Analysis of proximal femur DXA scans in growing children: comparisons of different protocols for cross-sectional 8-month and 7-year longitudinal data.

Dual-energy X-ray absorptiometry (DXA) is a widely used method for measuring bone mineral in the growing skeleton. Because scan analysis in children offers a number of challenges, we compared DXA results using six analysis methods at the total proximal femur (PF) and five methods at the femoral neck (FN). In total we assessed 50 scans (25 boys, 25 girls) from two separate studies for cross-sectional differences in bone area, bone mineral content (BMC), and areal bone mineral density (aBMD) and for percentage change over the short term (8 months) and long term (7 years). At the proximal femur for the short-term longitudinal analysis, there was an approximate 3.5% greater change in bone area and BMC when the global region of interest (ROI) was allowed to increase in size between years as compared with when the global ROI was held constant. Trend analysis showed a significant (p < 0.05) difference between scan analysis methods for bone area and BMC across 7 years. At the femoral neck, cross-sectional analysis using a narrower (from default) ROI, without change in location, resulted in a 12.9 and 12.6% smaller bone area and BMC, respectively (both p < 0.001). Changes in FN area and BMC over 8 months were significantly greater (2.3%, p < 0.05) using a narrower FN rather than the default ROI. Similarly, the 7-year longitudinal data revealed that differences between scan analysis methods were greatest when the narrower FN ROI was maintained across all years (p < 0.001). For aBMD there were no significant differences in group means between analysis methods at either the PF or FN. Our findings show the need to standardize the analysis of proximal femur DXA scans in growing children.

Statistical power for the two-factor repeated measures ANOVA.

Determining a priori power for univariate repeated measures (RM) ANOVA designs with two or more within-subjects factors that have different correlational patterns between the factors is currently difficult due to the unavailability of accurate methods to estimate the error variances used in power calculations. The main objective of this study was to determine the effect of the correlation between the levels in one RM factor on the power of the other RM factor. Monte Carlo simulation procedures were used to estimate power for the A, B, and AB tests of a 2 x 3, a 2 x 6, a 2 x 9, a 3 x 3, a 3 x 6, and a 3 x 9 design under varying experimental conditions of effect size (small, medium, and large), average correlation (.4 and .8), alpha (.01 and .05), and sample size (n = 5, 10, 15, 20, 25, and 30). Results indicated that the greater the magnitude of the differences between the average correlation among the levels of Factor A and the average correlation in the AB matrix, the lower the power for Factor B (and vice versa). Equations for estimating the error variance of each test of the two-way model were constructed by examining power and mean square error trends across different correlation matrices. Support for the accuracy of these formulae is given, thus allowing for direct analytic power calculations in future studies.

Lifestyle determinants of bone mineral: a comparison between prepubertal Asian- and Caucasian-Canadian boys and girls.

The purpose of this study was to examine the difference in lifestyle and morphometric factors that affect bone mineral and the attainment of peak bone mass in 168 healthy Asian (n = 58) and Caucasian (n = 110) Canadian, prepubertal girls and boys (mean age 8.9+/-0.7) living in close geographical proximity. DXA (Hologic 4500) scans of the proximal femur (with regions), lumbar spine, and total body (TB) were acquired. We report areal bone mineral densities (aBMD g/cm(2)) at all sites and estimated volumetric density (aBMD, g/cm(3)) at the femoral neck. Dietary calcium, physical activity, and maturity were estimated by questionnaire. Of these prepubertal children, all of the boys and 89% of the girls were Tanner stage 1. A 2x2 ANOVA demonstrated no difference between ethnicities for height, weight, body fat, or bone mineral free lean mass. Asian children consumed significantly less dietary calcium (35%) on average and were significantly less active (15%) than their Caucasian counterparts (P<0.001). There were significant ethnicity main effects for femoral neck bone mineral content (BMC) and alphaBMD (both P<0.001) and significant sex by ethnicity interactions (P<0.01). The Asian boys had significantly lower femoral neck BMC (11%), aBMD (8%), and vBMD (4.4%). At the femoral neck, BMFL mass, sex, and physical activity explained 37% of the total variance in aBMD (P<0.05). In summary, this study demonstrated differences in modifiable lifestyle factors and femoral neck bone mineral between Asian and Caucasian boys.

Augmented trochanteric bone mineral density after modified physical education classes: a randomized school-based exercise intervention study in prepubescent and early pubescent children.

