The aim of this study was to reveal the mechanism of exaggerated blood pressure rise during resistance exercise. Muscle sympathetic nerve activity (MSNA), heart rate (HR), blood pressure (BP) and grip force were measured during static handgrip exercise. After a 3-minute control period, intermittent static handgrip exercises (10 30-sec contractions with a 30-sec pause between contractions) at 30% of maximum voluntary contraction (HG 30) or with maximum voluntary effort (HGMX) were performed in nine healthy volunteers who gave their consent in advance to participate in this study. In the HG 30 study, MSNA did not increase compared with the control value until the fifth grip exercise, and BP rose during the third HG exercise. HR was elevated in the first grip exercise and remained elevated up to the 10th grip exercise. During HGMX, MSNA, HR and BP increased significantly during the first grip exercise compared to the control rest, and MSNA and BP rose even further as the contractions accumulated; while HR response remained almost constant throughout the contractions. Mean handgrip force decreased progressively with the increasing number of grip exercises. These results indicate that exaggerated BP rise during static muscle contraction dose not seem to be muscle reflex, at least, during the first several contractions; but rather other factors such as central command or mechanical compression of vessels. However, muscle reflex, for instance metaboor mechanoreflex may contribute to elevated BP when the number of contractions accumulate or muscle fatigue develops.
The purpose of this study was to examine the relationship between physical fitness and ability to coordinate exertion of force (ACEF) in 82 healthy middle and old-aged people aged 54 to 78 years (male 41, female 41), and to examine its sex differences. The ACEF test was conducted with the subject fitting the exertion value of grip strength to a changing demand value appearing on the display of a personal computer. The variable estimating ACEF was the total sum of the differences between the demand value and the produced strength value. The physical fitness items measured were : grip strength, shoulder arm strength (push and pull), vertical jump, vital capacity, foot balance with eyes open, trunk flexion, trunk rotation, whole body reaction time, finger tapping, and stepping. To clarify the relationship between the ACEF and physical fitness, multiple regression analysis was used after age-controlled partial correlations were computed. No sex difference was found in nervous function based on the exertion of maximal ability, but there was with the ACEF based on the exertion of sub-maximal strength. Also the relationship between the ACEF and age differed in men and women. The tests of nervous function and grip strength had little relation to the ACEF test. Each physical fitness factor and the fundamental physical fitness had low relation to the ACEF. It was inferred that ability measured by the ACEF test differs from that measured by general physical fitness tests based on the exertion of maximal ability. It is necessary to examine the relationship between the ACEF test and a similar test based on the exertion of sub-maximal strength.
Task-dependent changes in the cutaneous reflex in the upper and lower leg muscles were examined in normal human subjects (n=11) . After instruction, the subjects were asked to selectively contract agonist muscles (SC task) and to co-contract antagonistic muscles (CC task) for the ankle or knee joint while standing. The cutaneous reflex was elicited by applying non-noxious electrical stimulation to the superficial peroneal nerve at the ankle joint (200 Hz, 5 pulses) . The EMG signal was rectified, averaged (n=10), cumulatively summated up to 150ms after the end of the stimulation artifact, and then divided by the time interval for the summation (ACRE150) . A strong inhibitory effect was determined at a latency of 50 ms and was followed by a facilitatory effect after the electrical stimulation during the SC task in all muscles. In contrast, it was found that the early inhibition and the later facilitation tended to be decreased and increased during the cc task, respectively. A linear regression analysis between the ACRE150 and the background EMG revealed that the regression slopes were significantly decreased during CC task except for the tibialis anterior (TA) and biceps femoris. The reflex ratio (ACRE150/background EMG) was also negative for the SC task in all muscles tested, but was significantly reduced or showed a positive value for the CC task. These results suggest that the brain may control the cutaneous reflex pathways to enhance the facilitatory effects of the thigh and ankle extensor muscles during the CC task. This reflex action during the CC task may serve to prevent an undesirable fall in the center of gravity in response to a sudden tactile sensation to the dorsal surface of the foot.
