Running mileage, movement mileage, and fitness in male U.S. Navy recruits.

PURPOSE: The purpose of this study was to determine whether there is a relationship between overall fitness improvement and varying amounts of running and movement mileage. METHODS: Subjects were male U.S. Navy recruits (N = 1703, 25 divisions), ages 17-35 yr (mean age = 20.1 +/- 2.9 yr), who attended boot camp from April 1996 through August 1996. During the first week of training, recruits performed a 1.5-mile run to determine baseline fitness levels. The results from the initial run were compared with a final 1.5-mile run conducted 6 wk later. RESULTS: Based on an age-adjusted fitness scale for a 1.5-mile run time, about one third of the recruits began recruit training in "Excellent-Superior" condition (N = 558), one third began in "Good" condition (N = 582), and one third began in "Poor-Fair" condition (N = 563). Running mileage among divisions ranged from 11.5 to 43.5 miles for the entire 7-wk training period (mean = 22.7 +/- 7.2 miles; 8-22 run days, mean = 13 +/- 4 d). In addition to running, the divisions accumulated many movement miles (110-202 miles; mean = 145 +/- 26 miles) while marching in formation. Recruits who began training in Poor-Fair condition improved the most with an average decrease in run time of 1:55 +/- 1:06 min (15.6% improvement). The Good group improved by 47 +/- 37 s (7.3% improvement), and the Excellent-Superior group improved by 17 +/- 32 s (2.9% improvement). CONCLUSION: The magnitude of fitness improvement, as measured by run time improvement, was directly related to baseline fitness level but not related to movement mileage or high-intensity run mileage accrued during training.

Determining clinical laboratory science curriculum for the 21st century.

OBJECTIVE: To conduct a study to show possible differences in clinical laboratory science (CLS) education in relation to knowledge and skill levels deemed most important to job performance success of entry bench level CLS practitioners as determined by laboratory supervisors. Information gained from the study may indicate areas of program curriculum needing revision, or the incorporation of subject areas not presently offered. DESIGN: Survey. PARTICIPANTS: CLS educators from 100 different hospital-based and university-based CLS programs, and medical laboratory departmental supervisors from 209 different hospital laboratories. OUTCOME MEASURES: An analysis of the data from the survey consisted of individual item percentages generated by both surveys and a comparison of tasks deemed highly important by supervisors with class time estimates devoted to those tasks. RESULTS: The study indicated differences between what supervisors viewed as important knowledge and skills of entry bench level CLSs and the amount of class time devoted to those subjects by CLS educators. CONCLUSIONS: To ensure continuing professional credibility, additional study will be needed regarding the education and practice of CLSs as automation, emerging technologies, and laboratory restructuring will continue to change the laboratory environment.

Nonentrained circadian rhythms of melatonin in submariners scheduled to an 18-hour day.

The human circadian timing system has previously been shown to free run with a period slightly longer than 24 h in subjects living in the laboratory under conditions of forced desynchrony. In forced desynchrony, subjects are shielded from bright light and periodic time cues and are required to live on a day length outside the range of circadian entrainment. The work schedule used for most personnel aboard American submarines is 6 h on duty alternating with 12 h off duty. This imposed 18-h cycle is too short for human circadian synchronization, especially given that there is no bright-light exposure aboard submarines. However, crew members are exposed to 24-h stimuli that could mediate synchronization, such as clocks and social contacts with personnel who are living on a 24-h schedule. The authors investigated circadian rhythms of salivary melatonin in 20 crew members during a prolonged voyage on a Trident nuclear submarine. The authors found that in crew members living on the 18-h duty cycle, the endogenous rhythm of melatonin showed an average period of 24.35 h (n = 12, SD = 0.18 h). These data indicate that social contacts and knowledge of clock time are insufficient for entrainment to a 24-h period in personnel living by an 18-h rest-activity cycle aboard a submarine.

Bright light and LEET effects on circadian rhythms, sleep and cognitive performance.

