Electric motor assisted bicycle as an aerobic exercise machine.

The goal of this study is to maintain a continuous level of exercise intensity around the aerobic threshold (AT) during riding on an electric motor assisted bicycle using a new control system of electrical motor assistance which uses the efficient pedaling rate of popular bicycles. Five male subjects participated in the experiment, and the oxygen uptake was measured during cycling exercise using this new pedaling rate control system of electrical motor assistance, which could maintain the pedaling rate within a specific range, similar to that in previous type of electrically assisted bicycles. Results showed that this new pedaling rate control system at 65 rpm ensured continuous aerobic exercise intensity around the AT in two subjects, and this intensity level was higher than that observed in previous type. However, certain subjects were unable to maintain the expected exercise intensity because of their particular cycling preferences such as the pedaling rate. It is necessary to adjust the specific pedaling rate range of the electrical motor assist control according to the preferred pedaling rate, so that this system becomes applicable to anyone who want continuous aerobic exercise.

Development of a Portable Acceleration Monitor Device and its clinical application for the Quantitative Gait Assessment of the Elderly.

In this study, a handy gait assessment system with a tri-axial accelerometer has been developed and its application for a quantitative assessment of gait in the elderly was examined. This assessment system consists of a portable acceleration monitor device and PC analysis software. This portable device was fixed to the lower front of the subject, and the subject was asked to walk around a test course at a voluntary speed. The activities performed on the test course include standing up, normal walking, fast walking, and walking over a barrier. Gaits in 402 elderly people were measured three times every three months. These subjects were under nursing health services, such as expert place nursing, walking training, power rehabilitation, fall prevention training, and pool training. The measured acceleration was converted into relative velocity and relative displacement of the center of gravity of the subject. Four evaluation indices, i.e., physical activity, stability, symmetry, and average speed were calculated. The results reveal that both the physical activity and average speed decreased after six months under nursing services.

Virtual walkway system and prediction of gait mode transition for the control of the gait simulator.

A virtual walkway system is proposed in This work. This system consists of a new developed gait simulator and a HMD system to present virtual space to the user. The gait simulator is designed to permit the user to walk straight, change direction, go up and down stairs, etc. Main part of this gait simulator is two foot plates driven by three arms and actuators. Each foot plate follows the foot during swing phase and pulls it back during the stance phase while the user is walking straight However this gait simulator has one weak point, that is, this simulator cannot follow the change of gait mode sufficiently, like the start of walking or the end of walking. To solve this problem it is necessary to predict the change of gait mode to follow the transition perfectly. In this paper we chose the start and the end of straight walking and have tried to measure this transition of gait mode. To do this we paid attention on the anterior bending of the upper trunk. It is expected that the trunk bends forward before the start of walking and bends back before the stop of walking. In the experiment the distance between the upper trunk and the center of gravity (COG) was measured and it was proven that the measurement of this distance showed to be useful to know the transition of straight walking. This result was examined again on the gait simulator. Implanted control algorithm of gait simulator is as follows; two foot plates pull back the feet when the start of walking was predicted and stop when the stop of walking was predicted. Results show that the gait simulator was able to reproduce the start and the end of walking by this prediction algorithm.

Prolonged diastolic dysfunction following exercise induced ischaemia: a gated myocardial perfusion SPECT study.

Prolonged impairment of left ventricular (LV) systolic function following exercise induced ischaemia has been well demonstrated. The objective of this study was to examine the effect of exercise induced ischaemia on the post-stress LV diastolic function in patients with coronary artery disease (CAD). Seventy-four subjects with known or suspected CAD underwent gated myocardial single photon emission computed tomography (SPECT) 1 h after administration of 99mTc tetrofosmin according to a standard same day exercise rest protocol. LV volumes and ejection fractions (LVEFs) were determined by the Cedars-Sinai program. Fourier transformation of the gated SPECT volume curve was performed retaining the fourth order harmonics, and peak filling rate (PFR) and time-to-PFR (TPFR) were calculated from the derivative curve. In patients with exercise induced ischaemia (n =26), 1 h post-stress PFR (2.66+/-0.75 s(-1)) and TPFR (119+/-12 ms) were significantly impaired in comparison to the resting PFR (3.06+/-0.74 s; P=0.0002) and TPFR (114+/-10 ms; P=0.03), respectively. In normal subjects (n =26) and in patients with infarction (n =22), the post-stress indices were similar to the resting values. When reduction of PFR or LVEF greater than the variability (2SD) of differences between the post-stress and resting values in the normal group was defined as significant impairment, six of the 26 ischaemic patients (23%) had such changes in PFR. All these patients exhibited severe ischaemia and five of them had simultaneous systolic impairment. Only one (4%) of the normal subjects and none of the patients in the infarction group showed such impairments. Stepwise logistic regression analysis of stress, scan and coronary variables revealed that the summed reversibility score, a scintigraphic index of ischaemic severity, was the only determinant of post-stress changes in LVEF and PFR. In conclusion, exercise induced LV diastolic impairment persists for a prolonged period after resolution of the ischaemic episode. The incidence and magnitude of the diastolic impairment are determined by the severity of the exercise provoked ischaemia.

