The purpose of this study was to investigate the prognostic value of change in heart rate (HR) response to oxygen uptake (VO2) during exercise in patients with coronary heart disease (CHD). We retrospectively studied 204 patients with CHD who were sent to our exercise testing laboratory between August 1983 and February 1985. The following equation was used to determine the relation between VO2 and HR during a graded treadmill exercise test: HR= A・exp B･VO2, where the constant b was defined as the inclination of the exponential curve-fitting model for oxygen uptake and heart rate during graded treadmill exercise (I-ECOH). Data on mortality were determined in May 2006 by examining medical records from the outpatient clinic and/or conducting telephone interviews with the patients or their families. Among the 204 study subjects, there were 54 cardiac deaths during the entire 20-year follow-up period. Kaplan-Meier survival curves for 20 years of follow-up demonstrated a survival rate of 81.3% for patients with a lower I-ECOH (＜35) and 56.0% for those with a higher I-ECOH (≧35), showing a significant difference in survival (p＜0.001). Multivariate Cox proportional hazards analysis revealed left ventricular ejection fraction (LVEF), peak oxygen uptake (VO2 peak) and I-ECOH as independent predictors of survival. In this analysis, the prognostic power of minutes ventilation/carbon dioxide output (VE/VCO2)slope was insignificant. The patients were divided into two groups with (＜45%) and without (≧60%) LV dysfunction using LVEF for more detailed analysis. The VO2 peak and VE/VCO2 slope were significant independent predictors of survival in patients with LV dysfunction. However, the I-ECOH was a significant independent predictor of survival in patients with and without LV dysfunction. Our data indicate that I-ECOH provides independent prognostic information on CHD patients with and without LV dysfunction.
PORPOSE: This study aimed to compare the prevalence of metabolic syndrome (MS) risk factors and its components in different levels of aerobic fitness established by “Exercise and Physical Activity Reference for Health Promotion 2006 (EPAR2006)” in Japanese middle-aged and elderly people. METHOD: Men (n=102) and women (n=133), aged 30-69yrs, participated in this study. The prevalence of MS risk factors was evaluated as the number of MS risk factors, according to the diagnostic criterion for Japanese-specific MS. Aerobic fitness was quantified as maximal oxygen uptake (VO2max). Subjects were classified into the three groups by aerobic fitness level based on “Reference values” and “Reference range” established in EPAR2006; 1) High fitness group (H); VO2max (mL/kg/min) is higher than “Reference values”, 2) Medium fitness group (M); VO2max is below “Reference values” but within “Reference range”, 3) Low fitness group (L); VO2max is lower than “Reference range”. RESULTS: In men, M and L groups showed significantly higher frequency of risk factors for MS than H group (H: 1.09±0.98, M: 1.81±1.07, L: 2.27±0.70, P＜0.01). In women, L group showed significantly higher frequency of risk factors for MS than H and M groups (H: 0.57±0.80, M: 0.81±1.01, L: 1.53±1.07, P＜0.01). CONCLUSION: These results suggest that higher MS risk appears when the VO2max is lower than “Reference values” in men, and below “Reference range” in women, and that particularly, men with low aerobic fitness have higher MS risk.
The present study examined the relationship between rate of abnormal menstrual cycles in women who participated in competitive sports and long-term fertility. Longitudinal menstrual data were collected over 25 years from 33 women who graduated from physical education colleges The results were as follows: 1)Among the 33 women surveyed, the number of pregnancies for each woman ranged from zero to eight; the total number of pregnancies was 85 (mean 2.6). Sixty-five (76.5%) of the 85 pregnancies were carried out to delivery times. 2)The rate of spontaneous abortion was 15.3%. Four (12.1%) of the 33 women were infertile. 3)In women with fertility-related problems such as infertility, spontaneous abortion, premature delivery, and stillbirth, the rate of abnormal menstrual cycles tended to be higher with increase of the fertility-related problems. 4)In women with a high rate of abnormal menstrual cycles during college, the rate continued to be high after graduation. 5)In women without fertility-related problems, the rate of abnormal menstrual cycles during college varied widely. Also, the rate of abnormal menstruation decreased less than 30% after graduation, excluding one woman. Conversely, in women with fertility-related problems, the rate of abnormal menstrual cycles was higher than in women without fertility problems both during college and after graduation. 6)Changes in menstrual cycle length with age were more different than an individual. In women with fertility-related problems, abnormal menstrual cycles were observed between the ages of 18 and 42, and abnormal cycles were both longer and shorter than normal cycles. The results indicated that, in women who participated in competitive sports during their youth, abnormal menstrual cycles may remain long after retirement from sports. In addition, problems such as infertility and spontaneous abortion were observed to be associated with higher rates of abnormal menstrual cycles.
