The aerobic training reduces the artery stiffness and systolic blood pressure. The anaerobic training such as resistance training, however, is associated with higher artery stiffness. We hypothesized that low-intensity circuit training might improve the large artery stiffness. The purpose of this study was to determine the effects of long-term low-intensity circuit training on artery stiffness in sedentary women. Twenty healthy women divided into two groups (training group and control group). In the training group, subjects asked to perform the resistance exercises consisted of arm curls, bench presses, lateral pull-downs, leg presses and squats 3 days per week for 2 months. They conducted 5 sets at 30% of their 10RM. Aerobic capacity (ventilatory threshold [VT]), muscle strength, resting blood pressure, and arterial stiffness index (brachial-ankle Pulse Wave Velocity [baPWV]) were evaluated before and after training period. After the low-intensity circuit training, work rate at VT was significantly increased (108.6±25.6W to 128.1±24.3W). The baPWV was significantly decreased (988.7±80.5cm · sec-1 to 895.7±62.6cm · sec-1). In control group, however, there were no significant differences during same duration. These results suggested that long-term low-intensity circuit training attenuates the large artery stiffness in healthy women. This kind of exercise may have great potential to lower the risks of circulatory illness in aged men.
The purpose of this study was to investigate semitendinosus muscle (ST) behavior during isometric knee flexions. Healthy male subjects were directed to exert ramp isometric knee flexion up to a maximum of eight knee flexion angles (0, 15, 30, 45, 60, 75, 90, 105 degrees). Displacement of the tendinous intersection (TI) in ST was measured using ultrasonographic images. TI moved proximally 15.8±4.9mm by maximum isometric contraction at 0 degrees, and the displacement of TI was significant at over 30% ramp maximum. Maximum knee flexion torque significantly correlated to displacement of TI at every knee angle, and decreased as the flexion angle increased. These results suggested that TI moved proximally in accordance with flexion torque, and demonstrated the unique behavior of ST, that is, the proximal part concentrically contracted, whereas the distal part eccentrically contracted.
Background A behavioral science-based approach is essential for constructing effective intervention programs to promote the shift from a sedentary to active lifestyle. Recently, the influences of social and physical environment on physical activity have been recognized as key factors for promoting physical activity. The present study attempts to identify the social and physical environmental influences associated with physical activity promotion. Methods We recruited volunteers from a 14,000 population of community-dwelling adults. Seventy-two adults (intervention group : n=35, control group : n=37) participated in the present study. The intervention consisted of 8 sessions for 2 months using The Waseda Walking Program. We assessed social support for exercise, perceived neighborhood environment for walking, stages of change in exercise behavior and physical activity outcomes at baseline and 2 months. Ffifty-seven out of 72 subjects (intervention : n=30, control : n=27) completed all of the intervention including the final questionnaire. Results There were significant intervention effects on physical activity outcomes, stages of change and perceived neighborhood environment. However, no significant improvement in social support was found. In addition, improvement of perceived physical environment was related to an increase in physical activity. Conclusion Perceived neighborhood environment for walking would be identified as a key factor to influence an effect of physical activity promotion. On the other hand, social support would be influenced to the earlier stages of change in exercise.
