Effects of Changes in Frequency of Going Out during the COVID-19 Pandemic on ikigai (Sense of Purpose in Life) and Mental Health in Middle-Aged and Older Adults in Japan.

To clarify whether changes in frequency of going out due to the COVID-19 pandemic affect ikigai (sense of purpose in life) and mental health in Japanese middle-aged and older adults. In a questionnaire survey mailed to 16,866 adults aged > 40 years in Japan in September 2020, 7,973 responses were received (response rate, 47.3%) in October 2020. Following exclusions, data from 6,978 individuals (50.6% female, mean age 67.8 ± 12.2 years) were available for analysis. Respondents were categorized based on changes in frequency of going out, reflecting changes in social and/or physical activity, during the pandemic compared with before it: the previously active group went out often before but less often during the pandemic; the remained active group continued going out often; and the inactive group continued not going out often. Whether these changes affected the respondents' ikigai and mental health was investigated. The previously active group had a significantly higher proportion of individuals with decreased ikigai during the pandemic than the other groups. Mental health score decreased in all groups during the pandemic, but more so in the previously active group (-3.21), followed by the inactive and then the remained active groups (-1.45 and -1.28, respectively). Previously active individuals showed the greatest decline in ikigai and mental health among the three groups. These findings suggest that continuing to engage in appropriate physical and social activities, including going out, while following appropriate infection control measures, even under restrictions, can help people maintain ikigai and mental health.

Impact of subjective well-being on physical frailty in middle-aged and elderly Japanese with high social isolation.

Social isolation exacerbates physical frailty and is associated with subjective well-being. Even those with high levels of social isolation may have different health statuses depending on the type of isolation and their subjective well-being. However, the effect of subjective well-being on the relationship between social isolation and physical frailty remains unclear. This study examined whether the risk of physical frailty was the same for individuals with social isolation according to high and low subjective well-being. The study participants included 1,953 middle-aged Japanese adults aged 45 years and older. Physical frailty was assessed using a modified version of the Fried phenotype criteria. Probabilistic Latent Semantic Analysis was used to classify participants according to social isolation indicators. Subsequently, we focused on the groups with high social isolation and classified them according to whether their subjective well-being was high or low. Subjective well-being was evaluated using the Shiawase and Ikigai scales, which are concepts used in Japan. Finally, we used survival time analysis to examine the relationship between Shiawase or Ikigai and physical frailty in groups with high social isolation. The participants were classified into four groups based on their social isolation status. The physical frailty rate of the high social isolation class was 37.0%, which was significantly higher than that of the other classes. Survival time analysis revealed that among people with high social isolation, those with high Shiawase and Ikigai had a significantly lower risk of physical frailty than those with low Shiawase and Ikigai. All individuals with high social isolation are not at a high risk of physical frailty. The findings reveal that even those with high level of social isolation may have a lower risk of physical frailty if their subjective well-being is high. These results will contribute to promoting the prevention of frailty in middle-aged and older adults.

Does participation in municipality-initiated incentivized health promotion programs promote physical activity among the physically inactive? Verification in six Japanese municipalities.

Background: Physical activity can prevent lifestyle-related diseases, such as hypertension and diabetes. However, many people in society are physically inactive, especially middle-aged and older adults over 40. Therefore, this study examined the effects of a municipality-led incentivized health promotion program to clarify: (1) whether the average number of steps increased from the preparticipation period to the 18th month following the program; and (2) whether such increases were influenced by financial incentives. Design and methods: This study analyzed gender, age, step, and incentive type data from 5688 middle-aged and elderly participants in an incentivized health promotion program. The incentives were regional gift certificates that could only be used in local areas, national gift certificates, common points that could be used in department and convenience stores nationwide, and donations. The incentives were worth a maximum of 24,000 yen per year. Results: Both the physically active group and the physically inactive group had increased the step count markedly 18 months post-participation; however those participants chosing financial incentives showed significantly higher steps after 18 months than those who opted for non-financial incentives (time: p < 0.05, time × group: p < 0.05). Conclusions: Municipality-led financially incentivized health promotion programs could motivate increases in the average number of steps taken by those physically inactive residents.

