SEX DIFFERENCES IN THE MUSCLE VOLUME OF THE ILIOPSOAS IN THE ELDERLY / 体力科学

The purpose of this study was to investigate sex differences in the muscle volume (MV) of the iliopsoas, psoas major, and iliacus muscles, normalized by fat free mass (FFM), in the elderly. The subjects were 15 males and 15 females 65 years of age or over. Serial transverse 1.5T magnetic images (10 mm slice) of each subject were taken between the 12^th thoracic vertebrae and the lesser trochanter. FFM was measured with a bioelectrical impedance analyzer. The mean MV of each muscle on the right and left sides were calculated and used for regression analysis of the relationship between MV and FFM.A significant correlation was observed between MV and FFM of the iliacus in both sexes (p<0.01), but not between the MV and FFM of the psoas major. MV normalized by FFM and cross-sectional area (CSA) normalized by FFM^2/3 showed significantly greater values for the psoas major in the males than in the females (p<0.001), but there was no sex difference in the MV or CSA normalized by FFM of the iliacus.These results suggest that elderly males tend to have a greater muscle volume and cross-sectional area of the iliopsoas than elderly females, and that these sex differences are attributable to differences in the psoas major.

COMPARATIVE ELECTROMYOGRAPHICAL INVESTIGATION OF THE BICEPS BRACHII, LATISSIMUS DORSI, AND TRAPEZIUS MUSCLES DURING FIVE PULL EXERCISES / 体力科学

To compare the effectiveness of five different muscle training movements on the biceps brachii, latissimus dorsi and trapezius muscles, eight weight-trained men (age, 20.4±0.5 years) were asked to perform three repetitions, at 70% one repetition maximum, of upright rowing (UR) and bent-over rowing (BR) exercises using a barbell ; and seated rowing (SR), front lat pull-down (LPf) and back lat pull-down (LPb) exercises using a Universal Machine. The activities of the biceps brachii, latissimus dorsi, and trapezius during the elbow flexsion and elbow extension phases of each exercise were analyzed using integrated electromyography (EMG) and normalized I-EMG. The results were as follows :1. The mean nrmsEMG values for the biceps brachii were larger during UR and LPf exercises than during BR, SR, and LPb exercises, suggesting that UR and LPf are more effective than the other movements for training the biceps brachii. The mean nrmsEMG values for the latissimus dorsi were larger during SR, LPf, and LPb exercises, followed by BR and UR exercises (in descending order), suggesting that SR, LPf, and LPb exercises are more effective than the other movements for training the latissimus dorsi.2. The mean nrmsEMG values for the upper trapezius were larger during UR and BR exercises than during SR, LPf, and LPb exercises, suggesting that UR and BR exercises are more effective than the other movements for training the upper trapezius. The mean nrmsEMG values for the middle trapezius were larger during BR and SR exercises than during UR, LPf, and LPb exercises, suggesting that BR and SR exercises are more effective than the other movements for training the middle trapezius. The mean nrmsEMG values for the lower trapezius were larger during BR exercise than during other movements, suggesting that BR exercise is more effective than the other movements for training the lower trapezius.3. In all the exercises, each muscle showed a higher nrmsEMG value during the elbow flexsion phase than during the elbow extension phase. This observation suggests that the training method examined in this study should emphasize the elbow flexsion movement.The present results suggest that UR exercise is the most effective movement for training the biceps brachii and upper trapezius, BR is most effective for training the upper trapezius, middle trapezius and lower trapezius, SR is most effective for training the latissimus dorsi and middle trapezius, LPf is most effective for training the biceps brachii and latissimus dorsi, and LPb is most effective for training the latissimus dorsi.

