Physiological and behavioral responses to an exposure of pitch illusion in the simulator

BACKGROUND: It has been suggested that a pilot's physiological and behavioral responses during disorientation can provide a real-time model of pilot state in order to optimize performance. We investigated whether there were consistent behavioral or physiological "markers" that can be monitored during a single episode of disorientation. METHODS: An Integrated Physiological Trainer with a closed loop interactive aircraft control and point of gaze/eye-tracking device was employed. There were 16 subjects proficient in maintaining straight and level flight and with procedures in changing attitude who were exposed to yaw rotation and a brief head roll to 35 +/- 2 degrees. On return to upright head position, subjects were required to initiate either an ascent or descent to a prescribed attitude. BP, HR, skin conductance, eye movements, and point of gaze were monitored throughout the onset, duration, and immediately after the disorientation insult. Simultaneously, airspeed and power settings were recorded. RESULTS: Compared with the control condition, a significant increase (p < 0.01) in HR, HR variability, and mean arterial BP was observed during the disorientation. Flight performance decrement was reflected by a significant delay in setting power for attitude change and deviation in maintaining airspeed (p < 0.01). CONCLUSION: Changes in cardiovascular responses appear to be correlated with the onset of disorientation. The correlation of changing eye-tracking behavior and flight performance decrement is consistent with our previous findings. Further study is required to determine whether these findings can be extrapolated to repeated exposures and to other disorientation scenarios.     

科里奥利错觉研究进展

目的 综述科里奥利错觉的研究进展,概述不同重力惯性力水平下科里奥利错觉的特点,提出未来科里奥利错觉的研究方向。资源来源与选择 国内外正式发表的有关论文及部分权威论著。资料引用 相互引用,独立引用的资料。资料综合 综述从科里奥利错觉及反应、发生机制、在不同重力惯性力水平下的特点,预防克服和展望五个方面进行综合。结论 虽然科里奥利错觉已研究得比较深入,但科里奥利错觉,不同重力惯性力水平下科里奥利错觉的     

不同轴向的径向加速度对科里奥利错觉的影响

目的 X、Y轴向的径向加速度对科里奥利错觉的影响。方法 分别对10名青年男性健康志愿者在GL－2000高级空间定向模拟器上，由X轴向径向加速度为 0.27Gx与0Gz时，Y轴向径向加速度为 0.27Gy或0Gy时等量的科里奥利加速度刺激（0.16cm/s^2)引起的科里奥利错觉形态、持续时间、强度进行了比较。结果 同无径向加速度作用相比，在X轴向径向加速度为0.27Gx及Y轴向径向加速度为0.27Gy时，等量的科里奥利加速度刺激引起的科里奥利错觉形态不改变，错觉持续时间明显降低（P＜0.05)，错觉强度明显增强（P＜0.05)。结论 X、Y轴向径向加速度对科里奥利错觉形态无影响，对错觉持续时间及强度均有一定影响，必须加强对径向加速度作用下的科里奥利错觉的预防与克服措施的研究。     

Early effects of short-term aerobic training. Physiological responses to graded exercise

AIM: The aim of this study was to find out how early the moderate training effects appear and to check the hypothesis that familiarization with exercise protocol may contribute to an early physiological responses to training in previously sedentary subjects. METHODS: Twelve male, sedentary volunteers (22.0+/-0.7 yrs) were submitted to 3 weeks of a bicycle ergometer training, consisting of 45 min of exercise (at 70% VO(2)max), 3-4 times a week. The subjects performed 4 incremental exercise tests until volitional exhaustion: 2 before training (C1 and C2), and then after 1 (T1) and 3 (T3) weeks of training. During exercise HR, VO(2), electrical activity (EMG) of rectus femoris, biceps femoris, soleus and trapezius muscles were recorded and blood samples were taken for blood lactate (LA) determination. RESULTS: Already after 1 week of training HR decreased (p<0.05) with a further decline after 3 weeks the training (p<0.01). Maximal work load after 3 weeks of training increased to 277+/-10.4 W vs 250+/-9.5 W (p<0.05), VO(2)max achieved higher values than in C1 and C2 tests (p<0.05) and LA and EMG thresholds were elevated (p<0.05). CONCLUSION: A decrease in the resting and submaximal heart rate is the earliest effect of increased physical activity. Familiarization to exercise protocol decreased EMG of biceps femoris and soleus muscles during exercise, but did not influence that of rectus femoris muscle the most engaged during cycling.     

