Injuries before and after deployments to Afghanistan and Iraq.

OBJECTIVE: To examine outpatient injuries before and after deployments of elements of the 10th Mountain Division to Afghanistan (n = 505 men) and the 1st Cavalry Division to Iraq (n = 3242 men). STUDY DESIGN: Observational. METHODS: The military units provided a list of deployed soldiers, and soldiers' outpatient medical encounters were obtained from the Defense Medical Surveillance System. Cumulative injury incidence was examined for two consecutive 90-day periods before the deployments (Periods 1-2) and two consecutive 90-day periods after the deployments (Periods 3-4). RESULTS: Both groups showed post-deployment increases in the overall incidence of injury (Afghanistan group = 14.1%, 14.1%, 16.4, 23.4%; Iraq Group = 15.1%, 12.4%, 35.4%, 43.4%; Periods 1-4, respectively). Soldiers with pre-deployment injuries were 1.4-3.0 times more likely to experience post-deployment injuries. CONCLUSIONS: This study found a post-deployment increase in the incidence of outpatient injury. Also, soldiers with pre-deployment injuries were more likely to experience post-deployment injuries.

Maternal personality and reproductive ambition in women is associated with salivary testosterone levels.

Previous research has linked testosterone levels with sex-specific personality traits within women. The present study investigates the relation between salivary testosterone levels and specifically maternal personality traits in healthy adult women. Twenty-seven young women completed the Bem Sex Role Inventory (BSRI). Additional questions were asked about maternal personality (importance of having children, self-rated maternal/broodiness), reproductive ambition (ideal number of children, ideal own age at first child) and career orientation (importance of having career). Higher circulating testosterone levels were associated with lower scores on measures of maternal personality and reproductive ambition. There was no relation of career orientation with testosterone. A median split on BSRI masculinity revealed high scorers had higher testosterone levels than low scorers. There was no relation of BSRI femininity with testosterone. Results suggest maternal tendencies may be partly androgen driven.

The prevalence of exercise-induced bronchospasm among US Army recruits and its effects on physical performance.

STUDY OBJECTIVES: To measure the prevalence of exercise-induced bronchospasm (EIB) and to determine its effect on the physical performance response to training in otherwise healthy young adults. DESIGN: Observational, retrospective study. SETTING: Fort Jackson, SC, May to July 1998. PARTICIPANTS: One hundred thirty-seven ethnically diverse US Army recruits undergoing an 8-week Army basic training course. MEASUREMENTS AND RESULTS: Subjects underwent exercise challenge testing at the end of basic training to evaluate for EIB (defined as a decrease in FEV(1) of > or = 15%, 1 or 10 min after running to peak oxygen uptake on a treadmill). Those subjects who were unable to run to peak oxygen uptake, or who were unable to perform two baseline FEV(1) maneuvers the results of which were within 5% of each other, were excluded from analysis. We measured peak oxygen uptake on a treadmill and the scores achieved on the components of the US Army physical fitness test (APFT). Of 137 subjects, 121 (58 men and 63 women) met our inclusion criteria. Eight subjects (7%) had EIB. Subjects who experienced EIB and unaffected control subjects both showed statistically significant gains in performance on the APFT events during basic training. At the end of basic training, peak oxygen uptake levels and APFT event scores were not significantly different between subjects with EIB and unaffected control subjects. CONCLUSIONS: Seven percent of the US Army recruits who were tested had EIB, but this did not hinder their physical performance gains during basic training. EIB per se should not be an absolute reason to exclude individuals from employment in jobs with heavy physical demands.

Field use of D2 18O to measure energy expenditure of soldiers at different energy intakes.

To test the application of doubly labeled water under adverse field conditions, energy expenditures of 16 special operations soldiers were measured during a 28-day field training exercise. Subjects were matched by fat-free mass and divided equally between an ad libitum ready-to-eat meal diet and a 2,000 kcal/day lightweight ration. Subjects recorded intakes daily, and body composition was measured before and after the exercise. At the beginning of the study, subjects moved to a new northerly location and, therefore, a new water supply. To compensate for this, a group of soldiers who did not receive heavy water was followed to measure isotopic base-line changes. Energy expenditure by doubly labeled water was in agreement with intake/balance (3,400 +/- 260 vs. 3,230 +/- 520 kcal/day). The overall coefficient of variation of energy expenditure by doubly labeled water was half that of intake/balance (7.6 vs. 16.1%). The coefficient of variation of repeat measures with doubly labeled water was 7.3%. Energy expenditure of the ready-to-eat meal group, 3,540 +/- 180 kcal/day, was not significantly different from the lightweight ration group, 3,330 +/- 301 kcal/day. Doubly labeled water was valid under field conditions.

