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Biomedical subjects

Karl E Friedl

Publications and source records attributed to Karl E Friedl.

At least 19 recordsLinked to original sources
PubMed2006

Army research needs for automated neuropsychological tests: monitoring soldier health and performance status.

Information on the mental status of soldiers operating at the limits of human tolerance will be vital to their management in future deployments; it may also allow earlier intervention for conditions such as undiagnosed Gulf War illnesses and Parkinson's Disease. The Army needs a parsimonious set of neuropsychological tests that reliably identify subtle changes for: (1) early detection of individual health and military performance impairments and (2) management of occupational and deployment health risks. Testing must characterize cognitive lapses in healthy individuals faced with relevant operational stressors (i.e., anxiety, information overload, thermal strain, hypoxia, fatigue, head impact, chemical or radiation exposures, metabolic challenges). This effort must also explore the neuropsychological methods in militarily relevant conditions to extend our understanding of relevant functional domains and how well they correspond to modes of testing. The ultimate objective is unobtrusive real-time mental status monitoring.

Cognition Disorders↗
PubMed2006

Prevalence of iron deficiency and iron deficiency anemia among three populations of female military personnel in the US Army.

BACKGROUND: Iron deficiency is the most prevalent micronutrient deficiency disease in the world and occurs in young women in the United States. Female military personnel represent a unique population faced with intense physical and cognitive demands. OBJECTIVE: The objective of this study was to determine the prevalence of iron deficiency and iron deficiency anemia among three populations of female military personnel in the US Army. METHODS: Iron status was assessed in 1216 volunteers. Volunteers were recruited from three groups: immediately following initial entry to the Army (IET), immediately following basic combat training (AIT), or following at least six months of permanent assignment (PP). Iron deficiency was determined using a three variable model, including cut-off values for serum ferritin, transferrin saturation, and red cell distribution width (RDW). Iron deficiency anemia was categorized by iron deficiency and a hemoglobin (Hgb) value of <12 g/dL. RESULTS: The prevalence of iron deficiency was greater in women in the AIT group (32.8%) than in the IET and PP groups (13.4 and 9.6%, respectively). The prevalence of iron deficiency anemia was greater in the AIT group (20.9%) than in the IET and PP groups (5.8 and 4.8%, respectively). Furthermore, the prevalence of iron deficiency anemia was greater in Hispanic (21.9%) and African-American military personnel (22.9%) than in Caucasian military personnel (10.5%). CONCLUSIONS: These data indicate that female military personnel experience diminished iron status following training, and that iron nutriture is an important issue facing females in the military.

Adult↗
PubMed2006

Negative energy balance in male and female rangers: effects of 7 d of sustained exercise and food deprivation.

BACKGROUND: A challenging 7-d ranger field exercise (FEX) by cadets in the Norwegian Military Academy provided a venue in which to study the effects of negative energy balance. OBJECTIVE: We quantified total energy expenditure (TEE), food intake, and changes in body composition in male and female cadets. DESIGN: TEE (measured by doubly labeled water), food intake, activity patterns (measured by accelerometry), and body composition (measured by dual-energy X-ray absorptiometry) were measured in 16 cadets (10 men and 6 women aged 21-27 y). RESULTS: The physically active (approximately 23 h/d) and semistarved (0.2-2.2 MJ/d) cadets lost weight (x +/- SD: men, -7.7 +/- 1.1 kg; women, -5.9 +/- 1.1 kg; P < 0.05). Absolute TEE differed by sex (men, 26.6 +/- 2.0 MJ/d; women, 21.9 +/- 2.0 MJ/d; P < 0.05) but body weight-specific TEE did not (men, 343 +/- 26 kJ . kg(-1) . d(-1); women, 354 +/- 18 kJ . kg(-1) . d(-1); NS). Fat-free mass (FFM) loss differed significantly by sex (men, -4.0 +/- 1.2 kg; women, -2.5 +/- 1.1 kg; P < 0.05), but percentage FFM loss did not (men, -6.3 +/- 1.9%; women, -5.6 +/- 2.4%). In contrast, absolute FM loss did not differ significantly by sex (men, -3.45 +/- 0.72 kg; women, -3.42 +/- 0.22 kg), but fat oxidation (men, 5.2 +/- 1.0 mg . min(-1) . kg FFM(-1); women, 7.3 +/- 0.5 mg . min(-1) . kg FFM(-1)) and the relative contribution of FM to TEE (men, 74 +/- 14%; women, 89 +/- 6%) were significantly greater in women than in men (P < 0.05). CONCLUSION: Female cadets maintained a significantly more fat-predominant fuel metabolism than did male cadets in response to sustained exercise and semistarvation.

Absorptiometry, Photon↗
PubMed2006

Field studies of exercise and food deprivation.

PURPOSE OF REVIEW: The increase in obesity in developed societies drives interest in the interplay of energy intake, metabolic energy expenditure, and body energy stores. A better understanding of energy management in physically active and undernourished humans should help guide strategies to manage obesity safely and effectively. This review focuses on field studies of men and women engaged in prolonged strenuous activities, ranging from ranger training to extreme expeditions. RECENT FINDINGS: Although scientifically unconventional and limited, field studies of exercise and food deprivation have yielded interesting findings: 4-5% body fat is the normal lower limit to fat reserves in physically active underfed young adult men, and in response to exercise and underfeeding, women used more fat mass and less fat-free mass to meet metabolic fuel requirements. SUMMARY: Field studies have shown that fat energy reserves in young adult men can be estimated as percentage body fat minus 5%, and initial body fat mass has a significant positive influence on fat oxidation rates per kilogram of fat-free mass during rapid weight loss associated with underfeeding and exercise. Data logging pedometers, activity monitors, global positioning systems, and wireless body and personal-area networks promise to make it easier to study and care for free-living humans.

