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PubMed2005

Physical fitness as a resource in coping with stress among high school students.

AIM: Physical fitness may be considered as a personal resource helping to cope with stress. The aim of the study was to examine how physical fitness affects psychological distress and health status in adolescents. METHODS: This study was carried out for over 2 years and the participants were 253 Polish high school students (82 boys, 171 girls; mean age =15.4; SD=0.17). They were examined using the International Physical Fitness Test, Profile of Mood States, and a questionnaire developed by the author to assess the intensity of stress due to daily hassles, frequency of stress-related somatic symptoms, as well as self-assessed psychological well-being and physical health. RESULTS: ANOVA indicated significant interactions between physical fitness and gender for both sexes. While among boys better well-being, mood (i.e. higher levels of positive and lower intensity of negative mood states), and health (higher levels of self-rated health and less numerous physical complaints) were found in those with better physical fitness, among girls the relationship was reversed, i.e. more positive well-being, mood and health were exhibited by the less fit (0.05> or =p> or =0.01). Moreover, significant main effects of stress intensity and gender were noted: students with more intense stress experiences had lower levels of positive well-being (p<0.001), mood (positive states p=0.01; negative states p<0.001) and health (p<0.001); and girls not only less favorably assessed their health (p<0.001), experienced more somatic complaints (p=0.01) but also manifested more marked negative mood states (p<0.05). CONCLUSIONS: The study shows that physical fitness may be an important resource helping to cope with stress, and that its role in coping with stress may be different in boys than in girls.

Adaptation, Psychological↗
PubMed1994

The rate of increase in blood pressure in children 5 years of age is related to changes in aerobic fitness and body mass index.

OBJECTIVE: To determine whether changes in aerobic fitness and body mass index are related to the age-related rise in blood pressure in healthy preschool children. STUDY DESIGN: Longitudinal analyses of 196 free-living children aged 5 years at baseline who were followed over a mean of 19.7 months. Aerobic fitness was assessed using a treadmill. All measures were obtained on multiple occasions at scheduled visits as part of a longitudinal cohort study. SETTING: An inner-city medical center. OUTCOME MEASURES: Blood pressure was measured using an automated Dinamap device. RESULTS: Mean systolic blood pressure was 95.3 mmHg (SD 8.38) at baseline and increased by 4.46 mmHg per year. Mean diastolic blood pressure was 53.9 mmHg (SD 5.81) at baseline and did not change significantly. Children in the highest quintile of increase in fitness had a significantly smaller increase in systolic blood pressure compared to children in the lowest quintile (2.92 vs 5.10 mmHg/year; P = .03). Children in the lowest quintile of increase in body mass index did not differ significantly in rate of increase in systolic blood pressure compared to children in the highest quintile (3.92 vs 4.96 mmHg/year). In a multiple regression model including baseline systolic blood pressure, fitness, height, body mass index, and other covariates, greater increase in fitness (P = .03) and lesser increase in body mass index (P < .01) were associated with lower rates of increase in systolic blood pressure. In a similar multivariate analysis, an increase in fitness was also associated with a lower rate of increase in diastolic blood pressure (P = .02). CONCLUSION: Young children who increase their aerobic fitness or decrease their body mass index reduce the rate of the age-related increase in blood pressure. These observations may have implications for development of interventions directed at the primary prevention of hypertension.

Age Factors↗
PubMedDate not supplied

Relationships between self-reported physical activity and physical fitness in active men.

We examined relationships between self-reported physical activity and physical fitness in a group of 202 male military officers, 36 to 51 years of age. Physical activity was estimated from the Minnesota Leisure Time Physical Activity Questionnaire and classified as heavy, moderate, or light depending on the intensity of individual activities. Directly measured components of physical fitness included aerobic capacity (treadmill walking peak VO2), body composition (densitometry), muscle strength (isokinetic mode), and flexibility (bend-and-reach test). Both total and heavy activity were significantly (P < .05) related to aerobic capacity, body fat, fat-free mass, upper body strength, and flexibility. Moderate and light activity were not related to the fitness measures. We divided subjects into quartiles of physical activity and corrected the fitness measures for age and cigarette smoking status. Subjects with more total and heavy activity had higher aerobic capacity and lower body fat; subjects with more heavy activity also had greater upper body strength. Again, moderate and low activity were not related to any fitness measure. These data indicate that heavy physical activity is related to various components of physical fitness even after correction for age and smoking status in a group of men who are healthy, generally very active, and fit.

