Strength gains following different combined concentric and eccentric exercise regimens.

BACKGROUND: Loss of muscle strength and cross-sectional area is a well-recognized consequence of spaceflight. Existing countermeasures have not been fully effective in preventing muscle weakness and atrophy in microgravity. Resistance exercise programs that consist of both eccentric and concentric actions have resulted in strength and muscle mass gains in ground-based studies. HYPOTHESES: 1) A concentric/eccentric combination exercise regimen (with a bias of either concentric or eccentric exercise) will result in a greater strength gain than concentric exercise alone; and 2) an eccentrically biased regimen will result in the greatest strength gain of all. METHODS: The 31 subjects were randomly assigned to one of three isokinetic exercise groups (CON-ECC: 75% concentric and 25% eccentric; ECC-CON: 75% eccentric and 25% concentric; CON: 100% concentric); each subject trained the right leg 3 d per week for 5 wk. Pre- and post-training isokinetic concentric/ eccentric strength tests and DEXA scans assessed changes in muscle strength and/or mass. RESULTS: All three groups showed an increase in eccentric muscle strength with the CON group showing the smallest gain (10.1%). Significantly larger gains were noted in the two combination groups (19.5%, 18.1%; p < 0.042), with the largest gains in eccentric strength. No significant change was noted in muscle mass. CONCLUSIONS: A resistance exercise protocol which includes eccentric as well as concentric exercise, particularly when the eccentric exercise is emphasized, appears to result in greater strength gains than concentric exercise alone. Findings suggest eccentric exercise may be an important component of the in-flight resistance exercise protocol for long-duration spaceflight.

Relationship of psychological and physiological parameters during an Arctic ski expedition.

Considerable data (primarily physiological) have been collected during expeditions in extreme environments over the last century. Physiological measurements have only recently been examined in association with the emotional or behavioral state of the subject. Establishing this psychophysiological relationship is essential to understanding fully the adaptation of humans to the stresses of extreme environments. This pilot study investigated the simultaneous collection of physiological, psychological and behavioral data from a two-man Greenland expedition in order to model how specific relationships between physiological and psychological adaptation to a polar environment may be identified. The data collected describes changes in adrenal and other hormonal activity and psychological functioning. Levels of cortisol and testosterone were calculated. Factors influencing the plasma profiles of the aforementioned included 24-hour sunlight, high calorific intake of more than 28 000 kJ/day and extreme physical exercise. There was a difference between individual psychological profiles as well as self-report stress and physiological stress.

The effects of betaxolol hydrochloride ophthalmic solution on intraocular pressures during transient microgravity.

BACKGROUND: Intraocular pressure (IOP) has been found to increase during microgravity. After peaking in the first few hours of orbital flight, IOP slowly decreases to a level that is slightly elevated above baseline IOP's. These modest elevations in IOP do not require treatment. Just as in 1-G, a clinically significant elevation of IOP that occurred during spaceflight would require treatment. We are not aware of previous studies of the efficacy of IOP lowering agents under conditions of microgravity. METHODS: This double-masked, placebo-controlled study measured the IOP's of 11 adult subjects (22 eyes) at baseline, preflight, and zero-gravity aboard the NASA KC-135 aircraft, and postflight. One eye of each of the subjects was treated with betaxolol hydrochloride ophthalmic solution 0.5%, while the contralateral eye was treated with normal saline placebo, for 7 d prior to parabolic flight. IOP's were measured by the Tono-Pen 2, a gravity independent tonometer. RESULTS: A modest, but statistically significant reduction of 2.4 mmHg in mean IOP was noted in betaxolol treated eyes at the time of preflight measurement. During zero-G, the mean IOP's of both betaxolol treated eyes and placebo treated eyes increased approximately 20% over preflight levels. Postflight IOP's were similar to preflight IOP's. CONCLUSIONS: The effect of betaxolol on the IOP of eyes treated with for 1 wk prior to exposure to microgravity was statistically significant, but may lack clinical significance in normal eyes. Further research needs to be done to determine the efficacy during microgravity of betaxolol and other agents, in subjects who have upper normal to slightly elevated IOP's at 1 G.

Refining quality of life: validating a multidimensional factor measure in the severe mentally ill.

