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Biomedical subjects

J Puhl

Publications and source records attributed to J Puhl.

18 recordsLinked to original sources
PubMed2001

Growth hormone administration and exercise effects on muscle fiber type and diameter in moderately frail older people.

OBJECTIVE: Reduced muscle mass and strength are characteristic findings of growth hormone deficiency (GHD) and aging. We evaluated measures of muscle strength, muscle fiber type, and cross sectional area in response to treatment with recombinant human growth hormone (rhGH) with or without a structured resistance exercise program in frail older subjects. DESIGN: Placebo-controlled, randomized, double blind trial. SETTING: Outpatient clinical research center at an urban university-affiliated teaching hospital. PARTICIPANTS: Thirty-one consenting older subjects (mean age 71.3 +/- 4.5 years) recruited as a subset of a larger project evaluating rhGH and exercise in older people, who underwent 62 quadricep-muscle biopsies. INTERVENTION: Random assignment to a 6-month course of one of four protocols: rhGH administered subcutaneously daily at bedtime, rhGH and a structured resistance exercise program, structured resistance exercise with placebo injections, or placebo injections only. MEASUREMENTS: Muscle biopsy specimens were obtained from the vastus lateralis muscle. Isokinetic dynamometry strength tests were used to monitor individual progress and to adjust the weights used in the exercise program. Serum insulin-like growth factor-I (IGF-I) was measured and body composition was measured using a Hologic QDR 1000W dual X-ray densitometer. RESULTS: The administration of rhGH resulted in significant increase in circulating IGF-I levels in the individuals receiving rhGH treatment. Muscle strength increased significantly in both the rhGH/exercise (+55.6%, P =.0004) as well as the exercise alone (+47.8%, P =.0005) groups. There was a significant increase in the proportion of type 2 fibers between baseline and six months in the combined rhGH treated subjects versus those not receiving rhGH (P =.027). CONCLUSIONS: Our results are encouraging in that they suggest an effect of growth hormone on a specific aging-correlated deficit. IGF-I was increased by administrating rhGH and muscle strength was increased by exercise. The administration of rhGH to frail older individuals in this study resulted in significant changes in the proportions of fiber types. Whether changes in fiber cross-sectional area or absolute number occur with long-term growth hormone administration requires further study.

Age Factors↗
PubMed1998

Lack of an association between insulin-like growth factor-I and body composition, muscle strength, physical performance or self-reported mobility among older persons with functional limitations.

OBJECTIVE: The hypothesis that decreased growth hormone (GH) secretion contributes to the functional decline that occurs with aging is far from substantiated. There have been few studies addressing the distribution and correlates of IGF-I, an indicator of GH activity, in nonclinical populations. As part of a growth hormone intervention trial, we examined the cross-sectional relations between IGF-I levels and multiple measures of physical function, body composition, and strength in a group of older men and women exhibiting mild to moderate reductions in measured physical performance. METHODS: Using a variety of advertising techniques, 155 older subjects were recruited from a metropolitan area to participate in a growth hormone and exercise intervention study. At baseline, all subjects had blood drawn for IGF-I and underwent testing of body composition using dual X-ray absorptiometry, muscle strength using isokinetic dynamometry, and functional assessment using timed performance measures and self-report. Associations between levels of IGF-I, body composition, strength, and physical function were assessed after dividing men and women separately into tertiles of IGF-I as well as treating IGF-I as a continuous variable. RESULTS: Men had higher IGF-I levels than women, and a significant inverse correlation was observed between age and IGF-I in men (r=-0.29, P=.009). There were no clear trends for associations between tertiles of IGF-I, and any of the variables tested. Linear regression models with IGF-I treated as a continuous measure were not associated significantly with any of the measures of physical function, body composition, or strength (all P > 0.05). CONCLUSIONS: In conclusion, although IGF-I levels declined with age in men, these data did not demonstrate an association between IGF-I and measures of muscle strength, body composition, or physical functioning. These findings support the growing body of evidence that IGF-I levels may not be an indicator of growth hormone activity in older persons.

Aged↗
PubMed1993

Association among serum lipid and lipoprotein concentrations and physical activity, physical fitness, and body composition in young children.