A Structural Analysis of the Effects on the Lifestyle and Health Status of Exercise Class Participants Owing to COVID-19 Prevention Measures.

Objectives: In this study, we aimed to clarify and measure the interrelationships among decrease in communication, exercise, and physical and mental health under COVID-19 prevention measures, restricting individuals from going out of the house. Methods: Participants included 540 middle-aged and older adults who are regular exercise class members. The survey was conducted between April 15 and May 10, 2020. For the self- administered questionnaire survey, a municipal employee of City A and an exercise instructor visited the home of each participant to collect the survey data. The survey items were sex, age, limitation of going out, feeling of inactivity, interaction with others, health status, and forgetfulness; a covariance structural analysis was performed to clarify the interrelationship between lifestyle and health status. Results: Restrictions on going out due to the COVID-19 prevention measures were associated with the physical and mental health of middle-aged and older adults who regularly attended exercise classes because they enforced inactivity and decreased the frequency of conversation. Conclusions: Several waves of COVID-19 may arrive in Japan in the future. Therefore, it is necessary to implement measures to prevent secondary health damage and not focus only on infection prevention.

Changes in radioactive cesium concentrations from 2011 to 2017 in Fukushima coastal sediments and relative contributions of radioactive cesium-bearing microparticles.

Sedimentary cesium-137 concentrations around the Fukushima Daiichi Nuclear Power Plant (FDNPP) were measured from 2011 to 2017 at eight stations. Although high values were observed until 2013, decreasing trends were observed at the surface sediments of seven stations. We isolated 25 radioactive Cs-bearing microparticles (CsMPs; 1.0-5385 Bq per particle). The contribution ratio of CsMPs to each sample ranged from 4.1% to 99.5% (median 58.8%), with the contribution ratio of the CsMPs in the southern part of the FDNPP was low compared to that from the northern part. In the southern part of the FDNPP, small CsMPs that could not be isolated in this study were present in large quantities immediately after the accident, and gradually diffused away and/or were dissolved over time. In contrast, the CsMPs in the northern part of the FDNPP have most likely accumulated over time, as suggested by the silty nature of the sediments there.

Spatial variation in sedimentary radioactive cesium concentrations in Tokyo Bay following the Fukushima Daiichi Nuclear Power Plant accident.

Cesium-137 concentrations in sediment (137Cs) at Tokyo Bay were measured at 26 stations during 2017. Average 137Cs concentrations at the Arakawa river mouth (117 ±â€¯46 Bq kg-1) were approximately six times higher than those of the other stations in the bay (20 ±â€¯16 Bq kg-1). There were radiocesium-bearing microparticles in the bay sediment as well as in suspended matter of Fukushima coastal waters. Radioactivity of radiocesium-bearing microparticles was estimated to be 0.12 Bq. However, the contributions of radiocesium-bearing microparticles to each 137Cs concentration of the bulk sample were low; 3% was the maximum. The 137Cs inventory in sediment at the entire bay was 0.67 TBq, showing that a large amount of 137Cs was supplied to the bay from the river following the Fukushima Daiichi Nuclear Power Plant accident. Approximately 9.2% of the 137Cs which was fallout in the drainage basin has already flowed into the bay from the watershed, which is approximately 3.2 times higher than that of a previous estimate.

Radioactive cesium concentrations in coastal suspended matter after the Fukushima nuclear accident.

Radioactive cesium concentrations in the suspended matter of the coastal waters around the Fukushima Daiichi Nuclear Power Plant (FDNPP) were investigated between January 2014 and August 2015. The concentrations of radioactive cesium in the suspended matter were two orders higher in magnitude than those determined in the sediment. In addition, we discovered highly radioactive Cs particles in the suspended matter using autoradiography. The geometrical average radioactivity of particles was estimated to be 0.6 Bq at maximum and 0.2 Bq on average. The contribution ratio of highly radioactive Cs particles to each sample ranged from 13 to 54%, and was 36% on average. A major part of the radioactive Cs concentration in the suspended matter around the FDNPP was strongly influenced by the highly radioactive particles. The subsequent resuspension of highly radioactive Cs particles has been suggested as a possible reason for the delay in radioactive Cs depuration from benthic biota.

