We examined age-related changes in functional, morphological and metabolic adaptations of the rat diaphragm muscle to compensatory increased activity. Forty-two male Wistar rats (6, 48 and 100 weeks after birth) were randomly divided into control (CTL) and compensatory activation (CAC) groups (n=7 in each group). In the CAC group, denervation surgery in the hemidiaphragm was performed to induce compensatory activation on the contralateral hemi-diaphragm muscle. Four weeks later (10 weeks, 1 year and 2 years after birth), isometric contraction properties by in-vitro physiological measurement, fiber type composition and metabolic properties (succinic dehydrogenase (SDH), 3-hydroxyacyl-CoA dehydrogenase (HAD) and phosphofructkinase (PFK)) were analyzed by histochemical and biochemical procedures. In the CTL groups, significant prolongations in the contraction and half-relaxation times were found in 2-year group, as compared to 10-week group. This age-related changes were attributed to changes in muscle fiber type composition; selective hypertrophy in Slow-twitch Oxidative fiber. In 2-year CAC group, as compared to age matched CTL group, significant improves were found in the half-relaxation time, SDH activities in each fiber type, HAD and PFK activities of the diaphragm muscle. These results demonstrated that the aged diaphragm muscle has a tendency toward slow muscle in functional and morphological properties, and that the muscle has a high adaptability to compensatory increased activity, at least in metabolic properties.
Exercise intensity has been identified as a major determinant of the excess post-exercise oxygen consumption (EPOC). However, no studies have compared the prolonged EPOC after supramaximal intermittent exercise and supramaximal continuous exercise. Six young healthy male [age=26±3 (mean±SD) yr ; stature=175.4±5.7 cm ; body weight=66.8±6.7 kg ; maximal oxygen uptake (VO2max)=44.1±8.5 ml/kg/min] xercised on separate days on a cycle ergometer at two equated total energy expenditures (intermittent exercise : 7×30-second intervals at 150%VO2max with intervening 15-seconds rest periods ; continuous exercise : 5 min at 105%VO2max) and then sat quietly in an armchair for 3h. A control trial without any exercise was also performed in a counterbalanced research design. The VO2, carbon dioxide output (VCO2), pulmonary ventilation (VE), respiratory exchange ratio (RER), heart rate (HR) and blood lactate concentration (LA) were measured before exercise, during exercise and during the 3-h recovery period. The mean VO2 after intermittent trial at 150%VO2max were higher than these of the control trial and the continuous trials at 105%VO2max for 3-h recovery periods (p<0.05). The 3-h EPOC value for intermittent exercise trial (10.5±2.4L) was significantly greater than that of continuous exercise trial (4.8±2.7L) (p<0.05). The mean RER values for intermittent exercise trial were significantly lower than those of the control trial during 60-180 min post-exercise (p<0.05). We examined the effect of supramaximal exercise intensity on the magnitude of 3-h EPOC after 12-fasting. In the present study, 3-h EPOC was significantly greater for supramaximal intermittent exercise compared with the supramaximal continuous exercise when the amounts of work output performed are same. Therefore, our results indicate that exercise intensity may be a primary factor of 3-h EPOC even in a supramaximal exercise and that one of mechanisms for the 3-h EPOC would be related to the promoted lipid metabolism.
Vigorous exercise induces a muscular oxidative DNA damage due to increased generation of reactive oxygen species (ROS). However, it is not fully understood how ROS induces muscular DNA damage after vigorous exercise. This study examined the relation between muscle damage and the muscular oxidative DNA damage in the gastrocnemius (GAS) and soleus (SOL) muscles of rats after eccentric exercise. All rats performed level (0 degree ; L) or downhill (—17 degrees ; DH) running on a treadmill for 1h at 20 m/min. In GAS, the 8-hydroxy-2'-deoxyguanosine (8-OHdG) content, an indicator of DNA damage, showed a 2-3 times increase from that in the control after DH running, but not after L running (P<0.05). The 8-OHdG content was positively correlated with lipid peroxide (TBARS) (r=0.61, P<0.01). Moreover, plasma creatine kinase (CK) activity was positively correlated with 8-OHdG content (r=0.68, P<0.05) and TBARS (r=0.64, P<0.05) after both DH and L running. The 8-OHdG content in SOL showed larger changes than that in GAS during the 1-week recovery period following DH running. These findings show that the exercise-induced muscular DNA damage is reflected in plasma CK activity. Consequently, it is suggested that changes in plasma CK activity can also be useful as an indicator of muscular DNA damage.