Quality of life measurement has historically been characterized by a focus on physical functionality, great variability in definitions and insufficient attention to psychometric properties of measures. The present study examined four core subscales of the Quality of Life Enjoyment Scale (Q-LES-Q) designed to assess subjective quality of life (i.e. physical health, subjective feelings, leisure activities and social relationships) administered to 151 male and female subjects with severe mental illness admitted to a residential community treatment center or a university psychiatric hospital. The use of factor analysis is a common approach to examining construct validity of instruments through the examination of correlated clusters of item responses. Those sets of highly correlated item responses should identify a construct or dimension of related items (i.e. a factor). Two factor approaches, exploratory (i.e. the maximum number of possible factor is unspecified) and restricted (i.e. the maximum number of factors allowed is specified), were employed to examine construct validity of the four Q-LES-Q subscales. In addition, both orthogonal (i.e. independence between factors is maximized) and oblique (i.e. correlated factors are allowed) rotations (arrangements) of factor structure were also investigated to define subscale validity further. Results supported good construct validity for each subscale with either factor approach, i.e. the four proposed subscales were clearly identifiable in the factors (groupings) of correlated item responses from the sample. In both cases, the orthogonal (independent) rotation produced the simplest structure, i.e. the clearest groupings of items. These results indicate that the Q-LES-Q does appear to measure valid dimensions matching those proposed by the subscales and, thus, may be a useful and reliable tool for clinical applications.

A comparison of the evaluation and treatment of cervical dysplasia by gynecologists and nurse practitioners.

Cervical dysplasia, a precursor to cervical cancer, affects approximately 6% to 10% of women in the United States. Although cervical dysplasia traditionally is diagnosed and treated by gynecologists, nurse practitioners with special education and expertise in the evaluation and treatment of the condition have begun providing care to many women in rural and other medically underserved areas where there is limited access to specialized physicians. This study compared cervical dysplasia evaluation and treatment techniques of 11 gynecologists and 6 nurse practitioners using abstracted patient records. The MDs showed a greater variation in performance than nurse practitioner colposcopists (NPCs) when evaluated on 10 criteria. NPC practices fell within the range of MDs, and when they were statistically different, NPC practices were more consistent with generally accepted medical practice. These data suggest that NPCs were more likely to adhere to a consistent set of practices. It can be concluded that NPCs are viable alternative providers in the evaluation and treatment of cervical dysplasia.

Evaluation of cardiac rhythm disturbances during extravehicular activity.

This study represents the first systematic evaluation of dysrhythmias before, during, and after spaceflight including extravehicular activity (EVA). The data, based on 7 Shuttle crew members, revealed a nonsignificant decrease in ventricular and supraventricular ectopy during EVA, suggesting that the incidence of dysrhythmias is no greater during EVA than with any other phase of a mission or preflight.

Physical examination during space flight.

OBJECTIVE: To develop techniques for conducting a physical examination in microgravity and to describe and document the physiologic changes noted with use of a modified basic physical examination. DESIGN: On the basis of data gathered from physical examinations on KC-135 flights, three physical variables were assessed serially in astronauts during two shuttle missions (of 8- and 10-day duration, respectively). Preflight, in-flight, and postflight examinations were conducted by trained physician-astronauts or flight surgeons, who used this modified examination. MATERIAL AND METHODS: Five male and two female crewmembers participated in the "hands-on" physical examination of all physiologic systems except the genitourinary system. Level of edema, intensity of bowel sounds, and peripheral reflexes were assessed and graded. RESULTS: This investigation identified unique elements of a physical examination performed during space flight that will assist in the development of standard methods for conducting examinations of astronauts in weightlessness. In addition, demonstrable changes induced by microgravity were noted in most physiologic systems examined. CONCLUSION: The data support the hypothesis that the microgravity examination differs from that conducted on earth or in a 1g environment. In addition, alterations in the physiologic response can be detected with use of hands-on technique. These data are invaluable in the development of optimal medical care for humans in space.

The use of IQ assessment in astronaut screening and evaluation.

BACKGROUND: The screening and evaluation of astronaut candidates usually includes measures of cognitive and intellectual capacity. Questions of ceiling effects and discriminability when evaluating individuals assumed to be of above average intelligence should be considered. The current study examines ceiling effects and discriminability on IQ assessment between pilots vs. mission specialists and men vs. women in the selection of astronaut candidates. METHODS: IQ scores on 104 male and female Shuttle astronaut candidates as measured by the Multidimensional Aptitude Battery (MAB) were analyzed via factor analyses and tests of differences between genders, selection status, and job types. Total group, gender, and job type specificity and sensitivity and overall percent correctly classified were assessed on selected vs. unselected classification. RESULTS: Exploratory and confirmatory factor analyses failed to replicate the proposed factor configuration prompting reconfigured domain scores. Analyses of differences between gender, selection, and job categories found different results when using reconfigured IQ scores compared to the original formulation. The 10 subscales performed better than overall domain scores in sensitivity, specificity, and as significant predictors of individuals selected. Both versions of Verbal, Performance, and Full Scale IQ scores performed similarly regarding sensitivity and specificity. The reconfigured scores were better predictors of selection. DISCUSSION: Evidence for sensitivity, specificity, and classification prediction was better for subscales than overall domain scores. Some consideration to using reconfigured domain scores should be given to increase instrument utility.