OBJECTIVE: To examine the relationships among indicators of physical activity, physical fitness, and body composition with serum lipid and lipoprotein levels in young children. DESIGN: Cross-sectional and 1-year prospective cohort. SETTING: Studies of Child Activity and Nutrition (SCAN) program, Galveston, Tex. SUBJECTS: One hundred twenty-three 4- or 5-year-old black, Hispanic (of Mexican origin), and white children. MEASUREMENTS: Body composition, resting heart rate, and cardiovascular fitness variables and serum lipid and lipoprotein levels were measured at age 3 or 4 years (study year 1) and at age 4 or 5 years (study year 2), and day-long heart rate was measured and the Children's Activity Rating Scale was administered between study years 1 and 2. RESULTS: Year-1 waist/hip ratios were inversely correlated with total serum cholesterol (TSC) and low-density lipoprotein (LDL) levels. Mean activity level was inversely correlated with waist/hip ratios. On the basis of multiple regression analysis, the sum of seven skin-fold measurements, height, and gender explained 15.4% of the variation in triglyceride levels. The sum of seven skin-fold measurements was inversely correlated with the high-density lipoprotein (HDL) level. Resting heart rate, waist/hip ratio, and the slope of the exercise heart rate during fitness testing explained 19.5% of the variation in the concentration of an HDL subclass, HDL2. These children's levels of physical activity were associated with higher fitness levels. Year-1 waist/hip ratios and year-2 sum of seven skin-fold measurements were positively correlated with the LDL/HDL and TSC/HDL ratios. CONCLUSION: Higher levels of cardiovascular fitness and lower levels of fatness were associated with more favorable serum lipid and lipoprotein levels in these young children. Physical activity appeared to have an indirect association with serum lipid and lipoprotein values through its relationship with higher fitness levels and lower levels of fatness.

Activities of Daily Living↗
PubMed1993

Observations on physical activity in physical locations: age, gender, ethnicity, and month effects.

The level of physical activity of 3- and 4-year-old children was assessed in alternative physical locations by month and time of day and by age, gender, and ethnicity. Physical activity was assessed by observation with the Children's Activity Rating Scale (CARS) for up to 12 hours from 7:00 am to 7:00 pm. A sample of 191 three- and four-year-old children was observed for up to four times in the course of a year. The sample was tri-ethnic. Boys were significantly more active than girls. Activity was consistently higher outside than inside. There were significant differences in the amount of time children in this age group spent inside versus outside by time of year; the activity levels of boys and girls differed by time of year, particularly when outside. A model including gender, month, and location terms accounted for 75% of the variance in physical activity. These data further documented gender differences in physical activity among very young children using measures not subject to self-report biases but did not explain or clarify the gender differences. The substantial differences by physical location and time of year deserve future attention, but more refined methods will be needed to balance data by location and important seasonal times. An inference from these results is that activity levels among young children may be increased by encouraging them to spend more time outdoors.

Activity Cycles↗
PubMed1993

Evaluation of the Children's Activity Rating Scale (CARS) in young children.

We describe the daily activity patterns and the between-day and -year reliabilities of the Children's Activity Rating Scale (CARS) measured in 180 Anglo-, African-, and Mexican-American children aged 3 or 4 yr. Reliabilities were assessed at up to 11 measurement periods over 3 yr. CARS scores were measured by two trained observers (alternating 2-h shifts) up to 12 working hours. There were no significant ethnic or day of week differences in the activity levels. Males had higher mean activity levels than females and higher activity was performed in the summer and fall than the spring or winter. The all-measurements reliability for a mean of 5.34 d of observation over the 3 yr of measurement was 0.57. The reliability across all days and years of measurement was 0.73. The highest level of reliability (0.75) was found for the percent of minutes spent at CARS levels 3, 4, or 5 followed by an intraclass correlation of 0.74 for percent of minutes spent at CARS levels 4 or 5. These data support the utility of using the CARS as a measure of physical activity in younger children from different ethnic groups.

Activities of Daily Living↗
PubMed1993

Reliability and variability of indicators of heart-rate monitoring in children.

