A GENU VARUM EFFECTS ON EACH LOWER EXTREMITY MUSCLE ACTIVITY DURING LEGPRESS EXERCISE / 体力科学

[Purpose] A leg press generally included in a weight training program to develop the quadriceps. However little is known about the mechanism of the load in lower extremity by the different knee alignment. The purpose of this study is to compare the muscle activity in the different knee align ment during leg press exercise. [Methods] Four normal knee and Five gene varum performed the leg press using three stance of narrow, medium and wide stance with the load of 75%/1 RM. Surface EMG date were collected (1000Hz) from vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF), adductor longus (AL), biceps lemons (HF), tibialis anterior (TA), gastrocnemius (GAS), soleus (SQL) . Integrated EMG (iEMG) values were calculated for each muscle during each rep. A video camera recorded the performing form during leg press from the frontal plane. [Results and Discussion] As the leg press was to strengthen of the thigh muscle, VM, VL and RF of both groups worked strongly. However SQL of genu varum worked as strong as the level of activity of the thigh, iEMG of the SQL showed low value significantly by using wide stance. When the genu varum group performed maximal knee flexion using the narrow, their ankle was valuus on the video screen. This result may become cause of SQL higher activity during leg press. From this we can derive the argument that it will be necessary to take that stance into consideration when athletes who are genu varum performs leg press.

Electromyographic Activity of Shoulder Muscle at Different Positions During External Rotation / 体力科学

Electromyographic activity of the shoulder muscle at 20 and 90°abduction (20 Abd, 90 Abd) during external rotation was investigated in seven healthy men with no history of injury or instability of the shoulder joint.<BR>Electromyography (EMG) was recorded using intramuscular fine-wire electrodes inserted into the M. Supraspinatus, M. Infraspinatus and M. Teres minor, and with bipolar surface electrodes on the middle and posterior parts of M. Deltoid anti the upper and middle parts of M. Trapezius. To compare activity in different muscles, the integrated EMG (iEMG ) activity of each muscle was normalized.<BR>M. Infraspinatus and M. Teres minor showed significantly higher activity at both the 20 Abd and 90Abd compared with the middle and posterior parts of M. Deltoid and upper parts of M. Trapezius. M. Supraspinatus, the middle and posterior parts of M. Deltoid, and upper and middle parts of M. Trapezius all showed a difference in activity level between the two positions.<BR>These findings suggest that when M. Infraspinatus and M. Teres minor contribute to external rotation as a stabilizer and prime mover, consecutively, M. Supraspinatus, the middle and posterior parts of M. Deltoid, and upper and middle parts of M. Trapezius function according to the positions. Moreover, the activity of the upper and middle parts of M. Trapezius in 90Abd should influence stabilization, adduction and upward rotation of the scapula. Therefore, we conclude that the external rotation position is closely related to shoulder muscle activity and coordination.

Electromyographic analysis of shoulder muscles during shoulder external rotation with reference to load magnitude / 体力科学

Electromyographic muscle activities of the shoulder muscles during shoulder external rotation with reference to load magnitude were studied in 8 healthy male subjects without history of shoulder injuries. In addition, we discussed the relationship between rotator cuff muscles and superficial muscles. The subjects performed shoulder external rotation from 60°internal rotation to 45° external rotation at 20° of shoulder abduction and 20° of flexion. A Cybex dynamometer used to prescribe angle and velocity of the shoulder movement. At the same time, intramuscular wire electrodes were inserted into the supraspinous, infraspinous and teres minor muscles, and then surface electrodes were placed over the posterior deltoid and middle trapezius muscles. The load magnitude ranged 2-18 Nm and the angle velocity was set at 15 deg/sec. The rotator cuff muscles became significantly to be activated from 2 Nm (the supraspinous and infraspinous m.) and from 4-5 Nm (the teres minor m.) compared with the muscle activity during non-load. The superficial muscles became significantly to be activated from 4-7 Nm (the posterior deltoid m.) and from 3-6 Nm (the middle trapezius m.) compared with the muscle activity during non-load. Within the load range (18 Nm 46.8% MVC), %iEMG of the rotator cuff muscles was always larger than that of the superficial muscles. Therefore, we concluded that the contribution of the rotator cuff muscles was larger than that of the superficial muscles up to 3-4 Nm, and activities of the superficial muscles increased gradually from 3-4 Nm during shoulder external rotation.