Physiological and performance responses to tournament wrestling

PURPOSE: The purpose of this study was to investigate the physiological and performance responses to a simulated freestyle wrestling tournament after typical weight loss techniques used by amateur wrestlers. METHODS: Twelve Division I collegiate wrestlers (mean +/- SD;19.33 +/- 1.16 yr) lost 6% of total body weight during the week before a simulated, 2-d freestyle wrestling tournament. A battery of tests was performed at baseline and before and immediately after each individual match of the tournament. The test battery included assessment for body composition, reaction/movement time, lower and upper body power and isokinetic strength, and a venous blood sample. RESULTS: Lower body power and upper body isometric strength were significantly reduced as the tournament progressed (P < or = 0.05). Significant elevations in testosterone, cortisol, and lactate were observed after each match (P < or = 0.05). However, there was a significant reduction (P < or = 0.05) in resting testosterone values in the later matches. Norepinephrine increased significantly (P < or = 0.05) after each match, whereas epinephrine increased significantly (P < or = 0.05) after each match except the last match of each day. Plasma osmolality was consistently higher than normal values at all times including baseline, with significant increases observed after each match (P < or = 0.05). CONCLUSIONS: Tournament wrestling augments the physiological and performance decrements of weight loss and its impact is progressive over 2 d of competition. The combined effects of these stresses may ultimately be reflected in a wrestler's ability to maintain physical performance throughout a tournament.     

Physiological responses to treadmill and cycle exercise

This study aimed to identify differences in the acute cardio-respiratory, metabolic and perceptual responses between exercise performed on the treadmill and on the cycle ergometer at several intensities. The sample comprised of 20 voluntary male participants (age=22.5 ± 1.8 years; height=177.7 ± 7.0 cm; body mass=72.6 ± 7.9 kg; fat mass=7.87 ± 1.3%) that performed 5 submaximal 8 min exercise bouts, interspersed with a 10 min period of passive recovery. Exercise intensity used on the treadmill was 10, 12, 14, 15 and 16 km/h (0% gradient), and 80, 120, 160, 180 and 200 W on the cycle ergometer (65-70 rpm). There was a significant mode effect and also mode×intensity interaction in oxygen uptake and heart rate with higher values in the treadmill protocol (F=32.0 p=0.000, η2=0.65 and F=132.0 p=0.000, η2=0.88, respectively). The respiratory exchange ratio and blood lactate concentrations were not different across modes (F1, 18=1.9 p=0.183 and F1, 17=0.1 p=0.964, respectively) and rate of perceived exertion values were higher in the cycle ergometer (F1, 12=1.2 p=0.288). Generally, results showed a larger exercise mode effect on the cardio-respiratory variables with higher response patterns on the treadmill, differing according to exercise intensity.     

Physiological responses to nine different exercise:rest protocols

This study determined the metabolic responses to different exercise:rest protocols during circuit exercise using hydraulic resistance. In experiment 1, nine subjects underwent nine different 27 min exercise circuits. There were three variations of three exercise:rest protocols (2:1, 1:1, 1:2). The VO2 for the nine circuits averaged (mean +/- SEM) 1.94 +/- 0.03 l.min-1 (43% of treadmill VO2max), with the largest difference between the protocols being 13%. Heart rate averaged 152.2 +/- 3.1 beats.min-1, with the largest difference between the protocols being 8%. Increasing the exercise duration per minute or the number of exercise bouts per minute had minimal effects on the mean VO2 and heart rate response to hydraulic resistive exercise. In experiment 2, nine subjects underwent three different 9 min exercise circuits using exercise:rest protocols of 2:1, 1:1, and 1:2 while work and VO2 were simultaneously measured. Surprisingly, increases in work were not necessarily accompanied by corresponding increases in VO2.     