Angiotensin-converting enzyme genotype and physical performance during US Army basic training.

Prior studies have suggested that angiotensin I-converting enzyme (ACE) genotype correlates with superior physical performance in highly selected populations. This study assessed whether such an association exists in a heterogeneous population. Using polymerase chain reaction techniques, we determined the ACE genotypes (insertion/insertion, deletion/insertion, or deletion/deletion) of 62 male and 85 female US Army recruits. Before and after 8 wk of basic training, we determined peak oxygen uptake and performance on the Army Physical Fitness Test (APFT), which includes standardized measures of muscular endurance (sit-ups, push-ups) and a 2-mile run. Subjects of different ACE genotypes had similar peak oxygen uptakes and APFT scores, both before and after training. Subjects with genotype II had higher APFT scores than others, but the differences were not statistically significant. Furthermore, no ACE genotype group had a performance advantage in analyses that adjusted for baseline fitness. We conclude that ACE genotype does not have a strong effect on aerobic power or muscular endurance in healthy, young American adults drawn from an ethnically and geographically diverse population.

Risk factors for training-related injuries among men and women in basic combat training.

PURPOSE: Past investigations indicate that training-related injuries are associated with certain performance-oriented measures of physical fitness and certain lifestyle characteristics. This study examined associations between injuries, direct (physiological) measures of physical fitness, and lifestyle characteristics. METHODS: Subjects were 756 men and 474 women performing the standardized activities involved in U.S. Army Basic Combat Training (BCT). Before BCT, a subsample of subjects (182 men and 168 women) were administered a series of tests that included a treadmill running test (peak VO2), dual-energy x-ray absorptiometry (for body composition), several measures of muscle strength, a hamstring flexibility test, and a vertical jump. A questionnaire addressed smoking habits and prior physical activity. All subjects were administered the Army Physical Fitness test consisting of push-ups, sit-ups, and a 3.2-km run. Gender, age, stature, and body mass were obtained from physical examination records. Injuries incurred during BCT were transcribed from medical records; for each medical visit, the diagnosis, anatomical location, disposition (final outcome of visit), and days of limited duty were recorded. RESULTS: Women had over twice the injury rate of men. For men and women, fewer push-ups, slower 3.2-km run times, lower peak VO2, and cigarette smoking were risk factors for time-loss injury. Among the men only, lower levels of physical activity before BCT and both high and low levels of flexibility were also time-loss injury risk factors. Multivariate analysis revealed that lower peak VO2 and cigarette smoking were independent risk factors for time-loss injury. CONCLUSIONS: Lower aerobic capacity and cigarette smoking were independently associated with a higher likelihood of injury in both men and women during a standardized program of physical training. Further studies are needed to assess associations between injury and body composition and muscular strength.

The effects of litter carrying on rifle shooting.

This study investigated whether the use of a shoulder harness would affect shooting accuracy after patient litter carrying. Two- and four-person teams, 12 male and 9 female soldiers, fired at targets before and after (1) a 15-minute bout of rapid, short litter carries and lifts, and (2) a moderate speed 30-minute litter carry with and without a harness for both types of carries. Shooting accuracy was 10% poorer (p < 0.05) after the 15-minute bout (mean +/- SD = 8.9 +/- 1.9 mm) than after the 30-minute carry (8.1 +/- 1.7 mm). Four-person teams using litter-carriage harnesses had 17% tighter shot groups (45.5 +/- 30.4 mm2) (p < 0.05) than four-person teams that did not use harnesses (54.5 +/- 26.1 mm2) and two-person teams with (56.3 +/- 29.1 mm2) or without harnesses (54.9 +/- 30.7 mm2). The harness can potentially improve shooting accuracy after litter carrying.

The fitness training unit in U.S. Army basic combat training: physical fitness, training outcomes, and injuries.

