Relationship between anemia and circulating levels of amino acids in female endurance athletes / 体力科学

<p>The symptoms of anemia, decreases in the levels of circulating red blood cells (RBC), hemoglobin (Hb) and hematocrit (Ht) lead to decrease endurance performance, and the risk of anemia increases in female endurance athletes. Although Hb is composed of a large amount of amino acids, the relationships between circulating levels of amino acids and RBC, Hb and Ht in female endurance athletes have not been clarified yet. Thus, the purpose of the present study was to investigate the relationship between circulating levels of amino acids and RBC, Hb and Ht in female endurance athletes. Twenty-four female endurance athletes (19.8 ± 0.2 years) participated in this study. We measured circulating levels of RBC, Hb and Ht from blood. Also, we measured circulating levels of amino acids from plasma by use of comprehensive analysis. The levels of circulating RBC, Hb and Ht in all subjects were within the normal range. We found that circulating taurine levels were significantly correlated with RBC (r = 0.48, p < 0.05), Hb (r = 0.44, p < 0.05) and Ht (r = 0.42, p < 0.05) in female endurance athletes. In the present study, we demonstrated that circulating taurine levels were significantly associated with RBC, Hb and Ht in female endurance athletes. These results suggest that circulating taurine levels may be a predictor of anemia and treatment strategy for anemia.</p>

Retraction: PREDICTION MODELS OF SARCOPENIA IN JAPANESE ADULT MEN AND WOMEN / 体力科学

The purpose of this study was to develop prediction models of sarcopenia in 1,894 Japanese men and women aged 18-85 years. Reference values for sarcopenia (skeletal muscle index, SMI; appendicular muscle mass/height2, kg/m2) in each sex were defined as values two standard deviations (2SD) below the gender-specific means of this study reference data for young adults aged 18-40 years. Reference values for predisposition to sarcopenia (PSa) in each gender were also defined as values one standard deviations (1SD) below. The subjects aged 41 years or older were randomly separated into 2 groups, a model development group and a validation group. Appendicular muscle mass was measured by DXA. The reference values of sarcopenia were 6.87 kg/m2 and 5.46 kg/m2, and those of PSa were 7.77 kg/m2 and 6.12 kg/m2. The subjects with sarcopenia and PSa aged 41 years or older were 1.7% and 28.8% in men and 2.7% and 20.7% in women. The whole body bone mineral density of PSa was significantly lower than in normal subjects. The handgrip strength of PSa was significantly lower than in normal subjects. Stepwise regression analysis indicated that the body mass index (BMI), waist circumference and age were independently associated with SMI in men; and BMI, handgrip strength and waist circumference were independently associated with SMI in women. The SMI prediction equations were applied to the validation group, and strong correlations were also observed between the DXA-measured and predicted SMI in men and women. This study proposed the reference values of sarcopenia in Japanese men and women. The prediction models of SMI using anthropometric measurement are valid for alternative DXA-measured SMI in Japanese adults.

PREDICTION MODELS OF SARCOPENIA IN JAPANESE ADULT MEN AND WOMEN / 体力科学

The purpose of this study was to develop prediction models of sarcopenia in 1,894 Japanese men and women aged 18-85 years. Reference values for sarcopenia (skeletal muscle index, SMI; appendicular muscle mass/height², kg/m²) in each sex were defined as values two standard deviations (2SD) below the gender-specific means of this study reference data for young adults aged 18-40 years. Reference values for predisposition to sarcopenia (PSa) in each gender were also defined as values one standard deviations (1SD) below. The subjects aged 41 years or older were randomly separated into 2 groups, a model development group and a validation group. Appendicular muscle mass was measured by DXA. The reference values of sarcopenia were 6.87 kg/m² and 5.46 kg/m², and those of PSa were 7.77 kg/m² and 6.12 kg/m². The subjects with sarcopenia and PSa aged 41 years or older were 1.7% and 28.8% in men and 2.7% and 20.7% in women. The whole body bone mineral density of PSa was significantly lower than in normal subjects. The handgrip strength of PSa was significantly lower than in normal subjects. Stepwise regression analysis indicated that the body mass index (BMI), waist circumference and age were independently associated with SMI in men; and BMI, handgrip strength and waist circumference were independently associated with SMI in women. The SMI prediction equations were applied to the validation group, and strong correlations were also observed between the DXA-measured and predicted SMI in men and women. This study proposed the reference values of sarcopenia in Japanese men and women. The prediction models of SMI using anthropometric measurement are valid for alternative DXA-measured SMI in Japanese adults.

EFFECTS OF HABITUAL EXERCISE AND CANDIDATE GENE POLYMORPHISMS RELATED TO BONE ON CALCANEAL QUANTITATIVE ULTRASOUND IN MIDDLE-AGED AND ELDERLY JAPANESE / 体力科学

The purpose of this study was to investigate the interaction of habitual exercise and candidate gene polymorphisms related to bone on osteo sono-assessment index (OSI) by quantitative ultrasound (QUS) in middle-aged and elderly Japanese. Participants were classified into exercise group (E; n=172, 62.3 ± 7.7 yr) and sedentary group (S; n=65, 58.6 ± 9.2 yr). The OSI was measured with AOS-100. DNA was extracted from blood, and single nucleotide polymorphism in vitamin D receptor, estrogen receptor α, and transforming growth factor-βI were genotyped by TaqMan assay. Group E had significantly lower body weight and body mass index (BMI) than Group S. In men, although Group E was older than Group S, Group E had significantly higher OSI rather than Group S. There was no significant interaction between habitual exercise and each gene polymorphism on OSI. These results essentially remained unchanged even when analysis of covariance was applied after adjustment for age, body weight, and BMI. These results suggest habitual exercise and genetic factors have no interaction on OSI in middle-aged and elderly Japanese. Further investigations are needed to prove the interaction of other gene polymorphisms and exercise.