Physiological responses to exercise at altitude : an update

Studies performed over the past decade have yielded new information related to the physiological and metabolic adjustments made in response to both short- and long-term high-altitude exposure. These investigations have examined the potential mechanisms responsible for the alterations observed in such key variables as heart rate, stroke volume, cardiac output, muscle blood flow, substrate utilization and mitochondrial function, both at rest and during exercise of varying intensities. Additionally, the occurrence and mechanisms related to the 'lactate paradox' continues to intrigue investigators. It is apparent that exposure to high altitude is an environmental stressor that elicits a robust sympathoadrenal response that contributes to many of the critical adjustments and adaptations mentioned above. Furthermore, as some of these important physiological adaptations are known to enhance performance, it has become popular to incorporate an aspect of altitude living/training into the training regimens of endurance athletes (e.g. 'live high-train low'). Finally, it is important to note that many factors influence the extent to which individuals adjust and adapt to the stress imposed by exposure to high altitude. Included among these are (i) the degree of hypoxia; (ii) the duration of exposure to hypoxic conditions; (iii) the exercise intensity (absolute vs relative workload); and (iv) the inter-individual variability in adapting to hypoxic environments ('responders' vs 'non-responders').     

Rotation rate and duration effects on the somatogyral illusion

INTRODUCTION: Aviation spatial disorientation mishaps remain a concern, especially due to their fatality rate. Some of the most insidious disorientations are due to vestibular stimuli in the absence of visual cues. A category of such disorientations are known as somatogyral illusions. METHODS: To determine the effects of spin rate and duration on the perception of the somatogyral illusion, we examined the subjective response of pilots and non-pilots to rotation around the yaw axis in a flight simulator in a manner that would mimic two vestibular illusions found in flight: the washout of the semi-circular canals following sustained turns, and the illusory counter-rotation following return to straight and level flight. There were 29 subjects (14 pilots) who were seated blindfolded in a flight simulator which accelerated to constant plateau rotation rates of 20, 70, and 120 degrees x s(-1) and then decelerated to stationary; plateaus were 10, 20, or 40 s. Subjects reported 1) the time when the perception of rotation ceased (i.e., the subjective time until washout was reached); 2) the relative magnitude of the counter-rotation experienced; and 3) the time until the perception of counter-rotation ceased. Subjects also manipulated a slider to provide a continuous subjective measure of their experience of rotation. RESULTS: The two time measures increased with increases in both the duration and magnitude of the spin. The increase in perceived washout time with spin rate was non-linear (geometric). There was an interaction between spin duration and spin rate on the experience of illusory counter-rotation magnitude such that at low rates, spin duration had no effect, but its effect increased at faster rates. The time constant of adaptation of the semicircular canals was estimated to be 8.3 s. DISCUSSION: The effects were validated against a model of semicircular canal and cupola adaptation, which predicted the data with high accuracy. Pilots and non-pilots did not differ in their illusory experience.     

Physiological responses to different roller skiing techniques

This study compared the physiological responses during roller skiing with the V1 skate, kick double pole, and double pole techniques. Eight male nordic ski racers roller skied over a flat one-mile track at 14 and 18 km.h-1 using each of the three techniques under study. Heart rates and oxygen uptakes were measured during the last minute of each bout, ratings of perceived exertion were requested immediately after each bout, and capillary blood lactate concentrations were determined 3 min after each bout. The double pole technique was found to be significantly more economical (P less than 0.05) than the other techniques, as demonstrated by a 12% lower oxygen consumption. No differences were found between the V1 skate and the kick double pole techniques for any of the variables studied. The findings of similar physiological responses with the V1 skate and kick double pole techniques suggest that these techniques should induce similar cardiovascular adaptations when roller skiing at the same speed on flat terrain.     

Physiological effects of night vision goggle counterweights on neck musculature of military helicopter pilots

