The present study was performed to investigate heart rate responses and occurrence of arrhythmias caused by various diving maneuvers and swimming in infants. Forty four healthy infants (mean age 2.5±1.1, mean ±SD) served on this study. Condition of telemetry electrocardiograph recording was 1) rest on the land and in the water, 2) diving, 3) swimming and 4) “pass in water (PW) ”. Moreover, diving styles was classified for five patterns by presence of body movement or expiration (Apneic not move diving, Expiratory not move diving, Apneic kick diving. Expiratory kick diving and Underwater swimming) . “Diving bradycardia” was observed during diving and PW, and the magnitude of heart rate reduction was grater in diving without body movement than diving combined with body movement. Presence of expiration did not influence on the level of bradycardia during diving. Any kinds of arrythmias was observed 13 out of 44 subjects. In premature contractions, supraventricular premature contraction (SVPC, 7 subjects) was observed more often than ventricu-lar premature contraction (PVC, 3 subjects) . Another arrhythmias observed was atrioventricular junctional rhythm (AVJR, 1 subject), atrioventricular junctional escaped beat (AVJEB, 3 subjects) and wandering pacemaker (1 subject) . The danger arrhythmias which is necessary to restrict on exercise or swimming was not observed in this study.

Background : The incidence of anemia in the female athlete is high, and anemia causes not only a decrease in performance, but also various subjective symptoms. It is said that the cause of hemolysis -a type of anemia- is a decrease in antioxidants and an increase in the reactive oxygen species caused by exercise. Purpose : This study investigated the effect of acute exercise on hemolysis and oxidative stress in female athletes. Methods : On the basis of basal body temperature (BBT) data and urinary ovulation tests of the subjects (age 20.5±1.0 yr ), they were divided into two groups : eumenorrheic athletes (Eu, n=12) group, and irregular menstrual athletes (Am, n=9). The subjects performed an acute period of exhausting exercise on a bicycle ergometer. Lactate, hemoglobin, hematocrit, RBC, serum estradiol, haptoglobin, thiobarbituric acid reactive substances (TBARS) were determined in blood samples collected at rest and after exercise. Results : Lactate increased and hemoglobin, hematocrit, RBC, haptoglobin decreased after exercise in both the Eu and Am groups (p<0.05). However, serum TBARS did not show a significant change after exercise in both the Eu and Am groups. Conclusion : These results suggest that hemolysis may have developed, because haptoglobin decreased as a result of acute exercise. However, it is thought that the effect of oxidative stress is small because TBARS were not changed by acute exercise in both Eu and Am groups. In addition, there was no significant correlation between hemolysis and estrogen.

The purpose of this study was to evaluate the function of cardiac autonomic nervous activity and post-exercise vagal reaction during the menstrual cycle. The subjects were healthy young women (n=13, age 19.9±0.6 years) with normal menstrual cycles. Power spectral analysis of heart rate variability was used to examine cardiac autonomic nervous activity. In addition, the time con stant of heart rate decline for the first 30 sec (T₃₀) after exercise was used to examine post-exercise vagal reactivation.
Results show that the cardiac autonomic nervous activity changes during the menstrual cycle. Also, T₃₀ shows significant change during the menstrual cycle, especially T₃₀ retardation in the early luteal phase. These results suggest that an imbalance of estradiol and progesterone hormones may be responsible for these changes in cardiac autonomic nervous activity during the menstrual cycle.

‹Objective› In previous animal studies, it has been observed that ovarian hormones centrally alter baroreflex modulation of cardiovagal nervous control. If this central action of ovarian hormones is observed in human females, non-baroreflex modulation of cardiovagal nervous control should change with the menstrual cycle. The hypothesis in this study was that cardiovagal nervous response to facial cold stimuli (non-baroreflex modulation) changes throughout menstrual cycle.‹Subjects and methods› Eight young healthy women with a normal menstrual cycle participated in this study. The menstrual cycle was divided into 5 phases (menstrual, follicular, ovulatory, early luteal and late luteal) . Resing ECG RR intervals, cardiovagal nervous activity (by heart rate variability), RR intervals and cardiovagal nervous response to facial cold stimuli were measured during each menstrual phase. RR intervals and cardiovagal nervous response to facial cold stimuli were evaluated paying attention to the “quantity” and “quickness” of the changes.‹Results› There were no phase differences in resting RR intervals and cardiovagal nervous activity. Quantity of RR intervals and cardiovagal nervous response and quickness of. RR intervals to facial cold stimuli did not change throughout the menstrual cycle. The speed of cardiovagal nervous response to facial cold accelerated in the follicular phase, and to the contrary, slowed down in the early luteal phase, ‹Conclusion› These data suggest the speed of cardiovagal nervous response mediated non-baroreflex mechanism changes throughout the menstrual cycle.

The purpose of this study was to evaluate the change in dynamic and static balance ability during the menstrual cycle among young women. The subjects were young healthy women (n=12, age 20.4±1.2 years) with regular exercise and a normal menstrual cycle. The menstrual cycle was divided into 5 phases : Menstrual, Follicular, Ovulatory, Early luteal and Late luteal. Measurements were taken using the dynamic balance test, static balance test and looseness test. The dynamic balance test did not change during the menstrual cycle. Length Time within the static balance test increased in the late luteal phase compared to other menstrual cycle phases. The deviation of the mean of X within the static balance test increased in the follicular and late luteal phase and decreased in the ovulatory phase. Also, the deviation of the mean of X increased in the follicular phase compared to the menstrual phase and decreased in the menstrual and early luteal phases compared to the follicular and ovulatory. Left arm upper of laxity in hand on the back test within looseness test increased in the menstrual and early luteal phases compared to other menstrual cycle phases. These results suggest that static balance ability changes during the menstrual cycle.