This study involved a retrospective examination of physical fitness, training outcomes, and injury rates among personnel in the Fitness Training Unit (FTU). Personnel were assigned to the FTU based on low performance on push-ups, sit-ups, and/or a 1-mile run (N = 44 men, 95 women) and received an augmented physical fitness program before basic combat training (BCT). They were compared with 712 men and 379 women who took the same test but were not assigned to the FTU and went directly to BCT. FTU and non-FTU personnel trained in the same battalions. Army Physical Fitness Test scores and BCT outcomes (discharged or completed BCT in 8 weeks) were obtained from unit training records. Injuries during BCT were documented from a review of the medical records. On entry to BCT, FTU women had similar 2-mile run times compared with non-FTU women (21.6 vs. 21.5 minutes, respectively; p = 0.86); FTU men were considerably slower on the 2-mile run than non-FTU men (20.3 vs. 17.3 minutes; p < 0.01). FTU women and non-FTU women had similar graduation success (60% vs. 68%, respectively; p = 0.14) and time-loss injury rates (1.3 vs. 1.4 people injured/100 person-days, respectively; p = 0.90). FTU men were less likely to graduate than non-FTU men (55% vs. 82%; p < 0.01) and more likely to suffer a time-loss injury (1.2 vs. 0.7 people injured/100 person-days; p < 0.01). Efforts should be directed toward providing a sufficient training stimulus to improve the aerobic fitness level of men (as well as women) in the FTU.

Physical fitness and occupational performance of women in the u.s. Army.

The majority of jobs available to personnel entering the U.S. military services are physically demanding. Soldiers must maintain high levels of physical fitness to optimally perform their duties. High fitness levels are of particular importance to women in the military. Only strong, physically competent women will be fully successful in performing the physically demanding tasks of many occupational specialties. This paper describes the research that has been conducted to compare the physical fitness, physical training, and occupational performance of women and men in the U.S. Army.

Prediction of performance on two stretcher-carry tasks.

Pre-placement screening for physically demanding jobs should result in better job performance and fewer injuries, if the test components reflect job demands. The purpose of this study was to determine how seven strength measures, three Army Physical Fitness Test (APFT) scores, and three physical descriptors relate to performance on two stretcher-carry tasks: 1) a repeated short-distance carry and 2) a continuous long-distance carry. Twelve men and 11 women completed both tasks with and without (hand-carry) a shoulder harness. Pearson product moment correlation coefficients compared independent variables and forward stepwise multiple regression analyses were used for predictions. For repeated short distance stretcher-carrying, two-mile run time and handgrip were the best predictors of performance (hand-carry: r2=0.79, p<0.01; harness-carry: r2=0.75, p<0.01). The grip, which was more predictive during the hand-carry, required a sudden maximal contraction to peak force, followed by immediate release, while a sudden maximal contraction to peak force maintained for four seconds, was more predictive of the harness-carry. For the continuous hand-carry, the best predictor was a gradual buildup to a 6-second sustained grip strength (r2=0.74, p<0.01). These results illustrate the necessity for tailoring preplacement tests to accurately reflect job demands.

Energy cost and efficiency of a demanding combined manual materials-handling task.

Energy cost and crew performance were studied during a 45-hour continuous field-artillery loading exercise using a howitzer simulator. An interrupted peak $\dot{V}_{0_{2}}$ test, conducted in the simulator, was used to develop individualized equations to predict energy cost from heart rate. Nine experienced crew members rotated through six 1.5-hour loading cycles. Mission time (the time elapsed from the order to fire until task completion) was recorded and summed over cycles. Measures made at the end of each cycle included profile of mood state (POMS); rating of perceived exertion (RPE); rating of pain, soreness, and discomfort (RPSD); and isometric hand-grip strength. Results showed a significant decrease (p<0.01) in energy cost (8.0-6.2 kcal·min-1) and mission time (28.1-24.3 min) from Cycle 1 to Cycle 6. The POMS revealed an increase in fatigue and tension and a decrease in vigor (p<0.05); RPE increased (p<0.05) over time as did RPSD reported for the shoulders, arms, and hands (p<0.05). Isometric hand-grip strength decreased 8.6% (p<0.05) from Cycle 1 to Cycle 6. The efficiency of howitzer loading performance increased; however, the changes in RPE, POMS, hand-grip, and RPSD suggest that longer duration exercises may result in performance decrements. These data indicate that simulators can improve the performance of this task.

Salience of emotional displays of danger and contagion in faces is enhanced when progesterone levels are raised.

Findings from previous studies of hormone-mediated behavior in women suggest that raised progesterone level increases the probability of behaviors that will reduce the likelihood of disruption to fetal development during pregnancy (e.g. increased avoidance of sources of contagion). Here, we tested women's (N=52) sensitivity to potential cues to nearby sources of contagion (disgusted facial expressions with averted gaze) and nearby physical threat (fearful facial expressions with averted gaze) at two points in the menstrual cycle differing in progesterone level. Women demonstrated a greater tendency to perceive fearful and disgusted expressions with averted gaze as more intense than those with direct gaze when their progesterone level was relatively high. By contrast, change in progesterone level was not associated with any change in perceptions of happy expressions with direct and averted gaze, indicating that our findings for disgusted and fearful expressions were not due to a general response bias. Collectively, our findings suggest women are more sensitive to facial cues signalling nearby contagion and physical threat when raised progesterone level prepares the body for pregnancy.