Ambulatory monitoring of behavior in daily life by accelerometers set at both-near-sides of the joint.

In this paper we examined a new joint motion monitoring method by use of accelerometers to monitor subjects' detailed motion in daily activities. In this method two accelerometers are set at as near points of both sides around the joint as possible. The difference between these two sensors' outputs mainly depend on the joint angle because the centrifugal and the turning acceleration occurred by the rotation around the joint can be neglected. In the experiments we tried to monitor various subject's behaviors of his upper and lower extremities and whole body motion, and could show this method is useful for the ambulatory monitoring of behavior in daily life.

Ambulatory physical activity monitoring system.

In this study, we have developed an ambulatory behaviour map and physical activity monitoring system by equipping our portable digital biosignal memory device developed previously with a GPS sensor and piezoresistive accelerometers. By this system, we can get the subjects behaviour map, his physical activities and posture changes in daily life.

Ambulatory behavior map, physical activity and biosignal monitoring system.

In this study, we have developed an ambulatory human behavior map and physical activity monitoring system. This was accomplished by equipping our portable digital biosignal memory device developed previously with GPS sensors and piezoresistive accelerometers. Using this new system, we can get a subject's behavior map, and estimate his physical activities and posture changes in daily life.

Development of an ambulatory physical activity memory device and its application for the categorization of actions in daily life.

In this study, we developed an ambulatory physical activity memory device by equipping piezoresistive accelerometers with a portable digital biosignal memory device which we had previously developed. This ambulatory physical activity memory device can record our physical activity and posture in daily life. We also tried to categorize the acceleration data acquired by this device as individual actions in daily life; walking, standing, sitting, lying, getting in a vehicle and so on.

Microprocessor-based memory device for ambulatory heart rate and physical activity recording.

Using microprocessor techniques, a portable digital memory device has been designed for the ambulatory monitoring of heart rate and physical activity. The device consists of a microprocessor, an ECG amplifier to record the heart rate and an accelerometer to detect the physical activity. This accelerometer is piezo-resistive and is suitable for ambulatory physical activity recording, because this sensor requires low electrical power, has high durability and wide frequency response (DC approximately 1.2 kHz). Changes in heart rates and physical activity in daily life have been successfully recorded.

Functional neuromuscular stimulation system using an implantable hydroxyapatite connector and a microprocessor-based portable stimulator.

For developing functional neuromuscular stimulation (FNS) orthoses, percutaneous implants made of sintered hydroxyapatite (HAp) and a microprocessor-based portable stimulator were devised, and related basic studies were carried out. First, a button-shaped HAp was percutaneously implanted up to 23 months in the skin of dogs, and 30 months in human subjects. The HAp was closely contacted with the skin tissue. Then, button-shaped HAp electrical connectors were percutaneously implanted in the skin of rabbits. Sufficient contractions of the calf muscle were elicited by electrical stimuli delivered to intramuscular electrodes through the connector. These results indicated that the HAp electrical connector could be clinically utilized as an implantable skin interface for FNS. The microprocessor-based stimulator capable of processing control command signals and delivering 16-channels of electrical stimuli was developed. Usefulness of the stimulator was demonstrated by applying it to flexor and extensor muscles of the thumb in a C5 quadriplegic patient.

On a portable memory device for physical activities and informations of maternal perception.

The condition of patients must be known to attending doctors for adequate management of a disease, particularly of high risk pregnancy. For this purpose, we have developed a portable computerized disease condition memory device to record the physical activities with maternal perception of fetal movement and uterine condition in daily life, both at home and during work. This device taken out by the patient is a small battery-driven CMOS 8 bit computer system (size: 107 x 80 x 30 mm, 240 g) and is equipped with push-botton switches on the upper side and a mercury switch inside it. The time of maternal perception of fetal movement and uterine contraction are recorded by the patient pressing the corresponding switch. Meanwhile the mercury switch serves as a acceleration sensor and the physical activities were measured by counting ON-OFF actions of the mercury switch caused by her movements. Consequently, the device has recorded physical activities automatically by wearing this unit all day long. The continuously recordable time is more than two weeks. The evaluation about the sensitivity of physical activity measurement has indicated that the mercury switch sensor was well related to the oxygen consumption rate in rest and mild exercise. Using this device to five pregnant women, the data showed the quantitative difference in physical activities between rest in bed and normal home life, and daily changes could be clearly observed. From these results, the physical activities and the condition of the patient in daily life can be followed by this device.