[Objective] The aim of this investigation was to evaluate bone metabolism responses to acute resistance exercise during the menstrual cycle. [Methods] Subjects were young healthy sedentary women (n=7) with regular menstrual cycles. The subjects performed acute resistance exercise in each phase (follicular and luteal) of the menstrual cycle. Bone metabolism markers (bone formation marker BAP and bone resorption marker ICTP), bone metabolism related hormones (parathyroid hormone, calcitonin, calcium and inorganic phosphorus) and lactate were determined. Blood samples were collected before (Pre) and immediately following the exercise (Post), 1 hour (P1h) and 24 hours (P24h) after the exercise. [Results] BAP significantly increased at Post compared with Pre both in the follicular and luteal phases (p<0.05), but significantly decreased at P1h and P24h in the luteal phase. ICTP significantly increased at Post in the follicular phase (p<0.05) and significantly decreased at P1h and P24h in the luteal phase. The bone metabolism responses in the luteal phase moved to low-bone turnover at P1h and P24h. [Conclusion] The bone metabolism response to acute resistance exercise was different between menstrual phases. These results suggest that bone metabolism is influenced by the menstrual cycle.

Increased carotid arterial stiffness is associated with a risk factor of congestive heart failure. Thus factors that affect carotid arterial stiffness are of both physiological and clinical interest. The purpose of the present study was to examine the effects of regular aerobic exercise and menstrual cycle on carotid arterial stiffness in young female. The carotid β-stiffness index, an index of carotid arterial stiffness, was assessed in eight young female athletes (20.5 ± 0.4 years) and ten young female control subjects (21.3 ± 0.7 years). The carotid β-stiffness index was determined using ultrasound images of the common carotid artery with simultaneous recording of carotid arterial blood pressure by applanation tonometry. There was no difference in carotid β-stiffness index between the control and the athlete group both at the early follicular and the pre-ovulation phase of the menstrual cycle. On the other hand, the carotid β-stiffness index decreased from the early follicular phase to the pre-ovulation phase both in the control and the athlete group. These results suggest that carotid arterial stiffness in young females is not affected by regular aerobic exercise, but changes with the menstrual cycle, irrespective of exercise status.

Ten athletic women (5 normal ovulatory cycles, 5 short luteal phases) and 6 non-athletic women with normal ovulatory cycles were subjected to an investigation of episodic gonadotropin secretion. In the middle follicular phase, blood samples were obtained via an indwelling venous catheter every 15 minutes for 4 hours.
Mean levels of gonadotropins in both athletic groups were lower (p<0.001) than in the control group. LH pulse frequencies in the short luteal group were significantly lower than in the control group (p<0.001) . LH pulse amplitudes were similar in all groups. FSH dynamics were the same as those for LH.
In athletic women, low mean levels and infrequent episodic secretion of gonadotropins were obvious. These data suggest that strenuous athletic activity may cause hypothalamic-pituitary insufficiency, especially that of hypothalamic origin.

An investigation was conducted to clarify both the effect of water polo training on bone mass and the effect of training-induced menstrual disorders on bone. The subjects were 12 female college water polo players and 7 age-matched sedentary college women as a control group.
Menstrual condition was evaluated by 12 montes of basal body temperature measurement. Seven of the water polo players were eumenorrheic, and five had training-dependent (reversible) menstrual disorders (two with amenorrhea and three with cycle disturbances) .
Bone mineral measurement revealed differences between the water polo players and the sedentary women. The eumenorrheic water polo players had a higher bone mineral density (BMD) in the lumbar spine and total body skeleton than the sedentary control group, being 11.2% and 11.3% higher, respectively.
Effects of menstrual disorders (including cycle disturbance) were clear in the water polo players. The BMD of water polo players with menstrual disorders was 9.8% and 9.6% lower in the total body and lumbar spine that of eumenorrheic water polo players.
Hormonal examinations revealed a lower serum estradiol level in water polo players with menstrual disordsers in comparison with eumenorrheic water polo playes. Serum estradiol level showed a positive correlation with both total body BMD (r=0, 78, p<0.01) and lumbar spine BMD (r=0.71, p<0.01) .

Athletic women often exhibit menstrual disorders such as luteal insufficiency, oligomenorrhea and amenorrhea are often seen. It has been suggested that such disorders are related to prolactin release caused by physical activity. To investigate the mechanism by which the disorders are promoted, prolactin secretion was studied in 10 athletic women (5 with normal ovulatory periods, and 5 with short luteal periods) and 6 non-athletic controls. Blood samples were obtained during the early follicular phase of the menstrual cycle through an indwelling venous catheter at 15-minute intervals for 4 hours. The concentration of prolactin was measured by radioimmunoassay.
The mean prolactin concentration in the athletic group was lower than that in the control group (p<0.001), and pulse frequency in the athletic group was higher than that of the control group (p<0.01) . Pulse amplitude in the athletic women with short luteal periods was higher than that of those with normal ovulation. Pulse duration in the athletic women with short luteal periods was significantly longer than that of those with normal ovulation (p<0.01) .
These findings suggest that prolactin is one of the most important factors in menstrual disorders in athletic women.