Effects of daily walking on intermuscular adipose tissue accumulation with age: a 5-year follow-up of participants in a lifestyle-based daily walking program.

PURPOSE: Intermuscular adipose tissue (IMAT) accumulates with age. However, there has been no long-term intervention study examining whether daily walking prevents or decreases the age-related IMAT accumulation. The purpose of this study was to determine effects of a long-term lifestyle-based daily walking program on age-related IMAT accumulation after a 5-year follow-up. METHODS: Using a pedometer, daily step count was evaluated for 5 years in 24 middle-aged and elderly male and female participants. Using magnetic resonance imaging, thigh muscle, thigh subcutaneous adipose tissue, IMAT, abdominal subcutaneous adipose tissue, and visceral adipose tissue were examined at baseline and after 5 years. RESULTS: After 5 years, there was no significant increase in IMAT in all participants. In addition, IMAT significantly decreased in participants with a daily step count of > 9000 (4.0 ± 2.1 vs. 3.1 ± 1.6 cm2; p < 0.05). Moreover, changes in IMAT within 5 years correlated with changes in daily step counts, even after adjusting for confounding factors (p < 0.05). CONCLUSIONS: Long-term lifestyle-based daily walking program prevented the age-related IMAT accumulation in middle-aged and elderly adults. Furthermore, increased daily walking correlated with decreased IMAT over 5 years.

Who opts out of a project for health promotion with incentives?: Empirical research on the effect of rewards to motivate persistence.

Objectives　Although providing incentives for a better lifestyle has been of increasing concern, there is insufficient evidence about its effect. Therefore, this research aims to discover new insights by verifying the effect of rewards to motivate persistence in a project for health promotion.Methods　A total of 7,622 participants of an incentivized project for health promotion (Wellness Point Project) were recruited from 6 municipalities in Japan, namely Tohoku, Chubu, Kanto, Kinki, and Chugoku, of which the 4,291 individuals who had the necessary information for estimation were analyzed. Persistence in the project was judged by whether there was information about daily steps and/or participation in some fitness classes every month for one year at most. In addition, we used the reason participants chose certain rewards in order to categorize the characteristic of rewards, and estimated opt-out hazard ratios from the project using survival time analysis. Furthermore, the estimation in the model included individual features such as age, education, status of physical activity before joining the project, lifestyles such as smoking, drinking, and so on.Results　A multivariate analysis reveals that those who had chosen a reward for regional contribution were more likely to opt out than those who had chosen a certain reward because it is close to cash. The opt-out hazard ratio was 1.63 (95% CI: 1.18-2.25) among men and 1.40 (95% CI: 1.08-1.81) among women. In addition, insufficient physical activity, smoking, working for men, and physical condition for women were associated with opt-out.Conclusions　This research verified that a reward that participants felt was close to cash, compared to the internal motivation of regional contribution, could enhance the persistence rate of the project. Moreover, it was found that not only giving incentives but also considering participants' conditions is necessary to enhance persistence.

Relationship between thigh intermuscular adipose tissue accumulation and number of metabolic syndrome risk factors in middle-aged and older Japanese adults.

BACKGROUND: To evaluate the association between thigh intermuscular adipose tissue accumulation and number of metabolic syndrome risk factors in middle-aged and older Japanese adults. METHODS: Thigh muscle cross-sectional area, subcutaneous adipose tissue, thigh intermuscular adipose tissue, abdominal subcutaneous adipose tissue, and visceral adipose tissue were measured in 166 middle-aged and older (mean age, 69years) Japanese adults using magnetic resonance imaging. Daily physical activity was calculated using pedometers, and energy intake per day was evaluated using 3-day dietary records. Multiple linear regression analysis was used to assess the association between intermuscular adipose tissue and the number of metabolic syndrome risk factors. RESULTS: Multiple regression analysis indicated that intermuscular adipose tissue was significantly associated with the number of metabolic syndrome risk factors, after adjusting for age, sex, body mass index, daily physical activity, energy intake, thigh muscle cross-sectional area, and visceral adipose tissue (p<0.05). CONCLUSIONS: Thigh intermuscular adipose tissue accumulation was significantly associated with the number of metabolic syndrome risk factors in middle-aged and older Japanese adults, independent of age, sex, body mass index, daily physical activity, energy intake, thigh muscle cross-sectional area, and visceral adipose tissue.

