A decrease in testosterone levels and an increase in cortisol levels are observed in male athletes with the overtraining syndrome (OTS). Cortisol causes blood leptin levels to rise and testosterone has an inverse relationship with blood leptin levels. Therefore, we hypothesized that the hormonal changes as a result of OTS induce an increase in leptin. To test this hypothesis, we examined the relationship among changes in leptin, testosterone and cortisol in thirteen male collegiate distance runners (aged 20.3±1.1 years) before and after an 8-day strenuous training camp. Runners ran 284.1±48.2 km during the training camp. Body fat percentages and plasma glucose concentrations decreased significantly after the training. Non-ester fatty acids and total cholesterol concentrations in blood were unchanged. Serum cortisol concentrations showed a significant increase after the training camp (from 11.82±2.00 µg/dl to 16.78±3.99 µg/dl), and serum testosterone decreased significantly (from 408.0±127.6 ng/dl to 265.2±97.6 ng/dl). The ratio of testosterone to cortisol (TCR) dropped by 50% after training (from 35.62±13.69 to 16.94±8.47). These results suggest that the subjects reached a state of the OTS. Contrary to our hypothesis, plasma leptin was not significantly changed (from 1.34±0.29 ng/ml to 1.49±0.18 ng/ml). Δ Plasma leptin was not significantly correlated with Δ serum cortisol, Δ TCR or Δ fat percentage. However, Δ serum testosterone was positively correlated with Δ plasma leptin (r=596, p<0.05). Plasma leptin concentrations might modulate the secretion of testosterone in overtraining conditions. In conclusion, the change in blood leptin level is independent of the changes in cortisol, TCR and fat percentage in highly trained male athletes in the state of the OTS.
The aim of the study was to test the possible relationships of anthropometrical parameters, somatotype and body composition parameters with bone mineral content (BMC) and bone mineral density (BMD, total body, the dominant arm distal radius, antero-posterior lumbar spine–L2–L4, femoral neck) in strength- (n=33) and endurance- (n=32) trained and sedentary normal-weight (n=41) and overweight (n=23) young females. Their body height and mass were measured and BMI calculated. Nine skinfolds, thirteen girths, eight lengths and eight breadths/lengths were measured. Somatotype components were calculated according to Carter and Heath (1990). Whole body fat percentage, fat mass, lean body mass (LBM), BMC and BMD were measured by DXA. The relationship of different BMC and BMD values at each of the regions studied to the different anthropometrical and body composition parameters were analysed by using a stepwise multiple regression analysis. In all groups, BMC is highly dependent on the body mass (31.5–81.2%, R2×100). In the endurance-trained females, BMD is dependent on LBM, especially in both weight-bearing sites (66.2% in L2–L4 and 35.3% in the femoral neck). LBM explained 77.0% of the total variance of BMC in this group. BMC in the strength-trained group is dependent on the lower body anthropometrical parameters—thigh skinfold (18.2%), calf girth (25.2%), trochanterion length (24.1%) and sitting height (51.4%). From the endurance-trained group, BMC is dependent on hip girth (75.2%) or in combination with ankle girth (81.2%). From the length parameters, trochanterion is the most important (55.8%) and from breadths/lengths, sitting height (57.1%). In the normal-weight females, BMC is dependent on the calf girth (31.1%), trochanterion length (28.2%) and sitting height (29.8%). In the overweight group, only chest girth (20.1%) and biacromial breadth/length (27.0%) had a relationship with BMC. From somatotype components, only ectomorphy explained BMD in the endurance-trained females in the femoral neck (21.3%) and in the lumbar spine (20.9%). We can conclude that from the body composition parameters, LBM is a powerful predictor of BMC and BMD. From the anthropometrical parameters measured, lower body parameters are the most important. Somatotype components (ectomorphy) had a relationship with BMD only in the endurance-trained group. There are some differences that depend on the specific physical activity field. In the endurance-trained group, the anthropometry is more important than in the strength-trained group.
The purpose of this study was to examine the practice effect and what difference it makes in the pursuit rotor test for the dominant and non-dominant hands in 30 right-handed Japanese male adults aged 18 to 23 years (Age 20.8±1.4 yrs). The subjects performed the pursuit rotor test for 1 min in 20 trials with a 1-min interval alternately using the dominant and non-dominant hands. After continuing for 10 trials, a 5-min rest was taken. The measurement order was randomly assigned. Contact time of a steel pen and a target was measured in units of 1/10 sec. The measurements showed a constant increasing tendency at every trial until the 6th trial in both hands. Significant linear regressions were identified, but the increase-rate of the dominant hand was significantly larger. Individual differences showed a decreasing tendency at every trial in the dominant hand, but in the non-dominant hand it increased until the 4th trial then decreased. The relationships between measurements of the 1st and 10th trials in both hands and both hands in the 1st or 10th trial were not high. The performance of the pursuit rotor test improves at every trial in both hands, but the improvement rate decreases after the 7th trial. The improvement rate of the dominant hand is high. The change in individual differences differs in both hands and the relationship between the measurements is not high. It can be judged that the practice effect of the pursuit rotor test differs in the dominant and non-dominant hands.
