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Biomedical subjects

A R Behnke

Publications and source records attributed to A R Behnke.

At least 19 recordsLinked to original sources
PubMed1990

Relationships of body size, segmental dimensions, and ponderal equivalents to muscular strength in high-strength and low-strength subjects.

There are conflicting results in prior studies concerning the relationships among body size, muscle size, and muscular strength. The purpose of the present study was to evaluate how body size, body shape, and segmental dimensions related to individual differences in muscular strength. Subjects were tested on four dynamic measures of strength and then classified into one of two groups as high strength (HS; N = 21) and low strength (LS; N = 21). Individual differences in strength were then related to body composition and segmental anthropometry. Strength was assessed during high-resistance, low-velocity standing squat and supine bench press with an isokinetic dynamometer, and during seated bench press and knee extension with a hydraulic resistance dynamometer. Anthropometry and body composition included 11 girths, six fatfolds, predicted fat-free mass (FFM), thigh and upper arm volume, muscle + bone cross-sectional area (CSA), and the Behnke Ponderal Somatogram (PSom) body profiling system. There was a 21.3% difference in strength between HS and LS (p less than 0.05), but no significant differences in age, stature, and fatfolds. MANOVA revealed that seven of 11 girth components of PSom were larger for HS (p less than 0.05). The correlations between strength vs body mass, FFM, thigh and upper arm volume, and CSA and fatfolds in HS and LS ranged from r = -0.52 to 0.56 (r = -0.70 to 0.70 when corrected for restriction of range). We conclude that individual differences in muscular strength are poorly related to various measures of body size and segmental body dimensions.

Adult↗
PubMed1984

Arm x-ray assessment of percent body fat in men and women.

The present experiment determined the validity of arm radiography for quantifying total body fat in young and older men and women. One hundred subjects were measured for 1) body density by underwater weighing with correction for residual air volume to estimate percent body fat and 2) horizontal right upper arm x-ray at KV 76, exposure time 1/30th s, 300 MA, and focal length 72 inches. Total radiation was 10 millirems (mR). The width of fat on the x-ray was measured at three cross-sectional sites (FAT,x-ray). Errors of measurement and measurement for reliability were assessed from duplicate x-rays and repeated measures on the same x-rays (r = 0.92-0.99). The equation to convert FAT,x-ray to individual estimates of percent fat is %Fat = FAT,x-ray/3F X k constant, where 3F = 3 square root wt,kg/ht,dm, and the k constant is a previously determined mean value. The correlation between Fat,x-ray and percent fat (density) was r = 0.89 (N = 100, Se = +/- 2.54); for 25 young men (ages 18-30), r = 0.90 (Se = +/- 1.84); for 25 older men (ages 30-40), r = 0.89 (Se = +/- 2.20); for young (N = 25) and older (N = 25) women, r = 0.85 (Se = +/- 2.08) and 0.87 (Se = +/- 2.61), respectively. These results demonstrate that the new, arm radiogrammetric method is a reliable and valid technique for assessment of body composition in men and women ages 18-40 yr.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1980

Contribution of breast volume and weight to body fat distribution in females.

Breast volume and body composition were measured in 45 adult females to determine the contribution of breast weight and breast volume to total body fat. Plaster casts were filled with sand of known density to obtain breast volume. Breast weight was computed as breast volume times its density. The correlation between total breast volume and percent body fat was r = .40. Breast weight (mean = 484 grams) accounted for 3.5 percent of the total weight of body fat, and at most, 12 percent of the estimated quantities of sex-specific fat. A theoretical model is proposed for the distribution of body fat in the female which subdivides total body fat into three components: reserve storage fat, essential fat, and expendable storage fat.

Adipose Tissue↗
PubMed1979

The square-root principle in the calculation of one-stage (no-stop) decompression tables.

A square-root formulation, square-root time x excursion depth = k, developed at the Royal Navy Physiologic Laboratory (RNPL) predicts the safe duration of air excursions at 1 ATA for periods up to 6 h (air) and up to 3 h (heliox atmosphere). At pressures above 1 ATA, the value of k was initially considered to be proportional to Haldanian multiples of ATA and not to the square-root ATA used in this paper. Excursions of infinite (infinity) duration can also be predicted from a square-root formula derived from the systematic heliox saturation excursions conducted at the Experimental Diving Unit in which net excursion depth = k square-root P abs. This paper presents a broad spectrum format that extends the square-root principle: 1) to values of k above 1 ATA in the RNPL formula and 2) to excursions for (infinity) time from habitat depths to 820 ft; and 3) which demonstrates a relationship between fractional time excursions and excursions for infinite periods of time. Application of the generalization that net excursion depths are proportional to square-root P abs would reduce to a minimum the number of programmed test dives and would, in addition, allow such dives to be conducted at relatively low pressures, with only occasional validating tests at deep depths.

Atmospheric Pressure↗
PubMed1978

Routine anthropometry and arm radiography in assessment of nutritional status: its potential.