The purpose of this study was to investigate the effect of constant endurance cycling exercise below Ventilatory Threshold (VT), under different pedal rate/torque regulations (PTR), on muscle oxygenation, as well as cardio-respiratory function and energy metabolism. Eight healthy male adults participated in the study for three tests. The first test was to examine the maximum oxygen uptake (VO2max) using a ramp loading measurement of 60 rpm, 20 watt/min ; and an individual 80%VT load was obtained. The second and third tests (random) were to measure heart rate (HR), blood pressure (MAP), expired gas and NIRS data before, during and after 30 min 80%VT constant cycling exercise with low pedal rate/high torque (LPHT : 32 rpm, 23.3±6.0Nm) or high pedal rate/low torque (HPLT : 79rpm, 9.4±2.4Nm). As a result, HPLT showed higher values in HR (p<0.001), MAP (p<0.001), VO2 (p<0.001), VCO2 (p<0.001) and RER (p<0.05), than LPHT ; but LPHT showed a higher fat consumption rate than HPLT (p<0.05). Significant PTR effect were recognized for the parameters of the tissue hemoglobin index (THI) (p<0.001) and oxygenation hemoglobin (ΔO2Hb) (p<0.01) ; and both indicated higher values for HPLT than LPHT ; but LPHT showed insignificantly (p=0.066) higher de-oxygenation hemoglobin (ΔHHb) than HPLT. Moreover, the significant time effects of THI and ΔO2Hb were also recognized. In conclusion, this study indicated that during constant cycling exercise below VT, HPLT might result in greater muscle blood volume, higher muscle oxygenation concentration and higher HR and VO2 compared with LPHT. These results suggest that, HPLT might be effective in alleviating the working load on lower limbs, as well as promoting muscle oxygenation, cardiorespiratory function (systemic oxygen supply) and energy metabolism. Therefore, HPLT constant cycling exercise below VT could be used in a rehabilitation program as a beneficial exercise for elderly people with decreasing muscle strength in their lower limbs.
The purpose of this study was to examine the effects of long-term habitual exercise on daily total energy expenditure (TEE) and its components, body composition and maximal oxygen uptake (VO2max) in middle-aged Japanese women. Twenty-eight subjects aged 39 to 58 years were assigned either to a nonhabitual exercise group (Control ; n=12) or a habitual exercise group (Exercise ; n=16). TEE, physical activity level (PAL) and the daily physical activity energy expenditure (PAEE) were assessed by doubly labeled water (DLW) method. The exercise-induced energy expenditure (ExEE) and nonexercise-induced energy expenditure (NExEE) were evaluated based on the activity record investigation conducted simultaneously during the DLW measurement period. The result follows that TEE was significantly (p<0.01) higher in the Exercise group (2520 kcal · day-1) than in the Control group (1921 kcal · day-1). There was no significant difference in basal metabolic rate between the groups. PAEE and ExEE were significantly higher in the Exercise group than in the Control group (p<0.01). Habitual exercise induced an increase in TEE without resulting in a compensatory reduction of NExEE. The percentage body fat (fat%) was significantly lower in the Exercise group (25.5%) than in the Control group (30.9%). VO2max was higher in the Exercise group (1788 ml · min-1) than in the Control group (1417 ml. min-1). After correction for body weight, fat% was negatively associated with TEE (p<0.01), PAEE (p<0.01) and ExEE (p=0.05), while VO2max was positively associated with TEE (p<0.05), PAL (p<0.05), PAEE (p<0.05) and ExEE (p<0.01). These results suggest that habitual exercise is associated with the increase of TEE, the improvement of body composition and VO2max. The improvement of VO2max was mainly caused by the increase in ExEE, indicating that the exercise intensity is important to the improvement of cardiorespiratory endurance fitness.
The purpose of this study was to examine the effects of dynamic neck muscle training using a cervical extension machine (CEM) on isometric cervical extension strength (ICES) and a cross-sectional area of neck extensor muscles. Subjects were 18 male college judo athletes divided into a control group (n=10) and training group (n=8), respectively. In the training group, dynamic neck muscle training was performed for a 6 week training period, followed by a 10 week training period. There was a detraining period of 12 weeks between the first training period and the second. The ICES was measured at eight angles using a CEM, and the neck muscle cross-sectional area was determined using magnetic resonance imaging. The ICES and cross-sectional area of neck extensor muscles in the training group showed significant increases after the second training period. In particular, the increase in the cross-sectional area was greater in the deepest layer of the neck extensor muscles (rotator, multifidus and semispinaris cervicis muscles) than in the superficial layer (trapezius muscle). In the control group, no significant changes in ICES or cross-sectional area were observed. In conclusion, it was shown that dynamic neck muscle training using a CEM was effective in developing both ICES and the cross-sectional area of neck extensor muscles, especially in the deepest layer.