BACKGROUND: Of the few exercise intervention studies focusing on pediatric populations, none have confined the intervention to the scheduled physical education curriculum. OBJECTIVE: To examine the effect of an 8-month school-based jumping program on the change in areal bone mineral density (aBMD), in grams per square centimeter, of healthy third- and fourth-grade children. STUDY DESIGN: Ten elementary schools were randomized to exercise (n = 63) and control groups (n = 81). Exercise groups did 10 tuck jumps 3 times weekly and incorporated jumping, hopping, and skipping into twice weekly physical education classes. Control groups did regular physical education classes. At baseline and after 8 months of intervention, we measured aBMD and lean and fat mass by dual-energy x-ray absorptiometry (Hologic QDR-4500). Calcium intake, physical activity, and maturity were estimated by questionnaire. RESULTS: The exercise group showed significantly greater change in femoral trochanteric aBMD (4.4% vs 3.2%; P <.05). There were no group differences at other sites. Results were similar after controlling for covariates (baseline aBMD change in height, change in lean, calcium, physical activity, sex, and ethnicity) in hierarchical regression. CONCLUSIONS: An easily implemented school-based jumping intervention augments aBMD at the trochanteric region in the prepubertal and early pubertal skeleton.

Examination of the factorial validity of the Group Environment Questionnaire.

The purpose of this study was to test the hypothesized factor structure of the Group Environment Questionnaire (GEQ) with confirmatory factor analysis and to ascertain the degree of factorial invariance across gender and across type of sport (team, individual). Additionally, the underlying theoretical structure on which the GEQ was developed was examined by fitting the data to alternative hierarchical factor structures. These models were tested with GEQ data collected on 740 high school varsity athletes (426 males, 314 females). It was shown that the males and females had different factor structures and that neither group exhibited the hypothesized structure. Attempts to fit the data to a two-factor and a second-order hierarchical factor model were unsuccessful. Finally, exploratory factor analysis did not produce a satisfactory four-factor solution. It was concluded that the data from this sample do not support the hypothesized four-factor structure of the GEQ and that further examination of the factor structure of this instrument is required.

Opacification and border delineation improvement in patients with suboptimal endocardial border definition in routine echocardiography: results of the Phase III Albunex Multicenter Trial.

OBJECTIVES: This study was designed to assess the safety and efficacy of intravenously administered sonicated human serum albumin for enhancing echocardiographic delineation of the left ventricular endocardium and improving assessment of wall motion in patients with incomplete depiction of noncontrast echocardiography. BACKGROUND: Echocardiographic regional wall motion analysis is impaired by incomplete endocardial definition in as many as 10% of patients. Sonicated human serum albumin is a stable contrast material that, unlike other agents, opacifies the left ventricle when administered intravenously. METHODS: One hundred seventy-five patients were enrolled at eight centers on the basis of incomplete echocardiographic endocardial depiction. Sonicated 5% human serum albumin, a stable preparation of air-filled microspheres (size range 1 to 10 microns), was administered intravenously in divided doses: 0.08 ml/kg body weight in all patients, followed by 0.14 and 0.08 ml/kg or a single dose of 0.22 ml/kg, depending on the result of the initial dose. Investigators and independent reviewers blinded to the protocol scored the echocardiograms for degree of left ventricular opacification and improvement of endocardial border depiction. RESULTS: Overall, 81% of patients had at least moderate left ventricular chamber opacification with at least one contrast dose, and endocardial definition was improved in 83%. In the subgroup with inadequate left ventricular opacification from the initial dose, a second, larger dose (0.22 ml/kg) improved endocardial depiction in 64%. No significant side effects occurred. CONCLUSIONS: In patients with incomplete echocardiographic endocardial definition, sonicated human serum albumin is a safe, effective contrast agent that, when administered intravenously, produces left ventricular chamber opacification, improves endocardial depiction and enhances regional wall motion analysis.

Transition play in team performance of volleyball: a log-linear analysis.

