Incidence of upper respiratory tract infection and duration of weekly training among Japanese collegiate male and female athlete / 体力科学

Strenuous exercise induces upper respiratory tract infection (URTI), whereas moderate exercise prevents URTI. This study aimed to assess the incidence of URTI and the association between URTI episodes and exercise duration in Japanese collegiate athletes. A cross-sectional survey was conducted with 1,740 participants; 1,235 responses were eligible for analysis. Participants were classified into three groups: control group (weekly total exercise duration <60 min, n=405), exercise group (weekly total exercise duration >60 min, n=193), and athlete group (joined a sports club and weekly exercise frequency >5 days, n=637). We requested the following information from participants: basic characteristics, incidence of URTI symptoms (fever, runny or plugged nose, sore throat, and cough) or influenza for each month over the past year, day of the week exercise is typically performed, and duration of exercise per week. The incidence of URTI episodes per year was significantly lower in the athlete group (2.0 ± 2.4 episodes) compared to the control group (2.6 ± 2.4 episodes, p<0.001). The incidence of URTI episodes did not significantly differ between the control group and exercise group (2.9 ± 2.9 episodes, p=0.607). Although the frequency of URTI episodes and exercise duration were not significantly associated among male athletes (p=0.209), they were positively associated in female athletes (p=0.027). These results indicate that Japanese collegiate athletes experience fewer URTI episodes than non-athletes, but athletes who exercise for long durations may frequently experience URTI, particularly female athletes.

RELATIONSHIP BETWEEN IRON STATUS AND DAILY PROTEIN INTAKES IN FEMALE COLLEGIATE RHYTHMIC GYMNASTS / 体力科学

The present study aimed to investigate how nutritional status affected iron status, and how this knowledge might be used to prevent anemia in rhythmic gymnasts prior to a competition. We divided twenty-one subjects according to their iron status in just prior to competition into either an iron-deficiency group (n=12) and a non-iron-deficiency group (n=9), the latter of which represented the normal group. Iron-deficiency group was defined as a hemoglobin concentration below 12g/dl, a ferritin level below 12ng/ml and/or a transferrin saturation ratio under 16%. Physical, hematological, and nutritional assessments were made using a semi-quantitative food frequency questionnaire, once at 2 months before a competition, and once more just prior to the competition (‘pre-competition’).1) The iron-deficiency group had significantly lower body weight, body mass index and body fat at pre-competition compared to 2 months before the competition.2) Compared to the normal group, the iron-deficiency group had significantly lower serum iron and haptoglobin concentrations at the pre-competition.3) Intakes of energy, protein, iron, and vitamin C at the pre-competition were 1965±340kcal, 68.0±14.0g, 11.2±3.2mg, and 76±30mg in the normal group, and 1620±456kcal, 53.8±18.0g, 11.6±4.1mg, and 75±29mg in the iron-deficiency group, respectively. There was no significant difference in intakes of energy, protein, iron, and vitamin C between the groups, respectively.4) Pre-competition protein intakes per body weight (BW) were 1.46±0.33g and 1.08±0.31g in the normal group and the iron-deficiency group, respectively. Those levels were significantly lower in the iron-deficiency group than those in the normal group.5) Pre-competition protein energy ratio (13.9±1.6%) and animal protein ratio (56.0±6.7%) of the normal group were significantly higher than those measured 2 months before the competition. Conversely, those ratios remained constant for 2 months in the iron-deficiency group.6) Changes in the protein energy ratio and/or the animal protein ratio between the pre-competition and the 2 months before were significantly correlated with the pre-competition Hb levels.We conclude that the pre-competition iron status is closely associated with protein intakes in female collegiate rhythmic gymnasts.