Objectively measured light-intensity lifestyle activity and sedentary time are independently associated with metabolic syndrome: a cross-sectional study of Japanese adults.

BACKGROUND: Reducing sedentary time and increasing lifestyle activities, including light-intensity activity, may be an option to help prevent metabolic syndrome (MetS). The purpose of the present study was to examine whether objectively measured light-intensity lifestyle activity and sedentary time is associated with MetS, independent of moderate-vigorous intensity physical activity (MVPA). METHODS: The participants in this cross-sectional study were 483 middle-aged Japanese adults, aged 30-64 years. The participants were divided into those with or without MetS according to the Japanese criteria for MetS. A triaxial accelerometer was used to measure light-intensity lifestyle activity [1.6-2.9 metabolic equivalents (METs)] and sedentary time (≤1.5 METs). Logistic regression was used to predict MetS from the levels of light-intensity lifestyle activity and sedentary time with age, sex, smoking, calorie intake, accelerometer wear time, and MVPA as covariates. RESULTS: The odds ratios (OR) for MetS in the highest and middle tertiles of light-intensity lifestyle activity were 0.44 [95% confidence interval (CI): 0.24 to 0.81] and 0.51 (95% CI: 0.29 to 0.89) relative to the lowest tertile, after adjustment for age, sex, smoking, calorie intake, accelerometer wear time and MVPA (Ptrend = 0.012). Sedentary time was also associated with the risk of MetS (Ptrend = 0.018). Among participants in the highest tertile of sedentary time, the risk of MetS was 2.27-times greater than that in the lowest tertile (95% CI: 1.25 to 4.11). The risk of MetS was not significantly increased in subjects in the middle tertile of sedentary time. CONCLUSIONS: We found that light-intensity lifestyle activity and sedentary time were significantly associated with the risk of MetS, independent of MVPA. The results of our study suggest that public health messages and guidelines should be refined to include increases in light-intensity lifestyle activity and/or decreases in sedentary time, alongside promoting MVPA, to prevent MetS.

Lifestyle-based physical activity intervention for one year improves metabolic syndrome in overweight male employees.

Regular physical activity is associated with improvements of metabolic syndrome (MetS) risk factors. Furthermore, recent physical activity guidelines for health promotion recommend that moderate to vigorous physical activity should be performed in bouts lasting ≥ 10 min. Brisk walking is a popular and readily attainable form of moderate intensity physical activity and is suitable for the majority of individuals. However, it is unclear whether brisk walking lasting ≥ 10 min is associated with improvement in MetS. This study aimed to determine the effects of a 1-year lifestyle-based physical activity intervention with brisk walking of ≥ 10 min using a pedometer on the improvement in MetS. Three hundred and seventy-six overweight male employees with ≥ 1 MetS component(s) participated in this intervention study from 2008 to 2009 (age, 30-62 years; body mass index, 23.0-45.5 kg/m(2)). Overall, 316 participants (84%) completed the 1-year intervention. MetS was defined according to the Japanese criteria at baseline and after 1 year. Brisk walking lasting ≥ 10 min was significantly associated with the decrease in waist circumference (ß = -1.479) and triglyceride (ß = -31.260), and the increase in high-density lipoprotein cholesterol (ß = 2.117). The brisk walking step counts were also significantly associated with higher odds for an improvement in MetS (OR, 1.48; 95% CI, 1.05-2.09) and abdominal obesity (OR, 1.45; 95% CI, 1.12-1.87). In conclusion, the lifestyle-based intervention with brisk walking of ≥ 10 min is an effective strategy to improve MetS in overweight male employees.

Association between physical activity and metabolic syndrome in middle-aged Japanese: a cross-sectional study.