Increased helmet-mounted mass and specific neck postures have been found to be a cause of increased muscular activity and stress. However, pilots who use night vision goggles (NVG) frequently use counterweight (CW) equipment such as a lead mass that is attached to the back of the flight helmet to provide balance to counter the weight of the NVG equipment mounted to the front of the flight helmet. It is proposed that this alleviates this stress. However, no study has yet investigated the physiological effects of CW during an extended period of time during which the pilots performed normal operational tasks. Methods: Thirty-one Canadian Forces pilots were monitored on consecutive days during a day and a NVG mission in a CH-146 flight simulator. Near infrared spectroscopy probes were attached bilaterally to the trapezius muscles and hemodynamics, i.e., total oxygenation index, total hemoglobin, oxyhemoglobin, and deoxyhemoglobin, were monitored for the duration of the mission. Pilots either wore CW (n = 25) or did not wear counterweights (nCW, n = 6) as per their usual operational practice. Results: Levene's statistical tests were conducted to test for homogeneity and only total oxygenation index returned a significant result (p < or = 0.05). For the near infrared spectroscopy variables, significant differences were found to exist between CW and nCW pilots for total hemoglobin, deoxyhemoglobin, and oxyhemoglobin during NVG flights. The CW pilots displayed less metabolic and hemodynamic stress during simulated missions as compared to the nCW pilots. Conclusion: The results of this study would suggest that the use of CW equipment during NVG missions in military helicopter pilots does minimize the metabolic and hemodynamic responses of the trapezius muscles.     

Physiological and metabolic responses of repeated-sprint activities:specific to field-based team sports

Field-based team sports, such as soccer, rugby and hockey are popular worldwide. There have been many studies that have investigated the physiology of these sports, especially soccer. However, some fitness components of these field-based team sports are poorly understood. In particular, repeated-sprint ability (RSA) is one area that has received relatively little research attention until recent times. Historically, it has been difficult to investigate the nature of RSA, because of the unpredictability of player movements performed during field-based team sports. However, with improvements in technology, time-motion analysis has allowed researchers to document the detailed movement patterns of team-sport athletes. Studies that have published time-motion analysis during competition, in general, have reported the mean distance and duration of sprints during field-based team sports to be between 10-20 m and 2-3 seconds, respectively. Unfortunately, the vast majority of these studies have not reported the specific movement patterns of RSA, which is proposed as an important fitness component of team sports. Furthermore, there have been few studies that have investigated the physiological requirements of one-off, short-duration sprinting and repeated sprints (<10 seconds duration) that is specific to field-based team sports. This review examines the limited data concerning the metabolic changes occurring during this type of exercise, such as energy system contribution, adenosine triphosphate depletion and resynthesis, phosphocreatine degradation and resynthesis, glycolysis and glycogenolysis, and purine nucleotide loss. Assessment of RSA, as a training and research tool, is also discussed.     

Physiological responses to aerobic exercise during pregnancy and post-partum

Maternal physiological responses to exercise during pregnancy and post-partum were studied. The results indicated that: (a) the maternal submaximal oxygen consumption (1/min) at a constant heart rate remained essentially unchanged during the last two trimesters of pregnancy and eight months post-partum, (b) the fetal heart rate returned to near-baseline levels within a two-minute exercise recovery, and (c) the infant birth data were all within the normal range. It would appear that moderate aerobic exercise during pregnancy may be done without apparent harm to either mother or baby, and could possibly benefit the mother by maintaining her aerobic fitness during pregnancy.     

Physiological and perceptual responses to cyclic heat stress variations

The effect of the time presentation of a given external heat load was examined on five subjects exercising at a constant work load (50 W). The subjects, dressed in briefs, were exposed to cyclic variations for 120 min in air temperatures between 51 degrees C and 23 degrees C, under three different schedules involving heat pulses of 10-min, 20-min and 30-min duration, respectively. The strain induced by each of these conditions was compared in terms of both physiological and perceptual criteria. Results showed that between conditions, there were significant differences in skin temperature levels but not in core temperature levels, body heat storage, or body weight loss. Perception of effort and thermal sensation ratings both exhibited similar changes in all three conditions. Due to the time constant of the sweating response, sweating rates and skin wettednesses at the end of the heat pulses were lower for 10-min heat pulses than for those of 20- and 30-min duration, and these differences were perceived by the subjects. Lower perceived skin wettedness ratings are thus suggested as the main factor to explain why all subjects rated the 10-min heating-cooling cycle as the least strenuous and uncomfortable condition. It is concluded that under the conditions of this study, perceptual criteria associated with physiological criteria represent a useful means of discriminating slight differences in strain.     

