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PubMed1989

Statistical approach for the estimation of daily physical activity levels using the probability density function of heart rate.

An investigation was undertaken into the statistical properties of heart rate during daily physical activity. The probability density function of the heart rate was estimated using the Gram-Charlier series. In addition, the probability density was separated into two Gaussian distributions: relatively low and relatively high heart rates. The former appeared to correspond to the metabolic rate associated with basic daily living and the latter appeared to be associated with more active physical activity of the type necessary to sustain or elevate the level of physical fitness. The higher heart rate distribution of five subjects occupied 8.72 +/- 2.15% of a period of waking. The validity of the statistical approach was confirmed with fractional estimation error of 1.22 +/- 0.62%.

Heart Rate↗
PubMed2006

Anticholinergic drugs and physical function among frail elderly population.

Increasing evidence from experimental studies and human observations suggests that drugs with anticholinergic properties can cause physical and mental impairment. The aim of this study was to evaluate the relationship between the use of drugs with anticholinergic activity and measures of physical performance, muscle strength, and functional status in persons aged 80 years or older. Data are from baseline evaluation of 364 subjects enrolled in the ilSIRENTE study. The ilSIRENTE study is a prospective cohort study performed in the mountain community living in the Sirente geographic area (L'Aquila, Abruzzo) in Central Italy. Physical performance was assessed using the physical performance battery score (Short Physical Performance Battery), which is based on three timed tests: 4-meter walking speed, balance, and chair stand tests. Muscle strength was measured by hand grip strength. We defined as anticholinergic drugs all medications for which serum anticholinergic activity was previously demonstrated. Analyses of covariance were performed to evaluate the relationship of anticholinergic drugs with physical function. In the unadjusted model, all the physical performance, muscle strength, and functional measures showed significant associations with the anticholinergic drug use. After adjustment for potential confounders (age, gender, smoking, physical activity level, cognitive performance score, living alone, body mass index, congestive heart failure, lung diseases, diabetes), these associations were weaker but still statistically significant (physical performance battery score: non-users anticholinergic drugs 6.9, SE 0.1, users anticholinergic drugs 6.1, SE 0.2, P=0.05; hand grip strength: non-users anticholinergic drugs 31.3 kg, SE 0.8, users anticholinergic drugs 28.8 kg, SE 1.0, P=0.05; Activities of Daily Living scale score: non-users anticholinergic drugs 1.2, SE 0.1, users anticholinergic drugs 1.6, SE 0.1, P=0.03; Instrumental Activities of Daily Living scale score: non-users anticholinergic drugs 2.7, SE 0.1, users anticholinergic drugs 3.4, SE 0.1, P<0.001). The use of medication with anticholinergic properties is common among community older subjects in Italy. Our results suggest that among old-old subjects the use of anticholinergic drugs is associated with impaired physical performance and functional status.

Activities of Daily Living↗
PubMed2004

Factor analysis as a tool for survey analysis using a professional role orientation inventory as an example.

BACKGROUND AND PURPOSE: The purpose of this article is to illustrate how confirmatory factor analysis can be used to extend and clarify a researcher's insight into a survey instrument beyond that afforded through the typical exploratory factor analytic approach. The authors use as an example a survey instrument developed to measure individual differences in professional role orientation among physical therapists, the Professional Role Orientation Inventory for Physical Therapists (PROI-PT). SAMPLE: Five hundred three physical therapists responded to a mail survey instrument that was sent to a random sample of 2,000 American Physical Therapy Association members. METHODS: An adapted version of the Professional Role Orientation Inventory, a 40-item Likert-scale instrument developed to assess professional role orientation on 4 dimensions (authority, responsibility, agency, and autonomy), was used. Exploratory and confirmatory factor analyses were used to examine the factorial validity of the PROI-PT. RESULTS: Exploratory factor analysis served as a starting point for examining the factor structure of the instrument. Confirmatory factor analysis then was used to test the hypothesized factor structure and to suggest refinements to the PROI-PT that would improve a psychometric property (internal consistency). DISCUSSION AND CONCLUSION: Although further refinement of the PROI-PT is needed, an instrument that yields valid and reliable measurements of individual differences in professionalism among physical therapists could further our understanding of the psychosocial aspects of physical therapist practice. Exploratory and confirmatory factor analyses can be used by researchers who study various psychosocial constructs in physical therapy.