BACKGROUND: Although many studies have reported an association between self-reported physical activity and metabolic syndrome (MetS), there is limited information on the optimal level of physical activity required to prevent MetS. This study aimed to determine the association between objectively measured physical activity and MetS in middle-aged Japanese individuals. We also determined the optimal cutoff value for physical activity required to decrease the risk of developing MetS. METHODS: A total of 179 men and 304 women, aged between 30 and 64 years, participated in this study. Participants were divided into two groups using the Japanese criteria for MetS as those with MetS or pre-MetS, and those without MetS. Participants were considered to be physically active if they achieved a physical activity level of 23 metabolic equivalents (METs) h/week, measured using a triaxial accelerometer. The association between physical activity and MetS was analyzed using logistic regression with the following covariates: sex, age, sedentary time, low intensity activity, calorie intake, smoking, menopause and body mass index. We also evaluated the factors that determined the association between the prevalence of MetS and pre-MetS and the physical activity cutoff value using classification and regression tree (CART) analysis. RESULTS: The odds ratio for MetS and pre-MetS was 2.20 for physically inactive participants (< 23 METs h/week), compared with physically active participants (≥ 23 METs h/week). The corresponding odds ratios for men and women were 2.27 (P < 0.01) and 1.95 (not significant), respectively. CART analyses revealed that moderate-vigorous physical activity of > 26.5 METs h/week was sufficient to decrease the prevalence of MetS and pre-MetS in middle-aged Japanese men and women. CONCLUSIONS: The results of this cross-sectional study indicate that the Exercise and Physical Activity Reference for Health Promotion 2006 is inversely associated with the prevalence of MetS in men. Our results also suggest that moderate physical activity of > 26.5 METs h/week may decrease the risk of developing MetS and pre-MetS in middle-aged Japanese individuals.

Age differences in the relation between ACTN3 R577X polymorphism and thigh-muscle cross-sectional area in women.

The relation between ACTN3 R577X polymorphism and muscle mass in women has been reported, but its relation to age remains unclear. We investigated the relationship between ACTN3 R577X polymorphism and muscle mass in both middle-aged and elderly women. Two age groups (middle-aged and older) were formed among 162 healthy, nontraining Japanese women (mean ± SE, 58.6 ± 0.8 year). Their midthigh-muscle cross-sectional area (CSA) was assessed using magnetic resonance imaging, revealing no difference in thigh-muscle CSA among ACTN3 R577X genotypes in the middle-aged group (XX, 87.3 ± 2.5 cm(2); RR&RX, 86.1 ± 1.7 cm(2), p=0.7). In contrast, the XX genotype in the older group had a smaller thigh-muscle CSA adjusted to body weight than the RR&RX genotypes (XX, 67.8 ± 2.0 cm(2); RR&RX, 72.5 ± 1.2 cm(2), p<0.05). The present study showed an association between ACTN3 R577X polymorphism and smaller thigh-muscle CSA in a group of elderly women but not in a group of middle-aged women.

Effects of three consecutive days exercise on lymphocyte DNA damage in young men.

Intense exercise affects the immune system. This study examines effects of three consecutive days of 1 h high-intensity exercise on lymphocyte counts, oxidative DNA damage, and apoptosis in young untrained (n = 8, 23.8 +/- 3.2 years; UT) and endurance-trained (n = 8, 21.1 +/- 3.7 years; TR) subjects. The subjects performed cycle ergometer exercise at 75% VO2max 1 h daily for three consecutive days (exercise session). Blood samples were collected before exercise on the first day of the exercise session (day 1, D1) and at 24 h after the session (day 4, D4). Total lymphocyte counts, a lymphocyte oxidative DNA damage index using Comet assay with human 8-oxoguanine DNA glycosylase, oxidative stress markers, and apoptosis markers were measured. Lymphocyte counts at D1 in TR were significantly lower than in UT. Lymphocyte counts in TR changed little at D4 (from 1,988 +/- 475 to 1,854 +/- 363 cell/microl), but the lymphocyte counts in UT decreased significantly at D4 (from 2,583 +/- 564 to 1,911 +/- 528 cell/microl, P < 0.05). Lymphocyte oxidative DNA damage increased concomitantly with exercise sessions in both the groups (UT, from 31.3 +/- 17.5 to 48.9 +/- 15.7%; TR, from 21.9 +/- 5.2 to 62.1 +/- 12.5%, P < 0.05). Although no change was found in apoptosis markers over time, Annexin-V(+) cells decreased in TR (effect size D = 0.8 is large). Three consecutive days of 1 h exercise decreased lymphocyte counts with increased lymphocyte oxidative DNA damage in UT. Lymphocyte counts remained unchanged irrespective of increased oxidative DNA damage in TR. Decreased lymphocyte apoptosis might prevent the decrease of lymphocytes in TR.

