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.

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.

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.

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.

[Objective] The aim of this investigation was to evaluate serum steroid hormone responses to acute resistance exercise. [Methods] Subjects were young healthy males (n=6) and females (n=6) . Each group performed three sets of 10 leg press and 10 bench press exercises at an intensity of their individual 10-repetition maximum (1ORM), with 1 min rest between sets. Blood samples were collected before (Pre-Ex) and immediately following the exercise (P0), 30 mm (P30), 60 mm (P60), and 24 hours (P24h) after the exercise. Levels of blood lactate, serum testosterone, dehydroepian drosterone sulfate (DHEAS) and cortisol were determined. [Results] The levels of blood lactate in males and females significantly increased at P0 and P30 compared with Pre-Ex (p<0.05) . In males, the serum level of testosterone significantly increased at PO (p<0.05), whereas in females, it significantly decreased at P0, P30, P60, P 24 h. (p<0.05) . The level of DHEAS significantly increased at P0 in both males and females (p<0.05) . [Conclusion] The change in the level of testosterone was different between males and females, but that of DHEAS showed a similar pattern for both sexes. The data suggest that DHEAS could be a useful indicator for evaluating the anabolic status of acute resistance exercise in females.

[Purpose] A leg press generally included in a weight training program to develop the quadriceps. However little is known about the mechanism of the load in lower extremity by the different knee alignment. The purpose of this study is to compare the muscle activity in the different knee align ment during leg press exercise. [Methods] Four normal knee and Five gene varum performed the leg press using three stance of narrow, medium and wide stance with the load of 75%/1 RM. Surface EMG date were collected (1000Hz) from vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF), adductor longus (AL), biceps lemons (HF), tibialis anterior (TA), gastrocnemius (GAS), soleus (SQL) . Integrated EMG (iEMG) values were calculated for each muscle during each rep. A video camera recorded the performing form during leg press from the frontal plane. [Results and Discussion] As the leg press was to strengthen of the thigh muscle, VM, VL and RF of both groups worked strongly. However SQL of genu varum worked as strong as the level of activity of the thigh, iEMG of the SQL showed low value significantly by using wide stance. When the genu varum group performed maximal knee flexion using the narrow, their ankle was valuus on the video screen. This result may become cause of SQL higher activity during leg press. From this we can derive the argument that it will be necessary to take that stance into consideration when athletes who are genu varum performs leg press.