Biomedical subjects

Yi-Chang Wu

Publications and source records attributed to Yi-Chang Wu.

2 recordsLinked to original sources

PubMed2004

An electromyographic assessment of the anti-G straining maneuver.

BACKGROUND: The anti-G straining maneuver (AGSM), used by aircrew to enhance their +Gz tolerance and to reduce the potential risk of G-induced loss of consciousness, has been recognized as an effective technique. The purpose of this study was to establish an objective tool to evaluate the effectiveness of an aircrew member's AGSM. METHODS: There were 20 healthy subjects who participated in the study, including 8 senior aviation physiological trainers and 12 trainees. The former were familiar with the anti-G maneuver and had experienced high +Gz exposure, the latter had never been exposed to any high +Gz stress before the study. The analytic method of electromyography (EMG) was used to investigate the physical characteristics of the L-1 AGSM. RESULTS: Comparison of the EMG data from the two groups indicated that the mean duration of a breathing cycle of the trainer group was significantly longer than that of the trainee group (p < 0.001). The buccinator was the muscle that had the most rapid firing rate in both groups (p < 0.001). The trainer group had a significantly faster firing rate of the buccinator than the trainee group (p = 0.03). In addition, the trainee group performed the AGSM with a firing sequence of muscles that was different from that of the trainer group. CONCLUSIONS: An automated and quantitative system based on EMG can be used during AGSM training to augment or replace the current subjective evaluation of the trainee's performance.

Abdomen↗

PubMed2003

Contrast sensitivity after +Gz acceleration.

BACKGROUND: This study was designed to determine the extent and duration of contrast sensitivity (CS) loss after high sustained +Gz acceleration in a centrifuge. METHODS: The subjects were 12 healthy male flight surgeons between 20 and 22 (mean = 21.1) yr of age. The human centrifuge at the Aviation Physiology Research Laboratory in Tainan, Taiwan, was used to expose the subjects to an acceleration profile. Each subject experienced three centrifuge runs made up of one gradual onset and two rapid onset profiles. Contrast sensitivity (CS) was measured before, and at 5 min, 10 min, and 20 min for the right eye; and 7 min, 12 min, and 22 min for the left eye after the acceleration. Both eyes were measured with the right eye being tested first. RESULTS: There was a generalized depression of CS at 5-12 min for both eyes. The depression was more severe at low and medium frequencies (1.5, 3.0, 6.0 cycles per degree, cpd) than at a high spatial frequency (18.0 cpd). There was a significant decrease in CS of the right eye at 1.5 cpd (p < 0.05 between control and 5 min), and on the left eye at 3.0 cpd (p < 0.05 between control and 7 min, p < 0.05 between control and 12 min) and 6.0 cpd (p < 0.05 between control and 12 min). The CS loss was more obvious at 5-12 min for both eyes, and there was only partial recovery at 22 min after the acceleration. CONCLUSIONS: These results demonstrated that +Gz acceleration is associated with CS loss. The recovery time was greater than expected. Factors other than ocular blood flow may be involved in the prolonged CS loss.

Adult↗