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Biomedical subjects

J A Vogel

Publications and source records attributed to J A Vogel.

At least 19 recordsLinked to original sources
PubMed1997

Validity of percent body fat predicted from circumferences: classification of men for weight control regulations.

Each of the military services classifies individuals in their weight control programs using percent body fat predicted by circumference-based equations. Although derived independently from service-specific samples, each of the male equations relies on waist circumference adjusted by a neck circumference. In this study, the authors examined the performance of the equations in 496 young (< 40 years) male soldiers, compared to percent body fat measured by dual-energy X-ray absorptiometry. The strength of the relationship to percent body fat improved from body mass index (weight/height2), to a waist circumference alone, to the difference between waist and neck circumferences. Overweight men who were misclassified by overestimation of total percent body fat using the equations (2.6% of the total sample) had normal neck circumferences and height but large waistlines, indicating that they were still classified appropriately to the goals of the weight control programs, all of which center on abdominal adiposity. The authors demonstrate that each of the service equations yield substantially similar results and discuss why a single equation could be easily agreed to and used by the Department of Defense for male body fat prediction.

Absorptiometry, Photon↗
PubMed1996

Influence of age and physical training on measures of cardiorespiratory and muscle endurance.

This study describes associations between age, physical training and measures of muscle and cardiorespiratory endurance. The subjects were 5079 healthy male soldiers aged 18-53 years from 14 Army installations in the United States. The subjects completed as many push-ups as possible in 2 min, as many sit-ups as possible in 2 min, and performed a timed 3.2-km run. The training level was assessed by asking the subjects two questions about the frequency (times each week) and duration (hours each week) of their physical training. For all three performance events there were significant declines with age, but at a given age, groups that trained more demonstrated higher performance levels than groups that trained less. For the 3.2-km run, the age-associated rate of performance decline was less in the groups that trained more, and greater amounts of training resulted in progressively less performance decline with age. For push-ups and sit-ups, the training level did not systematically influence the age-related rate of performance decline. The results suggest that tasks involving different physiological systems may be influenced differentially by age and training. Training may slow age-associated performance declines in tasks requiring cardiorespiratory endurance but not in tasks requiring muscle endurance.

Adult↗
PubMed1994

Lower limit of body fat in healthy active men.

We examined body composition changes in 55 normal young men during an 8-wk Army combat leadership training course involving strenuous exercise and low energy intake, with an estimated energy deficit of 5.0 +/- 2.0 MJ/day and a resultant 15.7 +/- 3.1% weight loss. Percent body fat (BF) measured by dual-energy X-ray absorptiometry (DEXA) averaged 14.3% (range 6-26%) and 5.8 +/- 1.8% (range 4-11%) at the beginning and end of the course, respectively. Men who achieved a minimum percent BF (4-6%) by 6 wk demonstrated only small additional total and subcutaneous fat losses in the final 2 wk and sacrificed increasingly larger proportions of fat-free mass. Percent BF estimated from skinfold thicknesses reflected relative changes in fat mass, although actual percent BF was overestimated. Instead of reaching a plateau after fat stores were substantially depleted, abdominal, hip, and thigh girths continued to decline with body weight loss. Final percent BF for the leanest men was similar to that observed after a 25% body weight reduction in the 1950 Minnesota study (5.2% by underwater weighting), and height-corrected final fat mass was the same (1.0 +/- 0.2 vs. 0.9 +/- 0.7 kg fat/m2), suggesting that these values represent a minimal body fat content in healthy men and that weight loss subsequent to achieving this level is contributed from the fat-free mass. Our results suggest that 4-6% BF or approximately 2.5 kg fat represents the lower limit for healthy men, as assessed by DEXA or by underwater weighing.

Absorptiometry, Photon↗
PubMed1992

Reliability of body-fat estimations from a four-compartment model by using density, body water, and bone mineral measurements.

Reliability of body-fat estimation by a four-compartment model was tested in 10 subjects. Body densities were measured by underwater weighing (UWW), total body water (TBW) by deuterium dilution, and total body bone mass (TBBM) by dual-energy x-ray absorptiometry in three sessions in 1 wk. Percent body fat was determined by [2.559/density -0.734 (TBW/weight) +0.983 (TBBM/weight) -1.841] x 100. Reliability coefficients were 0.991 and 0.994, and within-subjects standard deviations were +/- 1.0 and +/- 1.1 for percent body-fat estimations from Siri's two-compartment and the four-compartment models, respectively; fat mass was +/- 0.8 kg with both models. These data suggest that additive errors in the multicompartment model do not offset the improved accuracy of fat estimations over those obtained from UWW alone. The greatest source of error came from UWW procedure itself (+/- 0.002 g/cm3, or approximately 1.0% of body weight), followed by error in TBW (+/- 0.5 L). More reproducible passive methods that are not dependent on hydration or TBBM may be especially useful after validation against the four-compartment model.