Difference in effects between "power-up type" and "bulk-up type" strength training exercise. (2). With special reference to muscle histochemical properties and capillary supply / 体力科学

A training experiment was carried out to investigate the difference in training effects between power-up type and bulk-up type strength training exercises from the aspects of muscle histochemical properties and capillary supply. The subjects were eleven healthy males. The power-up type group (five males) performed knee extension exercise for 5 sets at 90% of 1 RM (one repetition maximum) with a 3-min rest between sets (repetition method) . The bulk-up type group (six males) performed the same exercise for 9 sets at 80-40% of 1RM with a 30-s or 3-min rest between sets (interval method, multi-poundage system) . Both programs were carried out twice a week for 8 weeks.<BR>The main results were as follows ;<BR>1. Percentages of fiber types showed no recognizable changes in either group.<BR>2. Fiber area was significantly increased for all fiber types (Type I, Type IIA, Type JIB) in both groups. However, the rate of increase was greatest for type IIA fiber, followed by type JIB fiber and then type I fiber. Moreover, the rate of increase for all fiber types in the bulk-up group was higher than that in the power-up group.<BR>3. Percentage of fiber area showed no recognizable changes for any fiber types in the powerup group. However, the percentage area of type II fibers, especially type IIB fiber, was significantly decreased in the bulk-up group.<BR>4. CC (Type I), CC (Type IIA) and CC (Type IIB) (number of capillaries in contact with each fiber type) were significantly increased in both groups. However, in comparison with CC (Type I), CC (Type IIA · Type IIB) showed a higher rate of increase in the power-up group. On the other hand, in comparison with CC (Type IIA · Type JIB), CC (Type I) showed a higher rate of increase in the bulk-up group. Also, compared with the power-up group, the bulk-up group showed a signifi-cantly higher rate of increase of CC (Type I) .<BR>5. C/Fiber area (Type I), C/Fiber area (Type IIA) and C/Fiber area (Type IIB) (number of capillaries supplying each fiber area) were decreased in both groups.<BR>The above results show that power-up type exercise leads mainly to hypertrophy of type I, type IIA and type IIB fibers without any change in percentage fiber type or percentage fiber area, whereas bulk-up type exercise leads mainly to hypertrophy of each fiber type with decreases in percentage area of type II fibers, especially type JIB fiber. Also, power-up type exercise leads mainly to an increase in the number of capillaries around type II fibers, whereas bulk-up type exercise leads mainly to an increase in the number of capillaries around type I fiber. However, capillary development around all fiber types did not necessary coincide with muscle hypertrophy in either exercise.<BR>The authors reported previously that power-up type exercise is effective mainly for improving muscular strength and anaerobic power, whereas bulk-up type exercise is effective mainly for induc. ing hypertrophy and anaerobic endurance. The results of this study may help to clarify these effects from the viewpoint of the adaptations of muscle fibers and the capillary supply.

Studies on muscle metabolism and cross-sectional area in the elite Japanese soccer players using NMR / 体力科学

We investigated the muscle energetics using <SUP>31</SUP>P nuclear magnetic resonance (<SUP>31</SUP>P NMR) spectroscopy, muscle cross-sectional area by magnetic resonance imaging (MRI), isokinetic strength, maximal anaerobic power and 40-sec maximal cycling test (40 seconds power) in All Japan soccer players (JPN: n=6), Olympic and Youth representatives (OL: n=6), and Japan Soccer League players (JSL: n=5) . There was no significant difference in muscle energy metabolism measured by <SUP>31</SUP>P NMR between the JPN and the OL or JSL players at rest, during exercise, or in the recovery period. The total muscle cross-sectional area was significantly larger in the JPN players than in the OL players at the upper (70%) and the middle (50%) parts of the thigh (p<0.05) and than in the JSL players in the upper (p<0.01), middle (p< 0.05), and lower (30%) parts (p<0.01) . The isokinetic strength in left leg extension at 180 deg/sec was significantly greater in the JPN players than in the OL players (p<0.05) . Muscle strength was also greater in extension of both legs at 450 deg/sec (left p<0.05, right p<0.01) in the JPN players than in the JSL players. The maximum anaerobic power was significantly greater in the JPN players than in the OL players (p<0.05) and the JSL players (p<0.05), and the anaerobic power per kilogram of body weight was significantly higher in the JPN players than in the JSL players (p<0.01) . There was no significant difference in the 40 seconds power among the three groups. These results suggest that the JPN players have greater muscle power than the OL or JSL players because of the differences in the muscle mass.