The aim of the present study was to investigate, by analysis of motor unit action potential (MUAP) and motor unit mechanomyogram (MUMS) wave-forms, whether the synchronized activity of motor units (MUs) is a factor in increasing the integrated value of a mechanomyogram during muscle contraction at relatively low tension levels. MUAP and MUMS of m. vastus medialis were recorded by Ag/AgCl disc electrode ( 5mmφ) and condenser microphone ( 10mmφ), respectively, during muscle contractions, brief isometric constant contractions (BICC) and prolonged isometric constant contraction (PICC) at the target torques from just above the decruitment threshold torque of the objective MU to 20% of maximal voluntary contraction (MVC). The degree of synchronization of MUs, defined from the amplitude of late positive deflection (VLPD), could be seen in MUAP wave-forms. The amplitude of the positive phase in MUMS (MS-Vpositive) had no relationship with the increase of VLPD in BICC condition. During PICC, MS-Vpositive and VLPD increased with time. Applying linear regression analysis on the relation between VLPD and MS-Vpositive, except for data at 20%MVC, there was significant correlation. However, the scale of the time increments, between VLPD and MS-Vpositive, were different comparing exponential and logarithmic figures, respectively. Therefore, in the present experiment, the meaningful relationship between the two parameters could not be introduced. It is necessary to further investigate the relationship between the two parameters including the firing frequency of MU, intramuscular pressure and extent of recording area of both sensors.
The purpose of this study was to identify the angles of the shoulder complex which consist of glenohumeral joint, scapulothracic joint, and thoracic joint at the maximum external rotation (MER) of the shoulder complex during throwing in baseball players, and to analyze the correlation of each angle. The subjects were 19 collegiate baseball players. Throwing motion data was collected by three high-speed cameras and the three-dimensional (3D) coordinates of the shoulder complex were established by direct leaner translation method for the MER calculation. A 3D analysis was performed to obtain the external rotation (ER) angle of the glenohumeral joint, the posterior tilt angle of the scapula, and the extension angles of thoracic at MER of shoulder complex. The mean (±SD) value of the MER was 145.5±10.3°. The mean (±SD) values of the glenohumeral ER, the scapula posterior tilt angle and the thoracic extension angle at MER were 105.3±16.0°, 24.3±15.0°, and 9.1±7.2°respectively. Multiple linear regression analysis was used to relate the MER angle to each joint angle. The final linear regression model included the posterior tilting angle of scapula ( r=0.56, p＜0.05), and external rotation of the glenohumeral joint ( r=0.40, p＜0.05). Significant negative correlation was observed between the posterior tilting angle of the scapula and external rotation of the glenohumeral joint ( r=-0.52, p＜0.05). This finding suggested that scapula motion could be very important for the prevention of throwing injuries.
Objective: This study aimed to clarify changes in planter pressure at the 1, 2, 5 metatarsal head, and muscle activities resulting from exercise of the peroneus longus (PL) or tibialis posterior (TP) muscles. Method: Nine subjects (3 male, 6 female) were recruited. Before and after exercise, planter pressure at the metatarsal heads and the activities of PL, TP, tibialis anterior, and soleus muscles were recorded during heel raising using electromyography and a foot sensor. The first exercise was a maximal isometric contraction of the PL and peroneus brevis (PB). The second was contraction of the TP, and the third was of all three, the PL, PB, and TP. Result: The amount of planter pressure at the first metatarsal head increased after PL exercise. The standard deviation at the second metatarsal head decreased after PL and TP exercise, but showed no change after PL exercise. Conclusion: After PL and TP exercise, heel raises were possible with few perturbations at the metatarsal head. After PL exercise, the amount of planter pressure at the first metatarsal head increased, but there was no change in perturbations. The results show that it is necessary to consider the effect of short time exercise.
The purpose of this study was to examine the influence of autostretching and static stretching on range of motion (ROM) and running economy (RE) in long-distance runners. Twenty-two male distance runners were randomly assigned to an autostretching group (n=8), a static stretching group (n=7) and non-intervention control group (n=7). The experimental protocol was composed of interventions between treadmill runnings for RE. The interventions were either autostretching or static stretching, after the first treadmill running. The oxygen consumption (VO2) as RE was measured at three steady-state running speeds (240m/min, 268m/min, and 295m/min). Goniometric measurements of hip flexion and ankle dorsiflexion ROM were taken immediately before and after each treadmill running for RE. The results showed that the autostoretching group had a significant decrease in VO2 at 240m/min (p＜0.05), and at 268m/min (p＜0.05). On the other hand, the control group had a significant increase in VO2 only at 295m/min (p＜0.05). At the same time, the autostretching group had significant improvements in ROM for hip flexion (p＜0.05) and ankle dorsiflexion (p＜0.05). The static stretching group had no significant changes in RE or ROM. The results of this experiment suggest that autostretching had a positive effect in improving RE in subjects of this study, and indicate the possibility that improved RE leads to the improvement of long-distance runners' performance.