不同强度的科里奥利加速度刺激对人体主观感觉及眼震的影响

目的观察不同强度的科里奥利加速度刺激对人体主观感觉及眼震的影响,以探讨科里奥利错觉与不同强度的科里奥利加速度刺激间的相关性及眼震电图作为反映科里奥利错觉客观指标的可行性.方法在VTS-Ⅲ型前庭功能评定系统上,12名男性青年健康志愿者,每人按随机次序分别接受三次不同强度(π2/30、π2/20、π2/15cm/s2)的科里奥利加速度刺激2每次刺激后休息5min再进行下一次刺激.在刺激过程中嘱受试者用秒表记录下主观感觉(即科里奥利错觉)持续时间,并实时记录下受试者的眼震电图(包括水平眼震与垂直眼震),刺激后询问受试者的错觉形态.三次刺激完后让受试者对三次的错觉强度进行比较.结果不同强度的科里奥利加速度刺激对错觉形态具有一定影响,错觉持续时间、错觉强度随科里奥利加速度的增加而增加(P＜0.05),不同科里奥利加速度刺激下的眼震电图各参数差别均无显著性意义(P＞0.05).结论科里奥利错觉强度、错觉持续时间随科里奥利加速度的增加而增加,错觉形态也随之有一定的改变,但伴随的眼震电图各参数并没有明显变化.     

Visual scene effects on the somatogravic illusion.

This study attempted to determine which visual scene cues are most effective in overcoming the somatogravic illusion (SGI), a form of spatial disorientation that occurs when a shift in the resultant gravitoinertial force vector created by a sustained linear acceleration is misinterpreted as a change in pitch or bank attitude. Nine subjects were exposed to a gravitoinertial force shift of -30 degrees in the pitch plane, both with their eyes closed and while viewing computer-generated visual scenes through a wide field-of-view head-mounted display. The scenes depicted acceleration over a shoreline by means of horizon, texture, perspective, and color cues that were presented both in isolation and in various combinations. None of the scenes significantly reduced the magnitude of the SGI relative to the eyes-closed (baseline) pitch illusion, even though the textured scenes produced some linear vection. It remains to be established whether low-cost head-mounted visual displays can reliably reduce the magnitude of the SGI and other spatially disorienting illusions.     

Visual feedback to stabilize head position for fMRI.

Head motion is a common cause of technical failure in functional magnetic resonance imaging. A simple visual alignment system has been developed to provide visual feedback to the subject about his or her head position. The subject is able to readjust his or her head position accurately during a study, should motion occur. This sighting system is incorporated into a visor that fits onto the commercial head coil. The accuracy of correcting head motion and activation maps obtained with this device are demonstrated. The cognitive workload of using the alignment system does not significantly alter the activation pattern associated with eye movement paradigms.     

Ocular fixation during eye and head tracking with and without a visual cue to head position

PURPOSE: This experiment had two purposes. The first purpose was to compare ocular fixation during eye tracking, head tracking, and head tracking with a visual cue to head position. The second purpose was to compare head tracking with and without a visual cue to head position. METHODS: Eleven subjects tracked a pseudo-random laser target in three conditions. In one condition (Condition 1), subjects tracked the target primarily with the eyes. In a second condition (Condition HT), subjects tracked the target with the head but no visual cue to head position was provided. In the final condition, subjects tracked the target with the head and were given a visual cue to head position (Condition HR). RESULTS: On average, ocular fixation was worst in Condition HR and similar in Condition 1 and Condition HT. Mismatches in target and head velocity greater than 60 degrees x sec(-1) occurred more frequently in Condition HR than in Condition HT. CONCLUSIONS: Ocular tracking of a pseudo-random target is adversely affected in a minor way by head movement, but tracking declines significantly when head tracking is performed with a visual cue to head position. In terms of velocity matching, head tracking is also adversely affected by a head position cue.     

Physiological effects of walking and cycling to work

Sixty-eight previously sedentary volunteers (38 men and 30 women) were randomly divided into active and control groups and subjected to a 10-week programme of walking or cycling while commuting to and from work. The active commuters and the controls complied with the programme on 75–78% and 92% of the workdays, respectively. The mean walking distance was 3.5 km and that of cycling 10 km. Cardiorespiratory strain of approximately 50% of maximal oxygen uptake O_2max in walking and 60% of O_2max in cycling was observed. Statistically consistent improvements caused by active commuting were seen in cardiorespiratory responses to both maximal and submaximal work and in metabolic response to submaximal work. Cycling was more effective than walking. These findings indicate that low-intensity walking and cycling to and from work improved cardiorespiratory and metabolic fitness.