Background and aims of the study: Mechanical valves require anticoagulation therapy, and bioprostheses may need reoperation due to structural valvular deterioration (SVD). In older patients, the rate of SVD seems to be lower than in younger patients. The aim of this study was to evaluate a 12-year clinical experience of the Carpentier-Edwards pericardial bioprosthesis in the aortic position in patients over 60 years of age. Methods: A total of 652 patients over 60 years old (453 men, 199 women; mean age 72.2±6.7 years) underwent isolated aortic valve replacement with the Carpentier-Edwards pericardial bioprosthesis in our institution between July 1984 and December 1995. The main indication for valve replacement was idiopathic calcific stenosis in 476 cases (75%), while dystrophic insufficiency was present in 124 of the cases (19%). Other conditions were rheumatic, congenital, prosthetic valve dysfunction and endocarditis. All patients, except one, were followed up for an average of 4.36 years after surgery resulting in a total follow up period of 2, 802 patient-years (pt-yr). Results: The operative mortality rate was 3.1% (20/652) including 138 late deaths. Thirty patients died of valve-related causes (14 sudden deaths, 11 thromboembolisms, 3 prosthetic valve endocarditises (PVE) and 2 bleeding events). Twelve years after surgery, the actuarial rate of freedom from valve-related death was 76±24%. Valve-related complications included 37 thromboembolic episodes (1.4%/pt-yr), 9 bleeding events (0.4%/pt-yr), 14 PVEs (0.4%/pt-yr), 2 structural valve failures (0.07%/pt-yr) and 8 reoperations (0.3%/pt-yr). Twelve years after surgery, freedom from thromboembolism was 80±12%, freedom from bleeding events was 96±3%, freedom from PVE was 96±2%, freedom from structural valve failures was 98±2% and freedom from reoperation was 96±4%. Conclusion: With a low rate of structural valve failure 12 years after surgery and a good clinical performance, the Carpentier-Edwards pericardial bioprosthesis is a reliable alternative for patients over 60 years of age.

A study was conducted to evaluate and compare neck muscle strength between two levels of college American football players with the aim of preventing neck injuries. The subjects were American football players at N University (n=52) belonging to the first level league and American football players at G University (n=14) belonging to the third level league. The findings were as follows.
1. The neck muscle strength of freshman players at N University tended to be lower than that of senior players.
2. It was shown that the neck muscle strength/body weight of experienced American football players was 10-30% higher than that of inexperienced players.
3. There was a significant difference in neck muscle strength/body weight between N University and G University in 1997. However, there was no significant difference between them in 1998, because neck muscle strength/body weight of G University players increased by 13-30% after neck muscle training for about nine months. It was suggested that coaching staff must evaluate the neck muscle strength of each player, especially in freshmen who have had no experience of American football, in order to prevent neck injuries because mismatch of performance level may cause catastrophic neck injury.

It seems likely to consider that the bone density (BD) of athletes is higher than that of control subjects. But recently, many authors reported lower BD of amenorrheic female athletes, and suggested that strenuous exercise could decrease BD through, probably, endocrinological disorder.
So, we compared BD of second metatarsal in female athletes with irregular menstrual cycle (IM group) or with stress fracture (SF group) to that of normal menstrual athletes (NM group) or those without bony injuries (NF group), by MD/MS method.
MD/MS method, which is the screening method of BD by scanning mid-diaphysis of second metacarpal (or metatarsal) for 3cm by 20times in X-ray films, was developped from microdensitometry whose scanning was only once at the same part of the bone.
BD of IM group was lower than that of NM group, but without significant difference. BD of SF group was significantly lower than that of NF group.
The index of mechanical strength of the bone, “I”, that is area moment of inertia, did not increase in accordance with decrease of BD. We supeculate this as one of the factor of stress fracture in a sense of decreased mechanical strength.

Trunk motion and the mechanisms of postural control during pedaling was investigated by analyzing the lower trunk muscle activity and spinal motion.
Eight healthy adult men were assigned to pedal at the rate of 60 cycles per min. with the load of 100 W, 150 W and 200 W. Muscle activity was recorded with the surface electrodes from the m. multifidus, m, iliocostalis, m. obliquus externus, m; rectus abdominis, m. rectus lemons, m. adductor longus and m. semitendinosus. Spinal motion was filmed with 8 mm video camera located 5 m behind the subject and 1 m above the floor, and five markers were attached on the midline of the spine (C 7, Th 6, Th 12, S 1, Co) .
Muscle activity (iEMG) was quantified by integrating one cycle of recorded electromyogram, and significant increase was recognized in the trunk muscles and m. rectus femoris as the load increased. The angles between each segments were calculated and the largest deviation was observed in the lumbo-sacral portion. Focussing on the activity of the m. obliquus externus, four patterns of controling the trunk posture were observed, and as the load increased, the activity patterns changed in four subjects and the other four showed tremendous increase in iEMG without changing the pattern.
The results sugest that the pedaling may cause relatively large motion at lambo-sacral portion of the spine, and either the change in the activity pattern or the increase in the activity level of the trunk muscles, such as m, obliquus externus, should contribute to reduce the stress on the lambo-sacral portion.