We describe the daily heart-rate patterns and the between-day and within-day reliabilities of several heart rate indicators measured in 131 Anglo-, African-, and Mexican-American children aged 5-7 yr. Heart rates were measured over 12 waking hours with a Quantum XL Telemetry heart rate monitor. The percent of heart rates 25% above resting heart rate, an index of physical activity heart rate (PAHR-25 index), was found to have the highest within-day (0.92) and between-day (0.81) reliabilities. The Spearman-Brown prophecy formula indicated that only 9.3 h of observation would be needed to maintain a within-day reliability of 0.90. The percentage of heart rates 50% above resting heart rate (PAHR-50) was found to have slightly lower within-day (0.88) and between-day (0.56) reliability. Principal components analysis revealed that the PAHR-25 and PAHR-50 indicies only had one component throughout the day. The PAHR-25 and PAHR-50 indicies were weakly correlated with age, suggesting that they may be good indicators of relative PAHR. Male children had higher (P < or = 0.025) PAHR-25 index scores than females. There were no gender or ethnic differences in the PAHR-50 index.

Black or African American↗
PubMed1992

Reliability and variability of heart rate monitoring in 3-, 4-, or 5-yr-old children.

We describe the daily heart rate patterns and the between day and within day reliabilities of several heart rate variables measured in 159 Anglo-, African-, and Mexican-American children aged 3-5 yr. Heart rates were measured over 12 waking hours with a Quantum XL Telemetry heart rate monitor. There were no significant ethnic, gender, day of week, or season of the year differences in either mean resting heart rate, mean daily heart rate, mean longest duration of the heart rate sustained above 120 bpm for the day, nor percent of minutes of daily heart rate above 120 bpm. The reliabilities for these variables for 2 d of observation separated by 3-6 months ranged from 0.65 to 0.66. At this level of reliability, just over 4 d of recording are necessary to achieve a reliability of 0.80. All within-day across-hour reliabilities were greater than 0.80. However, for mean hourly heart rate and the longest duration of heart rate sustained above 120 bpm each hour, a principal components analysis revealed three distinct time components during the day. This suggests that monitoring heart rate during limited portions of the day will provide a biased estimate of overall heart rate. For the morning component, there were significant ethnic and gender differences in the children's heart rates and younger children had longer durations of heart rate sustained above 120 bpm than older children. Although daily heart rate monitoring is not a perfect indicator of children's physical activity, these data suggest that it may be a reliable measure among younger children from different ethnic and gender groups.

Black People↗
PubMed1991

Ethnicity, gender, and Type A differences in resting heart rate and blood pressure among young children.

We analyzed results of the Matthews Youth Test for Health for Anglo-American, black, and Mexican-American 5- and 6-year-old children to address three questions: (1) Do these children differ in the prevalence of type A behavior pattern or its component scales? (2) Are blood pressures or heart rates related to ethnicity, gender, or type A behavior pattern? (3) Can possible confounding factors account for observed differences? We identified several differences related to traditional risk factors: (1) Mexican Americans had the lowest systolic blood pressure, (2) girls had higher diastolic blood pressures than boys, and (3) black and Mexican-American boys had lower heart rates. Our analysis also revealed a significant gender-ethnicity interaction. Anglo- and Mexican-American girls had lower impatience-aggression scores than any other group. We detected no interaction effects for competitiveness scores, nor was there any significant relationship between competitiveness and blood pressure. We did find relationships between type A behavior pattern and blood pressure; these relationships were strengthened by use of the impatience-aggression subscale. Use of covariates strengthened observed associations. We conclude that the effects of type A behavior pattern on cardiovascular disease may be mediated by conventional risk factors.

Black or African American↗
PubMed1990

Children's Activity Rating Scale (CARS): description and calibration.

A five-level Children's Activity Rating Scale (CARS) was designed to categorize the intensity of physical activities and discriminate between levels of energy expenditure in young children. The CARS was used by trained observers over a 12-month period to assess physical activities of 3-4 year-old children during field observations. Agreement among observers using the CARS was 84.1% for 389 paired observation periods. The energy expenditure for each level was assessed by measuring VO2s and heart rates of 5-6 year-old children (12 boys, 13 girls) while they performed eight activities representing the CARS levels. Mean VO2s for the eight activities in Levels 1-5 ranged from 7.1 to 37.5 ml.kg BW-1.min-1 (1 to 5.42 METS; 14.5% to 80.6% of VO2max). Mean heart rates ranged from 89 to 183 b.min-1 for activities in Levels 1-5. VO2s and heart rates at each level were significantly different from all other levels. These data demonstrate that the CARS encompasses a wide range of energy expenditures, discriminates between levels of energy expenditure, and can be used by trained observers to reliably evaluate physical activity and estimate energy expenditure of young children.