Adult↗
PubMed1990

[Physical activity and coronary heart disease].

Epidemiological data suggest that in middle aged men a regular physical activity, occupational or in leisure time, may protect against a first coronary event. Randomized clinical trial of cardiac rehabilitation after myocardial infarction, including physical training, has shown a positive trend for reduced rates of all-cause death and coronary death in the intervention group. Although not statistically significant, physical training in coronary patients is recommended because the benefits of training include an improved exercise tolerance and risk factor profile. Furthermore, supervised cardiac exercise programmes appear to be safe for the average patient, with the possible exception of some patients with large anterior wall infarctions who might deteriorate and have, therefore, to be closely controlled during rehabilitation.

Coronary Disease↗
PubMed1996

Physical Self Description Questionnaire: stability and discriminant validity.

The Physical Self-Description Questionnaire (PSDQ) is a multidimensional, physical self-concept instrument designed to measure 11 scales: Strength, Body Fat, Activity, Endurance/Fitness, Sports Competence, Coordination, Health, Appearance, Flexibility, Global Physical Self-concept, and Global Esteem. High school students completed the PSDQ on four occasions over a 14-month period. Across the 11 PSDQ scales, the internal consistency at each occasion was good (median alpha = .92) and the stability over time varied from median r = .83 for a 3-month period to median r = .69 for the 14-month period. The data were used to demonstrate the application of confirmatory factor-analysis models of multitrait-multimethod (MTMM) data (with occasions as the multiple methods), which supported the discriminant validity of the PSDQ scales. Augmented MTMM models that included two field tests of cardiovascular endurance provided additional support for the construct validity of PSDQ responses and interpretation of the MTMM models. These results contribute to the growing body of support for the construct validity of physical-self-concept responses and illustrate the application of CFA MTMM models.

Adolescent↗
PubMed1991

Statistical analysis of DNA fingerprint data for ordered clone physical mapping of human chromosomes.

A statistical framework is proposed for analysing DNA fingerprint data from experiments aimed at constructing ordered clone physical maps of chromosomes. The fingerprint data consists of the lengths and hybridization states of restriction digest fragments and the paper develops a solution to the fundamental problem of deciding whether or not two randomly selected clones overlap. Overlap probabilities are calculated using Bayes' rule together with appropriate statistical descriptions of the chromosome and experimental procedure. The analysis is flexible, allowing a variety of assumptions to account for experimental errors and difficulties, such as unobserved fragments. The approach described here provides a basis for predicting the rate of progress of an experimental protocol and hence for comparing alternate protocols. It is readily generalized to related problems with a wide range of possible data. Results are presented for the clone mapping protocol currently being employed at Los Alamos National Laboratory on human chromosome 16 (Stallings et al., 1990, Proc. natl. Acad. Sci. U.S.A., 87, 6218-6222).

Animals↗
PubMed2005

Langevin trajectories between fixed concentrations.

We consider the trajectories of particles diffusing between two infinite baths of fixed concentrations connected by a channel, e.g., a protein channel of a biological membrane. The steady state influx and efflux of Langevin trajectories at the boundaries of a finite volume containing the channel and parts of the two baths is replicated by termination of outgoing trajectories and injection according to a residual phase space density. We present a simulation scheme that maintains averaged fixed concentrations without creating spurious boundary layers, consistent with the assumed physics.

Biophysics↗
PubMed2006

Adolescents involved in weight-related and power team sports have better eating patterns and nutrient intakes than non-sport-involved adolescents.

