation were given to the insulated needle inserted at the same site as the aforementioned groups. In the Control group, no operation was given after crush injury. Regeneration of the sciatic nerve were evaluated with the number and the latency of the evoked EMG recorded at 12 sites in the foot, the behavioral test score (BTS) at 1, 2, 3, and 4 week after crush injury, weight ratio of the tibialis anterior and morphological study at 4 weeks after crush injury. Every kind of evaluation indicated that regeneration of the peripheral nerve was faster in the Cathode distal group than those in the other group. In the Anode distal group, the number of the evoked EMG and BTS were significantly lower than those in the Control group with tendency of longer latency and lesser muscle weight ratio. We suggested that electro-acupuncture with cathode distal orientation accelerated regeneration of the peripheral nerve after crush injury, while anode distal orientation delayed the regeneration. The electro-acupuncture with cathode distal orientation might be one of the useful treatment having advantage to perform deeper insertion with minimal invasion.
The purpose of this study was to investigate the influence of a shoulder injury on rotator cuff muscle thickness and shoulder muscle strength in baseball players. Based on orthopedic medical checks performed by a doctor for 57 male collegiate baseball players, two groups, the pain-free normal group (NOR group, n=19) and the impingement test positive group (IMP group, n=17) volunteered to participate in the study. Muscle thickness of the supraspinatus, infraspinatus and posterior deltoid muscles was measured bilaterally using a B-mode ultrasound apparatus (SSD-500, Aloka) with a 5-MHz transducer. Isometric shoulder abduction strength was measured bilaterally with a hand-held dynamometer in the sitting position with the arm at 45 degrees abduction, and shoulder external and internal rotation strength were measured bilaterally with an isokinetic dynamometer in the sitting position with the upper arm at 90 degrees abduction. When the two groups were compared, the NOR group showed significantly greater values on the dominant side than on the non-dominant side for muscle thickness of the posterior deltoid. However, the IMP group showed significantly greater values on the non-dominant side than on the dominant side of muscle thickness of the supraspinatus, the muscle strength with the abduction and external rotation (300 deg/sec) and external internal rotation strength ratio (180 deg/sec) . Also, the IMP group had a significantly weaker dominant/non-dominant ratio of supraspinatus muscle thickness (p<0.05) and abduction strength than the NOR group (p<0.01) . These results suggest that baseball players with positive impingement show both a morphological and functional decline in the supraspinatus muscle. The dominant side supraspinatus weakness observed in the IMP group of this study may reflect muscle atrophy and chronic fatigue.
The purpose of this study was to compare the self-estimation and ideal figure of one's body between Japanese and Caucasian female students. A questionnaire was employed to examine three areas of inquiry : Language, Numerical value, and Model figure. The subjects were chosen from the following sources: Fifty seven Japanese female students (JF-group : BMI 20.9±1.9 kg/m2) and 53 male students (JM-group : 21.4±3.0kg/m2), and 28 Caucasian female students (CF-group : 23.1±3.3 kg/m2) and 26 male students (CM-group : 22.7±3.2 kg/m2) . The proportion of those who consi dered themselves as“fat”were as follows : JF-group at 75.4% and CF-group at 32.1% (X2=16.182, p<0.01) . The proportion of subjects considering the ideal figure as“slim”were as follows: JF-group at 91.2% and CF-group at 46.4% (X2=28.973, p<0.001) . However many subjects in the JM-group and CM-group selected“slightly slim”or“average”as the ideal figure for a woman. From BMI analysis, which calculates ideal body weight with the subjects' actual standing height, it was discovered that the JF-group averaged 18.7±1.3 kg/m2. This was a significantly lower level than 20.6±1.7 kg/m2 for the CF-group (p<0.001) . The value for the JF-group was almost the same as the JM-group (18.9±1.3kg/m2) . There was no difference in the BMI of the selected model as each group's physical self-perception, although there was significant difference between the actual body figure of the JF-group and CF-group. Using the BMI of the selected model as the ideal figure, the JF-group and CF-group averaged 18.4±1.1 kg/m and 19.6±1.5kg/m2 (p<0.01) . After controll ing for the actual BMI of the JF-group (BMI≥22.0 kg/m2) and CF-group, these tendencies did not change. Based on these findings, it was concluded that Japanese female students consider themselves far fatter than they actually are, and expressed a wish to become slimmer despite already being slim. Also, there are differences between females and males as to their images of the ideal body figure. Male students prefer fatter women than what Japanese female students imagine is the ideal figure.
We studied whether exercise fatigue affects somatosensorv input using somatosensory evoked potential (SEP) . Sixteen subjects performed intermittent grip strength exercises with muscle fatigue while ignoring electrical stimulation given to an elbow. We induced SEP in the exercise task (during contraction) in every stage (first stage, middle stage and final stage) . In addition, we induced SEP in the exercise task during relaxation in the first stage and final stage. As a result, the early component amplitude of SEP decreased with the progress of exercise (manifestation of muscle fatigue) during contraction and relaxation. Our findings suggested that somatosensory input decreased with the manifestation of muscle fatigue. Somatosensory input is necessary for control of voluntary movement. Therefore, we speculate that these factors play a role in decreased performance of athletes competing in long-duration events.
The purpose of this study was to compare estimates of human body composition determined from single-frequency bioelectrical impedance methods (S-BIM) and multi-frequency bioelectrical impedance methods (M-BIM) . The human body composition was assessed by dual energy X-ray absorptiometry (DEXA), 5 brands of S-BIM, and 2 brands of M-BIM. Forty-five women, aged 26-58 years, served as subjects. The S-BIM and M-BIM fat-free mass (FFM) estimates were highly correlated with the FFM measured by DEXA (r=0.82-0.93) . The standard errors of estimate (SEE) for FFM were approximately 2 kg. With the exception of the MLT-100 (which slightly underestimated FFM), all brands of BIM slightly overestimated FFM. The absolute mean differences between FFMDEXA and each of the 7 BIM estimates ranged from -3.02 kg to 3.46 kg. Although the 7 brands of BIM provided slightly different estimates, the results of this study suggest that 5-BIM and M-BIM are relatively valid in human body composition.
A study was conducted to investigate the relationships among changes of joint torque of the lower limbs, sprint ability such as sprint speed, stride length and stride frequency in 400 m running, and muscular endurance of the lower limbs. Subjects were 11 male track and field athletes who had a 400m running time of 48.75±1.32s. The experiment was composed of videotaping sprint form at 160 m and 360 m points during 400 m running, and measuring muscular endurance of hip and knee flexion and extension using Cybex NormTM. The main results were as follows: 1) There was a significant relationship between 400 m running time and ability to maintain a higher running speed at the 360 m point. 2) Running speed, stride length and stride frequency decreased significantly at the 360 m point. 3) Subjects who showed a smaller decrease in stride frequency at the 360 m could maintain higher running speed. 4) Subjects who showed smaller decrease in maximal joint torque of the lower limbs at the 360 m could maintain a higher running speed. 5) There was a significant relationship between an increase in support time and decrease in maximal joint torque of hip extension for the recovery leg. 6) Ability to maintain joint torque during 400 m running was influenced by muscular endurance of the lower limbs. These results suggest that the ability to maintain torque needed for higher performance in 400 m running is influenced by muscular endurance of the lower limbs.