Intra-abdominal pressure and rowing: the effects of inspiring versus expiring during the drive.

BACKGROUND: The lumbar vertebrae of rowers are subjected to high levels of shear and compression at mid-drive, but intra-abdominal pressure (IAP) may partially neutralize these forces. IAP fluctuates with breathing. This study compared the IAP between inspiring during the drive and expiring during the drive. EXPERIMENTAL DESIGN: ten volunteers performed one 5x2-minute repetition test while inspiring during the drive and one 5x2-minute repetition test while expiring during the drive on a rowing ergometer. The five work rates were: 100, 125, 150, 175 and 200 watts at 22, 24, 26, 28 and 30 strokes per minute, respectively. MEASURES: the movement of the body while rowing was analyzed using a position sensor, and IAP was measured using a pressure transducer catheter. RESULTS: A 2x5 repeated measures analysis of variance showed that there was a significant interaction for the dependent variable mid-drive IAP (p<0.05), with the mid-drive IAP increasing at a greater rate while expiring during the drive relative to inspiring during the drive. Across work rate, the mid-drive IAP and minimal IAP were significantly higher while expiring during the drive than inspiring during the drive (p<0.05). Across breathing pattern, the minimal IAP, maximal IAP, average change in IAP and mid-drive IAP increased significantly with work rate (p<0.05). CONCLUSIONS: The data show that expiring during the drive leads to a greater mid-drive IAP than inspiring during the drive.

A comparison of moleskin tape, linen tape, and lace-up brace on joint restriction and movement performance.

OBJECTIVE: There are several types of ankle prophylactics available. The purpose of this study was to compare the effectiveness of moleskin tape, linen tape, and a lace-up brace on motor performance and ankle/subtalar range of motion (ROM). DESIGN AND SETTING: PERFORMANCE WAS MEASURED IN CENTIMETERS AND SECONDS FOR VERTICAL JUMP AND SOUTHEAST MISSOURI (SEMO) AGILITY TEST, RESPECTIVELY, UNDER FOUR CONDITIONS: control/no support, tape (T), tape with moleskin stirrup reinforcement (TwMSR), and a lace-up brace (B). Motor tests were conducted on two separate days. On another day ankle/ subtalar ROM was measured before, during, and after 20 minutes of continuous exercise under the four conditions. All tests were conducted in the field house at Northem Illinois University. SUBJECTS: Ten college females with no recent history of ankle injury volunteered to participate in the study. MEASUREMENTS: Vertical jump was measured using a Vertec jump stand (centimeters), and the Southeast Missouri (SEMO) agility test was measured with a stopwatch (seconds) under the four conditions. Ankle/subtalar ROM was measured before, during, and after a 20-minute exercise protocol by a goniometer under the four conditions. The tape (T) application was a closed basketweave, the tape with moleskin stirrup reinforcement (TwMSR) consisted of a closed basketweave and a moleskin stirrup (7.62 cm, 3 inches), and the brace(B) was a Swede-O Universal (Swede-O, Inc, North Branch, MN). RESULTS: Vertical jumps were significantly shorter for all three ankle prophylactics when compared with the control/no-support condition. Among the three prophylactics, the vertical jumps were the same. Slower performance times were recorded for all three prophylactics as compared with the control/no-support condition. There were no significant differences, however, among the three ankle prophylactics. In comparison with the control/no-support condition, the TwMSR application significantly restricted four of the four ROMs (plantar flexion, dorsiflexion, inversion, and eversion) during the 20-minute exercise protocol. The T application significantly restricted three of the four ROMS (all ROMs except plantar flexion), and the B application also significantly restricted three of the four ROMs (all ROMs except eversion) during the 20-minute exercise protocol in comparison with the control/no- support condition. CONCLUSIONS: There does not appear to be any benefit in choosing one prophylactic over the others if near optimal performance and adequate ankle/subtalar restriction is desired. Other factors, such as comfort, ease of application, and cost, should be considered.

Effects of an aerobic activity program on the cholesterol levels of adolescents.