OBJECTIVE: To examine eating habits and energy and nutrient intake among adolescents participating in weight-related and power team sports and non-sport-involved adolescents. DESIGN: Data were drawn from Project EAT (Eating Among Teens), which was conducted with 4,746 adolescents from 31 middle and high schools in the Minneapolis/St Paul metropolitan area. SETTING: Urban secondary schools. SUBJECTS: Adolescents reporting participation in a weight-related sport, a power team sport, or no consistent participation in a sport. MAIN OUTCOME MEASURES: Meal and snack frequency, mean energy and nutrient intake, and mean physical activity. STATISTICAL ANALYSES PERFORMED: Analyses were conducted by sex across the three groups. General linear models were used to compare mean energy and nutrient intake, composite nutrient adequacy, and mean physical activity across the three groups. Percentages of youth meeting nutrient recommendations were compared across the three groups using chi(2) tests. RESULTS: For both males and females, youth involved in weight-related sports ate breakfast more frequently than non-sport-involved peers (females: 3.6 and 3.2 times per week, respectively, P<0.01; males: 4.7 and 3.7 times per week, respectively, P<0.01). Weight-related and power team sport-involved youth also had higher mean protein, calcium, iron, and zinc intakes than non-sport-involved peers. However, adolescent females had low calcium intake, regardless of sports involvement (weight-related sports 1,091 mg/day, power team sports 1,070 mg/day, and non-sport-involved 1,028 mg/day, P<0.05). CONCLUSIONS: Sport-involved adolescents have better eating habits and nutrient intake than their non-sport-involved peers. However, they are still in need of nutrition interventions, particularly around calcium intake.

Adolescent↗
PubMed2002

Asymmetric exclusion process and extremal statistics of random sequences.

A mapping is established between sequence alignment, one of the most commonly used tools of computational biology, at a certain choice of scoring parameters and the asymmetric exclusion process, one of the few exactly solvable models of nonequilibrium physics. The statistical significance of sequence alignments is characterized through studying the total hopping current of the discrete time and space version of the asymmetric exclusion process.

Algorithms↗
PubMedDate not supplied

Healthy patients who perceive poor health and their use of primary care services.

OBJECTIVE: To determine what proportion of patients who have poor health perceptions are physically healthy and to explore why some patients perceive a healthy state while others perceive illness. DESIGN: A prospective consecutive series of office patients completed the Rand Corporation's General Health Perceptions Questionnaire, and their physicians rated their physical health. Their use of health care services was determined for the following 12 months. SETTING: A rural teaching office practice. PATIENTS: Of 243 adult patients asked to complete the questionnaire, 32 were excluded, for dementia (8), illiteracy (4), illness (8), incomplete questionnaires (6), and other reasons (6). 208 patients (86%) formed the final study group. MEASUREMENTS AND MAIN RESULTS: 62 of 208 patients had poor health perception scores. 39 of the 62 were rated by physicians as physically healthy and were not statistically different in physical health ratings or numbers of prescribed medications from the 146 patients who had higher health perception scores. However, these 39 patients had significantly more health-related worry, acute pain, and depression than did the other 146 patients. They also made more office visits and telephone calls and had higher total primary care charges. CONCLUSIONS: This study suggests that 21% of adult primary care patients (39 of 208) have health perceptions lower than expected for their levels of physical health. These low health perceptions are correlated with increased emotional distress and higher utilization of health care resources. Strategies to identify these patients and interventions to improve their views of their health could reduce utilization.

Attitude to Health↗
PubMed1994

A comprehensive study of physical parameters, biomechanical properties, and statistical correlations of iliac crest bone wedges used in spinal fusion surgery. III. Multivariable regression analysis and practical formulas for strength prediction.