Elementary anthropometric and radiographic techniques, carefully executed and routinely employed in definitive surveys of healthy persons, are of potential value in assessment of patients, and provide the following: 1. Formulas to compute mean "ideal body weights" of young adults from stature (W = kh1.7). 2. A "unit size-weight" index (uS-W) with a mean value of 100 or nearly identical to 100 for all mean "ideal weights" relative to stature. 3. The distribution of values of the uS-W index for 80 and 90% of the population of young adults around the mean. 4. Conversion of body girths and stature to ponderal equivalents such that component A reflects fatness (if present) and component B, leanness and muscularity. 5. Conversion of skeletal diameters and stature to a relative "frame" size weight, designated component C, and employed as a "reference weight" (Ref W) for the calculation of lean body weight (LBW) in the male, and "minimal weight" as well as LBW in the female. 6. Conversion of skinfold thickness to estimates of body fat by means of a surface area formulation where: Weight of fat = SA x skinfold widths x k(fat). 7. The introduction of comprehensive arm radiography to reveal presumptive estimates of body fat from SA and of the amount of bone and muscle in the arm to LBW. 8. The visualization of body shape in the somatogram, and the value of photography under strictly controlled conditions.

Adolescent↗
PubMed1975

The effects of cosmic Particle radiation on pocket mice aboard Apollo XVII: V. Preflight studies on tolerance of pocket mice to oxygen and heat. Part I. physiological studies.

Tests were carried out on pocket mice to ascertain their tolerance to elevated oxygen pressures alone and to a combination of hyperoxta and heat in excess of that expected during the flight of the mice on Apollo XVII. the mice withstood oxygen partial pressures up to 12 pst at normal room temperature (24 degrees C, 75 degrees F) over a period of 7 days. A few mice previously exposed to increased PO2 died in the course of exposure to an oxygen pressure of 10 pst or 12 psi (517 mm or 620 mm Hg) for 13 d in ambient heat of 32 degrees C (90 degrees F). Supplemental vitamin E and physiological saline loading given prior to exposure had no apparent protective effect. The overall conclusion was that the pocket mice which were to go on Apollo XVII could readily survive the ambient atmosphere to which they would be exposed.

Adaptation, Physiological↗
PubMed1975

The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: VI. launch, flight, and recovery.

The final phase to fly five pocket mice in the Apollo XVII command module was carried out at the NASA Kennedy Space Center. Upon completion of the 13-d space flight, the package was removed from the spacecraft and, after having been purged with an oxygen-helium gas mixture, was flown to American Samo. Four of the five mice were recovered alive from the package. Analysis of the mouse that died during the flight revealed several factors that could have contributed to its death, the chief of which was massive hemorrhage in its middle ear cavities.

Animals↗
PubMed1975

The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: IX Results of examination of the nasal mucosa.

The olfactory epithelium, but not the nasal respiratory epithelium, of the four pocket mice (Perognathus longimembris) that survived their flight on Apollo XVII showed both diffuse alterations and numerous disseminated focal lesions. The olfactory mucosa of the mouse that died during flight was also affected, but to a minor degree insofar as could be determined. All this was in contrast to the normal appearance of the olfactory mucosa of the numerous control animals. A number of possible causes were considered: systemic or regional infection; inhaled particulate material (seed dust); by-products from the KO2 bed in aerosol or particulate form; gas contaminants originating in the flight package; volatile substances from the dead mouse; weightlessness; and cosmic ray particle radiation. Where feasible, studies were conducted in an effort to rule in or rule out some of these potentially causative factors. No definitive conclusions were reached as to the cause of the lesions in the flight mice.

Aerosols↗
PubMed1975

The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: X. Results of ear examination.

In the five pocket mice flown on Apollo XVII, no evidence was found that the inner ear had been damaged, though poor fixation precluded detailed study. On the other hand, the middle ear cavity was involved in all the mice, hemorrhage having occurrred in response to excursions in pressure within the canister that housed the mice during their flight. The same occurred in flight control mice which had been subjected to pressure excursions of much the same magnitude. A greater degree of exudation into air cells and greater leukotaxis were noted in the flight animals than in the control animals. There was no increase in leukocyte population along the paths of the 23 cosmic ray particles registered in the subscalp dosimeters that traversed the middle ear cavities of the flight mice. The increased exudation and the greater response by leukocytes in the flight mice may have been causally related to the lesions found in their olfactory mucosa but there were no data in support of this possibility.

Animals↗
PubMed1975

The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: IV. engineering aspects of the experiment and results of animal tests.

A closed passive system independent of support from the spacecraft or its crew was developed to house five pocket mice for their flight on Apollo XVII. The reaction of potassium superoxide with carbon dioxide and water vapor to produce oxygen provided a habitable atmosphere within the experiment package. The performance of the system and the ability of the mice to survive the key preflight tests gave reasonable assurance that to mice would also withstand the Apollo flight.

Animals↗