Raised salivary testosterone in women is associated with increased attraction to masculine faces.

Women's preferences for masculinity in men's faces, voices and behavioral displays change during the menstrual cycle and are strongest around ovulation. While previous findings suggest that change in progesterone level is an important hormonal mechanism for such variation, it is likely that changes in the levels of other hormones will also contribute to cyclic variation in masculinity preferences. Here we compared women's preferences for masculine faces at two points in the menstrual cycle where women differed in salivary testosterone, but not in salivary progesterone or estrogen. Preferences for masculinity were strongest when women's testosterone levels were relatively high. Our findings complement those from previous studies that show systematic variation in masculinity preferences during the menstrual cycle and suggest that change in testosterone level may play an important role in cyclic shifts in women's preferences for masculine traits.

Effects of psychophysical lifting training on maximal repetitive lifting capacity.

The purpose of this investigation was to determine the effectiveness of psychophysical lifting training on maximal repetitive lifting capacity. Maximal repetitive lifting capacity was defined as the maximum box mass that could be lifted for 1 hr to a height of 132 cm at a rate of 6 lifts/min. Eight male subjects participated in five psychophysical lifting training sessions each week for 4 weeks. During each session subjects were presented with one empty and one heavily loaded box and asked to adjust the box mass to the maximum load they felt capable of lifting for 1 hr. This load was lifted at a rate of 6 lifts/min to a height of 132 cm for two 15-min periods each session. Heart rate was recorded, and subjects were asked to provide a rating of their perceived exertion. At the end of 4 weeks of training, subjects did not select a heavier training load, exhibit a decreased training heart rate, or report a decreased rating of perceived exertion. The training program did produce a significant increase in 1-hr maximal repetitive lifting capacity, as indicated by a greater box mass selected, but there was no concomitant change in VO2, heart rate, or rating of perceived exertion. It can be concluded that 4 weeks of psychophysical training of inexperienced lifters can produce a substantial increase in work output for a given energy expenditure. These increases are attributed to neural factors (skill, neuromuscular coordination) and to possible increases in the muscular endurance of specific muscle groups occurring with practice.

A myth exposed: fast growth in diameter does not justify precocious abdominal aortic aneurysm repair.

OBJECTIVES: fast growth of abdominal aortic aneurysm (AAA) diameter is claimed to be an indication for repair. We investigated the validity of this claim. METHODS: between January 1988 and October 2000, 277 patients have had duplex sonography at six-monthly intervals in our aneurysm surveillance programme. During this period fast AAA growth was not an indication for operation in our unit. RESULTS: we identified 63 patients whose aneurysms had grown 0.5 cm or more in 6 months. Thirty-one of the 63 patients had aneurysms measuring 5.5 cm or greater in anterior-posterior diameter after the fast growth and all have been operated on unless deemed not fit due to anaesthetic risk. The remaining 32 patients continued in surveillance for a total of 50 patient years and none had rupture of their aneurysm. The calculated 95% confidence interval for the risk of rupture was 0-6 per 100 patient years. Six patients, who would have been operated on if fast growth had been an indication, have been spared surgery of whom 3 died and 3 became unfit. Nine patients remained in surveillance at the end of the study. CONCLUSION: our data support the view that rapid increase in AAA diameter is not an indication for elective AAA repair.

A cautionary case: the SynerGraft vascular prosthesis.

To date no prosthetic vascular prosthesis performs as well as autologous conduits for small diameter arterial reconstruction. We report the outcome of our first case using a new vascular prosthesis marketed by Cryolife, the SynerGraft. This Xenograft prostheses is claimed to eliminate the problems of the previous generation of gluteraldehyde treated grafts. Two 50 cm SynnerGrafts were anastomosed end to end and used as a femoral-posterior tibial bypass graft in a 68-year-old man who presented with an acutely ischaemic left leg. Our patient represented at 8 weeks with aneurysmal degeneration along the course of the graft. We urge caution in the use of these grafts until convincing data in humans is presented.

Maximal aerobic capacity for repetitive lifting: comparison with three standard exercise testing modes.

