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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
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↗
PubMed1979

Aerobic fitness and body fat of young British males entering the army.

Aerobic fitness and percent body fat were measured in a sample of 438 male Army recruits between the ages of 17 and 30 prior to the commencement of training. The sample came from all areas of England and Wales. Aerobic fitness, as represented by maximal oxygen uptake (VO2 max), was predicted from the Astrand submaximal bicycle heart rate test. Body fat was predicted from four skinfold measurements. Total group means +/- SD were: age, 19.5 +/- 2.5 years; VO2 max 41.7 +/- 8.3 ml/kg . min; and body fat, 14.5 +/- 4.8% of body weight. VO2 max varied with age, athletic participation and aptitude score. No relationship was found with occupation of parent, prior civilian occupation or smoking severity. When adjusted for methodological differences, VO2 max was slightly below similar Army entrants in Norway and the United States.

Adipose Tissue↗
PubMed1979

Physiological effects of a military training program on male and female cadets.

Tested at the beginning and the end of the 6-week training program which all incoming cadets (plebes) undergo upon entering the U.S. Military Academy were 29 males and 26 females (17-21 years old). The aerobic training consisted of running for 30 min 5-6 d/week at varied speeds depending upon performance in an initial 1.5-mile run test. Females responded to training with a significant increase (p is less than 0.001) in VO2 max from 46.0 +/- 1.0 to 49.7 +/- 0.8 ml/kg.min (7.9%). Males did not increase their initial VO2 max (59.4 +/- 1.1 ml/kg.min) significantly. Both groups significantly reduced HRmax and percent body fat. Their initial VO2 max values and activity history accounted for the lack of a significant increase in this highly-fit population of males. Blood lactates were significantly decreased (p is less than 0.05) at the same two submaximal workloads after training. The initial difference in aerobic power between males and females was reduced from 22% to 18%.

Adolescent↗
PubMed1978

Changes in aerobic fitness and body fat during army recruit training.

Aerobic fitness and related indices were evaluated in 254 soldiers at the beginning and near the end of initial army recruit training. Aerobic fitness in terms of maximal aerobic power was preidcted from the Astrand-Ryhming submaximal heart rate bicycle test. Estimated VO2 max increased by 8%, 42.0--45.3 ml/kg . min. Accompanying this increase in aerobic capacity was a decline in body fat content without a change in body weight. It is concluded that army recruit training at the time of this study was effective in terms of increasing aerobic work capacity and reducing excess body fat.

Adipose Tissue↗
PubMed1978

Psychological states and aerobic fitness of male and female recruits before and after basic training.

Psychological states and aerobic fitness were measured using a battery of psychological tests and a bicycle ergometer work test. A group of approximately two hundred male and female subjects were tested at the beginning of a six week basic training cycle and another group of two hundred were tested at the completion of basic training. A difference in mood, anxiety, self confidence and physical fitness was evident in the groups of male recruits, but not in the female recruits after training. A significant difference existed between males and females in terms of physical work capacity. These differences in work capacity and psychological responses should be considered in the assignment and selection of personnel for high work intensity military occupations.

Adolescent↗
PubMed1977

Perceived exertion of absolute work during a military physical training program.

The purpose of this study was to compare the rating of perceived exertion (PRE) and heart rate (HR) in two groups of 60 military personnel who differed in their level of fitness as determined by maximal oxygen uptake (VO2 max). At an initial testing period (T1), Group I represented a sample of personnel not participating in a training program while Group II had engaged in an endurance program (2--4 mile run/day) for 5 months. Six months later (T2), Groups I and II were retested after having participated in the program for 6 and 11 months, respectively. RPE and HR were measured at the end of each min of a 6 min run at an absolute workload of 6 mph, 0% grade on the treadmill. At T1, Group II had a significantly lower HR at each min of work but no difference existed in RPE between groups at any time during the run. At T2, both groups showed a significant decrease in HR and RPE during each min when compared lobgitudinally. The data suggest that the perception of the intensity of absolute work does not differ in groups differing in their level of fitness when studied cross-sectionally. However, significant reductions in perceived exertion occur following physical training.

Adult↗
PubMed1977

Cross-sectional and longitudinal evaluations of an endurance training program.

A comparison of the cardiorespiratory responses obtained using both a longitudinal and cross-sectional evaluation of an endurance training program was made in two groups of 60 young male military personnel. Both groups were initially tested (T1) and then retested 6 months later (T2). At T1, Group I was a sample of personnel not participating in a training program while Group II had undergone a 5-month endurance program (2-4 mile run/day). At T2, Groups I and II had been participating in the program for 6 and 11 months, respectively. Testing consisted of sub-maximal and maximal determinations of VO2, VE and heart rate (HR) using an interrupted treadmill test. VO2 max was 11% greater in Group II compared to Group I at T1 and increased 10% in Group I at T2. Similar results were also seen for HR submax, HR max and VE max. These results show that similar values indicative of an improved level of cardiorespiratory fitness can be obtained using either a cross-sectional or longitudinal design when relatively homogeneous groups are studied.

Adolescent↗