Adult↗
PubMed1993

Physical activity, fitness, and selected risk factors for CHD in active men and women.

The association of physical activity and cardiovascular fitness with risk factors such as blood pressure, body composition, and smoking habits was evaluated in middle-aged men and women active in sports. Data were available for 2009 men and 898 women, all volunteers over 40 yr of age who were active in sports, were available. Physical activity was recorded as sport activity (number and type of sport, frequency, and duration), occupational activity, and the use of the bicycle for transport. Cardiovascular fitness was expressed as maximal power output (Wmax.kg-1) achieved during a progressive maximal cycle ergometer test. Pearson's product moment correlations between cardiovascular fitness and risk factors indicated significantly lower risks among more fit individuals. Except for smoking habits all risk factors showed better associations with fitness in women than in men. The association of physical activity indicators and risk factors was less strong than the fitness-risk factor association in both genders. In both genders, joggers had the most favorable risk profile compared with subjects who were active in one of the other four most popular sports. We conclude that in this relatively active and healthy population comparable associations of physical activity and cardiovascular fitness with risk factors for cardiovascular disease were found as in studies on less active populations.

Adult↗
PubMed1996

The effect of physical fitness on intraocular pressure in Chinese medical students.

BACKGROUND: Virtually all the tissues and systems of the human body have been shown to be responsive to programs of exercise. Regarding the relationship between physical fitness and intraocular pressure (IOP), the existing literature is controversial with some associations inconsistent. In one study, IOP values were not dependent upon changes in physical fitness. In contrast to this, another study demonstrated that physical fitness significantly reduces intraocular pressure levels. In recent years it has been noted that intraocular pressure is a dynamic function and is subject to many influences both acutely and over the long term. The variety of results of previous studies may have come from several factors which can affect intraocular pressure. The present study was planned to investigate the effects of physical fitness on intraocular pressure in Chinese medical studies, after elimination of other affecting factors. METHODS: Forty medical students were categorized into control and experimental groups, each consisting of 20 subjects. The experimental group took a supervised exercise program for 10 weeks. Physical fitness was evaluated by measurement of maximum oxygen uptake with a Beckman O2 analyzer. Intraocular pressure was measured with the Goldmann applanation tonometer. RESULTS: After exercise training, the experimental group showed a marked increase in physical fitness. The difference of IOP between the control and experimental groups before exercise conditioning was 0.3 +/- 0.1 mmHg (P > 0.05). After 10 weeks, this difference increased to 1.1 +/- 0.4 mmHg (p < 0.05). CONCLUSIONS: This study concludes that physical fitness reduces intraocular pressure. Whether exercise conditioning has a role as a nonpharmacologic approach or as an addition to medical therapy must be left to future investigations.

Adult↗
PubMed1994

The exercise test as a component of the total fitness evaluation.

In this article, physical fitness has been defined as a dynamic state of energy and vitality that enables one to carry out daily tasks, to engage in active leisure-time pursuits, and to meet unforeseen emergencies without undue fatigue. In addition, physically fit individuals are described as being at low risk for hypokinetic diseases and being more able to function at the peak of intellectual capacity while experiencing "joie de vivre." The measurable elements of physical fitness have been categorized into two groups: skill-related fitness and health-related fitness. The former category includes agility, balance, coordination, speed, power, and reaction time. The latter includes cardiorespiratory endurance, body composition, and musculoskeletal fitness, which incorporates flexibility, muscular strength, and muscular endurance. It is highly recommended that clinicians provide comprehensive fitness testing for their patients because of the well-established health-related benefits that are related to each component.

Body Composition↗
PubMed1998

Cardiovascular fitness, physical activity and selected coronary heart disease risk factors in adults.