Exercise-induced oxidative DNA damage and lymphocytopenia in sedentary young males.

UNLABELLED: Post high-intensity exercise lymphocytopenia is well documented, but its underlying mechanisms have not been fully elucidated. A possible mechanism is a reactive oxygen species-induced DNA damage after high-intensity exercise. Furthermore, lymphocyte apoptosis related to DNA damage might contribute to exercise-induced lymphocytopenia. PURPOSE: This study examined lymphocytopenia, lymphocyte oxidative DNA damage, and apoptosis in young healthy sedentary males after acute high-intensity exercise. METHOD: Fifteen subjects exercised on bicycle ergometers for 1 h at 75% of their VO2max. Venous blood samples were taken before exercise (PRE) and hourly after exercise until 4 h (P0-P4). Lymphocyte counts, oxidative DNA damage evaluated using the Comet assay with human 8-oxoguanine DNA glycosylase, and serum lipid peroxide (LPO) concentration were measured. Furthermore, lymphocyte superoxide, Fas receptor (CD95), and Annexin-V-positive lymphocyte apoptosis cells were measured in 10 subjects who exercised and gave blood samples as described above. RESULTS: Lymphocyte counts became significantly lower than the PRE value (P < 0.05): 20.4% at P1, 24.3% at P2, and 16.3% at P3. Moreover, LPO significantly increased by P2 (P < 0.05): 1.6-fold. The % DNA in tail, indicating oxidative DNA damage, was significantly higher at P3 (54.3 +/- 12.8%) than at PRE (42.6 +/- 11.1%, P < 0.05). The lymphocyte superoxide level was significantly higher (51.3%) than the PRE value (P < 0.05). Neither CD95 nor Annexin-V-positive cells were significantly different than the PRE value. CONCLUSION: Results of this study suggest that lymphocyte oxidative DNA damage can relate to lymphocytopenia, although DNA damage was not associated with apoptosis in healthy young sedentary males.

Reducing exercise-induced muscular injury in kendo athletes with supplementation of coenzyme Q10.

Intensive physical exercise may cause muscular injury and increase oxidative stress. The purpose of this study was to examine the effect of an antioxidant, coenzyme Q10 (CoQ10), on muscular injury and oxidative stress during exercise training. Eighteen male students, all elite Japanese kendo athletes, were randomly assigned to either a CoQ10 group (n 10) or a placebo group (n 8) in a double-blind manner. Subjects in the CoQ10 group took 300 mg CoQ10 per d for 20 d, while subjects in the placebo group took the same dosage of a placebo. All subjects practised kendo 5.5 h per d for 6 d during the experimental period. Blood samples were taken 2 weeks before, during (1 d, 3 d, 5 d) and 1 week after the training. Serum creatine kinase (CK) activity and myoglobin (Mb) concentration significantly increased in both groups (at 3 d and 5 d). Serum CK (at 3 d), Mb (at 3 d) and lipid peroxide (at 3 d and 5 d) of the CoQ10 group were lower than those of the placebo group. The leucocyte counts in the placebo group significantly increased (at 3 d) and neutrophils significantly increased in both groups (at 3 d and 5 d). Serum scavenging activity against superoxide anion did not change in either group. These results indicate that CoQ10 supplementation reduced exercise-induced muscular injury in athletes.

Effect of moderate exercise training on T-helper cell subpopulations in elderly people.