Baseball elbow and elbow joint instability / 体力科学

97 baseball players from high school, universities and companies were subjected to this study in order to attempt to clarify the relationship between derangement of the elbow joint and lateral instabilitly by measuring various conventional parameters and the degree of lateral instability.<BR>From the survey by questionnaire, 29 out of 97 players complained of elbow pain, paticularily on the medial side of the joint. The painful phases of the throwing motions were the acceleration phase (23 players, 61%) and release phase (7 players, 46%) . The hyperexten sion of the elbow on the dominant side was significantly smaller than that observed on the undominant side. X-ray examination revealed osteophyte formation at the tip of olecranon and medial joint space.<BR>On the application of 63 kg⋅cm torque force, the varus deflection angle for the dominant side was 8.3° and that for the undominant side was 8.8°. The valgus angle for the dominant side was 12.2° and that for the undominant side was 10.8°. The varus stiffness (kg⋅cm/angle) was 9.5 for the dominant side and 8.4 for the undominant side. Valgus stiffness were 6.3 for the dominant side and 9.2 for the undominant side.<BR>Thses results indicate that the lateral side become stiffer and medial side become looser in the dominant elbow than in the undominant one.<BR>The unphysiological valgus stress at the acceleration phase would induce the osteophyte formation as well as the elongation of the medial collateral ligament on the medial side of the elbow. At the same time the impigement of the olecranon at follow through phase, would induce the osteophyte formation around the olecranon. Thses two factors would considerably influence the range of motion and the instability of the elbow joint.

INJURIES OF WATER POLO PLAYERS / 体力科学

102 water polo players were interviewd about the injuries caused by water polo. 13% of the subjects had knee pain at least once a year. 73% of which were chronic cases. For 24 players, clinical examinations, including X-ray examination, A-P knee laxity measurement, isokinetic strength measurement of knee muscles, and photo analysis of the vertical egg beater kick motion were performed to elucidate the cause of knee pain.<BR>The summary of the results were as follows;<BR>1. The most common site of knee pain was the medial portion of the knee joint.<BR>2. Protrusion of the medial femoral epicondyle and sharpning of the tibial intercondylar eminentia as well as spur formation of the superior pole of the patella were observed in most subjects.<BR>3. Injured subjects had stiff knees and weak knee extensor muscles.<BR>4. The vertical egg beater kick motion must be the main factor of the painful knee.

Injuries of water polo players - In special regard to the knee joint / 体力科学

102 water polo players were interviewd about the injuries caused by water polo. 13% of the subjects had knee pain at least once a year. 73% of which were chronic cases. For 24 players, clinical examinations, including X-ray examination, A-P knee laxity measurement, isokinetic strength measurement of knee muscles, and photo analysis of the vertical egg beater kick motion were performed to elucidate the cause of knee pain.<BR>The summary of the results were as follows;<BR>1. The most common site of knee pain was the medial portion of the knee joint.<BR>2. Protrusion of the medial femoral epicondyle and sharpning of the tibial intercondylar eminentia as well as spur formation of the superior pole of the patella were observed in most subjects.<BR>3. Injured subjects had stiff knees and weak knee extensor muscles.<BR>4. The vertical egg beater kick motion must be the main factor of the painful knee.

Knee joint troubles in tea pickers / 日本農村医学会雑誌

Investigation was made into knee joint problems among tea pickers through a questionnaire. Following this, physical examinations were given and radiography was taken.<BR>Of the male respondents, 18.9% said that they have pains in the knee (s). The corresponding figure for the women was a high as 38.5%. The number of men and women who complained of knee pain increased with age. However, it was not clear whether the incidence of knee pain has any bearing on the number of years they had worked or working hours per day. Rather, it seems to depend on the configuration of the plantation.<BR>Knee pain occurs more frequently in persons working on sloping and hilly lands than those working on flat land. The difference in Q-angle is wider in the hilly area than in the flat land.<BR>X-ray examination of the knee joint of the persons who complained of sensations revealed degenerative changes in the form of the synovial cavity. Changes in the form of the patella were more evident in the persons working on the sloping land than on the flat land.<BR>On the slope, tea pickers have to bend their knees, requring femoral quadriceps and crural triceps to maintain contraction for cours. Thus the level of stress on the kneecaps becomes high.<BR>To prevent knee joint injuries, improvement of footings, mechanization of collecting work, decreases in the frequency of decending and ascending the slop, and having a rest at proper intervals are necessary.<BR>Furthermore, it is necessary to strengthen femoral quadriceps by excercise and control weight.