A multi-stage, repetitive lifting maximal oxygen uptake (VO2max) test was developed to be used as an occupational research tool which would parallel standard ergometric VO2max testing procedures. The repetitive lifting VO2max test was administered to 18 men using an automatic repetitive lifting device. An intraclass reliability coefficient of 0.91 was obtained with data from repeated tests on seven subjects. Repetitive lifting VO2max test responses were compared to those for treadmill, cycle ergometer and arm crank ergometer. The mean +/- SD repetitive lifting VO2max of 3.20 +/- 0.42 l.min-1 was significantly (p less than 0.01) less than treadmill VO2max (delta = 0.92 l.min-1) and cycle ergometer VO2max (delta = 0.43 l.min-1) and significantly greater than arm crank ergometer VO2max (delta = 0.63 l.min-1). The correlation between repetitive lifting oxygen uptake and power output was r = 0.65. VO2max correlated highly among exercise modes, but maximum power output did not. The efficiency of repetitive lifting exercise was significantly greater than that for arm cranking and less than that for leg cycling. The repetitive lifting VO2max test has an important advantage over treadmill or cycle ergometer tests in the determination of relative repetitive lifting intensities. The individual curves of VO2 vs. power output established during the multi-stage lifting VO2max test can be used to accurately select work loads required to elicit given percentages of maximal oxygen uptake.

Effects of team size on the maximum weight bar lifting strength of military personnel.

Teamwork is an essential element in the majority of critical Army lifting tasks. Therefore, an understanding of the relationship between individual and team lifting capacity is of great tactical importance. Twenty-three male and 17 female U.S. Army soldiers were randomly assigned to single- and mixed-gender teams of two, three, and four persons. Individual lifting strength was the one-repetition-maximum (1RM) load lifted from floor to knuckle height using a weight bar. A square-shaped bar was used for two- and four-person lifting, and a triangular-shaped bar was used for three-person lifting. Team lifting strength as a percentage of the sum of individual lifting strength (%sum) did not change with team size. The %sum for teams of men (87.3%) was less than for teams of women (91.1%, p < 0.05). The %sums for both single-gender teams (all men and all women) were greater (p < 0.01) than for mixed-gender teams (80.2%). The number of people lifting a large object was increased to four with no decrease in the effectiveness of the individual lifter beyond that found for two persons. The 1RM loads presented in this paper were lifted under ideal conditions by young soldiers and do not represent norms for an industrial population.

Gender comparison of peak oxygen uptake: repetitive box lifting versus treadmill running.

The gender differences in peak oxygen uptake (VO2peak) for various modes of exercise have been examined previously; however, no direct gender comparisons have been made during repetitive lifting (RL). In the present study the VO2peak between RL and treadmill running (TR) was compared between 20 men [mean (SD) age, height, body mass and body fat: 21 (3) years, 1.79 (0.06) m, 81 (9) kg, 19 (6)%, respectively] and 20 women [mean (SD) age, height, body mass and body fat: 21 (3) years, 1.63 (0.05) m, 60 (7) kg, 27 (6)%, respectively]. VO2peak (l x min[-1]), defined as the highest value obtained during exercise to volitional fatigue, was determined using discontinuous protocols with treadmill grade or box mass incremented to increase exercise intensity. For RL VO2peak, a pneumatically driven shelf was used to lower a loaded box to the floor, and subjects then lifted the box, at a rate of 15 lifts x min(-1). VO2peak (l x min(-1) and ml x kg(-1) x min[-1]) and minute ventilation (VE, l x min[-1]) were determined using an on-line gas analysis system. A two-way repeated measures analysis of variance revealed significant gender effects, with men having higher values for VO2peak (l x min(-1) and ml x kg(-1) x min[-1]) and VE, but women having higher values of the ventilatory equivalent for oxygen (VE/VO2). There were also mode of exercise effects, with TR values being higher for VO2peak (l x min(-1) and ml x kg(-1) x min[-1]) and VE and an interaction effect for VO2peak (l x min(-1) and ml x kg(-1) x min[-1]) and VE/VO2. The women obtained a greater percentage (approximately 84%) of their TR VO2peak during RL than did the men (approximately 79%). There was a marginal tendency for women to decrease and men to increase their VE/VO2 when comparing TR with RL. The magnitude of the gender differences between the two exercise modalities appeared to be similar for heart rate, VE and R, but differed for VO2peak (l x min(-1) and ml x kg(-1) x min[-1]). Lifting to an absolute height (1.32 m for the RL protocol) may present a different physical challenge to men and women with respect to the degree of involvement of the muscle groups used during lifting and ventilation.