This study examined the influence of chair seat heights on floor reaction force (FRF) and strength of lower-limbs during sit-to-stand (STS) movement. Fifteen young・adult male subjects participated in this study (age: 20.7±2 .6 yr, height: 172.8±4.8 cm, body-mass: 66.3±5.2 kg, lower-thigh-length: 40.2±1.7 cm). The subjects performed STS movement twice from a chair height adjusted to 80, 100 and 120% of their lower-thigh-length (LTL). Vertical FRF and electromyogram (EMG) on the rectus femoris and tibialis anterior muscles during STS movement were measured to evaluate the force of knocking over and the burden on the legs. Fifteen parameters (FRF: 10, EMG: 5) were selected for analysis. The FRF at the time of hip-syneresis, the impulse between movement onset and hip-syneresis, and the active mass of the rectus femoris and tibialis anterior muscles from the beginning of movement to finishing were significantly greater in the 80% LTL condition than in the 120% LTL condition. The results of this study suggest that the force of knocking over at the instant of hip-syneresis and the active mass of lower legs muscles during STS movement were greater in the 80% LTL condition as compared with the 120% LTL condition. It is, therefore, inferred that the legs have a greater burden during STS movement in the 80% LTL condition and subjects have more difficulty in achieving STS movement. Moreover, judging from the time-series change of EMG on the rectus femoris and tibialis anterior muscles, their roles in achieving STS movement are different .Namely, the former may contribute mainly to transferring the center of mass upward and the latter may mainly maintain body balance.

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This study investigated 1) differences in electromyographic (EMG) activation patterns during prolonged static contractions at relatively different workloads, 2) whether the alternate activity among synergistic muscles is observed at relatively higher load. Ten healthy men performed fatiguing static contractions in the triceps surae muscles at an ankle joint angle of 110° at 10% and 30% maximal voluntary contraction (MVC). EMG recordings from lateral gastrocnemius, medial gastrocnemius, and soleus muscles under the different condition of workloads showed different EMG patterns in the time course, i.e., alternate activity between muscles at 10% MVC and tremulous rhythmic activity of EMG grouping at 30% MVC. Iln 10% MVC condition, significantly (p<0.05) greater number of events of alternate activities was observed in the second half of all exercise times. In 30% MVC, on the other hand, the number and the period of events showing a repetitive grouped discharge with rhythmic bursting cycle of 8-9Hz were significantly (p<0.05) greater in the second half than in the first half of all exercise times. It is demonstrated that the alternateactivity among the synergists is easy to occur under the condition of relatively low-level static contractions. These results suggest intrinsic differences in the recruitment strategy in the synergists for prolonged muscle contractions at the different loads of 10% and 30% MVC.

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To examine the factors influencing the excess CO_2 output (CO_2 excess) during and after intensive exercise, seven healthy men performed 40 s intensive exercise on a cycle ergometer after ingestion of CaCO_3 (control condition) and NaHCO_3 (alkalosis condition). Increase of blood lactate concentration (⊿[La^-]) and decrease of blood bicarbonate concentration (⊿[HCO_3^-]) showed maximal values at 5 min postexercise in both conditions. There was no significant difference in the ⊿[La^-] between the two conditions, but the ⊿[HCO_3^-] was significantly higher in the alkalosis condition. There was no significant difference in the changes of main strong cations between the two conditions. In addition, although [HCO_3^-] decrease was significantly different between the two conditions, CO_2 excess was similar for the two conditions. Arterialized blood PCO_2 decreased below resting level during recovery in the control condition, but not in the alkalosis condition. These results suggest that the excess CO_2 output during and after intensive exercise is affected by the shift of strong anions including lactate into blood and the decrease in arterial PCO_2.

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The purpose of the study was to investigate whether the use of hyperoxic gas generator is effective in recovery from fatigue after exercise. Ten healthy male subjects performed two trials; each consisting of ten minutes of exercise at a workload of 65%VO_2max on a bicycle ergometer and twenty minutes of recovery. The hyperoxic gas generator was applied to the one trial during recovery in order to determine its effect. The gas generator used in this study was fitted with a special film to raise oxygen concentration of the air and sent the concentraed air (30%O_2) through a pipe. The end of the pipe was set in front of the nostril within a couple of cm in accordance with the user's manual. Blood samples were collected at 3, 6, 10, 15 and 20 min after each exercise session, and blood lactate concentration was measured. Pulmonary ventilation and heart rate were measured during the experiments. The subjects were questioned as to their condition afler each trial using a questionnaire. With regard to ventilation, heart rate and blood lactate concentration responses during recovery, no significant difference was found between the cases using ie hyperoxic gas and those not using it. The questionnaire investigation showed no significant difference either. These results indicate that the hyperoxic gas generator is not effective in the recovery after exercise fatigue under these experimental conditions.

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A questionnaire was carried out in 178 home-living ADL-independent elderly people (53 males and 125 females; mean age 74.6 years) to clarify their water drinking behavior and factors that affect it. (1) The mean daily water intake was estimated to be 13±0.6 L, the water intake was significantly greater (p<0.05) in the females, and the frequency of water intake was about 7 times/day in both the males and females. (2) The water intake was greater in those living alone than in those living with their families (p<0.01), in the females who were aware of increased frequency of urination than in those who were not, and in those who did not self-restrain water intake than in those who did (p<0.05). (3) The actual water intake was close to the water intake considered necessary by the subjects. Those who considered that the risk of dehydration increases in the old age had a greater water intake than those who did not (P<0.05). These results suggest that water drinking behavior is affected not only by physiologic factors but also by the household composition and knowledge about water intake and that support in consideration of these factors is necessary for the prevention of dehydration in elderly people.

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The effects of rinsing the mouth with lemon-flavored water (LW) on saliva secretion and taste thresholds were studied. The saliva secretion from the parotid gland, taste thresholds (saltiness, sourness, sweetness, and bitterness), and subjective feeling in 20 healthy female students were examined 5 minutes after rinsing the mouth with distilled water (DW), 5%LW, 10%LW, and 15%LW. The saliva secretion was significantly and concentration-dependently higher (p<0.01) after rinsing the mouth with 5-15% LW. Only the threshold of bitterness decreased at 5-10% LW compared with DW(p<0.05). The feeling after rinsing was positive for DW and 5%LW but negative fbr 10-15%LW. These results suggest the usefulness of 5-10%LW fbr reducing the threshold of bitterness and 5-15%LW for promoting saliva secretion but the necessity of improvements in the feeling after use for 10-15%LW.

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