BACKGROUND: The aim was to investigate the associations between cardiovascular fitness and physical activity, and their relationship to selected coronary heart disease (CHD) risk factors. METHODS: This was a cross-sectional study for one week. All participants were Japanese living in the City of Toyota, Japan. Two hundred and twenty-two healthy Japanese (104 men and 118 women), with ages between 20 and 62 years old. Cardiovascular fitness (VO2max) was measured by a progressive submaximal bicycle ergometry test. Physical activity was estimated by an accelerometers attached to the subject's waist for one week, CHD risk factors included blood pressure, fasting levels of blood lipids, and apolipoprotein concentrations. RESULTS: Cardiovascular fitness and physical activity were positively related (r = 0.41 in men and 0.65 in women). For both genders, Pearson coefficients as well as age-adjusted partial correlations indicated that fitness was more closely linked to CHD risk factors than activity was. Also, CHD risk factors were analyzed by three groups of fitness and activity levels in both genders, which indicates that subjects who are physically fitter and/or more active tend to have better CHD risk profiles. CONCLUSIONS: As favorable CHD risk profile was related to cardiovascular fitness, but not to physical activity in both genders, it can be concluded that fitness may be a more important independent predictor for CHD risk factors than activity measured by accelerometer over one week.

Adult↗
PubMed2003

The cost-effectiveness of hearing-aid fitting in the Netherlands.

OBJECTIVE: To determine the cost-effectiveness of hearing-aid fitting. DESIGN: Cost-effectiveness analysis using a Markov model based on aggregate data and results from a prospective intervention study. SETTING: The cost-effectiveness study was based in the general community. The prospective study was hospital based, as 85% of the first-time hearing-aid users attend a hospital in the process of hearing-aid fitting. PATIENTS: The prospective intervention study included adult first-time hearing-aid users with no contraindications for hearing-aid use. INTERVENTION: The usual process of hearing-aid fitting in the Netherlands. MAIN OUTCOME MEASURE: Costs per quality-adjusted life-year (QALY). The QALYs were based on EuroQol scores. We included direct and indirect costs in the analysis. RESULTS: The mean improvement on the EuroQol measure was 0.03 (95% confidence interval [CI], -0.03 to 0.08), and on the hearing-specific visual analog scale, 0.27 (95% CI, 0.22-0.31). The base-case outcome based on the EuroQol was 15 807/QALY (US dollars 17 072/QALY) (CI, -24 239/QALY to 3718/QALY). CONCLUSIONS: On the basis of this base-case estimate, fitting of hearing aids is considered a cost-effective health care intervention. The CI indicates that the result is not unambiguously positive, probably because the EuroQol lacked sensitivity for the evaluation of hearing-aid fitting. Until now, no study has found an effect of hearing-aid fitting on generic quality of life. Therefore, measures are needed that are suitable for the evaluation of the effects of interventions for sensory disabilities, such as the fitting of hearing aids, on generic quality of life.

Adult↗
PubMed2000

Analysis of a local fitness landscape with a model of the rough Mt. Fuji-type landscape: application to prolyl endopeptidase and thermolysin.

A method of analysis of a local fitness landscape for a current biopolymer is presented. Based on the assumption of additivity of mutational effects in the biopolymer, we assigned a site-fitness to each residue at each site. The assigned values of site-fitnesses were obtained by the least-squares method to minimize discrepancies between experimental fitnesses and theoretical ones. As test cases, we analyzed a section of a local landscape for the thermostability of prolyl endopeptidase and that for the enzymatic activity of thermolysin. These sections were proved to be of the rough Mt. Fuji-type with straight theta values of larger than 1.0, where straight theta is defined as the ratio of the "mean slope" to the "degree of roughness" on the fitness surface. Furthermore, we theoretically explained discrepancies between the fitnesses of multiple mutants and those predicted based on strict additivity of the component mutations by using a model of the rough Mt. Fuji-type landscape. According to this model, the discrepancies depend on the local landscape property (such as the straight theta value) and the location of the wild type on the landscape and the mean change in fitness by the component mutations. Our results suggest that this model may provide a good approximation of real sections of local landscapes for current biopolymers phenomenologically.

