The purpose of this study was to clarify the characteristics of the gait function for the elderly with a special reference to the angle of the ankle joint and that of the metatarsophalangeal (MP) joint at heel contact and toe off. Five healthy young men (aged 22 to 23 yrs) and five healthy elderly men (aged 65 to 71 yrs) participated as the subjects in this study. The angle variation of the right ankle joint and that of the MP joint detected in goniometers were analyzed synchronously with the data of the force plate and the image data of bare foot movements during free, slow, and fast gait. The following results were obtained:
1. The walking speed, step length, and cadence for the elderly during free gait were significantly small. Furthermore, the step length of the elderly was shorter than that of the younger subject even with the same height. Moreover, it was found that the fluctuation in both the step length and cadence resulted in an fluctuation in walking speed.
2. One reason for the decrease in step length and cadence, and the increase in duration of the double supporting time for the elderly is the lowering of walking speed.
3. The angle of the ankle at heel contact, the angle of the ankle at toe off, and the angular displacement of the MP joint were significantly smaller for the elderly during free gait and during walking within a range of speeds. Also, the angle of the ankle at heel contact, and the angle of the ankle at toe off for young and elderly subjects were separated into two groups during walking within a range of speeds. It may be showed that the reason for the smallness of the angle of the ankle at heel contact and the angle of the ankle at toe off for the elderly irrespective of walking speed is due to an elderly behavior that unconsciously makes the angle smaller to prevent the danger of falling.
In conclusion, the difference in variables between young and elderly subjects during free gait and walking within a range of speeds exemplifies the characteristics of gait function for the elderly.

Background: We assessed the relationship between patient age and remifentanil dosing rate in patients managed under general anesthesia with spontaneous breathing using low-dose remifentanil in sevoflurane. Methods: The participants were patients with an American Society of Anesthesiologists Physical Status of 1 or 2 maintained under general anesthesia with low-dose remifentanil in 1.5-2.0% sevoflurane. The infusion rate of remifentanil was adjusted so that the spontaneous respiratory rate was half the rate prior to the induction of anesthesia, and γH 　(µg/kg/min) was defined as the infusion rate of remifentanil under stable conditions where the respiratory rate was half the rate prior to the induction of anesthesia for ≥ 15 minutes. The relationship between γH and patient age was analyzed statistically by Spearman's correlation analysis. Results: During dental treatment under general anesthesia using low-dose remifentanil in sevoflurane, a significant correlation was detected between γH and patient age. The regression line of y = − 0.00079 x + 0.066 (y-axis; γH , x-axis; patient's age) was provided. The values of γH provide 0.064 µg/kg/min at 2 years and 0.0186 µg/kg/min at 60 years. Therefore, as age increases, the dosing rate exhibits a declining trend. Furthermore, in the dosing rate of remifentanil when the patient's respiratory rate was reduced by half from the preanesthetic respiratory rate, the dosing rate provided was around 0.88 mL/h in all ages if the remifentanil was diluted as 0.1 mg/mL. EtCO2 showed 51.0 ± 5.7 mmHg, and SpO2 was controlled within the normal range by this method. In addition, all dental treatments were performed without major problems, such as awakening and body movement during general anesthesia, and the post-anesthetic recovery process was stable. Conclusion General anesthesia with spontaneous breathing provides various advantages, and the present method is appropriate for minimally invasive procedures.