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PubMedDate not supplied

Skylab task and work performance (experiment M-151--time and motion study).

The primary objective of Experiment M151 was to study by means of time and motion analytic techniques the inflight adaptation of Skylab crewmen to a variety of task situations involving different types of activity. A parallel objective was to examine astronaut inflight performance for any behavioral stress effects associated with the working and living conditions of the Skylab environment. Training data provided the basis for comparison of preflight and inflight performance. Efficiency was evaluated through the adaptation function, namely, the relation of performance time over task trials. The results indicate that the initial changeover from preflight to inflight (or, from 1-G to zero-G) was accompanied by a substantial increase in performance time for most work and task activities. Equally important was the finding that crewmen adjusted rapidly to the weightless environment and became proficient in developing techniques with which to optimize task performance. By the end of the second inflight trial, most of the activities were performed almost as efficiently as on the last preflight trial. In addition, the analysis demonstrated the sensitivity of the adaptation function to differences in task and hardware configuration. The function was found to be more regular and less variable inflight than preflight. Translation and control of masses (large or small) were accomplished easily and efficiently through the rapid development of the arms and legs (and the entire body) as subtle guidance and restraint systems. Finally, the adaptation function provided no evidence of behavioral stress effects attributable to the Skylab environment.

Adaptation, Physiological↗
PubMed1976

Crew health status and monitoring summary: the second manned Skylab mission.

We have attempted to show that objective data used to assess crew health comes to the responsible physicians from the laboratories of the experimenters in sporadic and overwhelming amounts, but rarely in the real-time or near real-time frame which is preferred. The crew surgeon generates little hard data by his own efforts. Because of these factors, whenever an over-all clinical assessment of a particular crewman's fitness to continue a mission is an immediate necessity, it must too often be given on what the clinician would consider less than adequate data. Beginning on MD 28, weekly conferences were held with senior NASA management to make a "Go" or "No-Go" recommendation to continue or terminate the mission. In the absence of absolute indications of an unacceptable declining crew health, a clinical judgment was required. To tighten the criteria for decision-making, the authors selected factors that seemed indicative of overall health and plotted them both as real-time and percentage changes from preflight means. Other plots of the most readily available real-time and near real-time data were also developed for this purpose. The major success of this effort was the initiation of a method which indicated interesting and worthwhile possibilities if continued, refined, and computerized for more rapid availability. Correlation of actual post-flight findings with results anticipated from this method was gratifying but not statistically defensible. Whether or not this method would have forewarned of a serious decrement in crewmen's health cannot be known because, in fact, they were healthy and remain healthy.

Adult↗
PubMedDate not supplied

Skylab experiment M-092: results of the first manned mission.

Blood pressure at 30-sec intervals, heart rate, and percentage increase in leg volume continuously were recorded during a 25-min protocol in the M092 Inflight Lower Body Negative Pressure (LBNP) experiment carried out in the first manned Skylab mission. These data were collected during six tests on each crewman over a 5-month preflight period. The protocol consisted of a 5-min resting control period, 1 min at -8, 1 min at -16, 3 min at -30, 5 min at -40, and 5 min at -50 mm Hg LBNP. A 5-min recovery period followed. Inflight tests were performed at approximately 3-day intervals through the 28-day mission. Individual variations in cardiovascular responses to LBNP during the preflight period continued to be demonstrated in the inflight tests. Measurements of the calf indicated that a large volume of fluid was shifted out of the legs early in the flight and that a slower decrease in leg volume, presumably due to loss of muscle tissue, continued throughout the flight. Resting heart rates tended to be low early in the flight and to increase slightly as the flight progressed. Resting blood pressure varied but usually was characterized by slightly elevated systolic blood pressure, lower diastolic pressure, and higher pulse pressures than during preflight examinations. During LBNP inflight a much greater increase in leg volume occurred than in preflight tests. Large increases occurred even at the smallest levels of negative pressure, suggesting that the veins of the legs were relatively empty at the beginning of the LBNP. The greater volume of blood pooled in the legs was associated with greater increases of heart rate and diastolic pressure and larger falls of systolic and pulse pressure than seen in preflight tests. The LBNP protocol represented a greater stress inflight, and on three occasions it was necessary to stop the test early because of impending syncopal reactions. LBNP responses inflight appeared to predict the degree of postflight orthostatic intolerance. Postflight responses to LBNP during the first 48 hours were characterized by marked elevations of heart rate and instability of blood pressure. In addition, systolic and diastolic pressures were typically elevated considerably both at rest and also during stress. The time required for cardiovascular responses to return to preflight levels was much slower than in the case of Apollo crewmen.