The purpose of this study was to investigate the effects of different intensities of exercise on α-tocopherol and thiobarbituric acid reactive substance (TBARS) levels in the plasma and liver of rats. Male Wistar rats were divided into a sedentary control group and exercise groups. The exercise groups were forced to exercise by treadmill running at 30%, 60% and 80% of maximum oxygen uptake (VO2max) for 120 minutes. Some animals in each exercise group were sacrificed immediately and others at 6 hours after the exercise period, α-Tocopherol levels in the plasma and liver were analyzed by HPLC. Plasma α-tocopherol levels of rats sacrificed immediately after the exercise period decreased significantly in the 60% and 80%VO2max groups compared to controls. In all exercise groups, plasma α-tocopherol levels were significantly higher 6 hours after the exercise period compared to those sacrificed immediately after the exercise period. Liver a -tocopherol levels were also lower in all exercise groups 6 hours after the exercise period, especially in the 80% VO2max exercise group. There were no differences in TBARS levels between the control and exercised groups. These results indicate that acute exercise induces oxidative changes in the liver, but the liver is able to compensate by increasing the consumption and release of α-tocopherol to neutralize any damage.
The purpose of this study was to determine the differences between walking stairs one step at a time versus using alternating feet by evaluating muscle tensions and joint forces. This quantitative basic knowledge will be useful in setting safe guidelines for stair walking in rehabilitation programs. Five healthy young males participated as subjects. Ascending and descending motions were measured by utilizing a 3 D motion analysis system, a force platform and an EMG telemetry system. Measurements were made for three conditions : 1) Both limbs during alternating feet walking (normal stair walking : NW), 2) The leading limb (LL) and 3) The trailing limb (TL) when walking stairs one step at a time. Moments of force on the joints, muscle tensions and joint forces were calcu-lated using two mathematical models (the link segment and musculoskeletal models, Yamazaki (1992) ) . When ascending, maximum flexion angles of three joints in the TL were smaller than during NW. Also, quadriceps tension in the TL and soleus tension in the LL were smaller than during NW. Except for joint force, which was directed toward the anterior of the tibia, knee joint forces in the TL were smaller than during NW. When descending, maximum flexion angles of the three joints of the LL were smaller than during NW. The quadriceps tension and the soleus tension in the LL were smaller than during NW. Knee joint forces in the LL were smaller than during NW. The results suggested that : 1) When ascending, if a patient has a failure in the system of knee extension, the unaffected side should be made the LL and the affected side the TL. Also, if there is a failure in the system of plantar flexion, the unaffected side should be the TL and the affected side the LL. 2) When descending, if there is a failure in one limb, the unaffected side should be the TL and the affected side the LL.
The effects of insulin administration on the normal growth of mouse skeletal muscle and its effect on induction of muscle hypertrophy by tenotomy were investigated in this experiment. 1) The influence of insulin dosage on rat body weight was investigated. The results of examining the influence of insulin dosage on body weight showed significant increases in body weight in the 8.0U/Kg dosage group and 16.0 U/Kg dosage group compared to the control group. 2) The influence of insulin dosage on rat blood glucose levels was investigated. The blood glucose values of the 1.0 U/kg dosage group were significantly lower than in the control group. They were significantly lower in the 1.0 U/kg dosage group than in the other dosage groups. The positive utilization of glucose in the peripheral organization was suggested. 3) The effect of insulin dosage on skeletal muscle weight was tested. ANOVA shows a significant difference in soleus muscle weight as the insulin dosage rose. Soleus muscle weight at the 1.0 U/kg dosage was significantly higher than in the other groups. By contrast, no significant differences in muscle weight were observed in the control group as the dose insulin increased. The weight of fast muscle was unaffected by the size of the insulin dosage. 4) The influence of insulin dosage on the compensatory muscle hypertrophy was examined. The influence of insulin dosage to the compensatory muscle hypertrophy was examined after one week. A 75% increase in soleus muscle after tenotomy was observed in the control group. Although the plantaris muscle showed an average 30% increase, the difference was not significant. A tendency for the weight of soleus muscle and plantaris muscle to increase after tenotomy was observed in the 2.0 U/kg dosage group, but the increments were not significantly different. Effect of tenotomy was observed weight of the soleus from an average of 7.3% in the 16.0 U/kg dosage group, but the increment was not significant. On the other hand, plantaris muscle weight increased about 65% and the increment was significant.