The purpose of this study was to determine the effects of a 15-week aerobic activity program on the total cholesterol (TC) and high-density lipoprotein cholesterol (HDL-C) levels of 25 high school students, ages 14-17 years (experimental group = 14, control group = 11). Participants in the activity program exercised 4 days per week in a specially designed physical education class, while the control group participated in the regular physical education program. Results of the analysis of covariance found significant reductions in TC in the training group (control group Adj M = 190.2 mg/dl, experimental group Adj M = 173.1 mg/dl, p < .05), but no significant changes in HDL-C (control group Adj M = 49.8 mg/dl, experimental group Adj M = 50 mg/dl). While the exercise program appeared to have a beneficial effect on TC in 12 of 14 participants (86%), HDL-C also dropped in 12 of 14 participants (86%).

Objective measurement of figure skating performance.

Figure skating uses the median rank aggregation system for determining medal winners. Unfortunately, the system can be influenced by idiosyncratic ratings made by some judges unlike the skating ability measures from a many-facet Rasch analysis. These measures are constructed to be independent, as statistically possible, of item difficulties, judge severities, and the rating scale structure. A many-facet Rasch analysis was conducted on data from the controversial ladies event at the 1994 Olympics. The results illustrate how the idiosyncratic ratings of the judges were not accounted for by the median rank system, thus biasing the selection of the gold medal winner. All sports that rely on judges' ratings should investigate the use of a many-facet Rasch model in order to bring more objectivity and fairness to the winner selection process.

The task difficulty of free throw shooting for males and females.

The study demonstrated how the binomial trials model could be used to enhance performance evaluation of a psychomotor task. The study was designed to accomplish three purposes: (a) calibrate the task difficulty of shooting free throws; (b) determine if free-throw shooting is a more difficult task for females than males; and (c) demonstrate how grading scales could be developed when a difference in task difficulty exists. Adults (202 males and 196 females) ranging in age from 18 to 55 years shot 17 consecutive free throws. The performance scores were analyzed using the binomial trials model. The model fit the data for the total group and the females. Because no males scored 0 or more than 13, the model did not fit the data at the extremes of the score continuum. The task difficulty for females was 0.793 (SE = 0.084) and 0.068 (SE = 0.081) for males, which indicated differential item functioning, Chi 1(2) = 38.73, p < .0001. Shooting free throws with a men's regulation basketball was a more difficult task for females than males, which indicates the task does not measure the same latent trait ability for both groups. On average the males' probability of making a free throw was .146 units higher than for the females. Ability estimates were mapped to observed scores for males and females separately and used to illustrate how fair grading scales could be developed.

Differences in physical characteristics in collegiate baseball players. A descriptive position by position analysis.

Physical characteristics including height, weight, body composition, and somatotype of NCAA Division II baseball players were evaluated to determine if differences in physical profiles exist by position at this level of competition. Differences in height, weight, lean body weight and somatoplots were found among various players. Pitchers were found to be taller that infielders and outfielders and displayed more endomorphy and less mesomorphy than the outfielders. Among the infielders, first basemen were taller than second basemen and third basemen while shortstops were found to be taller than second basemen. With respect to weight, first basemen and catchers were found to be heavier than second basemen. The second basemen had less lean body mass than all other infield groups. The data reveal more than a general description is warranted when describing the physical characteristics of baseball players at this level of play.

Physiologic responses to forward and retrograde simulated stair stepping.

This study compared the physiologic responses to forward and retrograde simulated stair stepping on the StairMaster 4000 PT. Twenty male subjects (mean age 23.65 +/- 1.63 years) volunteered for this study. Subjects completed a practice trial of 6 minutes of both forward and retrograde stepping at Level 5. Each experimental trial was divided into four 3-minute stages: Level 3, Level 5, Level 7, and Level 9. Heart rate, blood pressure, and rating of perceived exertion (RPE) were recorded during the second minute of each stage. Expired gases were analyzed and averaged over the last 2 minutes of each stage. Caloric expenditure and delta efficiency were later calculated. Data were analyzed using a 2 x 4 ANOVA (direction by level) and 2 x 3 ANOVA (for delta efficiency). Compared to forward responses, retrograde heart rates were significantly higher at Levels 7 and 9 (p < 0.01). Retrograde responses for RPE, metabolic equivalents (METS), and caloric expenditure were significantly higher at (p < 0.01) Levels 5, 7, and 9 when compared to forward responses. However, the results of this study show that these differences between forward and retrograde stepping are not practically meaningful.

Validation of the Rockport Fitness Walking Test for adults with mental retardation.