EFFECT OF AN INCREASED SUPPLEMENTATION OF EGG WHITE PROTEIN ON THE POST-EXERCISE LEUKOCYTE SUBSETS AND THE PLASMA IL-6 LEVELS IN MALE COLLEGIATE RUNNERS / 体力科学

This study was undertaken to compare the effect of the pre-exercise intake of a dry egg white protein supplement (86 kcal) on the post-exercise alterations in leukocytes and the plasma interleukin-6 (IL-6) concentrations in male collegiate runners. The 43 runners who participated in this study were divided into 2 groups, namely those with (E groups) and without (C groups) a 12,000 m pace run, and then they were further divided into 4 subgroups in which the subjects were given the 86 kcal nutrient supplemented including either 0, 5, 10, or 20 g protein from egg white. Peripheral blood samples were collected before supplementation (Pre), just after running (Post 0h), and at 1 h after running (Post 1h). The concentrations of the leukocytes, neutrophils, and monocytes in both groups E and C remained unchanged at Post 0 h. Furthermore, these concentrations increased significantly at Post 1 h. The lymphocytes were not significantly different at Pre. The plasma IL-6 concentrations were significantly higher at Post 0 h than at Pre or Post 1 h. In addition, no effect of the protein supplementation on the leukocytes, leukocytes subsets, or the IL-6 concentrations was observed. These observations suggested that such isocaloric supplementation as described above may therefore be able to help control the changes in the concentrations of leukocyte and leukocyte subsets immediately after running a 12,000 m time trial.

THE PHYSICAL ACTIVITY AND NUTRITIONAL INTAKE IN COMMUNITY-DWELLING ELDERLY:THE NAKANOJO STUDY / 体力科学

Purpose : This study was undertaken to examine the relationship between pedometer counts and food intake in Japanese elderly people.Methods : One-hundred-eighty healthy, community-dwelling elderly people were divided into three groups according to age. The number of steps taken by each subject was recorded with a pedometer over a 30-day period in August. The dietary and nutritional intakes were estimated using a food frequency questionnaire.Results : There was no significant difference in the pedometer counts between men and women. The number of steps significantly decreased with age (p<0.01). The intake of energy, protein and carbohydrate were significantly higher in men than in women (p<0.05), and they were nearly the same among the three aged groups. The calcium and vitamin C intakes after adjusting for sex and age increased with the number of daily steps, except for the intakes of energy, protein and carbohydrates.Conclusion : A higher number of daily steps was found to be associated with the calcium and vitamin C intakes.

EFFECT OF DIETARY HEME-IRON INTAKES ON THE PREVENTION OF IRON-DEFICIENCY ANEMIA / 体力科学

Purpose : This study was undertaken to clarify the effect of heme-iron supplementation on the prevention of iron-deficiency anemia in male collegiate distance runners.Methods : Forty-one male collegiate runners were divided into three groups, consisting of a heme-iron group (HI), a citrate-iron group (CI), and a non-iron group (NI). Iron tablets (heme-iron or citrate-iron) were administered at a dose of 7 mg per day for two months. The blood components and nutritional intakes were estimated before and after the intervention.Results : The nutritional intakes did not differ among the three groups. The red blood cell, hemoglobin, hematocrit, ferritin, Glutamic-Pyruvate Transferase and <i>γ</i>-Glutamyl Transpeptidase levels were unchanged throughout the experimental periods. After the intervention, the serum iron levels significantly decreased in the NI group but not in the iron-supplemented groups, while the reticulocytes counts increased among the three groups.Conclusion : The small amount of heme-iron supplementation was thus found to have a preventive effect on iron deficiency anemia without causing any negative side affects.

DIETARY INTERVENTION MIGHT ENHANCE THE RBC CELL METABOLISM / 体力科学

Purpose : Rhythmic gymnasts sometimes develop severe iron-deficiency anemia. Preventing such anemia could thus enhance both their performance and health. We compared the relationship between a dietary intervention and RBC metabolism.Methods : Ten female rhythmic gymnasts were recruited for this study. Changes in the RBC delta-aminolevulinate dehydratase (δ-ALAD) activity were used as an index of biosynthesis, and changes in the haptoglobin (hp) were used to assess degradation.Results : During the one month intervention period, the athletes consumed traditional Japanese foods which provide 1500 kcal energy, 2 g/kg body weight protein, 200 g carbohydrate and 15 mg iron. No main effect of this intervention on the hematological indexes was observed. The δ-ALAD activity was significantly greater in August than in July or September. Hp concentration was significantly lower in August in comparison to the other periods.Conclusion : Dietary intervention might enhance the RBC turnover by increasing the capacity for erythrocyte biosynthesis and degradation.