Absorptiometry, Photon↗
PubMed1992

Body fat assessment in women. Special considerations.

Methods of in vivo body fat estimation are based on simple assumptions about body composition which work reasonably well for men, while estimations in women have been largely extrapolated from the male studies so that women are treated as men with just more of the same fat. Compared to men, fat regulation in women is considerably more elaborate, with more and different sites for storage and a larger proportion of fat distributed to the extremities and in subcutaneous locations. Thus, a ratio of waist-to-hips girth which reflects increasing fatness in men only specifies 2 different extremes of a broader spectrum of possibilities for fat distribution in women. This complicates anthropometric prediction of total fatness and clearly limits the generalisability of any female equations. Anthropometric methods are further confounded by difficulties in the criterion methods against which they are developed. For example, the validity of assumptions about the fractional contributions of bone mineral and body water to fat-free mass and density may not hold through the reproductive cycles. Women athletes involved in weight-bearing or strength training may increase bone mineral content above average values but if they become amenorrhoeic, bone mineral density may fall significantly below average values. Fit premenopausal women distribute fat differently and have a higher bone mineral content than unfit postmenopausal women. Genetic factors which also affect criterion method assumptions in men are superimposed on these additional complications in women. Body fat in female athletes extends across almost the entire range of female fatness, with some of the lowest measurements in distance runners and body builders which fall into the normal male range, but also with some relatively high values in swimmers and strength athletes, which would classify these women as obese by male standards. Thus, total body fat reflects a more complex regulation and has a different meaning to health and performance in women than it does for men. Predictive equations for women athletes should be developed with a view to the specific group and ultimate purpose to which they will be applied.

Adipose Tissue↗
PubMed1992

Injuries associated with strenuous road marching.

Injuries were recorded during and up to 12 days after a maximal effort road march. Light infantry soldiers (N = 335) carried a total load of 46 kg over a 20 km course. Twenty-four percent of the soldiers suffered one or more injuries, resulting in 44 days of limited duty. All injuries involved the lower extremities and/or the back. Foot blisters and back problems were the most common complaints (35% and 23%, respectively, of the total injuries). These data indicate that units without recent road marching training can expect a high incidence of injuries as a result of a single demanding road march.

Adult↗
PubMed1988

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.

Adult↗
PubMed1986

An analysis of aerobic capacity in a large United States population.

This study presents a description of aerobic capacity in a large US population comprised of 1,514 men and 375 women. Such influencing factors as age, training state, occupation, and body composition were evaluated. The population consisted of new recruits entering the US Army from civilian life as well as soliders in a variety of assignments and physical training programs. Age ranged from 17 to 55 yr. With the exception of one older group, aerobic capacity was determined as maximal O2 uptake measured directly by the Douglas bag technique during a standard discontinuous treadmill running procedure. New male and female recruits representing a young civilian population entered the service with maximal O2 uptake of 51 and 37 ml X kg body wt-1 X min-1, respectively, and thereafter increased 5% during initial basic training. The difference between genders, 30% on an absolute basis, was 14% when expressed as a function of fat-free weight. Aerobic capacity was less after occupational training and continued to decrease with age at an average yearly rate of 10%, or 0.5 ml X kg body wt-1 X min-1. Aerobic capacity varied with intensity of the occupational physical demand, except in groups with significant physical training programs. This first large US population study of aerobic capacity, using a direct treadmill procedure, demonstrates levels consistent with any previously reported population.

Adipose Tissue↗
PubMed1985

The influence of muscle metabolic characteristics on physical performance.