Amino Acid Sequence↗
PubMed2000

Physical fitness, body fatness, and physical activity: The Amsterdam Growth and Health Study.

The purpose of this study was to examine sex-specific longitudinal relationships between physical fitness (cardiopulmonary and neuromotor fitness) and body fatness (sum of skinfolds) and to examine the influence of physical activity (weighted activity score) on these relationships. The data were obtained from the Amsterdam Growth and Health Study (AGHS), an observational longitudinal study of 98 females and 83 males, with six repeated measurements over a period from 13 to 27 years of age. The longitudinal relationship between body fatness and physical fitness was analyzed using generalized estimating equations (GEE). For each of the eight fitness items used as outcome variables, standardized regression coefficients were calculated for the relationships with body fatness and for the relationships with physical activity with and without correcting for height and weight. In all analyses, body fatness was inversely related to running speed, standing high jump, leg lift speed, and maximal oxygen uptake. Physical activity was positively related to leg lift speed and maximal oxygen uptake, and only in females to the standing high jump. Thus, body fatness is inversely related to most fitness items, while physical activity is positively related to only several fitness items. Further, body fatness and physical activity are independently related to physical fitness. Am. J. Hum. Biol. 12:593-599, 2000. Copyright 2000 Wiley-Liss, Inc.

Journal Article↗
PubMedDate not supplied

Quantitative magnetic resonance spectroscopy by optimized numerical curve fitting.

A technique is reported for generating the quantitative area under selected peaks within a 31P NMR spectrum. A numerical iterative method generates the fitted curve so as to minimize the RMS deviation between the fit and the experimental data. The curve is constructed from elemental grains of spectral density ('spexels'), each of which represents an elemental Lorentzian distribution, where the centre frequency and line width of the spexel may be varied within predetermined limits. This provides a fit that in principle is not restricted to a Lorentzian model. The method allows peak areas to be estimated, including the case of overlapping peaks. The method has been tested using simulated spectra containing six overlapping spectral lines each of known amplitude (ranging from 367 to 661 mV) and area; together with additional Gaussian noise with a standard deviation ranging from 30 to 646 mV. The results of fitting both unfiltered and filtered spectra were compared. The variation of quality of fit with spectral noise and filtering has been evaluated. In all cases, the method fitted the peak amplitudes to within 1% of the simulated value. The optimization processes provide an excellent non-linear spectrum filtering algorithm. Provided the noise in the spectra did not exceed ca 400 mV, prefiltered data could be adequately fitted.

Computer Simulation↗
PubMed1999

Multiple molecular pathways for fitness recovery of an RNA virus debilitated by operation of Muller's ratchet.

Repeated bottleneck passages of RNA viruses result in fitness losses due to accumulation of deleterious mutations. We have analysed the molecular events underlying fitness recovery of a highly debilitated foot- and-mouth disease virus (FMDV) clone, upon serial passage in BHK-21 cells. The debilitated clone included an unusual, internal polyadenylate extension preceding the second functional AUG initiation codon, and a number of additional mutations scattered throughout the genome. Comparison of entire genomic nucleotide sequences in the course of passaging documented that loss of the internal polyadenylate was the first event in the process of fitness recovery. Further increases of fitness were associated with very few true reversions and with the accumulation of additional mutations affecting non-coding and coding regions. Remarkably, four biological subclones of the same debilitated FMDV clone gained fitness through three separate molecular pathways regarding correction of the internal polyadenylate: (i) a true reversion to yield the wild-type sequence at the second functional AUG; (ii) a shortening of the internal polyadenylate tract; or (iii) a deletion of 69 residues spanning the site of the polyadenylate extension. The results document that an RNA virus can find multiple pathways to reach alternative high fitness peaks on the fitness landscape.

Adaptation, Physiological↗
PubMed1996

Repeated transfer of small RNA virus populations leading to balanced fitness with infrequent stochastic drift.