To determine the effects of ammonium chloride (NH4Cl) dosage and swimming exercise training during 4 weeks on bone metabolic turnover in rats, seven-week-old female 24 Wister-Kyoto (WKY) rats were investigated by bone status including bone mineral density (BMD) and biomechanical markers from blood and urine. Twenty-four rats (initial weight: 191.2±7.6 g) were randomly divided into four groups: baseline (8 weeks old) control group (n=6, BC), 4-week control group (n=6, Con), 4-week swimming exercise loading group (n=6, Swim) and 4-week chronic NH4Cl dosage group (n=6, Acid). All rats were fed an AIN93M diet (Ca: 0.5%, P: 0.3%), and both Con and Swim groups were pair-fed by feeding volume of the NH4Cl dosage group. The acid group only received 0.25 M NH4Cl distilled water ad libitum. At the end of the experimental period, rats were sacrificed with blood drawn and femur and tibia were removed for analysis of bone mineral density (BMD) by dual energy X-ray absorptiometry (DEXA). In the Swim group, 24-hour urinary deoxypiridinoline (Dpd) excretion, reflecting bone resorption, was significantly increased (p<0.05) with a tendency towards decrease of BMD (N.S.), and body weight and abdominal fat weight were decreased in approximately 7% (p<0.05) and 58% (p<0.001), as compared with age matched Con rats. In the Acid group, 24-hour urinary calcium (Ca) and phosphorus (P) excretion were increased approximately 2.1-fold (p<0.05) and 2.0-fold (p<0.01), respectively, with increase of kidney weight as much as in the Con groups. Serum Ca and P concentration, as well as urinary Dpd excretion were, however, not significantly changed. These results suggest that blood Ca and P concentrations in the chronic acidosis condition during the 4-weeks might be maintained by hypercalciuria and hyperphosphaturia with kidney disorder, and swimming exercise training leads to decrease in BMD with stimulation of bone resorption and reduction of body fat.
This study examined the specific physiological responses of women with primary dysmenorrhea during the severely painful menstrual (days 1–2 of menstruation) and the non-painful follicular phases (days 5–8 after the onset of menstruation). Subjects consisted of 10 severe primary dysmenorrheic (Group P) and 10 non-dysmenorrheic women (Group C) with regular menstrual cycles. However, only 9 out of 10 and 8 out of 10 subjects of Groups P and C participated during the follicular phase. Physiological measures were taken in a resting state for 60 min. In the menstrual phase, the pain ratings and secretory immunoglobulin A (s-IgA) concentrations of Group P were significantly higher than those of Group C, with relatively significant decreases in the leg-skin temperature in the former as well. In addition, the systolic (SBP) and diastolic blood pressure (DBP) at 45 min after rest in Group P were significantly higher than those found in Group C. These reactions strongly suggest activation of the sympathetic-adrenal–medullary axis (SAM axis) by painful stress. Furthermore, the low-frequency (LF) component of the SBP variability (SBPV) was significantly higher in Group P than Group C, even during the follicular phase. These findings imply that Group P may well have elevated activities of the SAM axis throughout the whole menstrual cycle. As such, it suggests that dysmenorrheic women may be affected by certain stressors other than pain per se and pain-derived emotions throughout the whole menstrual cycle. The findings also indicate that women with dysmenorrhea have more sensitive responses to the SAM system than non-dysmenorrheic women during stress. Moreover, the high-frequency (HF) component of heart rate variability (HRV), or the index for the vagus nerve activity, displayed a consistently higher value in Group P than C. It is postulated that the human body may have responded to pain in an attempt to maintain the homeostatic state by enhancing vagus nerve activity.
The present study examined the effects of low humidity and hypobaric conditions on hematological change in venous blood of the lower leg during quiet prolonged sitting. Ten healthy male students participated as the subjects after singing a consent form to participate in this study. Their diet and water intake were controlled from 19:00 on the day before the experiments. The subjects sat for 130 min in a climatic chamber. Four experimental conditions in the chamber were designed from a combination of relative humidity (20% or 60%) and air pressure (sea level or equivalent to an altitude of 2,000 m). Ambient temperature was maintained at 24°C in every condition. Venous blood was sampled from the lower leg before and after exposure to the experimental conditions, and was analyzed for blood viscosity and hematological indices. Also, body weight and leg circumference were measured as indices of total water loss and edema, respectively. Regarding the results of ANOVA, significant interactions between humidity and time were observed in blood viscosity, red blood cell count and hematocrit (each p<0.05). However, there were no significant differences in these indices among the conditions. Significant increases were observed in leg circumference (p<0.01), platelet count (p<0.05) and total protein (p<0.05) after the exposure compared with those before the exposure. There were no noticeable effects of hypobaric conditions in every measurement. In conclusion, prolonged sitting seems to be a more hazardous factor for thrombogenesis low humidity and hypobaric conditions during a long-distance flight.
July 27, 2015 There had been a system trouble (from July 26‚ 2015 15:25 to July 27‚ 2015 1:00 (GMT)). The service has been back to normal.
July 15, 2015 A new online journal "Mechanical Engineering Letters" has been launched by The Japan Society of Mechanical Engineers (JSME). This publication of such a letter journal is not only a new experience but also a tremendous challenge for the mechanical engineering society.
May 01, 2015 Please note the "spoofing mail" that pretends to be J-STAGE.