Efficiency and Rolling Resistance in Manual Wheelchair Propulsion.

The efficiency and the rolling resistance in wheelchair propulsion play an important role in the comfort and the health of wheelchair users in daily life. Here we identify these fundamental interactions of wheelchair-user system on treadmill and on track. We measured the oxygen uptake (input) and the propelling torque (output) as the parameters with velocity and tire pressure. The efficiency increased about 9-13% as the velocity increased on treadmill and it increased around 11-12% as the tire pressure reduced on track. The mean coefficient of rolling resistance was 0.012 on treadmill and that were 0.016 (200 kPa) and 0.026 (30 kPa) on track. Our experimental results indicated that the efficiency and the rolling resistance were strongly dependent on the velocity and tire pressure.

Advantages of Unstable Manual Wheelchair.

In this study, many test runs were conducted using experimental manual wheelchair on various floor surface conditions. In the result, operability of manual wheelchair would be improved by shifting the position of drive wheels forward.

Biomechanics and Physiology for Propelling Wheelchair Uphill Slope.

A vertical slope of sidewalks significantly inhibits to the mobility of manual wheelchair users in their daily life. International guidelines of the vertical slope are specified approximately 4% or 5% (1:20) gradient or less as preferred, and allow 8.3% (1:12) as its maximum when it is impossible. Relevant research of the physical strain for wheelchair users with pushing on slopes, and the validity assessment of slope guidelines have been investigated. However, the analysis for the effect of a slope distance and their transient performance are still remained. The purpose of this study is to clarify the physiological and biomechanical characteristics of manual wheelchair users that propelling a wheelchair on an uphill slope. We measured these data by a metabolic analysis system, a heart rate monitor system and an instrumented wheelchair wheel. Sixteen unimpaired subjects (non-wheelchair users) were examined to investigate the effect of a long slope with 120m distance and 8% gradient. And five wheelchair users with cervical cord injury were examined to evaluate the influence of different gradients (5%, 6.7%, 8.3%, 10% and 12.5%) with 3m length in laboratory. Our experimental results of the long slope showed that wheelchair propulsion velocity and power increased considerably at the beginning of the slope where the peak mean value of them were 0.96 m/s and 70.8W and they decreased linearly to 0.55m/s and 33.6W at final interval. A mean oxygen uptake and heart rate were increased as the distance increased and their results indicated the extremely high exercise intensity at a final interval that were 1.2liter /min and 152bpm. While wheelchair pushing cadence reduced after an initial interval, mean of strokes per10m increased to compensate the decrease of upper limb's power. The results of different gradients indicated that the normalized power of subjects with cervical cord injury was significant difference between each subject in the ability to climb a slope. Mean normalized power were 0.23W/kg on a 5% slope, 0.24W/kg on 6.7%, and 0.26W/kg on 8.3% respectively. Based on these findings, we examined the relationship between the theoretical normalized power and the lowest velocity to climb a slope, and we might indicate the ability to push on an uphill slope for the persons with manual wheelchair user.

Effect of Tire Pressure to Physical Workload at Operating a Manual Wheelchair.

It is often experienced that low tire pressure of the wheelchair not only increases running resistance, but also reduces parking brake performance. In this study, the required driving forces for different tire pressures were experimentally measured and evaluated. It was indicated from the result that the wheelchair with proper tire pressure could be run with less workload of wheelchair-user. Then it was also indicated that the wheelchair with a lower tire pressure needed more workload of wheelchair-user even on hard level surface.

Does sex difference influence the neuromuscular blocking potencies of vecuronium?

One hundred and fifty patients of ASA class I-II undergoing elective surgery were given vecuronium 0.1 mg·kg-1 under fentanyl- (NLA), halothane, enflurane, isoflurane, or sevoflurane anesthesia, and the spontaneous recovery was monitored to study the sex differences as to onset time, duration [(T1, train of four (TOF)], and recovery index (T1, TOF). The onset time was significantly shorter in women than in men under isoflurane and sevoflurane anesthesia. No significant differences were seen between the sexes in terms of duration and recovery index of both T1 and TOF. We suggest that the results regarding onset time were due to the differences in distribution volume and extracellular fluid volume influenced by the proportions of lean body mass, fat tissue, and the occasional menstruation in women. It remains unclear, however, whether or not the effects of volatile gases to the sensitivity of receptors may contribute to the observed sex difference. Similar durations and recovery indexes in any anesthetic method indicate that the drug's rate of elimination is similar between the sexes. In conclusion, female patients favor the rapid onset of vecuronium when used under isoflurane or sevoflurane, but the recovery from the paralysis seems to be the same between the sexes regardless of the type of general anesthesia used.