The purpose of this study was to evaluate the relationship between onset of blood lactate accumulation (OBLA) and long-distance running performance in order to examine whether OBLA can be a good predictor of long-distance running performance even in elite male runners with similar performance levels. Eleven highly-trained male long-distance runners participated in this study. The average running velocities of the individuals’ running performance were 5.918 ± 0.084 m·s-1 and 5.672 ± 0.095 m·s-1 for 5000 m (V5000) and 10000 m (V10000), respectively. The blood lactate concentrations and heart rate responses were measured immediately after field running, and the average value of running velocity corresponding to OBLA (VOBLA) was 5.447 ± 0.132 m·s-1. Variations of these three velocities expressed as a coefficient of variance (CV) ranged from 1.4 to 2.4%. A strong inverse relationship between heart rate corresponding to OBLA (HROBLA) and performance was observed (r=-0.709, p<0.02 for V5000 and r=-0.830, p<0.01 for V10000), while there was a lack of significant relationship between VOBLA and performance (r=0.293, NS for V5000 and r=0.130, NS for V10000). Furthermore, the average value of HROBLA obtained in this study (174.5 ± 8.2 b·min-1) was quite similar to that of the heart rate threshold reported by some previous researchers. In conclusion, VOBLA alone could not explain the small variation of long-distance running performance, and HROBLA should be used in place of VOBLA for evaluating long-distance running performance in elite runners with quite similar performance levels.
This study investigated the metabolic demands of deep water running (DWR) compared with those of treadmill running (TMR) while the water and ambient temperatures were kept under thermoneutral condition. Two maximal tests, one on treadmill and the other running in deep water using the Wet Vest (Lincoln life jacket) were undertaken by twenty healthy non-smoker males (Age=28.0 ± 9.2 years). The order of trials was counterbalanced with half of the subjects completing the treadmill first and the rest completing the water running first. Oxygen consumption (VO2), ventilation, heart rate (HR), respiratory exchange ratio (RQ), ratings of perceived exertion (RPE) and blood lactate were measured. VO2max (2.68 vs 3.40 ml/kg/min), HRmax (171.5 vs 190.8 beats/min), maximal minute ventilation (98.5 vs 113.3 l/min), and peak blood lactate value (10.44 vs 12.47 mmol/l) in response to DWR were significantly lower than those of TMR in the thermoneutral conditions. The lower VO2max and HRmax values of DWR compared to those of TMR are shown to be attributed to the hydrostatic effects caused by water and different muscle recruitment patterns between DWR and TMR.
Pachinko is a popular form of recreation in Japan. However, in recent years, along with Pachinko’s popularity, “Pachinko dependence” has become topical news. The purpose of this study was to investigate beta-endorphin, catecholamines, immune system responses and heart rate during the playing of Pachinko. The following significant results were observed. (1) Plasma concentration of beta-endorphin increased before playing Pachinko and while in the Pachinko-center (p<0.05). (2) Beta-endorphin and norepinephrine increased when the player began to win (i.e. at “Fever-start”) compared to baseline (p<0.05). (3) Beta-endorphin, norepinephrine and dopamine increased when the winning streak finished (i.e. at “Fever-end”) compared to baseline (p<0.05-0.01). (4) Norepinephrine increased past 30 minutes after “Fever-end” compared to baseline(p<0.05). (5) Heart rate increased before “Fever-start” compared to baseline, peaked at “Fever-start” and rapidly decreased to match rates measured at rest. But the increase was observed from 200 seconds after “Fever-start” (p<0.05-0.001). (6) There was a positive correlation between the number of hours subjects played Pachinko in a week and the differences between beta-endorphin levels at “Fever-start” and those at rest (p<0.05). (7) The number of T-cells decreased while the number of NK cells increased at “Fever-start” compared to baseline (p<.05). These results suggest that intracerebral substances such as beta-endorphin and dopamine are involved in the habit-forming behavior associated with Pachinko.
The present study investigated the validity, reliability, objectivity, and practicability of methods with skinfold caliper (SF), ultrasound (US), bioelectrical impedance (BI), and sulfur hexafluoride (SHD) using identical subjects, and evaluated comprehensive usefulness by comparing selected methods or equations. In examining validity, underwater weighing (UW) was employed to obtain the criterion of validity. The subjects were healthy Japanese, 16 males and 15 females, aged 18 to 32 years. The prediction equation developed by Nakadomo et al. (1990b) was considered to be suitable for BI. With respect to the validity, BI and SHD assessing total body when estimating body composition would be more valid than those assessing partial subcutaneous skinfold thickness. A comprehensive evaluation through an examination with respect to the validity, reliability, objectivity, and practicability suggests that the BI could be the best method to assess human body composition in vivo.
Heart rate variability (HRV), a non-invasive index of autonomic controls of the heart, has extensively been employed in various fields of study. The application range of this index persists to expand over the research horizon, and the need continues to demand technical complements for hitherto known deficiencies. Concurrent technical advances in recent years have yielded methodological techniques capable of performing quantitative analysis of HRV. However, as various approaches designed for HRV analysis exist, quantitative comparisons of the investigations have become difficult. Current physiological interpretations of the components of HRV are also inconsistent. Moreover, the issue of respiratory control has been much disputed when determining the HRV. In an attempt to clarify the current controversial state in HRV measurement, the present paper, based on the physiological background of HRV, pursued various procedures of HRV measurement and furnished global explanations for special features characterizing the various analytical approaches adopted thereof.
The present study attempted to design and evaluate a small portable electromyogram (EMG) amplifier that can output enhanced EMG and its root mean square (RMS) value. The production and design were of a laboratory scale without any special or high cost circuit construction. The designed amplifier was actually innovated according to the actual working conditions based on physiological anthropology. The present amplifier was compared with commercially available products and proved to be of practical use. The device was installed with a sufficiently small body depicting 8-channel variable gain AC amplifier and variable time-window RMS-to-DC converter. The prototype was battery-driven and well-shielded to minimize external noise interference.