MUSCLE VOLUME AND STRENGTH CHARATERISTICS OF THE ROTATOR CUFF AND DELTOID MUSCLES IN ASYMPTOMATIC BASEBALL PITCHERS / 体力科学

The purpose of this study was to investigate muscle volume (MV) and strength characteristics of the rotator cuff (supraspinatus, infraspinatus, teres minor, and subscapularis) and deltoid muscles in each shoulder of asymptomatic baseball pitchers. Twelve collegiate baseball pitchers (PG) and ten male students (CG) who never played an overhand sports volunteered to participate in this study. Magnetic resonance imaging (Straits II, Hitachi Medico, 1.5 T) was used to measure the MV of rotator cuff and deltoid muscles in both shoulders of each subject. Since the individual muscles were difficult to identify on MRI scans, the infraspinatus and teres minor were analyzed as one infraspinatus muscle. Shoulder abduction (ABD), external rotation (ER), and internal rotation (IR) strengths were measured each side using a hand-held dynamometer (Power Track II, Jtech Medical Industry) . The MV of deltoid muscle was significantly larger value on the dominant side (DOM) than on the non-dominant side (NDOM) in both the PG and CG groups (p<0.05) . However, no significant differences in the MV of the rotator cuff muscles and the measured shoulder strength (ABD, ER, and IR) were observed between both sides in either group. Similarly, no significant differences in the DOM/NDOM ratio of the muscle volume and the measured shoulder strength were observed between the two groups. These results suggest that the rotator cuff muscle volume and strength does not differ in both sides of the PG, and DOM/NDOM ratios of the rotator cuff muscle volume and strength of the PG does not differ in those of the CG.

MORPHOLOGICAL AND STRENGTH CHARACTERISTICS OF THE ROTATOR CUFF AND DELTOID MUSCLES IN COLLEGIATE BASEBALL PLAYERS / 体力科学

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.<BR>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) .<BR>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) .<BR>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.

On the analyzing results of three lifting movements of the weightlifters in Tokyo Olympic Games, mainly / 体力科学

High ranking Japanese weightlifters in Tokyo Olympics and high ranking adults and high school students in the 20th Japan National Athletic Meeting were chosen for the subjects. We made research about them for many patterns of movements of the Olympic three lifts which seemed to be the most reasonable way in analyzing the movements of the lifters, by comparing the results which were gotten by the 16 mm 64 frames side filming method with their official records and lifting marks. This led to the following conclusion :<BR>1) At the begining of the clean, dead-lift, for the press the excellent lifters accelerate the bar at a higher speed, but the increase of speed after the begining is not so much. The Olympic lifters pull up the bar bending more forward, at a knee level. But excessive forword bending makes many lifters fail to clean weell.<BR>2) Exellent lifters bigin pressing at a high speed by vigorous extension of their body, Less-trained lifters can not use vigorous extension of their body because of presing forward, or comming down the bar again, and bending the kenee joints.<BR>3) In the snatch excellent lifters pull up the bar at a higber speed to the knees, but they at a speed of lower acceleration from the knees. Even if they are excellent lifters, they often fail to snach in the case of pulling with over-acceleration at that point. It is inportant also in the snatch to use effectively the power of lower ports of the body.<BR>4) It is evident from the loci of the bar that, if the bar travells upward vertically, or near vertically, squat-style lifters need to jump back properly In the case they do not jump back the for moves back and forth excessively, many lifters fail to snatch if they jump back too much.<BR>5) In the clean for the jerk an increasing acceleration in dead lift phase during clean is necessary to become a successful lifter. It is necessary to concentrate the power of the lower parts of the body as much as possible to accelerate on the bar to a knee level. From the knee level exce lent lifters pull the bar by using the pulling power of shoulders more aectively. The barbell falling down from the dead point must be held moderately not to fall down at a high speed.<BR>6) If lifters overstrain the shoulder muscle groups and arms at the starting of the jerk and can not dip their body well in accordance weith dropp ing movement of the bar, they will fail to jerk.<BR>7) The dropping speed of the bar at the first step of the jerk must be marked more carefully at the second phase than at the first phase. Many who make it increase more at the second phase will fail to jerk.<BR>8) The bar of the excellent jerker goes up with very high speed at the begining. But of the speed of the bar after that there is no diffrence between lifters.