Aim of the present study is to clarify energy expenditure of gymnastic exercise during water immersion. Method : 13 males participated to the test. Oxygen consumption (VO2) and ventilation were continuously measured by open circuit. Heart rate (HR) was automatically obtained by telemetoring. Six kinds of repeating movement of extremities were performed on land and in water in the same manner. Immersing depth was to the xyphoid level. Rhythms of the movement were adjusted so as to continue for several minutes. Result : Their OPW were 14∼20 ml/kg/min, MV were 38∼53 l/min. OPW increased remarkably by swings of both arms crossing in front of chest or alternant back-and-forth, and swings of a hemi-leg in water, compared to that on land. OPW was as half as on land by jump in situ, and equivalent by steps like marching. Notably, oxygen pulse increased by arm and leg exercise more than that on land, accompanied by increase of ventilation. Gymnastic exercise in water showed different effect on oxygen consumption and cardiac response from that on land. Manner of the movements in water also affect the difference. Those kinds of exercise in water can be utilized clinically for training and promotion of fitness.
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.
N-3 polyunsaturated fatty acid supplementation has been recognized to affect the peripheral oxygen delivery system with increasing blood rheology. The purpose of the present study was to investigate whether n-3 polyunsaturated fatty acid supplementation, using purified perilla oil rich in α-linoleic acid, improves aerobic capacity in young women. Eighteen young, sedentary female college students were divided into an n-3 polyunsaturated fatty acid supplemented control group (PUFA-C, n=10) and an n-3 polyunsaturated fatty acid supplemented trained group (PUFA-T, n=8). All subjects took 20g of perilla oil (11g of n-3 polyunsaturated fatty acid) in addition to the usual diet throughout the experimental period of 4 weeks. PUFA-T subjects exercised for 30 min on a bicycle ergometer (intensity, 60% of VO2max) 4 times a week for 4 weeks. Maximal oxygen uptake (VO2max) and oxygen uptake at the ventilatory anaerobic threshold level (VT) significantly (p<0.05) increased after treatment in both groups. However, the endurance time in the exhaustive exercise test significantly (p<0.05) increased in the PUFA-T group only. Increasing rates of VO2max and VT with treatment for the PUFA-C group were lower than those for the PUFA-T group (VO2max, 12.6% vs 14.4%, VT, 9.7% vs 16.9%). After treatment, these values returned to baseline levels within 2 months of the recovery period without n-3 polyunsaturated fatty acid supplementation in both groups. Only for the PUFA-T group, VO2max and VT at 2 months after the treatment period were significantly (p<0.05) higher compared with baseline levels. These results suggest that n-3 polyunsaturated fatty acid supplementation might have a beneficial effect on improving aerobic capacity with increasing peripheral oxygen delivery. However, n-3 polyunsaturated fatty acid supplementation was less effective than aerobic training.
[Objective] The purpose of this study is to examine the relationships between shoulder's function and damage for handball players. Subjects were nine female handball players with dominant shoulder pain. [Methods] Clinical diagnosis was done from the medical doctor's opinion and MRI. Then, the shoulder joint movement was measured with X rays. [Results] Most of them had admitted a lot the impingement syndrome and the subacromial bursitis. The trunk rotation angle at zero-positions was significantly larger in the symptomatic shoulder (dominant shoulder) than in the asymptomatic shoulder (nondominant shoulder). That is, it was obvious that the damage of the shoulder changed tilting angle of scapula medially. [Conclusion] It is reported that the damage of the shoulder causes abnormality to the “scapulohumeral rhythm” by the previous research. But, these results, suggested to need to understand not only “scapulohumeral rhythm” but also movement to the position of the scapula, when the shoulder joint function was observed for the handball player mainly composed of throwing motion.