The purpose of this study was to investigate the reappearance of the post-absorptive resting metabolic rate (PARM) during a prescribed diet. The subjects were 10 sedentary female college students (20.1±0.7yrs) . Thyroid function was judged in all of them to be within a normal range. Subjects stayed in a metabolic ward at the National Institute of Health and Nutrition for 18 days. The post-absorptive resting metabolic rate was measured 4 times during the experimental period. Moreover, blood was collected five times, and general health care including the measurement of thyroxin by blood biochemical examination was carried out. As for the actual metabolic measurements, a high reappearance was confirmed by the intra-individual coefficient of variation (CV) of the post-absorptive resting metabolic rate (3.5±1.8%) and the inter-individual CV (7.2%) . The smallest CV was the standard value of PARM/body surface area, followed by PARM/body weight, PARM/LBM, and PARM/urine creatinine. On the other hand, weight (50.8±4.9 vs 50.3±4.6 kg ; p<0.01), hemoglobin concentration (13.7 ± 0.5 vs 12.8±0.5g/dl ; p<0.05), serum total cholesterol level (194±41 vs 175 ± 37 mg/dl ; p<0.05) and post-absorptive resting oxygen uptake (0.149±0.01 vs 0.142±0.011/min ; p<0.01) decreased significantly during the experiment. According to the Japanese Recommended Dietary Allowances (RDAs) (1999), basal metabolic rate (BMR) was calculated at 1, 210 kcal/day or 23.6 kcal/kg body weight/day for women within the 18-29 year age group. But the results (the mean of all measurements) of this research suggested that this value was 1, 033 ± 79 kcal/day, or 20.7 ± 2.0 kcal/kg body weight/day based on the method of Weir ; and was approximately 10% lower than RDAs. Future investigation is required to explain the reasons for the difference in BMR between this study and that of previous ones.
The present study aimed to investigate the level of muscular activities such as postural mainte nance and change, and body weight transfer during daily physical activities, through electromyogram (EMG) recordings. In each of 27 prescribed movements, EMGs of a total of 8 muscles located in the upper arms, trunk and lower limbs were recorded in 12 young adult men and women using a port-able surface electromyograph apparatus. The percentage of integrated EMG per time (mEMG) to that during isometric maximum voluntary contraction (MVC) was calculated as an index by assessing the muscular activity level in each of the prescribed movements. In most of the prescribed movements, the muscular activity level of every muscle corresponded to about 20-30% of MVC, and tended to be higher in women than men. However, some actions induced an activity level of 40% and more of MVC in the soleus muscle. The activity levels of the lower limb muscles in going up and down stairs and a slope at a fast speed, and jogging were higher compared to other prescribed movements. Thus, the results indicate that body weight transfer actions in daily life raise the activities of the lower limb muscles to a level sufficient for maintaining and increasing their function.
In this study, we investigated the effects of prolonged voluntary running training on bone mass in the tiba of growing male SD rats. At 5 weeks old, the rats were divided into 4 groups : group 15 VE (n=7) exercised voluntarily on a running wheel for 10 weeks from 5- to 15-weeks old ; group 35 VE (n=7) exercised voluntarily on a running wheel for 30 weeks from 5- to 35-weeks old ; in groups 15SC (n=6) and 35 SC (n=5), rats were housed individually in normal plastic cages for the same periods as groups 15 VE and 35 VE, respectively. At the end of each experimental period, the right tibia from each rat was used for bone- mass analysis using peripheral quantitative cumputed tomography (pQCT) . The evaluated portions were the proximal methaphysis and the diaphysis, with total, cortical, and trabecular data from these portions being obtained as volumetric bone mineral content (vBMC) and volumetric bone mineral density (vBMD) . The results indicated that 1) although voluntary running distance tended to decline during the later period (1635 wk old) in 35 VE rats, some mean values obtained for bone mass parameters using pQCT were significant greater in 35 VE than in 35SC ; 2) the mean values from those parameters in 15 VE were not significantly different from those in 15 SC. These results suggest that the continuation of voluntary exercise may be important for bone- mass enhancement in rat tibia.