CD28 molecule expression on the surface of T cells plays a critical role in upregulation of various cytokines synthesis and T-helper (Th) cell proliferation and differentiation. However aging induces a decrease in CD28 expression and unbalance of Th1/Th2, leading to impairment of Th-cell mediated immune function. The purpose of this study was to assess the effects of moderate exercise training on CD28 expression and the balance of Th1/Th2 cells in elderly people. Forty-eight elderly subjects were assigned to an exercise training group (EXC: 13 males, 15 females; aged 61-76) or a non-exercise control group (CON: 7 males, 13 females; aged 62-79). Subjects in EXC participated in exercise sessions 5-days a week for 6 months. Meanwhile, subjects in CON maintained their normal physical activity levels during the study period. Blood samples were collected before and after the training period. Samples were measured for the number of leukocytes and lymphocytes, as well as for CD3+, CD4+, CD28+CD4+, IFN-gamma+CD4+, IL-4+CD4+ cells. The number of leukocytes, lymphocytes, and CD3+ cells did not change after 6 months in both EXC and CON. The number of CD4+ and CD28+CD4+ cells significantly increased after the training in EXC (P < 0.05), while CON did not show significant changes. In the EXC group, IFN-gamma+CD4+ cell numbers were significantly higher following the training (P < 0.05), but the number of IL-4+CD4+ cells was not changed. In the CON group, there were no significant alterations in IFN-gamma+CD4+ and IL-4+CD4+ cell numbers. In conclusion, moderate exercise training in the elderly is associated with improvement of expression of CD28 on Th cells and Th1/Th2 balances. Therefore, exercise training could up-regulate Th cell-mediated immune functions and be helpful for a decrease in the risk of infections and autoimmune diseases in elderly people.

Proanthocyanidin promotes free radical-scavenging activity in muscle tissues and plasma.

The present study was carried out to clarify the effect of oral administration of proanthocyanidin (PA) on radical-scavenging activity in muscle and plasma using electron spin resonance (ESR). Eight-week-old male Wistar rats were orally administered with 3 doses per day of 1 mL of 0.05% (PA0.05), 0.5% (PA0.5) or 5% (PA5) PA for 1 week. Control animals received the same volume of distilled water. We also examined the effect of a single dose of 0.5% PA. Blood and muscle were collected from rats 1 h after the final administration. Scavenging activity against superoxide anions in the plasma and m. soleus (Sol), m. plantaris (Pla), deep and surface areas of the m. gastrocnemius (GasD and GasS, respectively) and myocardium (Hrt) was determined using ESR with the spin trap, 5,5-dimethyl-1-pyrroline-N-oxide The scavenging activity in plasma for all groups given PA was 34%-44% higher than the control (p<0.05). The scavenging activity in Hrt, Sol and GasD increased by up to 50% compared with the control and tended to increase depending on the dose of PA (p<0.05). The impact of a single dose of PA was undetectable in all tissues. These results suggested that 1 week of oral PA improves the radical-scavenging activity in both plasma and muscle, especially in highly oxidative muscle. A single dose of PA was insufficient to improve the antioxidative capacity of muscle tissues.

Eccentric muscle contractions induce greater oxidative stress than concentric contractions in skeletal muscle.

The purpose of this study was to examine oxidative stress in skeletal muscle after eccentric and concentric muscle contractions. Eight-week-old Institute of Cancer Research (ICR) mice (n = 90) were divided into 3 groups: eccentric muscle contraction group (ECC, n = 42), concentric muscle contraction group (CON, n = 42), and control group (pre, n = 6). The tibialis anterior muscle was stimulated via the peroneal nerve to contract either eccentrically or concentrically. The tibialis anterior muscle was isolated before and 0, 6, 12, 18, 24, 72, and 168 h after muscle contraction. Immediately after muscle contractions, thiobarbituric acid reactive substances (TBARS) in skeletal muscle significantly increased (p < 0.05) in both ECC and CON conditions. However, in the ECC group alone, the TBARS level peaked at 12 and 72 h after the contractions. There was greater migration of mononuclear cells in ECC than in CON muscle. In addition, there was a correlation between TBARS in skeletal muscle and migration of mononuclear cells in ECC muscle (r = 0.773, p < 0.01), but this correlation was not apparent in CON muscle (r = 0.324, p = 0.12). The increased mononuclear cells may reflect inflammatory cells. These data suggest that eccentric muscle contraction induces greater oxidative stress in skeletal muscle, which may in turn be due to enhanced generation of reactive oxygen species (ROS) by migrating inflammatory cells.