This study describes the influence of muscle fiber type composition, enzyme activities and capillary supply on muscle strength, local muscle endurance or aerobic power and capacity. Muscle biopsies were obtained from m. vastus lateralis in thirteen physically active men. Histochemical staining procedures were applied to assess the percentage of fast twitch (FT) fibers, muscle fiber area, and capillary density. Also, the activity of citrate synthase (CS), creatine kinase (CK), hexokinase (HK), lactate dehydrogenase (LDH), and phosphofructokinase (PFK) were analysed using fluorometrical assays. Peak torque at 'low' and 'high' angular velocities was measured during leg extension. Similarly, muscle fatigue (e.g. peak torque decline) and recovery from a short-term exercise task were measured during maximal, voluntary consecutive leg extensions. Aerobic power (VO2max) and aerobic capacity (e.g. onset of blood lactate concentration; OBLA), as defined by a blood lactate concentration of 4 mol X 1(-1) were measured during cycling. Peak torque at a high angular velocity was positively correlated with % FT area (p less than 0.001). Fatigue and recovery were correlated with LDH X CS-1 (p less than 0.001). WOBLA was best correlated with PFK and PFK X CS-1 (p less than 0.001). Hence, muscle strength was partly determined by fiber type composition whereas local muscle endurance, recovery and aerobic capacity reflect mainly capillary supply and the activity of key enzymes involved in aerobic and anaerobic metabolism.

Adult↗
PubMed1985

Does fever or myalgia indicate reduced physical performance capacity in viral infections?

To study prospectively the effects of a brief febrile viral infection on parameters of muscle and circulatory function, seven volunteers were inoculated with sandfly fever virus and two control subjects with sterile saline. During but not after fever, decreased isometric and dynamic strength and endurance were recorded in various muscles. Impairment could not be explained by altered activities of relevant muscle enzymes in serum or muscle tissue or by altered muscle ultrastructure, but correlated with the severity of perceived symptoms, including myalgia, as rated by each subject. Compared to baseline, cardiac stroke volume was lower during and after fever. During fever, an increased heart rate maintained cardiac output at pre-inoculation values, whereas cardiac output fell in early convalescence. This decrease in cardiac output correlated significantly with the severity of fever. Thus, in brief viral infections a transient impairment of muscle performance capacity is correlated to subjective symptoms such as myalgia, rather than to fever, whereas a decreased cardiac output following such infections seems to be associated with the fever reaction.

Adult↗
PubMed1984

Effects of acute cold exposure on submaximal endurance performance.

The purposes of this study were to assess VO2max and submaximal endurance time to exhaustion (ET) during acute cold-air exposure. Eight male subjects (means age = 19.9 yr) were alternately exposed in groups of four to chamber temperatures of +20 degrees C and -20 degrees C for 30 h each. A week was allowed between exposures. Maximum oxygen uptake was measured using a mechanically-braked cycle ergometer, and ET was determined on the same ergometer using a 17-min/3-min exercise/rest schedule until the subject was unable to maintain pedal rate. Maximum oxygen uptake was not significantly different between conditions: 3.43 +/- 0.09 l X min-1 at +20 degrees C and 3.35 +/- 0.10 l X min-1 at -20 degrees C. During endurance exercise, intensities equaled 77.1 +/- 1.4% and 78.9 +/- 2.0% of VO2max at +20 degrees C and -20 degrees C, respectively. Heart rate and VO2 values obtained between 8 and 10 min of the endurance run were not significantly different (156 +/- 2 bpm and 2.63 +/- 0.08 l X min-1 at +20 degrees C and 158 +/- 3 bpm and 2.65 +/- 0.11 l X min-1 at -20 degrees C). Endurance time to exhaustion however, decreased 38% (P less than 0.05) from 111.9 +/- 22.8 min at +20 degrees C to 66.9 +/- 13.6 min at -20 degrees C. The data support the contention that aerobic capacity is not altered by cold exposure but suggest a marked decrease in submaximal endurance performance.

Adolescent↗
PubMed1983

Effects of travel across time zones (jet-lag) on exercise capacity and performance.

Eighty-one healthy male soldiers, aged 18-34, were studied for 5 d before and 5 d after an eastward deployment across six time zones to determine the effects of translocation on exercise capacity and performance. Fatigue, weakness, headache, sleepiness, irritability, and other commonly reported symptoms occurred in the majority of subjects. Most, but not all, of the symptoms were diminished or absent by the fifth day following the translocation. Cardiorespiratory function and perception of effort during both submaximal and maximal treadmill exercise were unaffected. Isometric strength of the upper torso, legs, and trunk extensor muscles also was not changed. Dynamic strength and endurance of elbow flexors declined significantly. Dynamic knee extensor strength and endurance scores exhibited a progressive decrement prior to translocation and were inconsistent suggesting that the stress of repetitive testing outweighed any jet-lag effects on performance capacity. Performance times for a 270 m sprint were increased for the first 4 d following translocation as were times for a 2.8 km run on the second and third days and for a 110 m lift and carry on the third day after deployment. Times for a 6.5 m rope climb did not change. These findings indicate that certain symptoms and physiological capacities are affected as a result of multiple time zone translocation. However, the specific mechanisms involved, the factors influencing the magnitude of any physiological alterations, and the ultimate impact of these capacity changes on actual physical performance remain to be clarified.

