Summary(-)-Hydroxycitrate (HCA) is known to inhibit increasing malonyl CoA con centration during endurance exercise. Furthermore, a short-term administration of HCA enhances endurance exercise performance in mice. Therefore we investigated the short term administration of HCA on the exercise performance of athletes. Subjects were adminis tered 250mg of HCA or placebo as a control (CON) for 5 d, after each time performing cycle ergometer exercise at 60% VO2max for 60min followed by 80% VO2max until exhaustion. Blood was collected and expired gas samples analyzed at rest and every 15min. The respira tory exchange ratio was significantly lower in the HCA trial than in the CON trial (p<0.05). Fat oxidation was significantly increased by short-term administration of HCA, and carbo hydrate oxidation was significantly decreased (p<0.05) during exercise, presumably result ing in increasing the cycle ergometer exercise time to exhaustion after 1h of 60% VO2max exercise (p<0.05). These results suggest that a short-term administration of HCA enhances endurance performance with increasing fat oxidation, which spares glycogen utilization during moderate intensity exercise in athletes.
This paper describes the results of several experiments conducted on a Cartesian feedback amplifier with soft landing. This amplifier uses a new method for adaptively controlling the local signal phase in a Cartesian demodulator. We tested the soft-landing Cartesian feedback (SL-CFB) method in the 900 MHz band using d4-shifted QPSK modulation to determine its applicability for pocket terminals in Japanese digital cellular systems.We developed a smooth loopgain control mechanism using a variable gain amplifier with an FET and a continuous phase-shifter control circuit for digital processing in the IF band. We showed that the SL-CFB method can maintain the optimum local signal phase in the demodulator. This method therefore solves the problem at applying CFB amplifiers. We adopted circuit configurations that are easy to incorporate into LSI chips so that the amplifier can be used in compact terminals.The results show that the SL-CFB amplifier is a promising candidate for developing highly efficient linear amplifiers, which are very important in digital cellular telephone terminals.
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