The population dynamics of RNA viruses have an important influence on fitness variation and, in consequence, on the adaptative potential and virulence of this ubiquitous group of pathogens. Earlier work with vesicular stomatitis virus showed that large population transfers were reproducibly associated with fitness increases, whereas repeated transfers from plaque to plaque (genetic bottlenecks) lead to losses in fitness. We demonstrate here that repeated five-plaque to five-plaque passage series yield long-term fitness stability, except for occasional stochastic fitness jumps. Repeated five-plaque passages regularly alternating with two consecutive large population transmissions did not cause fitness losses, but did limit the size of fitness gains that would otherwise have occurred. These results underscore the profound effects of bottleneck transmissions in virus evolution.

Animals↗
PubMed2005

Atrial cell action potential parameter fitting using genetic algorithms.

Understanding of the considerable variation in action potential (AP) shape throughout the heart is necessary to explain normal and pathological cardiac function. Existing mathematical models reproduce typical APs, but not all measured APs, as fitting the sets of non-linear equations is a tedious process. The study describes the integration of a pre-existing mathematical model of an atrial cell AP with a genetic algorithm to provide an automated tool to generate APs for arbitrary cells by fitting ionic channel conductances. Using the Nygren model as the base, the technique was first verified by starting with random values and fitting the Nygren model to itself with an error of only 0.03%. The Courtemanche model, which has a different morphology from that of the Nygren model, was successfully fitted. The AP duration restitution curve generated by the fit matched that of the target model very well. Finally, experimentally recorded APs were reproduced. To match AP duration restitution behaviour properly, it was necessary simultaneously to fit over several stimulation frequencies. Also, fitting of the upstroke was better if the stimulating current pulse replicated that found in situ as opposed to a rectangular pulse. In conclusion, the modelled parameters were successfully able to reproduce any given atrial AP. This tool can be useful for determining parameters in new AP models, reproducing specific APs, as well as determining the locus of drug action by examining changes in conductance values.

Action Potentials↗
PubMed2001

How important are direct fitness benefits of sexual selection?

Females may choose mates based on the expression of secondary sexual characters that signal direct, material fitness benefits or indirect, genetic fitness benefits. Genetic benefits are acquired in the generation subsequent to that in which mate choice is performed, and the maintenance of genetic variation in viability has been considered a theoretical problem. Consequently, the magnitude of indirect benefits has traditionally been considered to be small. Direct fitness benefits can be maintained without consideration of mechanisms sustaining genetic variability, and they have thus been equated with the default benefits acquired by choosy females. There is, however, still debate as to whether or not males should honestly advertise direct benefits such as their willingness to invest in parental care. We use meta-analysis to estimate the magnitude of direct fitness benefits in terms of fertility, fecundity and two measures of paternal care (feeding rate in birds, hatching rate in male guarding ectotherms) based on an extensive literature survey. The mean coefficients of determination weighted by sample size were 6.3%, 2.3%, 1.3% and 23.6%, respectively. This compares to a mean weighted coefficient of determination of 1.5% for genetic viability benefits in studies of sexual selection. Thus, for several fitness components, direct benefits are only slightly more important than indirect ones arising from female choice. Hatching rate in male guarding ectotherms was by far the most important direct fitness component, explaining almost a quarter of the variance. Our analysis also shows that male sexual advertisements do not always reliably signal direct fitness benefits.

Animals↗
PubMed1999

The fit-1 common integration locus in human and mouse is closely linked to MYB.

The fit-1 locus was originally identified as a common insertion site for feline leukemia virus (FeLV) in thymic lymphosarcomas induced by FeLV-myc recombinant viruses, suggesting that it harbors a gene that cooperates with Myc in T-cell leukemogenesis. We have previously mapped the fit-1 locus to feline Chromosome (Chr) B2. We have now identified conserved sequences that allow the mapping of the murine homolog using the European Interspecific Backcross (EUCIB). This shows that fit-1 is located on mouse Chr 10, 1cM proximal to Ahi-1, a murine retroviral integration locus that is closely linked to Myb. Moreover, the physical linkage to MYB is maintained in the human genome, as shown by cloning of the human homolog of fit-1 from a Chr 6 cosmid library and a series of overlapping PAC clones. Generation of a contig map around the human homolog of fit-1 reveals that it is approximately 100-kb upstream of MYB. In addition to fit-1 and Ahi-1, two other common insertion sites, Mis-2 and Mml-1, have also been mapped adjacent to Myb on mouse Chr 10. Previous analysis of tumors carrying insertions at fit-1, Mml-1, Mis-2 and Ahi-1 showed no obvious abnormalities in Myb expression. However, the cluster of viral insertion loci in this region suggests either the presence of a closely linked activation target or that subtle effects on Myb have been overlooked.