Adaptation, Physiological↗
PubMed1976

Lower body negative pressure: the second manned Skylab mission.

Results of orthostatic evaluations of the crew of Skylab 3 with lower body negative pressure (LNBP) stress tests during their 59-d mission are reported. The test protocol was identical to that used in the first manned Skylab mission and the latter Apollo flights. Except for an inflight increase (rather than a decrease) in resting heart rates, results were essentially parallel to those observed in crewmen of the shorter Skylab 2 mission. Exaggerated elevations in heart rate and decreases in pulse pressure during LBNP stress inflight and immediately postflight corresponded to lowered orthostatic tolerance. Large decrements in resting calf size inflight and in total leg volume postflight indicated significant headward fluid shifts as had already been seen in the Skylab 2 crewmen. In addition, decreases in calf circumference gave no certain indication of a plateau over the 59 d inflight. On the other hand, percentage volume increase in calf size during LBNP stress inflight was greater than those in either preflight or postflight tests. Hypotheses elaborated after the Skylab 2 mission seem to have been substantiated, but several enigmas await data from the last and longer mission for clarification.

Adult↗
PubMed1976

Pre- and postflight systolic time intervals during LBNP: the second manned Skylab mission.

After space flight of 59 d, Skylab 3 astronauts were stressed with lower body negative pressure (LBNP). During this stress procedure vectorcardiograms, pneumograms, phonocardiograms, and carotid pulse tracings were monitored and recorded onto analog tape. Accepted techniques were used to measure the intervals of systole. The postflight results were compared to multiple preflight tests and each of the three crewmen served as his own control. Immediately postflight, there were elevations in heart rate and blood pressure in response to a fixed level (-50 mm Hg) of LBNP. Total electromechanical systole, (Q-S2) I, was unchanged. Ejection time index (ETI) was depressed at rest and during stress, while pre-ejection period was elevated compared with preflight values. Systolic time intervals (STI) were within preflight limits after 1 month on earth in all crewmen. Resting STI returned sooner than did stressed STI. The magnitude and direction of STI in the postflight period were similar to those obtained from patients with moderate heart disease, although signs and symptoms were absent in the astronauts. However, the abnormality of the stressed STI persisted after both blood volume repletion and lowered afterload. These findings suggest a compromise in cardiac function, peripheral circulatory integrity, or both after exposure to long-duration space flight, and are consistent with findings reported after 3 weeks of absolute bedrest.

Adult↗
PubMed1976

Determination of cardiac size following space missions of different durations: the second manned Skylab mission.

A simple method to estimate cardiac size from single frontal plane chest roentgenograms has been described. Pre- and postflight chest X-rays from Apollo 17, and Skylab 2 and 3 have been analyzed for changes in the cardiac silhouette size. The data obtained from the computed cardiothoracic areal ratios compared well with the clinical cardiothoracic diametral ratios (r = .86). Though an overall postflight decrease in cardiac size is evident, the mean difference was not statistically significant (n = 8). The individual decreases in the cardiac silhouette size postflight are thought to be due to decrements in intracardiac chamber volumes rather than in myocardial muscle mass.

Adult↗