Effects of exercise on the iron balance in human body examined by the excretion of iron into urine, sweat and feces / 体力科学

In order to evaluate iron balance in the human body, we studied the effects of exercise on iron excretion in urine, sweat and feces. The subjects were five healthy male, college athletes. The daily intake of nutrients by the subjects was regulated by a prescribed diet (Calorie Mate, Ohtsuka), and the control measurements and the exercise measurements were performed within seven days. Excretion of iron in the urine during the exercise period was significantly higher than in the control period. The excretion of iron in the sweat was 1.076±0.118 mg, i. e, , about 70% of total iron physiologically excreted from the human body. The excretion of iron in the feces during the exercise period was significantly lower than during control period. Feces volume was positively correlated with energy expenditure and negatively correlated with the excretion of iron in the feces. Iron absorption during the exercise period was significantly higher than during the control period. These findings suggest that exercise stimulates not only iron excretion via urine and sweat, but iron absorption, and that iron balance remains positive in healthy male subjects who have normal iron status.

The effect of iron supplemented food intake on iron status, hematological profiles and aerobic work capacity of female athletes / 体力科学

In order to prevent sports anemia, caused especially by iron deficiency or shortage, a special type of food supplementation was designed. This was called“iron-food”and contained 510% of the therapeutic iron dose. According to hemoglobin (Hb) values, female subjects who had been performing hard daily training were divided into two groups ; an anemia group (A group, Hb≤11.9 g/dl, n=4) and a potential anemia group (PA group, 12.0≤Hb≤12.9g/dl, n=4) . Then the iron-food was administered for six weeks following placebo treatment. Iron status, hematological profiles and aerobic work capacity of the two groups were examined before and after the two periods to investigate the effect of the iron-food. Serum iron, iron saturation and ferritin were significantly increased in the PA group. Serum iron tended to be increased in the A group, but not significantly. Red blood cell count, Hb and hematocrit were significantly increased in the PA group, and the reticulocyte count was also increased in the A group. These results suggest that iron-food helped to increase daily iron intake in the anemic subjects, but not to a sufficient extent to aid recovery from anemia. However the ironfood was effective for improving iron status in subjects with potential anemia (latent iron deficiency) .

Effects of exercise intensity on purine catabolism / 体力科学

In order to elucidate effects of the exercise intensity on purine catabolism, we performed exhausitve exercise (Exh-ex), 80% VO<SUB>2</SUB>max exercise (80%-ex) and 70% VO<SUB>2</SUB>max exercise (70%-ex) test by a bicycle ergometer, and estimated the purine catabolism by the changes in blood ammonia, plasma oxypurines and urinary oxypurines in five healthy male subjects who were given allopurinol. The results were summarized as follows;<BR>1) Plasma oxypurines concentrations (POP) increased gradually after exercise with each intensity. The order of their maximal levels and of cumulative areas under the curves of POP were exh-ex>80%-ex>70%-ex>control, respectively, and that of urinary excretions of oxypurines was exh-ex>80%-ex>70%-ex≥control.<BR>2) Blood ammonia concentrations (BNH<SUB>3</SUB>) increased sharply after exercise with each intensity. The order of their maximal levels was 80%-ex = exh-ex>70%-ex>control, and that of cumulative areas under the curves of BNH<SUB>3</SUB> was 80%-ex>exh-ex>70%-ex>control.<BR>3) Blood lactate concentrations (BLA) increased sharply after exercise with each intensity. The order of their maximal levels and of cumulative areas under the curves of BLA were exh-ex =80%-ex>70%-ex>control, respectively.<BR>These results suggest that the purine catabolism leading to uric acid production is activated by the physical exercise in the order of increasing intensities. The discrepancy between the increase in ammonia and those in oxypurines suggests that the increased purine catabolic pathway was mediated not only by AMP deamination but also by other factors.

Effect of the difference of exercise intensity on the changes in ammonia and oxypurines / 体力科学

We investigated the effect of the difference of exercise intensity on the changes in ammonia and oxypurines (hypoxanthine·xanthine) . The subjects were 7 male university students who belonged to the Judo club. By using a bicycle ergometer with the same total work load (kpm), they performed following exercise : light exercise (27.1±0.8% HRmax), moderate exercise (72.6±2.5% HRmax) and exhaustive exercise. After light exercise, blood ammonia, serum oxypurines and urinary oxypurines excretion did not increase. Urinary uric acid excertion increased significantly, but serum uric acid decreased slightly. After moderate exercise, the significant increase was observed with blood ammonia (+ 35.3±5.9μmo<I>l</I>/<I>l</I>) . Urinary oxypurines excretion also increased significantly, while serum oxypurines did not change. Also, serum uric acid rose slightly. After exhaustive exercise, the significant increase was observed with blood ammonia, serum oxypurines and serum uric acid. Each peak level and appearance time were +67.2±15.1μmo<I>l</I>/<I>l</I> after 3 min, +31.4±7.6μmo<I>l</I>/<I>l</I> after 30 min, 155.7±39.9μmo<I>l</I>/<I>l</I> after 1 hr of exercise, respectively. These results suggest that AMP deamination occur during moderate intensity, while remarkable production of oxypurines which lead the increase of serum uric acid occur in higher exercise intensity.