Adipose Tissue↗
PubMed2006

The effect of proposed improvements to the Army Weight Control Program on female soldiers.

OBJECTIVE: To comply with Army Regulation 600-9, The Army Weight Control Program (AWCP), soldiers must meet age-adjusted body fat standards, regardless of whether they meet or exceed weight-for-height allowances. Recent revisions to Department of Defense (DoD) policies require changes to the AWCP. Specifically, we assessed the effects of increasing weight-for-height allowances and adoption of the DoD body fat equation on compliance with the AWCP in women. METHODS: Weight, height, circumferences (neck, forearm, wrist, waist, and hip) to measure body fat, and Army Physical Fitness Test results were obtained from 909 female soldiers (mean (SD) age, 26.2 (6.5) years; body mass index, 24.6 (3.3) kg/m2; body fat, 29.7% (5.0)). RESULTS: Increasing the screening weight-for-height allowances resulted in a 20% reduction in those requiring a body fat measurement (from 55% [n = 498) to 35% [n = 319]). Adopting the DoD body fat equation did not change the proportion of overfat women, i.e., noncompliant with the AWCP, (from 26% [n = 232] to 27% [n = 246]). More women with a waist circumference > 35 inches (i.e., at increased disease risk) were identified as noncompliant with the AWCP by the proposed body fat equation (from 76% [n = 61] to 96% [n = 77]). CONCLUSIONS: Proposed changes reduce the proportion of women unnecessarily measured for body fat and do not change the proportion of women on the AWCP, yet select more women at increased disease risk and most in need of an effective intervention.

Adipose Tissue↗
PubMed2005

Biomedical research on health and performance of military women: accomplishments of the Defense Women's Health Research Program (DWHRP).

In 1994, Congress provided dollar 40 M for biomedical research on issues of importance for military women. This supported 104 intramural and 30 extramural studies and launched an era of research to narrow the knowledge gap on protection and enhancement of health and performance of military women. Projects addressed issues specific to female physiology (e.g., gynecological health in the field, maternal malaria), problems with higher prevalence for women (e.g., marginal iron deficiency, stress fracture), and issues of drug and materiel safety that had only been extrapolated from studies of men (e.g., chemical agent prophylaxis, fatigue countermeasures). Several important assumptions about female physiology and occupational risks were found to be astoundingly wrong. Hormonal changes through the menstrual cycle were less important to acute health risks and performance than predicted, exercise did not increase risk for amenorrhea and consequent bone mineral loss, and women tolerated G-forces and could be as safe as men in the cockpit if their equipment was designed for normal size and strength ranges. Data on personal readiness issues, such as body fat, physical fitness, nutrition, and postpartum return to duty, allowed reconsideration of standards that were gender appropriate and not simply disconnected adjustments to existing male standards. Other discoveries directly benefited men as well as women, including development of medical surveillance databases, identification of task strength demands jeopardizing safety and performance, and greater understanding of the effects of psychosocial stress on health and performance. This surge of research has translated into advances for the welfare of service women and the readiness of the entire force; relevant gender issues are now routine considerations for researchers and equipment developers, and some key remaining research gaps of special importance to military women continue to be investigated.

Attitude to Health↗
PubMed2004

Can you be large and not obese? The distinction between body weight, body fat, and abdominal fat in occupational standards.

Weight control is an important early intervention in diabetes, but the nature of the association between weight and disordered metabolism has been confused because fat mass and its distribution are only partly associated with increasing body size. Weight, fat, and regional fat placement, specifically in the abdominal site, may each have distinctly different associations with diabetes risk. Abdominal circumference may be the common marker of poor fitness habits and of increased risk for metabolic diseases such as diabetes. This is an important question for public health policy as well as for occupational standards such as those of the military, which are intended to promote fitness for military missions and include strength and aerobic capacity, as well as military appearance considerations. U.S. soldiers are heavier than ever before, reflecting both increased muscle and fat components. They also have better health care than ever before and are required to exercise regularly, and even the oldest soldiers are required to remain below body fat limits that are more stringent than the current median values of the U.S. population over age 40. The body fat standards assessed by circumference-based equations are 20-26% and 30-36%, for various age groups of men and women, respectively, and the upper limits align with threshold values of waist circumference recommended in national health goals. The basis and effects of the Army standards are presented in this paper. U.S. Army body fat standards may offer practical and reasonable health guidelines suitable for all active Americans that might help stem the increasing prevalence of obesity that is predicted to increase the prevalence of Type 2 diabetes.

Abdomen↗
PubMed2004

Research requirements for operational decision-making using models of fatigue and performance.

Sustained human performance is critical to job and mission success in many federal agencies including national defense, aerospace exploration, and transportation. For the responsible agencies, applications of the basic biomedical and applied human factors science provide the best available solutions to help individuals perform more effectively and with increased safety. Key products of this research are biomathematical models that predict periods of impaired performance, with applications in planning tools, real time monitoring, and intervention decision aids. Since it is difficult to quantify the number of judgment errors or accidents averted, metrics of success for fatigue management systems must be largely based on the accuracy of performance predictions derived from laboratory-based research studies and the extent to which such results can be generalized to the field environment. Performance metrics must, at a minimum, be correlated with occupational task performance to demonstrate relevance to real-world applications. This paper outlines broad goals for human effectiveness research related to fatigue, alertness, and performance. To advance from the present state of knowledge to useful predictive models requires a well-coordinated commitment from federal agencies. Users should be made aware that current models and tests are not likely to encompass all of the aspects of human performance that are relevant to field environments and occupations.

Decision Support Techniques↗