RESUMO
We developed a new electrothermo-acupuncture instrument which employs a curved heating plate, and we compared this new one and the old hitherto used electrothermo-acupuncture instrument in terms of radiation temperature, using two male volunteers. The results showed that the 2nd step in the old instrument equaled the fifth channel in the new one. The radiation temperature increase of 140°C seen in 10 minutes was the same, between the two instruments, but the old one continued to increase its temperature, whereas the new one held at a plateau of about 140°C. Therefore, we considered that the new electrothermo-acupuncture instrument is safer than old one.<br>Next, we investigated the relation between effective Kampo formulas and endurance time in the fifth channel of the new electrothermo-acupuncture instrument, in nineteen patients. We found that Kampo formulas used in the resistant phase of Yang-syndrome disease, is effective in less than 10 minutes of endurance time, and the Kampo formula containing Aconite Tuber is effective for over 30 minutes.<br>We considered, because of the relation between endurance time and Kampo diagnosis, that the new electrothermo-acupuncture instrument can be useful in a supplementary way in deciding Kampo diagnosis.
RESUMO
The purpose of this study is to examine the validity of muscle fatigue evaluation using maximum voluntary torque (MVT), and to identify the dependence of individual's tolerance for fatigue on the capacity to exert MVT. In 14 young male subjects (10 regular exercisers and 4 sedentary), MVT was measured during isometric knee extension, and voluntary activation (VA), which reflects motor unit activation, was evaluated using the twitch interpolation technique. In addition, the maximum endurance time (ET) was measured, and behavior of the mean power frequency (MPF) and the average rectified value (ARV) of surface EMGs from the vastus lateralis muscle were analyzed during constant force isometric contractions of 60% MVT (short-duration fatigue task; SDF task) and 20% MVT (long-duration fatigue task; LDF task) . Correlations were examined among these five variables.<BR>The results were as follows:<BR>1) Subjects were divided into a high voluntary activation group (HVA group) and a low voluntary activation group (LVA group) . Four sedentary subjects were included in the latter group.<BR>2) MVT was significantly larger in the HVA group than in the LVA group (p<0.01) . A significant positive correlation (r=0.72) was found between MVT and VA (p<0.01) .<BR>3) A significant negative correlation (r=-0.71) was found between MVT and endurance time (ET) for the LDF task (p<0.01) . The ET was significantly longer in the LVA group than in the HVA group (p<0.01) .<BR>4) The MPF of voluntary EMG decreased consistently, as ARV increased during isometric contraction in both tasks (p<0.01), indicating the development of fatigue in the muscle. The final change of MPF relative to the initial value was significantly greater in the SDF task than in the LDF task (p<0.05) .<BR>5) A significant correlation (r=-0.83) was seen between the relative change in MPF and ARV in the SDF task (p<0.01) .<BR>6) For the SDF task, the final change of MPF and ARV relative to the initial value was significantly greater in the LVA group than in the HVA group (p<0.05) .<BR>These results indicate that tolerance for local muscle fatigue usually evaluated as maximum endurance time, may depend on individual differences in VA, the VA, in turn, depending on adapta-tion to exercise, and that there appears to exist a corresponding adaptative strategy of the neuromuscular system during fatiguing contractions. Usefulness of our procedure using the twitch interpolation technique in evaluating muscle fatigue was also suggested.
RESUMO
The purpose of the present study was to investigate the relationship between endurance time and fatigue factors at varying intensities of handgrip isometric exercise. Seven subjects performed isometric contractions at 10%, 30% and 50% of maximum voluntary contraction (MVC) sustained to exhaustion. Continuous changes in high-energy phosphates and muscle oxygen content (oxy-Hb/Mb) in the forearm flexor muscle were measured by <SUP>31</SUP>P magnetic resonance spectroscopy (<SUP>31</SUP>P-MRS) and near infrared spectroscopy (NIRS), respectively. The endurance time to exhaustion was 963±236 (mean±S. D.), 209±41.9 and 95.3±13.6s at 10%, 30% and 50%MVC, respectively, From the onset of exercise at each %MVC, both PCr and oxy-Hb/Mb fell and Pi (H<SUB>2</SUB>PO<SUB>4</SUB>-) rose linearly with time, whereas intracellular pH remained relatively constant at resting values during the early phase. Thereafter, intracellular pH showed a linear decline. The rates of pH decline were 0.03±0.02, 0.22±0.14 and 0.51±0.17 pHunit/min, while the rates of H<SUB>2</SUB>PO<SUB>4</SUB>- increase were 20.9±19.3, 118±48.9 and 434±242 (% of resting) /min at 10%, 30% and 50%MVC, respectively. There were correlations between the changes in endurance times to exhaustion and the rates of pH decline (r= -0.58--0.87) and H<SUB>2</SUB>PO<SUB>4</SUB>- increase (r=-0.37--0.74, (n=7) ) at each intensity of exercise. In particular, significant correlations (p<0.05) between endurance time and the rate of pH decline were found at both 10% and 30%MVC. These results suggest that muscle fatigue (endurance time) at each intensity in handgrip isometric exercise is closely correlated with the rate of pH decline.