It is generally accepted that exercise induces a decrease in splanchnic circulation, because of the increase of blood in working skeletal muscle. On the other hand, ingestion of a meal increases blood flow in splanchnic circulation. However, it remains to be clarified whether splanchnic circulation decreases due to exercise after ingestion of a meal. The present study examined the effect of different intensities of cycling exercise after ingestion of a carbohydrate-drink on portal venous blood flow, blood glucose, serum insulin and plasma catecholamine concentrations. Six volunteers ingested 200 ml of martodextrine solution (12%) [M (200) ] before 20 min exercise sessions of 30% maximal oxygen uptake (VO2max) and 60% VO2max. Before and after the exercise sessions, portal venous blood flow was measured by a combined ultrasonic system of an electronic sector scanner and pulsed Doppler flowmeter. Portal venous blood flow in the exercise at 30% VO2max increased due to the M (200) ingestion. However, a decrease in portal blood flow resulting from exercise at 60% VO2max was observed in spite of a M (200) ingestion compared with portal blood flow after both rest and the exercise at 30% VO2max. Immediately after exercise, an increase in blood glucose and serum insulin level was shown for 30% VO2max with M (200), but not 60% VO2max. In addition, plasma epinephrine concentration after taking M (200) did not increase as a result of either exercise intensity. These results suggest that the response of portal venous blood flow caused by carbohydratedrink ingestion immediately before exercise is influenced by exercise intensity, and it corresponds to the changes in blood glucose, serum insulin and plasma epinephrine. We concluded that ingestion of food, rather than exercise, has a regulatory action in splanchnic circulation in low intensity exercise.
The purpose of this study was to examine the effects of walking exercise on the mental activity of 44 elderly patients with slight, long-term cerebral infarction. Walking exercise, mental activity and brain morphology were determined by the number of steps taken per day, modified Hasegawa's dementia scales-R and computed tomography, respectively. The results are as follows : The average number of steps taken per day for the group of normal mental activity was 3489±1692, for subnormal 2073±980, pre-dementia 1458±1241, and dementia 570±1132. Sylvian fissures enlargement ratio in the normal group was 4.3±1.7%, subnormal was 4.1±0.8%, predementia 6.0±2.3%, dementia 6.3±1.8%. The difference between the right and left sylvian fissure enlargement ratio in the normal group was 1.8±0.9% (right) vs. 2.5±1.3% (left), subnormal: 1.7±0.4% (right) vs. 2.5±0.5% (left), predementia : 2.6±0.9% (right) vs. 3.4±1.5% (left), dementia: 3.0±1.2% (right) vs. 3.2±0.9% (left) . Cerebrum-cranial cavity ratio in the normal group was 80.6±5.0%, subnormal 78.6±5.0%, predementia 74.6±4.8%, dementia 72.7±3.4%. The lateral ventricles-cranial cavity ratio for normal was 14.3±4.5%, subnormal 14.7±3.1%, predementia 17.3±3.6%, dementia 16.8±4.7%. The difference between good walking patients (over 1000steps/day) and poor walking patients (less than 1000steps/day) concerning the sylvian fissures-cranial cavity ratio (A), cerebrum-cranial cavity ratio (B) and lateral ventricles-cranial cavity ratio (C) was as follows: (A) 4.4±1.5% vs. 6.4±1.9% (p<0.001), (B) 78.4±6.7% vs. 74.0±3.4% (p<0.05), (C) 15.2±3.9% vs. 16.5±4.5% (ns) . The above data indicates that there is an interrelationship among walking exercise, mental activity and brain morphology.