GENDER DIFFERENCES IN MUSCLE FORCE AND OXYGENATION RECOVERY FROM INTERMITTENT HANDGRIP EXERCISE / 体力科学

To investigate a relationship between gender differences in recovery from skeletal muscle fatigue and muscle oxygenation, we examined whether there is a difference in oxygen supply and consumption of the working muscles after intermittent handgrip exercise between young males and females using near-infrared spectroscopy (NIRS). Healthy young subjects (25.8±3.9 years ; males, n=10 ; females, n=10) repeated static maximal voluntary contractions (MVC) with a handgrip for 5 seconds followed by 5 seconds rest for a period of 4 minutes in Study 1. The MVC force was measured before, each minute during the handgrip exercise, and 2, 5, and 10 minutes following the exercise. In Study 2, the selected 10 subjects (males, n=5 ; females, n=5) performed the same exercise and their total- and deoxy- hemoglobin/myoglobin level was measured using the venous occlusion NIRS method; and O₂ supply index (OSI) and O₂ consumption index (OCI) calculated before and after the exercise. In Study 1, females exhibited higher %MVC force at the end of the exercise and during the recovery period than males (p<0.05). In Study 2, the %OSI was significantly lower in females than in males at 5 and 10 minutes in the recovery period (p<0.05), but no significant differences were detected in %OCI. Furthermore, %MVC of the recovery period correlated with %OCI of the recovery period in females (r=0.724, p=0.015), but not in males. These findings suggest that female working muscles can convert consumed oxygen more effectively after an intermittent handgrip exercise, and therefore, be able to recover muscle force faster.

BASAL GENE EXPRESSION OF VASCULAR ENDOTHELIAL GROWTH FACTOR-RELATED TRANSCRIPTIONAL FACTORS IN RAT SKELETAL MUSCLE DIFFERS BETWEEN SLOW AND FAST FIBER TYPES / 体力科学

Skeletal muscle is comprised of multiple fiber types. Slow-twitch oxidative muscle fibers have greater capillary density compared with fast-twitch glycolytic fibers of skeletal muscle. To gain insight into the molecular mechanism underlying the difference of capillary density, we investigated whether the basal gene expression of vascular endothelial growth factor (VEGF), a major angiogenesis-related factor, and its transcriptional factors (hypoxia-inducible factor-1α, transforming growth factor-β1, c-jun, and c-fos) differs between these two fiber types of rat skeletal muscle. The mRNA expression of VEGF and its transcriptional factors was significantly higher in slow type fiber of muscle (soleus muscle) compared with fast type fiber of muscle (plantaris and tibialis anterior muscles). These results suggest that the difference of basal gene expression of VEGF and its transcriptional factors between slow and fast fiber types of skeletal muscle may partly contribute to the difference in capillary density between these two fiber types.

Echographic size and doppler blood flow profile of ascending aorta in endurance-trained athletes / 体力科学

In a recent study, endurance athletes, i.e. cyclists and long-distance runners, were found to have larger arterial conductance vessels than untrained controls. The aim of the present study was to determine the blood flow profiles of dilated vessels in these endurance-trained athletes. Twelve endurance-trained athletes (ET group) and twelve untrained control subjects (UC group) volunteered for the study. The cross-sectional area (CSA), peak and mean blood velocity in the ascending aorta (pV and mV), blood pressure (BP), and heart rate (HR) were measured in the semi-supine position on a cycle ergometer fitted with a backrest, at rest and during exercise at 40%, 60%, and 80%Vo<SUB>2</SUB>max. Furthermore, stroke volume (SV), cardiac output (CO), total peripheral resistance, and double product were calculated. The SV and CO of the ET group were significantly larger than those of the UC group during exercise. The CSA of the ascending aorta in the ET group was significantly larger than that in the UC group at rest and during exercise. There were no differences in the mV and mean BP between the two groups. Upon comparison at the same SV, pV, mV, the total peripheral resistance, and double product of the ET group were lower than those of the UC group. These results suggest that the dilation of the arterial conductance vessels with endurance training contri-butes to an increase in blood flow to the exercising muscles without a rise in mechanical stress (shear stress and pressure) to the aortic wall. In other words, the arterial conductance vessels adapt morphologically to maintain an adequate degree of the mechanical stress on the aortic wall.

Comparison of blood velocity profile in the left ventricle at rest and during exercise between endurance trained and sedetary control subjects / 体力科学

The purpose of the present study was to compare between healthy male endurance trained athletes (T, n=6) and sedentary control subjects (S, n=6) for the blood velocity profile in left ventricle at rest and during exercise. Peak velocity of blood injection into the left ventricle at diastole (dV), peak velocity of blood ejection out of the left ventricle at systole (sV), duration of blood injection (dD) and duration of blood ejection (sD) were measured by pulsed Doppler sonography at rest and during cyclic ergometer exercise at intensity of 40, 60 and 80% maximal 0<SUB>2</SUB> uptake (VO<SUB>2</SUB>max) . The dV tended to be higher T than S at rest and during exercise at all intensities, and statistical significance existed at rest and during exercise at 80%VO<SUB>2</SUB>max. However, there was no significant differences in the sV between T and S. In addition, the dV/sV in T was significantly highter than that in S at rest and during exercise at all intensities. These results indicate that Pulling velocity on the left ventricle in T was faster than that in S. In other words, these indicate that preload on the left ventricle in T was larger than that in S. Moreover, the relationship between stroke volume and dV (r=0.50, p<0.001) was closer than that between stroke volume and sV (r=0.30) in all subjects at rest and during exercise. These data suggest that the contribution of enhanced dV was stronger than that of sV to the larger stroke volume observed in dV.