Male mice of dd-strain, at 4 and 8 week-ages were used at the start of the trained. The trained continued for successive during 4 to 34 week-ages and 8 to 70 week-ages. The trained group was exercised on a treadmill, and the untrained group used as control under normal laboratry condition. The skin of the right dorsum near the tail was sampled and its collagen content was examined by means of concentration of hydroxyproline. The collagen content in the skin of the trained group is lower than in that of the untrained one at each week-age, 14-18, 27-34 and 63-70 week-ages. The trained group was depressed hydroxyproline concentration of defatted skin, compared with untrained one at each weekage. The continuous exercise reduced the accumulation of collagen in the skin of mice.

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It was the purpose of this study to examine the property of skeletal muscle fiber in middle- and long-distance runners, and to evaluate the relationship between the property of skeletal muscle fiber and aerobic work capacity.
Biopsy samples were taken from M, vastus lateralis of 23 middle- and long-distance runners, and analyzed for muscle fiber composition, capillary supply and SDH activity. Aerobic work capacity was measured on a treadmill with continuous method.
The mean value for % ST in M. vastus lateralis was 61.3%, and the muscle fiber distribution showed the tendency of slow type. The crosssectional area of ST and FT fibers ranged approximately from 3, 000 μm² to 13, 000 μm², and the cross-sectional area of ST fiber tended to be larger than that of FT fiber. The mean values for CD, C/F ratio, and CC (/ST) as capillary supply were 279/mm², 1.62 and 5.7, respectively. The mean value for SDH activity was 5.86 μmoles/g/min, and was lower than reported previously for elite runners. In addition, SDH activity correlated with % ST and CC (/ST) (r=0.480, p<0.05, r=0.640, p<0.01) . On the other hand, the mean value for VOG₂max was 68.5 ml/ kg/min (4, 066 ml/min), while VO₂@AT averaged 45.9 ml/kg/min (2, 756 ml/min) . And it was found that VO₂max and VO₂@AT correlated significantly with % ST, CC (/ST) and SDH activity. Particular, VO₂ max was most strongly related to SDH activity (r=0.612, p<0.01) .
The results of this study suggest that in regard to middle- and long-distance runners, structural characteristics of the ST fiber and capillary are some of the indispensable factors to regulate such a functional property as SDH activity and that the distinctive characteristics of the skeletal muscle fiber might possibly influence aerobic work capacity to a great extent.

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The maximal isometric strength of the knee extension (KES) and cross-sectionl area of m. quadriceps femoris (MQF) were measured on 89 male Japanese elite athletes and 14 untrained men to evaluate the morphological and functional characteristics of athletes in the knee extensor muscles. Athletes were specialized in seven different sport events; 16 sumo wrestlers, 22 oarsmen, 8 volleyball players, 16 speed skaters, 12 association football plyers, 5 sprinters, 10 middle and long distance runners. KES was measured by using a specially designed straingages dynamometer at knee angle of 110 degrees (180 degrees= fully extended) . Cross-sectional area of MQF at the mid-thigh was determined by ultrasonic apparatus. The following results were obtained.
1. Sumo wrestters showed highest mean values (110.18 cm²) in MQF area among athlete groups. Lower mean values in MQF area were found in sprinters (86.34 cm²) and distance runners (73.86 cm²) whose values were not significantly different from that of untrained (75.32 cm²) .
2. In the cross-sectional area of each muscle bundle of MQF, sumo wrestlers, volleyball players and speed skaters showed higher mean values, and sprinters and distance runners had lower mean values as well as untrained men.
3. Higher mean values in percentage of MQF area to the total muscle area of thigh were observed in volleyball players (58.66%) and oarsmen (57.53%), lower mean value in association football players (53.81%), respectively. However, there were no significant differences in percentage of MQF area between untrained and each athlete group.
4. In the percentage of each muscle bundle area to MQF area, m. rectus femoris of association football players and m. vastus lateralis of speed skaters were significantly higher mean values compared with the untrained and other athlete groups.
5. KES were significantly related to the MQF area at 0.1% level (r=0.657) . There were significant relationships KES and each muscle bundle area in MQF area at 0.1% level. In the relationship between KES and each muscle bundle area, m. vastus lateralis showed the highest correlation coefficient (r=0.603) .
6. Association football players showed highest mean value (8.97 N/cm²) in KES per unit of MQF area among athlete groups. Its value was significantly higher than that of untrained men (8.06 N/cm²), distance runners (7.31 N/cm²), volleyball players (7.10N/cm²), and sumo wrestlers (7.50N/cm²) . There were no significant differences in KES per unit of MQF area intra athlete groups except for association football players.

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Fifty-two trained athletes (15 short-distance runners, 20 long-distance runners, and 17 jumpers) and 5 controls were examined for leg length discrepancy, pelvic obliquity, scoliosis, leg strength discrepancy, and leg injury. Forty-seven subjects (90%) in the trained group and 4 subjects (80%) in the control group had leg length discrepancies. Differences of the femur lengths and tibia lengths, not of the joint space or soft tissue, were main factors of leg length discrepancies. There were no significant differences in leg length discrepancy and in pelvic obliquity between the trained and control groups. The trained group had twice as many leg length discrepancies and pelvic obliquities as the control group in average. A positive correlation between leg length discrepancy and pelvic obliquity was noted (p<0.001) . Among the jumpers, those who had suffered from hamstring muscle strain showed significantly more discrepancies in the right and left knee flexion strengths than the jumpers who had never experienced such muscle strain (p<0.41) . The rate of knee flexion strength against extension strength was significantly lower in the jumpers who had experienced knee joint injuries (p<0.01) .
The results indicate that leg length discrepancy affects on the pelvic obliquity and scoliosis. Differences of the femur lengths and tibia lengths were main factors of length discrepancy. It is possible that an inequality of load on the right and left legs may cause leg length discrepancy.

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The purpose of this study was to investigate effects of intermittent running trainings with trot and gallop on glycogen consumption patterns of antagonistics (m. gastrocnemius and m. tibialis anterior) in male Wistar strain rats (4 weeks after birth, n=46) . The animals were devided into three groups, control (n=18), trot training (n=14), and gallop training (n=14) . In order to evaluate glycogen consumption patterns, serial sections of the muscles were stained for Myosin ATPase, DPNH-diaphorase, and Periodic acid-Schiff (PAS) reaction.
The results were summarized as follows ;
1) Significant change in fiber distribution occurred on both training groups, where the percentage of FOG fiber increased and there was a concomitant decrease in the FG fiber percentage. On the gallop tiaining group this effect was shown in the deep and peripheral regions of both muscles, but on the trot training group that wasn't shown in the peripheral region of m. tibialis anterior.
2) According to glycogen depletion patterns after transient running exercises, during gallop the participation of m. tibialis anterior was shown a tendency to increase.
3) With the trainings, decrease of glycogen consumption in muscle fiber occurred in deep and peripheral regions of the both muscles on gallop training group and in the m. gastrocnemius on trot training group.
These results suggest that the trainings with different running forms have different effects on the antagonistics.

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