Effect of Body Iron Stores on Indices of Biosynthesis and Destruction of Red Blood Cells after a Single Session of Cycling Exercise / 体力科学

Objectives : The present study investigates the effects of body iron stores upon indices of biosynthesis and destruction of red blood cells (RBC) induced by a single session of cycling exercise.<BR>Design : Eight sedentary female students were divided into groups depending on their body iron stores : normal (C group, n=5) and iron deficient (D group, n=3) . Blood samples were collected at five time points of before (pre), immediately after (0 hours), then 1, 3 and 6 hours after exercise (248±31 kcal, 70% V0<SUB>2</SUB> peak level) . Osmotic fragility and serum haptoglobin (hp) concentration served as of for degradation, and δ-aminolevulinate dehydratase (ALAD) activity, erythropoietin concentration and number of reticulocytes served as indices of RBC biosynthesis.<BR>Results : A single session of cycling exercise did not affect the level of RBC, hemoglobin, hematocrit, serum iron, ferritin, transferrin saturation, hp and osmotic fragility in either groups. The δ-ALAD activity increased at 3 (p<0.05) and 6 hours (p<0.01) after exercise compared with that at 0 hours in the C group. In contrast, δ -ALAD activity in the D group was significantly lower at 3 hours after exercise than that of C group (p<0.001) . Reticulocytes and erythropoietin concentration increased gradually in the C group after exercise, but not in the D group.<BR>Conclusions : A single session of cycling exercise under our experimental conditions enhanced RBC biosynthesis indicated by δ -ALAD activity, whereas exercise-induced hemolysis was not evident. Body iron stores affect the δ -ALAD activity induced by a single bout of cycling exercise.

Biochemical and immunohistochemical changes in gastrocnemius muscle of rats fed low protein diet following electrical stimulation / 体力科学

We investigated biochemical and morphological changes in electrically stimulated gastrocnemius muscle of rats fed normal (20% casein) and low-protein (5% casein) diets. Tissue weight and protein content per tissue weight of gastrocnemius muscle were significantly decreased in rats fed 5% casein diet than in rats fed 20% casein diet. Immunohistochemically, cathepsin B antigen was detected in inflammatory cells, and injured sites determined immunological intensity of anti-cathepsin B were lower in 5% casein diet group than 20% casein diet group. Electron microscopically, there was delayed repairment of muscle components (sarcometric units) in 5% casein diet as compared with that in 20% casein diet group.

Nutritional assistance for elite athletes / 体力科学

We performed dietary guidances for 15 male elite athletes (23±3 years of age) participating a training program for vigorous endurance run. Nutrient allowances for the athletes were determined by the guidelines of Japanese Dietary Allowances (5 th ed.), considering their physical activities at the highest level IV; total energy 3, 500 kcal, protein 140g, lipid 100g, carbohydrate 510g, calcium 1, 500 mg, iron 25 mg, vitamin A 8, 000 IU, thiamine 4.0 mg, riboflabin 5.0 mg and vitamin C 200 mg per day. We also developed food group allowances for the athletes based on their nutrient allowances and current young-aged Japanese dietary styles ; cereals 400 g, potatoes and starches 60 g, sugars 20 g fats and oils 30g, pulses 120g, meats 150g, fishes and shellfishes 150g, eggs 80g, milks 600g, green and yellow vegetables 300 g, the other vegetables 350 g, fruits 400 g and algae 20 g per day. For the experimental period of 45 days, daily diets adjusted to approximate 120% of the dietary allowances were served to the athletes who were free taking snacks and drinks. Dietary guidances for the athletes were assessed by monitors of their dietary intakes, physical constitution and clinical examinations in blood. Means of the dietary intakes of the athletes were 96-99% of the dietary allowances, determined by a nutritional survey with the 24 hrs recall method. There were less changes in the physical constitution of the athletes before, during and after the experimental period; body weight 57±2 kg and body fat 8.8 ± 2.4%. Values of the clinical marks in the blood of the athletes were maintained normally for a half year including the experimental period; red blood cells 507±9×104 cells/mm3, hemoglobin 15±0.4g/dl and hematocrit 46.6±0.7%.<BR>It is concluded that suitable nutritional guidances and managements for young-aged male vigorous endurance runners lead good in their health and physical maintenances, which may have important consequences for their physical development as elite athletes.