Shift work and jet lag can disrupt cicadian rhythms, with detrimetnal effects on alertness, performance and sleep. This study examined the effects of two interventions to adapt circadian rhythms, sleep and performance to a 10-h phase delay of the work-rest cycle. Bright light was administered from 2200 to 0200 each night to promote phase delay of circadian rhythms. Low energy emission therapy (LEET) was administered for 20 min prior to daytime sleep periods to promote sleep. Twelve subjects received bright light, 12 subjects received LEET, 11 received both interventions and 10 control subjects received only placebo treatments. Bright light accelerated phase delay of the circadian melatonin rhythms after the work-rest schedule shift. Further, subjects who received bright light had greater total sleep time (TST) and improved sleep continuity. LEET treatment produced a trend (p = 0.16) for increased TST, but LEET did not affect the melatonin circadian rhythm. After the schedule shift, cognitive performance measures showed few significant differences. Some minor improvements in cognitive performance were producced by light treatments but not by LEET.

Decrements in logical reasoning performance under conditions of sleep loss and physical exercise: the factor of sentence complexity.

Baddeley's Logical Reasoning Test was used in a series of Sustained Operations (SUSOP) studies involving 100 US Marine Corps enlisted subjects, to assess the effects of sleep loss and long-term physical exercise on the ability to process complex information. The percent correct answers to the eight Logical Reasoning sentence types involving different voice (active vs passive), use of negatives, and outcome (true vs false) were analyzed over three days across three levels of exercise and rest conditions in the seven studies. A multivariate analysis of variance indicated no differences on the baseline day among the seven studies. Analyses on the baseline day and throughout the next two continuous workdays (CWs) showed consistently higher percent correct for the actively worded than for the passively worded sentences. The sleep loss over the two CWs resulted in a significant decrease in percent correct for the statements which had active wording. Sleep loss had no effect on statements with passive wording. There were no differences in comprehension between groups which had different rest conditions (no rest, 3- or 4-hr. nap, 8-hr. sleep) between the two CWs for any of the sentences; and there was no recovery from prerest to postrest. Fatigue due to exercise during either CW had no effect on comprehension for any of the sentence types. The sleep loss effects on comprehension seem due to a lessening of the attention given to those more simple sentences in active voice, whereas increased arousal may have been elicited by the more complex sentences in passive voice. The increased attention to the passive statements may have overcome the effects of sleep loss. The present study shows the usefulness of analyzing responses to the logical reasoning test by sentence complexity for indicating selective cognitive changes in the processing of information.

Simplified scaling for life change events.

A relative simple interval scaling method for adjustment to life change events was compared to the original, more difficult, proportinate scaling method. Ranking of life events by both methods was extremely similar. Evidence also was found that today Americans scale several minor life change events as requiring greater adjustment than that estimated for these events a decade earlier.

Serum uric acid, cholesterol, and psychological moods throughout stressful naval training.

Navy recruits, all 51 volunteers for a preliminary underwater demolition team (UDT) training program, were followed through 4 weeks of training; 27 men passed and 24 failed the training course. Serum uric acid and serum cholesterol levels, as well as psychological moods data were collected on all volunteers at the start of training and at the end of each of the four training weeks. Men who passed training were compared to those who failed. In addition, these same measures were carried out with a control group of 66 naval recruits. Pre-UDT trainees who passed the program demonstrated high levels of positive moods, early peaks in serum uric acid level, and stable serum cholesterol levels throughout training. These findings supported previous work with successful UDT trainees. Pre-UDT trainees who failed the program demonstrated intermediate levels of positive moods, a midtraining period peak in serum uric acid, and a significant rise in serum cholesterol during the final 2 weeks of the course. The serum cholesterol rise seen during a period shortly prior to failure substantiates previous findings. A comparison group showed low levels of positive moods, an initial peak in serum uric acid, and stable serum cholesterol levels. Two mood scales had siginificant correlations with serum uric acid for only men who passed training. A motivation scale, given at the start of training, correlated with serum uric acid levels for men who failed training.

Attitudes and accidents aboard an aircraft carrier.

A 22-item questionnaire, developed to measure various behavioral attitudes reportedly associated with accidents, was given to 879 enlisted air wing support personnel and 156 aviators on an aircraft carrier at the start of deployment. A factor analysis of these 22 items indicated six underlying concepts for which scales were created. Personnel injuries for the air wing and aircraft accidents for the aviators were recorded for the duration of the cruise, and correlations of these criteria with the 22 items and six scales were computed. Three items significantly predicted accidents in both populations and all three appeared in the same factor. The Adventurous scale developed from this factor was significantly (p less than or equal to 0.01) correlated with accidents in both groups. This scale appears to measure attitudes toward risk taking, which was the only concept found useful for the prediction of future accidents in this study.