Adaptation, Physiological↗
PubMed1983

Response of age forty and over military personnel to an unsupervised, self-administered aerobic training program.

The Army recently extended mandatory physical training and testing to include personnel 40 yrs of age and older. The purpose of this study was to describe the profile of aerobic fitness in a representative group from this age population and to evaluate the response of such a group to a self-administered, unsupervised training program. Maximal oxygen uptake (Vo2 max) and percent body fat (%BF) were assessed in 260 military personnel (40-53 yrs of age) before and after 6 mo of physical training consisting of a progressive walk/run mode of exercise. Before training the mean +/- S.D. for Vo2 max and %BF for all subjects was 38.1 +/- 6.2 ml/kg . min and 26.1 +/- 4.7%, respectively. Subjects were divided into three groups based upon their initial level of physical activity determined by interview as follows: inactive, moderately active and active. Upon retesting after 6 mo, 40% of the inactive group had not participated to any appreciable degree in the program and subjects of this group who did participate showed only a slight and insignificant increase (4.4%) in Vo2 max. The pretraining level of Vo2 max for the total population studied was similar to that reported in other studies on comparably aged subjects. However, changes with training were well below those seen with supervised group programs of 6 mo duration.

Adult↗
PubMed1983

Height, weight, percent body fat, and indices of adiposity for young men and women entering the U.S. Army.

The purpose of this investigation was to describe the height (H), weight (W), and percent body fat (%BF) of young men and women (ages 17-35 years) entering the U.S. Army and to determine an index of adiposity that fit criteria described in the literature. H and W were measured with a digital scale and anthropometer, respectively. %BF was calculated from four skinfolds thickness. Men and women were both separated into four age categories. Very little difference in H was found with increasing age. W and %BF increased progressively with age in the males but no increase in either parameter was seen within the three youngest age groups of women. For males, W/H2 was found to be the most appropriate index of adiposity of those studied, having a correlation with %BF of 0.75 and a standard error of estimate of +/- 3.4 %BF. W/H1.5 was the most appropriate index for females, having a correlation with %BF of 0.69 and a standard error of estimate of +/- 3.2 %BF. It was suggested that these indices could be used to replace or supplement the current H-W charts used in the Army. A table for predicting %BF from these indices has been provided.

Adipose Tissue↗
PubMed1982

Evaluation of a maximal predictive cycle ergometer test of aerobic power.

A maximal predictive cycle ergometer (CE) test for estimating maximal oxygen uptake (VO2 max) was evaluated in 15 male and 12 female subjects. The test consisted of pedalling a cycle ergometer (Monark) at 75 rev X min-1, beginning at an intensity of 37.5 watts and increasing by this amount each min until the subject could no longer maintain pedal rate. The highest work rate achieved was recorded as the endpoint of the test and used to construct regression equations to predict VO2 max. This was compared with two direct measures of VO2 max [an interrupted treadmill (TM) run and an interrupted CE procedure at 60 rev X min-1] and with the submaximal predictive test of Astrand-Rhyming. When compared to TM VO2 max, VO2 measured during the final 30 s of the maximal predictive CE test was 16.0% and 16.2% lower for males and females respectively; compared to VO2 max determined by the direct CE test, it was lower by 2.9% for males and 5.2% for females. Correlation coefficients for VO2 max predicted from the maximal predictive CE test and VO2 max measured directly by CE and TM were 0.89 and 0.87 for males and 0.88 and 0.83 for females (p less than 0.01), respectively. The VO2 max predicted from the Astrand-Rhyming test correlated significantly with VO2 max measured by CE and TM only in the male group. Test-retest reliability coefficients for intensity (watts) on the maximal predictive CE test were 0.95 and 0.81 for males and females respectively (p less than 0.01). The data suggest that this CE test gives a reliable and valid estimate of VO2 max.

Adult↗