The purpose of this study was to develop and test a method to analyze and evaluate sequential skill performances in a team sport. An on-line computerized system was developed to record and summarize the sequential skill performances in volleyball. Seventy-two sample games from the third Federation of International Volleyball Cup men's competition were videotaped and grouped into two categories according to the final team standing and game outcome. Log-linear procedures were used to investigate the nature and degree of the relationship in the first-order (pass-to-set, set-to-spike) and second-order (pass-to-spike) transition plays. Results showed that there was a significant dependency in both the first-order and second-order transition plays, indicating that the outcome of a skill performance is highly influenced by the quality of a preceding skill performance. In addition, the pattern of the transition plays was stable and consistent, regardless of the classification status: Game Outcome, Team Standing, or Transition Process. The methodology and subsequent results provide valuable aids for a thorough understanding of the characteristics of transition plays in volleyball. In addition, the concept of sequential performance analysis may serve as an example for sport scientists in investigating probabilistic patterns of motor performance.

Statistical analyses of volleyball team performance.

The purpose of this study was to investigate the playing characteristics of team performance in international men's volleyball. The specific purposes were (a) to examine differences in playing characteristics (in particular, the set and spike) between the Attack Process and the Counterattack Process; (b) to examine changes in playing characteristics as a function of team success (as indicated by single-game outcomes and by final tournament standings); and (c) to determine the best predictor, or a set of predictors, of team success among the selected skill components. Seventy-two sample games from the Third Federation of International Volleyball Cup men's competition were recorded using a computerized recording system. Results showed that the significant differences between Team Standing and Game Outcome were due to better performances on those skills used in the Counterattack Process. Among the eight selected skills, the block and spike were the most important in determining team success. The methodology used in this study and the subsequent results provide valuable aids for the coach in the evaluation of team performance and ultimately in the preparation of training sessions in volleyball.

Early experience with mitral valve reconstruction for mitral insufficiency.

Mitral valve repair for mitral regurgitation has been reported to have more favorable early and late results than mitral valve replacement. From July 1985 through July 1990, 63 patients have undergone valve repair at Good Samaritan Hospital. Twenty-two men and 41 women whose ages ranged from 34 to 81 years (mean 67.9 years) were treated. Twenty-eight patients were in New York Heart Association functional class III or IV. Twelve (19%) had undergone prior cardiac surgery. Isolated valve repair was performed in 18 patients. Valve repair was combined with coronary artery bypass grafting, other valve procedures, or aneurysm resection in the remainder (71%). Two patients (3%) died while in the hospital, and four deaths (one valve-related) occurred after discharge. Leaflet resection for ruptured chordae was done in 24 patients (38%), chordal shortening in 5 patients (8%), and leaflet transposition in 2 patients. Rigid ring annuloplasty (Carpentier) was performed in 62 patients. Eight patients required mitral valve replacement at the same operation because of unsatisfactory valve repair. Results of valve repair evaluated by echocardiography at discharge show that 48 patients (88%) are free of significant regurgitation. Follow-up to date reveals that all surviving patients who underwent valve repair have clinically improved and are stable. Four of five patients with moderate mitral regurgitation are currently asymptomatic. There have been two valve-related late failures requiring reoperation. Based on this early experience, we conclude that valve repair compared with mitral valve replacement has a low operative mortality with good early results. Continued efforts to preserve native mitral valve function in the presence of mitral regurgitation appear justified.

Qualitative research: comments and controversies.

Larry Locke's timely and well-written introduction to qualitative research procedures will undoubtedly serve its purpose. It makes us reassess our traditional beliefs and practices, educates us on the rudiments of qualitative methodology, and, hopefully, makes us more tolerant and appreciative of alternate ways of conducting research. Although Locke focuses his paper on pedagogical research issues, it is important to realize that many other sub-disciplines within the general field of physical education also utilize qualitative procedures. For example, 10 years ago Martens (1979) called for a paradigm shift in sport psychology by appealing to researchers to abandon their labs and to embark on naturalistic field studies. While North American sport psychologists, and psychologists in general, have been slow to formalize qualitative techniques, the European psychology community has been much more active (e.g., Ashworth, Giorgi, & de Koning, 1986). Perhaps Locke's article will encourage researchers in all our sub-disciplines to consider the utility of qualitative research. Hopefully, readers will treat Locke's article as an introduction to the broad area of qualitative research and not as a rigorous set of procedures for conducting participant observation research in school physical education studies. Additionally, it must be recognized that there are other approaches and other applications, that the area has its critics and its unresolved methodological problems, and that qualitative research does not necessarily exclude the application of formalized data analyses. Keeping these issues in mind, the addition of qualitative approaches to our repetoire of research methodologies can only enhance the quality of research in physical education and exercise and sport science.

Analysis of wheelchair track performances.