Iliac crest wedges are commonly used in spinal fusion procedures and must be capable of withstanding considerable mechanical stress during the healing process. Physical parameters, mechanical properties, correlations among physical parameters, and correlations of mechanical properties versus physical parameters have been presented by the authors in companion papers. In this study, mathematical formulas have been developed, using multi-variable regression analysis, which permit calculation of the axial load-bearing capacity and compressive strength of a wedge, provided donor age, cortical bone cross-sectional area, total cross-sectional area, and wedge "width" are available. The formulas proposed are simple, easy to use, and provide acceptable accuracy. For the predicted load-bearing capacity, experimentally determined data illustrated that 59% of the calculated values had either less than 10% error or their predicted values were smaller than the observed values, 75% of the calculated values had either less than 20% error or their predicted values were smaller than the observed values. Similar accuracies were estimated for calculation of compressive strengths. Charts are generated from the established formulas, which permit a visual determination of load-bearing capacity and compressive strength of a wedge.

Aging↗
PubMed1997

A radiologist's guide to the imaging in the diagnosis and treatment of developmental dysplasia of the hip. I. General considerations, physical examination as applied to real-time sonography and radiography.

Developmental dysplasia of the hip (DDH) has a broad spectrum of presentation with the minor findings resolving spontaneously and the most severe ones resulting in disability, if not diagnosed early in life. Diagnosis in the first few months of life allows conservative treatment with complete resolution in most cases. Suspicion of DDH is based on ethnic, family, and pregnancy history, and on physical examination of the newborn. Imaging assists in the diagnosis and follows the treatment. Different modalities have their own advantages and disadvantages. This article deals with the description of the disease, risk factors, statistics, the physical examination as applied to real-time sonography, and imaging (plain radiography, arthrography, computed tomography, and magnetic resonance imaging.

Hip Dislocation, Congenital↗
PubMed1999

Distractors--can they be biased too?

Numerous work has been done on item bias and differential item functioning. Although there is some research on distractor analysis, no detailed study has been attempted to examine the way distractors in an item function, with regards to comparing distractor performance. This paper examines how distractors function differentially and compares various methods for identifying this. The Pearson chi-square, likelihood ratio chi-square and Neyman weighted least squares chi-square tests are some of these methods. Possible causes of distractor bias are discussed with illustrations from a physics problem-solving scale.

Adolescent↗
PubMed1997

Equating the MOS SF36 and the LSU HSI Physical Functioning Scales.

This study equates the physical functioning subscales of the Medical Outcomes Study Short Form 36 (SF36) and the Louisiana State University Health Status Instruments (LSU HSI). Data from the SF36's 10-item physical functioning scale, the PF10, and the LSU HSI's 29-item Physical Functioning Scale (PFS), were fit to separate and mixed Rasch rating scale models. Data were provided by a convenience sample of 285 patients waiting for appointments in a public hospital general medicine clinic. Difficulty estimates for a subset of similar items from the two instruments were highly correlated (.95), indicating that the items from the two scales are working together to measure the same variable. The measures from the two equated instruments correlate .80 (.86 when disattenuated for error). Of the two instruments, the PFS's error is lower, model fit is better, and reliability coefficients are higher. Both instruments measure physical functioning, and can do so in a common unit of measurement. Conversion tables are provided for transforming raw scores from either instrument into the common metric.

Adult↗
PubMed1998

Psychological factors in the prediction of Lyme disease course.

OBJECTIVE: To determine whether history of severe, long-term, premorbid, psychological stress is associated with increased incidence of chronic physical symptoms in presumed Lyme disease patients. METHODS: Fifty-seven patients presenting at Lyme Disease Clinic of Long Island Jewish-Hillside Medical Center were studied for presenting symptoms, presence or absence of Lyme disease, and past history of psychological trauma. They were restudied 1 to 1.5 years later for presence or absence of physical symptoms. Statistical analyses compared symptom course for patients with and without Lyme disease, antibiotic and nonantibiotic treatments, and past history of psychological trauma. RESULTS: There was correlation between history of past traumatic psychological events and chronicity of physical symptoms whether or not the patient had presumed Lyme disease or had received antibiotic treatment. CONCLUSION: Traumatic psychological experiences predating onset of Lyme disease symptoms may play an important etiologic role in the chronicity of these symptoms.

Adult↗