Isao Muraoka

Recommended level of physical activity and health-related quality of life among Japanese adults

BackgroundThe benefits of a recommended level of physical activity on physiological health indicators such as morbidity and mortality are well-accepted, but less research has addressed whether or not the association between the recommended level of physical activity and a health-related quality of life (HRQOL) exists in the Japanese population. Thus, the present study examined whether the recommended physical activity would be associated with HRQOL in the general Japanese middle-aged population.MethodsData were obtained from 1211 male and female respondents (39.4 ± 10.9 year, mean ± SD) from an Internet-based survey of registrants of an Internet research service. Physical activity level was estimated from the short form of the International Physical Activity Questionnaire. HRQOL was assessed with the Medical Outcomes Survey Short Form-8 questionnaire (SF-8). Based on the current national guidelines for exercise in Japan, respondents were divided into a recommended group, an insufficient group, and an inactive group according to their estimated weekly physical activity level. Multivariate analyses of covariance were utilized.ResultsAcross both genders, the recommended group had significantly higher physical functioning (PF) scores than the inactive group (p < .05). Additionally, across both genders, the recommended group had significantly higher general health perception scores than the insufficient and inactive groups (p < .05). The recommended group had significantly higher vitality scores than the insufficient and inactive groups in males, and higher than only the inactive group in females (p < .05). The insufficient group had significantly higher PF scores than the inactive group across both genders (p < .05). The recommended group had significantly higher physical component scores than the inactive group (p = .001).ConclusionIndividuals who attained the recommended level of physical activity had better scores on some dimensions of HRQOL than those who did not, suggesting that the recommended level of physical activity may be applicable not only to the physiological objective outcomes but also to some dimensions in both the physical and mental aspects of HRQOL.

Psychological, social, and environmental factors to meeting physical activity recommendations among Japanese adults

BackgroundAlthough the benefits of the recommended level of physical activity on reducing chronic diseases are well-established, most of the Japanese population is not sufficiently active. Thus, examining correlates is an important prerequisite for designing relevant polices and effective programs. The present study investigated psychological, social, and environmental factors associated with meeting physical activity recommendations among Japanese adults.MethodsData were analyzed for 1,932 men and women (43.6 ± 13.0 years), who responded to an Internet-based cross-sectional survey. Self-reported measure of physical activity, psychological (self-efficacy, pros, and cons), social (social support, health professional advice), environmental (home fitness equipment, access to facilities, neighborhood safety, enjoyable scenery, frequently observing others exercising, residential area), and demographic (gender, age, marital status, educational level, household income level, employment status) variables were obtained. Based on the current national guidelines for exercise in Japan (23 METs·hour per week), respondents were divided into two categories–recommended and not recommended (insufficient and inactive)–according to their estimated weekly physical activity level. An adjusted logistic regression model was utilized.ResultsWhen adjusting for all other variables, self-efficacy (men: OR = 2.13; 95% CI: 1.55–2.94, women: OR = 2.72; 95% CI: 1.82–4.08) and possessing home fitness equipment (men: OR = 1.55; 95% CI: 1.14–2.10, women: OR = 1.41; 95% CI: 1.01–1.99) for both genders, social support (OR = 1.44; 95% CI: 1.06–1.97) for men, and enjoyable scenery (OR = 1.60; 95% CI: 1.09–2.36) for women were positively associated with attaining the recommended level of physical activity. In women, cons (OR = 0.47; 95% CI: 0.33–0.67) and living in rural areas (OR = 0.50; 95% CI: 0.25–0.97) were negatively associated with meeting the physical activity recommendations.ConclusionIn the psychological, social, and environmental domains, significant correlates of attaining the recommended level of physical activity were observed. Men and women had different patterns of psychological, social, and environmental correlates. These findings suggest that an intervention design that accounts for those correlates may more effectively promote physical activity among Japanese adults.

Fasting-related autophagic response in slow- and fast-twitch skeletal muscle.

This study investigated regulation of autophagy in slow-twitch soleus and fast-twitch plantaris muscles in fasting-related atrophy. Male Fischer-344 rats were subjected to fasting for 1, 2, or 3 days. Greater weight loss was observed in plantaris muscle than in soleus muscle in response to fasting. Western blot analysis demonstrated that LC3-II, a marker protein for macroautophagy, was expressed at a notably higher level in plantaris than in soleus muscle, and that the expression level was fasting duration-dependent. To identify factors related to LC3-II enhancement, autophagy-related signals were examined in both types of muscle. Phosphorylated mTOR was reduced in plantaris but not in soleus muscle. FOXO3a and ER stress signals were unchanged in both muscle types during fasting. These findings suggest that preferential atrophy of fast-twitch muscle is associated with induction of autophagy during fasting and that differences in autophagy regulation are attributable to differential signal regulation in soleus and plantaris muscle.

Differential cell death regulation between adult-unloaded and aged rat soleus muscle

Sarcopenia is characterized by increased regenerating myofibres and decreased myofibre size. Sarcopenia progression might be partially regulated by ageing-related signals associated with necrotic fibre disruption and nuclear apoptosis. This study sought to identify ageing-related signals in aged atrophying skeletal muscle by comparison with unloaded muscle atrophy in adults. Adult (6-month) and old (32-month) rats were used. Some adult rats were subjected to 2 weeks of hindlimb unloading (6-month-HU). Histological analysis found that regenerating fibres increased by about 30-fold only in 32-month aged soleus muscle compared with 6-month rats. The number of apoptotic DNA fragmented nuclei was increased by 3.9-fold in 6-month-HU and 2.8-fold in 32-month rats. Cleaved caspase-3 was observed at high levels on basal membranes and in nuclei in 32-month rats. By Western blot analysis additional ageing-related signals could be identified since (1) phosphorylated Bcl-2 content was increased in both cytosolic and mitochondrial fractions; (2) ER stress signal proteins caspase-12, CHOP/GADD153, and GRP78 were increased; and (3) stress-inducible chaperone HSP70 was decreased in soleus muscle from 32-month but not changed in 6-month-HU rats. We conclude that activation of ageing-related signals may mediate necrotic myofibre disruption and nuclear apoptosis induction that contribute to progression of sarcopenia.

