Kai Tanabe

Effect of 12 weeks of moderate–intensity resistance training on arterial stiffness: a randomised controlled trial in women aged 32–59 years

Background: Resistance training has been increasingly incorporated into the overall exercise programme because of its effect on muscle strength, functional capacity and osteoporosis. High-intensity resistance training increases arterial stiffness. However, the effect of moderate-intensity resistance training on arterial stiffness is unknown. Objective: To determine whether 12 weeks of moderate-intensity resistance training increases arterial stiffness in middle-aged women. Methods: 35 middle-aged women (age range 32 to 59 years) volunteered to participate. The subjects were randomly assigned to one of three groups: resistance training (RT) group, aerobic exercise training (AET) group or control group. The RT and AET groups performed 12 weeks of moderate-intensity resistance training or aerobic exercise training (two days/week). Results: In the RT group, one-repetition maximum strength significantly increased after the intervention. Interestingly, aortic (carotid–femoral) pulse wave velocity (PWV; an index of arterial stiffness), and peripheral (femoral–ankle) PWV did not change with moderate-intensity resistance training. In contrast, in the AET group, carotid–femoral PWV significantly decreased after the intervention. Resistance training and aerobic exercise training did not affect blood pressure. Conclusions: This study found that moderate-intensity resistance training did not increase arterial stiffness in middle-aged women, which may have great importance for health promotion with resistance training.

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

BackgroundAlthough 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.MethodsA 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.ResultsThe 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.ConclusionsThe 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.

ACTN3 polymorphism affects thigh muscle area.

Muscle mass is an important factor influencing the activity of daily living in older adults. We aimed to investigate whether alpha-actinin-3 (ACTN3) gene R577X polymorphism affects muscle mass in older Japanese women. A total of 109 women (mean+/-SD, 64.1+/-6.0 years) were genotyped for the R/X variant of ACTN3. Mid-thigh muscle cross-sectional area (CSA) was assessed using MRI and compared using analysis of covariance models adjusted for body weight. In addition, physical activity and protein intake were measured as the living environmental factors affecting muscle mass. The ACTN3 R577X genotype distributions of the subjects were 19, 63 and 27 for the RR, RX, and XX genotypes, respectively. No differences in physical activity and protein intake were observed among the genotypes. The XX genotype showed lower thigh muscle CSA compared with RR&RX genotype (mean+/-SEM; XX: 69.1+/-1.8 cm(2), RR&RX: 73.6+/-1.1 cm(2); p<0.05). The results of the present study suggest that ACTN3 R577X polymorphism influences muscle mass in older Japanese women.

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.

Antioxidant capacity in rat skeletal muscle tissues determined by electron spin resonance

The amount of radical scavenging activity in muscle is unknown. The present study examines whether electron spin resonance (ESR) could measure and distinguish antioxidant capacity in muscle with different contractile and metabolic characteristics. Specimens of the soleus, plantaris, gastrocnemius (deep/surface portions), heart and diaphragm were obtained from female Wistar rats (n=7; 12 weeks old). Scavenging activity against superoxide anions in these specimens were determined by ESR using a spin-trapping chemical (5,5-dimethyl-1-pyrroline-N-oxide). The ESR signal intensity of reaction mixtures containing muscle tissues was significantly lower in the heart, soleus, diaphragm and deep portion of the gastrocnemius than in the plataris and surface portion of the gastrocnemius. Thus, the amount of scavenging activity converted into superoxide dismutase activity was the highest in the heart, and higher in the soleus, diaphragm and deep portion of the gastrocnemius than in other muscles (ANOVA, P<0.01). In addition, scavenging activity significantly correlated with citrate synthase activity (r=0.72, P<0.01, n=42) and myoglobin content (r=0.63, P<0.01, n=42). These findings suggested that ESR and spin-trapping can be detect differences in free radical scavenging activity among muscle tissues with different metabolic characteristics.

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.

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.

Effect of spontaneous exercise on antioxidant capacity in rat muscles determined by electron spin resonance.

Aims:  The effect of physical activity on antioxidant capacity in muscle remains unknown. This study investigated the effect of spontaneous exercise on antioxidant capacity in rat muscles determined by electron spin resonance (ESR), which is a technique for the direct detection of free radicals.

Determinants for stair climbing by elderly from muscle morphology.

The relationship between muscle cross-sectional area (CSA) of the hip joint and lower extremities and speed of stair ascent/descent was investigated in a sample of 127 elderly women (ages: 60–70 years old). The participants performed ascent and descent of stairs with 12 steps for which the speeds for ascent and descent separately from video film were calculated. The ascent speed significantly correlated with CSAs of knee extensor (r = .21, p<.05) and psoas major muscle (r = .25, p<.01), which were assessed by magnetic resonance imaging. The descent speed also correlated with CSAs of the same muscle groups (with knee extensor: r = .20, p<.05, with m. psoas major: r = .18, p<.05). The rest of the muscle groups were not related to the ascent/descent speeds of the step. These results suggested that the muscle mass of the knee extensor muscle group and also the psoas major muscle could be a factor in potential capacity in stair ascent/descent by humans.

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.