The purpose of this study was to analyze the performance in wheelchair races with respect to the level of impaired functional musculature of the athletes. The data consisted of the world records and 1984 World Wheelchair Games track finalists' performances in the seven competitive classes for males and females. Peak wheelchair record speed, regardless of level of disability, of 6.43 m.s-;1 for males occurs in the 200 m event which decreases to 5.75 m.s-1 at 5000 m. Comparable female speeds are 5.60 and 4.67 m.s-1, which are similar to male-female differences in running records. Analysis of variance of wheelchair finalists' average speeds indicated a significant (P less than 0.05) difference between the sexes, distances, and classes of athletes. Females were slower than males and tetraplegics slower than paraplegics over all distances. Tetraplegics did not show any significant change in speed over distance. Significant linear and quadratic trends over distance were noted for male paraplegics due to a generally decreasing speed with duration of the race and a peak speed at 200 m, respectively. Male paraplegics had a faster speed in the marathon compared to their longest track event, reflecting the greater speeds attainable during downhill wheeling.

Employee health service for teaching and nonteaching staff: a needs assessment.

This paper reports the results of a needs assessment conducted for an Employee Health Service in a metropolitan school district. Survey questionnaires were distributed to the entire district staff with a return rate of 49% (n = 2,268). In order to identify the subgroups of employees who may be at greatest health risk, data were analyzed utilizing an Automatic Interaction Detection Analysis technique. As a means of determining whether particular subgroups perceive stress differentially, multivariate analyses of variance were also performed. Results indicate that "degree of stress" is the health risk variable which can best differentiate employees on the basis of health risk predictors. In general, for teachers, coping ability differentiates those who have high versus low stress, whereas for nonteachers, satisfaction with social support shows the strongest relationship to stress. Furthermore, classification of individuals by job category results in the most pronounced differences between groups on ten stress subdomains. Overall, task-based stress is deemed to be the most stressful of the subdomains. Results are discussed with regard to planning prevention and intervention efforts.

Changes in lipid and lipoprotein levels after weight training.

Lipid and lipoprotein levels were prospectively studied in previously sedentary men (mean age, 33 years) and women (mean age, 27 years) undergoing 16 weeks of weight-training exercise. Women demonstrated a 9.5% reduction of cholesterol, 17.9% decrease in low-density lipoprotein (LDL) cholesterol and 28.3% lowering of triglycerides. The ratios of total cholesterol-high-density lipoprotein (HDL) cholesterol and LDL cholesterol-HDL cholesterol were reduced 14.3% and 20.3%, respectively. Among men, LDL cholesterol was reduced 16.2%, while the ratios of total cholesterol-HDL cholesterol and LDL cholesterol-HDL cholesterol were lowered 21.6% and 28.9%, respectively. Weight-training exercise appears to result in favorable changes in lipid and lipoprotein levels in previously sedentary men and women.

The development of a test of overarm throwing: an application of generalizability theory.

Although much effort has been directed toward an understanding of sequential progressions between and within motor skills, little evidence is available to indicate that teachers have incorporated this material into instructional practice. The fact that pupil progress has been evaluated primarily through movement achievement (distance, velocity), rather than through movement content (analysis of form), has been postulated as a reason for this non-use. It was thus the purpose of this study to develop a reliable, objective and practical method of measuring one particular manipulative skill--that of overarm throwing. As such, previously developed sequential progressions were analyzed and modified to produce a measure which did not require the use of a camera. A system of rating throwing performance was adopted which allows for separate rating of the three components: "foot placement", "body rotation", and "arm action". Each component depicts five hierarchically arranged levels, or "steps", and performance is rated on a scale ranging from 1-5. The throwing test was administered to 78 subjects by three trained observers. Reliability analyses, through the use of generalizability theory, showed high objectivity (r's of approximately .90) and good day-to-day reliability (r's of .75 to .93) for most testing conditions. It was concluded that this test is a reliable, valid and practical test for the analysis of overarm throwing in children.

Variable error: variance-covariance heterogeneity, block size and type L error rates.