The purpose of this study was to investigate the relationships of ankle ligamentous injuries with physical and positional characteristics in college football players. Specific hypothesis was addressed whether medial ankle ligamentous complex (MALC) injury was often caused by oversized players, offensive or defensive linemen.
53 subjects participated in this study. We examined their previous history of ankle ligamentous injuries and classified them into three groups: (1) the lateral ankle ligamentous complex (LALC) in-jury group; (2) the MALC injury group; and (3) the no ankle ligamentous (NAL) injury group. Regarding MALC injury, we obtained the following results. First, MALC injury occupied 35% of total ankle ligamentous injuries. Second, both body weight and BMI of the MALC injury group were signi-ficantly the heaviest and largest of the groups. Lastly, OL, LB, and DL occupied highest occurring percentage (75%) of MALC injury.
We concluded that MALC injury tended to be incurred by the players with heavier body weight and/or larger BMI. Players OL, LB, or DL also suffered MALC injury. Thus, these results suggest that body weight, BMI and position are considered as the risk factor for MALC injury.

This study examined age-related changes in dynamic balance (DB) ability, and the relationship between DB ability and isometric knee extension strength (IKES). Subjects were 100 females who regularly performed some light gymnastic exercises at a gymnastics club once or twice a week. Subject ages ranged from 20 to 85 years old. The measured items were height, body weight (BW), IKES, and DB ability. Results were as follows: 1. The average DB ability tended to gradually decrease as the subjects got older. There were some significant differences in the average DB ability between the 20 to 29 and 60 to 69 age groups, and between the 20 to 29 and over 70 age groups. 2. It was shown that there was a significant negative correlation between age and DB ability (r=0.471, p<0.001). 3. There was a significant negative correlation between age and IKES/BW (r=0.579, p<0.001). 4. It was shown that there was a significant positive correlation between IKES/BW and DB ability (r=0.368, p<0.001). 5. There was a significant negative correlation between BMI and DB ability (r=0.370, p<0.001). This study showed that DB ability rapidly decreased over 60 years old, and also the value tended to be higher in persons with a higher knee extension strength and lower BMI. Therefore, it was suggested that it is important to increase the knee extension strength and maintain an appropriate BMI in order to maintain DB ability.

The purpose of this study was to examine the effect of two kinds of neck muscle training on the isometric cervical extension strength (ICES) and cross-sectional area (CSA) of the neck extensor muscles.The subjects which were examined consisted of 22 male college judo athletes. Each was assigned to one of three groups: shrug and upright rowing training (SU); shrug, upright rowing and dynamic neck muscle training (COM); and control (CONT). The SU and COM groups trained 3 days per week for 9 weeks. The ICES and CSA of the neck muscles were measured before and after muscle training.The ICES of the COM group showed a significant increase after training. For the CSA, although a significant increase was only found in a superficial area of the neck extensor muscles in the SU group, the COM group showed significant increases in all areas.This study determined that combined neck muscle training is effective for developing the neck extensor muscles.

The purpose of this study is to evaluate and compare isometric cervical extension strength (extension strength) of college American football players belonging to different level leagues at the eight cervical positions measured by a cervical extension machine (Medx Inc.) and give some suggestions for preventing neck injuries. The subjects were American football players at N University (n=41) belonging to the first-level league and at G University (n=32) belonging to the third-level league. The findings were as follows.
1. The isometric cervical extension strength/body weight of players at N University was sig-nificantly higher than that of G University at 72°, 54°and 36° (a neutral cervical position) .
2. The extension strength/body weight of the linemen at N University was significantly higher at 108°, 54°and 36°than that of the linemen at G University. While there were no significant differences between universities in the eight cervical positions of back players herein referred to as‘backs’.
In conclusion, it was shown that there were significant differences in the extension strength and the extension strength/body weight between teams of different levels. The differences tended to be larger between the linemen than between the backs. Therefore, it was suggested that the evaluation of neck muscle strength was important for preventing neck injuries especially caused by a mismatch of players at different performance levels.

The purpose of this study was to investigate the relationship between low back pain (LBP) any physical characteristics in university wrestlers. We especially focused on radiological abnormalitie (RA) in their lumbar regions.
Physical characteristics and isokinetic trunk muscle strength of the 55 male university wrestlers were measured. MRI was used to evaluate the cross-sectional areas of trunk muscles between lumbar spine 3 and 4 (L3/4) . Evaluations of LBP were based on the diagnose of orthopedic surgeons and the questionnaire test. According to this evaluation, we assigned all wrestlers into two groups as the LOP group and the no LOP group. Furthermore, four groups were defined by having RA based on X-ray and MRI diagnose.
We obtained the following results. In comparison between the LOP group and the no LOP group, the trunk muscle extension flexion strength ratio of the LOP was significantly lower than that of the no LOP group. In addition, the LOP without RA group showed significant low strength of their trunk extensors in comparison with the no LOP without RA group.
We considered that the relative low strength of trunk extensors should have some effect on LBP in university wrestlers.

The purpose of this study was to investigate relationships between low back pain (LBP) and psychological conditions in university wrestlers.
We examined psychological conditions of seventy male university wrestlers using the Psycholo gical Condition Inventory (PCI) test and evaluated whether psychological conditions have some relationships with LBP. Evaluations of LBP were based on a questionnaire test and the diagnosis of orthopedic surgeons. Based on the LBP evaluation, we assigned all wrestlers into two groups as the LBP group and the non-LBP group.
We obtained the following results. There were twenty-eight university wrestlers (40%) in the LBP group and forty-two wrestlers (60%) in the non-LBP group. Wrestlers in the LBP group showed significantly high values in all factors relating to fatigue in comparison to the non-LBP group.
We conclud that the university wrestlers with LBP feel fatigue in their minds and bodies.