Animals↗
PubMed2006

Hybridization, recombination, and the genetic basis of fitness variation across environments in Avena barbata.

We created Recombinant Inbred Lines (RILs) derived from a cross between ecotypes of Avena barbata associated with moist (mesic) and dry (xeric) habitats in California. Traits which were correlated with fitness across RILs mapped to the same Quantitative Trait Loci (QTLs) as fitness. However, different QTL affected fitness in different environments so that fitness was weakly correlated across environments. Recombination released considerable heritable variation both in fitness, and in ecologically relevant traits. Many traits showed transgressive segregation caused by recombination of QTL associated in repulsion phase in the parents. In addition, some traits were uncorrelated, allowing novel combinations of those traits to be created. Recombination also created heritable variation in reaction norms for at least one trait (root allocation). Altogether these results suggest that recombination can combine the most selectively advantageous genes and traits of the parents to produce broadly adapted genotypes that are capable of outperforming the parents. Indeed, two of the RILs showed higher fitness than the parental ecotypes across a range of environmental treatments in the greenhouse, but their superiority was less pronounced in the field. Although late-generation recombinants exhibited hybrid breakdown, being less fit, on average, than the mid-parent, early generation hybrids appear to exhibit hybrid vigour through the expression of dominance effects in the heterozyotes. This vigour may offset the effects of hybrid breakdown in the early generations following a cross, enhancing the opportunity for recombination to create broadly adapted genotypes. We discuss the implications of these findings to the evolution of colonizing species.

Acclimatization↗
PubMed2005

Error estimation and global fitting in transverse-relaxation dispersion experiments to determine chemical-exchange parameters.

Off-resonance effects can introduce significant systematic errors in R2 measurements in constant-time Carr-Purcell-Meiboom-Gill (CPMG) transverse relaxation dispersion experiments. For an off-resonance chemical shift of 500 Hz, 15N relaxation dispersion profiles obtained from experiment and computer simulation indicated a systematic error of ca. 3%. This error is three- to five-fold larger than the random error in R2 caused by noise. Good estimates of total R2 uncertainty are critical in order to obtain accurate estimates in optimized chemical exchange parameters and their uncertainties derived from chi2 minimization of a target function. Here, we present a simple empirical approach that provides a good estimate of the total error (systematic + random) in 15N R2 values measured for the HIV protease. The advantage of this empirical error estimate is that it is applicable even when some of the factors that contribute to the off-resonance error are not known. These errors are incorporated into a chi2 minimization protocol, in which the Carver-Richards equation is used fit the observed R2 dispersion profiles, that yields optimized chemical exchange parameters and their confidence limits. Optimized parameters are also derived, using the same protein sample and data-fitting protocol, from 1H R2 measurements in which systematic errors are negligible. Although 1H and 15N relaxation profiles of individual residues were well fit, the optimized exchange parameters had large uncertainties (confidence limits). In contrast, when a single pair of exchange parameters (the exchange lifetime, tau(ex), and the fractional population, p(a)), were constrained to globally fit all R2 profiles for residues in the dimer interface of the protein, confidence limits were less than 8% for all optimized exchange parameters. In addition, F-tests showed that quality of the fits obtained using tau(ex), p(a) as global parameters were not improved when these parameters were free to fit the R2 profiles of individual residues. Finally, nearly the same optimized global tau(ex), p(a) values were obtained, when the 1H and 15N data sets for residues in the dimer interface, were fit independently; the difference in optimized global parameters, ca. 10%, was of marginal significance according to the F-test.

Data Interpretation, Statistical↗