The degree to which blocked (VE) data satisfies the assumptions of compound symmetry required for a repeated measures ANOVA was studied. Monte Carlo procedures were used to study the effect of violation of this assumption, under varying block sizes, on the Type l error rate. Populations of 10,000 subjects for each of two groups, the underlying variance-covariance matrices reflecting a specific condition of violation of the homogeneity of covariance assumptions, was generated based on each of three actual experimental data sets. The data were blocked in various ways, VE calculated, and subsequently analyzed by a repeated measures ANOVA. The complete process was replicated for four covariance homogeneity conditions for each of the three data sets, resulting in a total of 22,000 simulated experiments. Results indicated that the Type l error rate increases as the degree of heterogeneity within the variance-covariance matrices increases when raw (unblocked) data are analyzed. With VE, the effects of within-matrix heterogeneity on the Type l error rate are inconclusive. However, block size does seem to affect the probability of obtaining a significant interaction, but the nature of this relationship is not clear as there does not appear to be any consistent relationship between the size of the block and the probability of obtaining significance. For both raw and VE data there was no inflation in the number of Type l errors when the covariances within a given matrix were homogeneous, regardless of the differences between the group variance-covariance matrices.

Physical fitness of students in British Columbia: a criterion-referenced evaluation.

In 1979, the Ministry of Education completed a comprehensive study on the status of physical education in British Columbia. The purpose of this paper is to present the findings of this assessment, with respect to the physical fitness of public school children at the end of primary (grade 3), intermediate (grade 7), and secondary (grade 11) levels. Approximately 3000 students were tested on measures of cardiovascular endurance, static and dynamic muscular endurance, static and explosive strength and flexibility. Separate panels, one to determine "acceptable ranges of performance" and one to interpret the findings, were established by the provincial Ministry. Evaluation was of a criterion-referenced nature and ratings of "weak", "marginally satisfactory", "satisfactory", "very satisfactory", and "strong" were assigned. The results of the study indicate that fitness levels of both sexes, at the grade 3 and 7 levels, as well as the grade 11 females, were generally rated "weak" to "marginally satisfactory". "Satisfactory" ratings were recorded for the grade 11 males. Variables of particular concern were those of cardiovascular endurance and static muscle endurance. It was concluded that B.C. students, while comparing favourably with other provincial, national and international samples, fell well below the "acceptable ranges" set by the provincial evaluative panels.

Physical activity and sport: attitudes and perceptions of young Canadian athletes.

The failure of the literature to report consistent attitude-behaviour relationships or show evidence of stability in children's attitudes toward physical activity (CATPA) led to an examination of the construct physical activity as an attitude object. Five hundred and fifty young male and female athletes were surveyed to obtain the following information; CATPA, children's attitudes toward the specific sport (CATSS) in which they were involved, and the activities perceived to be representative of six physical activity subdomains. Significant differences among sport groups were found in three of the attitude subdomains, the most noticeable being for females in the Aesthetic subdomain. In general, the athletes' perceived physical activities represented the sport in which they were participating. The small differences between CATPA and CATSS mean scores, along with the results of both canonical analysis and factor analysis, led to the conclusion that children's attitudes toward the construct physical activity are essentially equivalent to their attitudes toward a specific sport. The validity of physical activity as a well defined attitude object ws substantiated for young Canadian athletes.

Academic achievement and involvement in hockey: a post-hoc longitudinal study.

Academic achievement, absenteeism, and athletic involvement (hockey) data were collected on 484 boys throughout British Columbia. School and minor hockey records were used to obtain longitudinal data for each boy from Grade 1 until high school graduation or school withdrawal. Results indicated that hockey players exhibit less school absenteeism than non hockey players, but are not different with respect to grade point averages. Hockey players, at the juvenile level or lower, tend to attain a slightly higher grade point average during the years they are playing hockey in comparison with their academic achievement during the years they are not playing hockey. Of the hockey players with lower than average I.Q.'s, those who exhibit poor achievement tend to drop out of hockey earlier than those who have average or above average grades.

Relationships among measures of preferred tempo and motor rhythm.

Male and female subjects (Ns = 100) performed an accuracy task involving consecutive arm swings at a self-paced tempo. Following this, the subjects performed a motor rhythm task keeping in cadence with audio-visual stimuli presented at their preferred tempo. Previous findings regarding the magnitude of individual differences in preferred tempo and within-individual variability were replicated, as was the absence of sex differences for these attributes. With regard to motor rhythm, the findings indicated that (a) constant and variable error, and not absolute error, were the appropriate measures of performance, (b) there were no sex differences either in spatial or temporal accuracy or in trial-to-trial consistency of performance, (c) substantial individual differences were present in rhythmic accuracy, as were moderate individual differences in variability, (d) neither rhythmic accuracy nor variability was appreciably related to preferred tempo, and (e) spatial and temporal accuracy are relatively independent components of rhythmic accuracy.