The purpose of this study was to examine the effect of physical inactivity, produced by prolonged bed rest, on the excitability of the spinal motor neuron pool in humans, using the activity of soleus H-reflex. Eight healthy male subjects underwent continuous bed rest with 6 degree head-down tilt for 20 days (BR group) . Ten different healthy male subjects maintained their usual daily life during the observation period for 20 days (control group) . Recruitment curves of H-reflex and M-wave were obtained from every subject. H slope/M slope (H slp/M sip) which shows the excitability of spinal motor neurons was calculated by using data in the recruitment curve. The H sip/M sip in the BR group significantly increased after BR, compared to the pre-BR values (p<0.05) . In the control group, however, there were no significant differences in the H slp/M sip between the pre and the post-observation values. At the baseline, the H slp/M sip showed no significant differences between the BR group and the control group. After the BR, the H slp/M sip in the BR group significantly increased compared to the control group after the observation period (p<0.05) . This study suggests that the excitability of the monosynaptic spinal motor neuron pool is facilitated by physical inactivity during BR.
Side to side difference in tennis players' mid-radius and cross-sectional study on mid-tibia of jumpers and sedentary controls suggest that the improvement of mechanical properties of cortical bone in response to long-term exercise is related to geometric adaptation and not to volumetric bone mineral density. In the present study, geometric and mechanical properties of right tibia were estimated along 64 directions centering center of gravity of the bone on cross-sectional peripheral quantitative computed tomography (pQCT) images. The tibias of 17 jumpers (7 females, 10 males) and 15 controls (8 females, 7males), aged 18-23, were scanned at mid site using pQCT. Periosteal and endocortical radius were larger, cortical thickness was thicker, and mechanical properties (moment of inertia of area and strength strain index) were greater in jumpers compared to those of controls. The differences in cortical thickness between the two groups were dependent on direction of measurement. Defined a direction from tibia's center of gravity to fibula's as 0°, difference in the cortical thickness between jumpers and controls was the greatest at around 240°. Along this direction, differences in mechanical properties were also the most significant, suggesting that the site-specific adaptation of bone to long-term exercise is due to geographical relation of bone to muscle.
The purposes of this study were to 1) develop“cramp screening tests”to investigate susceptibility to exercise induced muscle cramp (EIMC) and 2) examine the effect of muscle fatigue and dehydra. tion-rehydration on EIMC using the tests. Twenty healthy male subjects were placed into three groups based on their experience of EIMC ; high (n=4, frequent cramps in daily life), low-medium (n=12, cramps with special conditions such as strenuous exercise), and no cramps (n=4), and performed two cramp screening tests for the toe flexors and hamstrings. The results indicated that the higher the frequency of muscle cramps in daily life, the higher the cramp induction rates in the tests. To investigate the effect of muscle fatigue on EIMC, 15 out of the 20 subjects performed 100 rhythmic isometric (knee joint angle of 90°) or isokinetic contractions (range of motion : 60-120°, flexion : 60°/s, extension ; 300°/s) of the knee flexors in separate days. Susceptibility to EIMC decreased in the exercised muscle after the fatiguing exercises, but significantly increased in the toe of the exercised limb. To verify the effect of dehydration on EIMC, nine out of the 20 subjects were dehydrated to reduce 3 % of body weight by an intermittent sauna exposure and rehydrated by giving the dehydrated amount of plain water. Dehydration significantly increased the susceptibility to EIMC, and rehydration did not contribute to decrease the susceptibility. These results suggest that the susceptibility to EIMC would be estimated by using the tests, and dehydration is associated with EIMC, but muscle fatigue does not seem to be a direct factor for EIMC.
The purpose of this study was to investigate differences between underwater and land-based exercise in leg muscle activity. Nine healthy males (mean age : 21.7±0.5 years, mean height : 173.4±2.2 cm) had electrodes placed on their left leg muscles (Tibialis Anterior ; TA, Medial Gastrocnemius ; MG, Soleus ; SOL, Rectus Femoris ; RF, and Biceps Femoris ; BF), and their muscle activity was measured during various exercises. The subjects performed six types of exercise such as the forward walk, backward walk, squat, calf raise, leg range, and one leg wave, both in the water (waist level) and on land. These exercises were categorized as 3 types of leg movement according to direction ; horizontal, vertical, and mixed movement. In the forward walk and backward walk, categorized as horizontal movements, the integrated electromyogram (IEMG) significantly increased during underwater exercise compared with on land. In the squat, as a vertical movement, the IEMG showed a similar change under both conditions. In the calf raise, as a vertical movement, and leg range and one leg wave, as mixed movements, the IEMG significantly decreased during underwater exercise compared with on land. These results suggest that leg muscle activity during underwater exercise is different based on the movement direction of the legs. In a word, it was apparent that movement in a horizontal direction underwater provides greater activity for leg muscles than on land; but movement in a vertical and/or mixed direction underwater provides less activity for leg muscles than on land. In prescribing an exercise program, it may be helpful to understand the differences between underwater and land-based exercise in leg muscle activity.