Influence of two different modes of resistance training in female subjects

In resistance training, it has been empirically accepted that muscle hypertrophy is developed by low intensity and high volume training, while muscle strength and power are developed by high intensity and low volume training. The purpose of the present study was to investigate the influence of two different modes of resistance training on isokinetic strength and muscle cross-sectional area (CSA) in females. Eleven females, who had no experience in resistance training, participated in this study and were randomly divided into two groups. The former consisted of 4-5 sets of 15-20 RM (repetition maximum) with sufficient rest between sets (Group H), while the latter consisted of 8-9 sets of 4-6R M with 90 s of rest between sets (Group S). The former was assumed to be appropriate for muscle hypertrophy and the latter muscle strength, respectively. All subjects completed isotonic knee extension exercise three times a week for 8 weeks. Measurements were made on quadriceps muscle cross-sectional area (CSA) and isokinetic torques at 0, 60, 180, and approximately 300 degrees before training, at the fifth week and the end of training period. Muscle CSA was defined as the sum of CSA measured at 30, 50 and 70% of femur length. After training, muscle CSA had significantly increased in both groups: 3.3 +/- 0.7% (p < .05) for group H and 3.6 +/- 1.1% (p < .05) for group S, respectively. While the changes in isokinetic torque were 43.4 +/- 47.5% (p < .05) for group H and 27.4 +/- 31.3% (p < .05) for group S, respectively. In both groups the percentage changes of the isokinetic strength were significantly higher than those of the CSA. No significant difference in these variables were found between the two groups. These results suggest that during the early phase of resistance training two different modes of resistance training may have similar effects on muscle CSA and isokinetic strength in untrained females.

Prolonged exercise training induces long-term enhancement of HSP70 expression in rat plantaris muscle.

Skeletal muscle may develop adaptive molecular chaperone enhancements as a potential defense system through repeated daily exercise stimulation. The present study investigated whether prolonged exercise training alters the expression of molecular chaperone proteins for the long term in skeletal muscle. Mature male Wistar rats were subjected for 8 wk to either a single bout of acute intermittent treadmill running (30 m/min, 5 min x 4, 5 degrees grade) or prolonged treadmill running training (15-40 m/min, 5 min x 4, 5-7 degrees grade). Levels of five molecular chaperone proteins [heat shock protein (HSP)25, HSP60, glucose-regulated protein (GRP)78, HSP70, and heat shock cognate (HSC)70] were measured in response to acute exercise and prolonged training. HSP70 levels were increased 6 and 24 h after acute exercise, but expression returned to control level within 2 days. In contrast, prolonged training had a long-term effect on HSP70 expression. Levels of HSP70 were notably increased by 4.5-fold over control 2 days after prolonged training; the enhancement was maintained for at least 14 days after training ended. However, other molecular chaperone proteins did not show adaptive changes in response to prolonged training. In addition, HSP70 enhancement by prolonged exercise training was not accompanied by transcription of HSP70 mRNA. These findings demonstrate that prolonged training can induce long-term enhancement of HSP70 expression without change at the mRNA level in skeletal muscle.

Forearm vascular responses to combined muscle metaboreceptor activation in the upper and lower limbs in humans

Our previous studies showed that venous occlusion or passive stretch of the lower limb, assuming a mechanical stimulus, attenuates the vasoconstriction in the non‐exercised forearm during postexercise muscle ischaemia (PEMI) of the upper limb. In this study, we investigated whether a metabolic stimulus to the lower limb induces a similar response. Eight subjects performed a 2 min static handgrip exercise at 30% maximal voluntary contraction (MVC) followed by 3 min PEMI of the upper limb, concomitant with or without 2 min static ankle dorsiflexion at 30% MVC followed by 2 min PEMI of the lower limb. During PEMI of the upper limb alone, forearm blood flow (FBF) and forearm vascular conductance (FVC) in the non‐exercised arm decreased significantly, whereas during combined PEMI of the upper and lower limbs, the decreases in FBF and FVC produced by PEMI of the upper limb was attenuated. Forearm blood flow and FVC were significantly greater during combined PEMI of the upper and lower limbs than during PEMI of the upper limb alone. When PEMI of the lower limb was released after combined PEMI of the upper and lower limbs (only PEMI of the upper limb was maintained continuously), the attenuated decreases in FBF and FVC observed during combined PEMI of the upper and lower limbs was not observed. Thus, forearm vascular responses differ when muscle metaboreceptors are activated in the upper limb and when there is combined activation of muscle metaboreceptors in both the upper and lower limbs.

Cardiorespiratory functions in children with high and low performances in endurance running

SummaryTo elucidate the characteristics of cardiorespiratory functions during exercise in young children in relation to their performances in endurance running, Twenty six 6-year-old children participated in the present study. They were divided into two groups (fast and slow) from the results of three endurance performances (1,500 m, 4,000 m, and 8,850 m).Maximal oxygen uptake (

Resistance Training Augments Cerebral Blood Flow Pulsatility: Cross-Sectional Study

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