Body Weight↗
PubMed1989

Ethnic differences in anthropometric characteristics of young children and their parents.

The distribution of body fat, or fat patterning, is an important risk factor for cardiovascular disease and diabetes, independent of obesity. Furthermore, the incidence of cardiovascular disease and diabetes varies by ethnicity. We documented ethnic differences in anthropometric characteristics and body fat distribution between Anglo, Black, and Mexican American men (n = 101), women (n = 245), boys (n = 111), and girls (n = 111). We used aggregates of skinfold measures to examine ethnic differences in the deposition of fat in body compartments (body, trunk, leg, and arm) and analyzed trunk-extremity skinfold ratios to determine which best reflected ethnic differences in fat distribution. The results show that Mexican American mothers have larger skinfold ratios and more body fat (as determined by skinfold aggregates) than either Anglo or Black American mothers, whereas Black American mothers have larger ratios than Anglo American mothers. Mexican American fathers also have larger skinfold ratios but not more body fat (skinfold aggregates) than Anglo American fathers. Mexican American fathers have more body fat than Black American fathers, but we found no differences between skinfold ratios. The ethnic differences among children in skinfold ratios and aggregates are similar to those found among fathers, with more differences among girls than boys. Fat patterning differences do exist among the three ethnicities, with greater trunk fat among Mexican and Black Americans. Those ethnicities are known to be at higher risk for cardiovascular disease and diabetes.

Adult↗
PubMed1985

Physical and physiological characteristics of elite women volleyball players.

The purpose of this study was to compare various physical and performance characteristics of two elite groups of athletes, the 1980 U.S. Women's National Volleyball Team and the collegiate players who composed the 1979 U.S. Women's University Games Volleyball Team. The characteristics compared were age, height, weight, body composition determined via hydrostatic weighing, vertical jumping distance, vertical jumping height, maximal oxygen consumption, heart rate max and respiratory exchange ratio. Significant differences (p less than 0.05) in age (23 +/- 2.6 yr. and 21.5 +/- 0.7 yr.), percent of body fat (11.7 +/- 3.7% and 18.3 +/- 3.4%), and vertical jumping distance (52.4 +/- 4.5 cm and 45.5 +/- 6.4 cm), between the two teams were demonstrated, with the National Team being significantly older, having a lower percentage of body fat and possessing a larger vertical jumping distance. These results indicate trainers of elite (national and international caliber) women volleyball players should consider including techniques to reduce percentage of body fat and increase vertical jumping distance.

Adult↗
PubMed1983

Sports physiology: testing the athlete.

The Sports Physiology Laboratory at the Olympic Training Center has essentially three responsibilities. (1) education of the athlete and coach, (2) service to National Governing Bodies that request, on behalf of their substructure, testing or educational programs, and (3) research on specific questions of interest to an athletic group.

Biomechanical Phenomena↗
PubMedDate not supplied

The throw: biomechanics and acute injury.

The throw and its modifications are integral components of many sports. This study correlates case histories of acute injuries in throwing with a biomechanical analysis of the throwing mechanism. Comparisons are made with a similar analysis of the kick analyzed by the same film technique and computer program. Just prior to ball release, the pitching arm extends through an arc of about 73 degress in 40 msec, beginning with the elbow flexed at 80 degrees. This produces an axial load on the humerus and coincides with a pulse of external torque at the shoulder. This acts as stress protection to the humerus which is developing an internal torque of 14,000 inch-lb prior to ball release. The change in angular velocity, or the angular acceleration, during the throw is acquired in a much shorter time than in the kick. Torque is directly proportional to angular acceleration. This necessitates the development of substantially higher torques in the humerus during the throw than about the knee during a kick. The kinetic energy in the arm is 27,000 inch-lb during the throw. This is much higher than the kinetic energy in the kicking leg because the kinetic energy varies proportionally with the square of the angular velocity of the extremity. The angular velocity of the arm is about twice that of the leg. Thus, the pitching arm contains about four times as much kinetic energy as the kicking leg. These severe overloading conditions predispose the upper extremity to injury in the throwing mechanism.

Adolescent↗