[Objective] The aim of this investigation was to evaluate salivary dehydroepiandrosterone (DHEA) responses during a competitive period among female football players. [Methods] Subjects were college female football players (n=9) . Saliva and blood samples were collected at 18 : 00 (6 : 00 pm) and the profile of mood state (POMS) was recorded during a period of normal training (Pre), 3 days of competition (Competition), and a recovery period (Post) . Levels of salivary DHEA, cortisol, and serum creatin kinase (CK), urea nitorogen (UN), were determined. [Results] The levels of salivary DHEA significantly increased during competition (2 nd days) compared with Pre (p<0.05), and significantly decreased after competition compared with Pre (p<0.05) . The levels of salivary cortisol significantly increased during the competition (2 nd and 3 rd days) compared with Pre (p<0.05) . Whereas it decreased after competition compared with Pre. The levels of serum CK significantly increased during the competition (2 nd days) compared with Pre (p<0.05) . The levels of serum UN did not change during the study. The fatigue score of POMS significantly increased during competition (2 nd days) compared with Pre (p<0.05) . [Conclusion] These data suggest that DHEA could be a useful endocrinological indicator for evaluating training status in female athletes.
The purpose of this study was to investigate the relationship among torque, motion of lower limbs during the take-off phase and muscle strength of lower limbs. Subjects were 12 male track and field athletes who had a top record of 6.84±0.41 m. Several variables of the 12 subjects, such as displacement, velocity, angle and angular velocity, and maximum torque of the knee and hip joints during the take-off phase, were obtained from film analysis and measurement of lower limb strength by Biodex. The main results were as follows: 1. Subjects who had a lower angular velocity of the take-off knee joint after landing showed a lower decreasing ratio of velocity during the takeoff phase. 2. There was a significant relationship between records for the long jump and hip flexion torque of the take-off leg during the last part of the take-off phase (r=-0.678, P<0.05) . 3. Subjects who showed a higher value of hip flexion torque of their free leg during the last part of the take-off phase showed lower take-off angles. 4. There was a significant relationship between knee extension strengths (60, 180, 300 deg/s) and knee joint angles at the middle of the take-off phase (r=0.700 P<0.01, r=0.672 P<0.05, r=0.751 P<0.01) . 5. Subjects who maintained a larger knee angle for their take-off leg indicated a decrease in knee extension torque of their take-off leg during the last part of the take-off phase. 6. Subjects who showed higher hip extension strength made the transition to hip flexion torque of the take-off leg from the middle to the last part of the take-off phase. From these results, it can be seen that knee extension strength is important for efficient take-off, and hip joint torque is one of the factors that influences one's record in the long jump.
In order to give more effective instruction for running in sports medicine, the mechanical stresses in the knee joint during running at various speeds and step lengths were investigated. The subjects were five male sprinters. Running conditions were as follows : 1) running at four speeds (2.5 m/s, 4.5 m/s, 6.5 m/s and maximum running speed) with natural step lengths, 2) run-ning with three different step lengths (1.0 m, 1.5m and preferred step length) at 4.5 m/s running speed, and 3) running at maximum speed using four different step lengths (1.0 m, 1.5m 2.5m and preferred step length) . Running movements were recorded using a high speed video camera. And ground reaction forces were also measured by a force platform. The compressive force and shear force in the tibiofemoral joint were computed from the results of two dimensional motion analysis. That is, the external force caused by ground reaction forces, the internal force produced by the mus-cle to develop joint torque and total force (external+internal force) were computed for both com-pressive and shear forces. The total compressive force that affects the meniscus and articular cartilage in the tibiofemoral joint depended on the magnitude of internal force. The total compressive force increased with running speed and step length. Therefore, caution should be employed in changing running speed and step length for regulating the magnitude of total compressive force on the tibiofemoral joint. On the other hand, the total shear force that caused traction stress in the posterior cruciate ligament depended on the magnitude of external force. The posterior shear force was generated during the foot contact period, and increased with step length. As for total shear force in the tibiofemoral joint, care must be taken to regulate step length.