To clarify the effects of varying skin temperature due to several types of clothing on temperature responses and heat-stress during exercise, we analyzed thermoregulatory responses while wearing various types of sportswear including soccer (SC), baseball (BB), and fencing uniforms (FU), and while wearing water-perfused suits (WS) and vests (WV) during exercise in a hot environment. We also compared these results with those obtained under a semi-nude condition (NU). Eight male subjects performed three 20-min cycling sessions at light intensity (250W/m2) in a room maintained at 28°C (wet-bulb globe temperature, WBGT). The experiment was performed under ten conditions, with six sets of clothing, WS and WV at 14°C (WS14, WV14), 20°C (WS20, WV20) and 26°C (WS26, WV26), and FU, SC, BB or NU. While wearing sport-swear, increases in esophageal (ΔTes), mean skin (Tsk), mean body (Tb) temperature, heart rate (HR), thermal sensation (TS) at the end of exercise, and total sweat loss (msw,tot) during exercise were significantly (p<0.01) higher in BB and FU than in NU. In comparison to WS or WV conditions, ΔTes was significantly (p<0.01) higher under WV conditions than under NU, while there was no significant difference in ΔTes between WS and NU. Tsk, Tb, HR, TS and msw,tot tended to be lower in WS14 and 20, and higher in WV26 than in NU. Under all conditions at the end of exercise, the ΔTes markedly increased when Tsk exceeded 34°C ; and ΔTes was significantly correlated with Tsk (r=0.861, p<0.01) for all conditions except WS14 and 20. For Tsk less than 34°C, however, ΔTes remained constant. ΔTes, Tsk, and Tb significantly correlated with HR (r=0.932, p<0.001), TS (r=0.888, p<0.001), and msw,tot (r=0.961, p<0.001), respectively. These results show that during light exercise under hot conditions, 1) in several types of clothing, a critical level of skin temperature causing core temperature elevation may exist, 2) cooling the skin temperature can alleviate heat-stress due to body temperature elevation, and 3) the semi-nude condition is the simplest method of alleviating core temperature elevation without using body cooling materials such as WS or WV.
Markedly smaller myofibers including branched myofibers (SF) were contained in regenerated skeletal muscles. However, its functional properties are not yet sufficiently understood. The present study examined the metabolic, contractile properties and hypertrophy of SF included in rat skeletal plantaris muscles regenerated from eccentric contraction-induced muscle injury. Succinate dehydrogenase and alpha-glycerophosphate dehydrogenase activity of SF were respectively similar to that of other normal size myofibers (NF) within regenerated muscles. The shortening velocity of skinned fibers prepared from branched myofibers isolated from regenerated muscles was slightly slower than that of control muscles. In addition, the extent of glycogen depletion in SF was similar to that of NF after exhaustive running. Therefore, SF were innervated by motoneurons and recruited during the contractile activity of the skeletal muscle. No matter when the regenerated muscle was loaded by synergistic ablation, the continued existence of SF was observed. Therefore, the ability of hypertrophy in SF may be distinct from that in NF. The physiological properties of SF were similar to that of normal myofiber, except for the ability to regulate hypertrophy.
The present article briefly overviews the principal pathway of ethanol metabolism in the liver cell and hormonal regulations of ethanol metabolism, and a relationship between alcohol drinking volume (=alcohol consumption) and the degree of alcohol intoxication. This article also focuses on a possible mechanism of sex difference in rat liver cytosolic alcohol dehydrogenase (ADH) activity, and the effects of bile, bile acids, vegetable oils and unsaturated fatty acids on plasma ethanol levels and gastric emptying in ethanol-administered rats. Finally, the recent findings concernig a relationship between alcohol drinking and human health are described.