This study determined if the generalized equations created for the Rockport Fitness Walking Test were a valid estimation of cardiorespiratory fitness for adults with mental retardation (MR). Subjects included 25 males and females (mean age = 33.3 +/- 7.4 yr) with MR. A maximal treadmill test was administered (mean VO2peak = 29.5 +/- 7.2 ml.kg-1 x min-1; 2.2 +/- 0.62 l.min-1). Subjects' age, weight, sex, walk time, and immediate post-HR were used in the generalized equations for predicting VO2peak (mean VO2peak = 36.5 +/- 7.6 ml.kg-1 x min-1 and 2.7 +/- 0.66 l.min-1). Significant correlations (P < 0.01) were obtained between the measured and predicted peak VO2 levels. However, significant and consistent differences were also observed between the measured and predicted VO2peak values (P < 0.02). Only 28% (l.min-1) and 36% (ml.kg-1 x min-1) of the subjects' measured VO2peak fell within the prespecified value of the predicted VO2peak, thus indicating that the prediction equations overestimated the VO2peak and cardiovascular fitness levels of adults with MR.

Effects of violating local independence on IRT parameter estimation for the Binomial Trials Model.

The appropriateness of the Binomial Trials Model for test data that consist of multiple attempts of the same item needs to be determined because the presence of learning or fatigue effects may violate the model's assumption of local independence. The purpose of this study was to determine what effect the severity of the violation of local independence (VLI), coupled with different sample size (SS), test length (TL), and test difficulty (TD) had on the estimation of the model difficulty parameter, b, using computer simulation techniques. Each of the following conditions was replicated 100 times under a completely crossed design: SS (100, 200, 500, 2,000); TL (5, 10, 20, 25 attempts); TD (-1.2, 0.0, 1.2); and VLI (from no violation to complete violation). Examinee ability or latent trait was pseudorandomly drawn from a standard normal distribution, and the b-parameter was estimated using a maximum likelihood procedure on generated test scores. Regardless of SS, TL, and TD, the b-parameter tended to be overestimated for situations in which the VLI condition simulated fatigue and underestimated when the VLI condition simulated late-test learning or practice effect. The findings suggest that violations of local independence, at least as simulated in this study, could seriously bias the difficulty parameter estimates if all examinees tested exhibited the dependency.

The reliability and validity of the 20-meter shuttle test in American students 12 to 15 years old.

The purpose of this study was threefold: to determine (a) the test-retest reliability of the 20-m shuttle test (20 MST) (number of laps), (b) the concurrent validity of the 20 MST (number of laps), and (c) the validity of the prediction equation for VO2max developed by Léger, Mercier, Gadoury, and Lambert (1988) on Canadian children for use with American children 12-15 years old. An intraclass coefficient of .93 was obtained on 20 students (12 males; R = .91 and 8 females; R = .87) who completed the test twice, 1 week apart (MT1 = 47.80 +/- 20.29 vs. MT2 = 50.55 +/- 22.39 laps; p > or = .13). VO2peak was obtained by a treadmill test to volitional fatigue on 48 subjects. The number of laps run correlated significantly with VO2peak in males (n = 22; r = .65; F [1, 20] = 14.30 p < or = .001), females (n = 26; r = .51; F [1, 24] = 8.34; p < or = .01), and males and females = (r = .69; F [1, 46] = 42.54, p < or = .001). When the measured VO2peak (M = 49.97 +/- 7.59 ml.kg-1.min-1) was compared with the estimated VO2max (M = 48.72 +/- 5.72 ml.kg-1.min-1) predicted from age and maximal speed of the 20 MST (Léger et al., 1988) no significant difference was found, t (47) = -1.631; p > or = .11, between the means; the r was .72 and SEE was 5.26 ml.kg-1.min-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Validity and generalizability of social dance performance ratings.

The purpose of three related studies was to develop a social dance instrument that had logical validity and generalizable performance ratings. Three social dance experts critiqued the instrument and concluded the items described the characteristics of good social dance performance. Twelve couples from a social dance class were videotaped for 5 min while performing the fox trot. Their performances were evaluated by a different set of coders in each of the three generalizability (G-) studies conducted (Subjects x Coders x Days ANOVA design). Dance performances were held constant across coding occasions so the day facet represents degree of consistency in coding, not stability of subjects' performances. Decision (D-) studies were also conducted for various measurement conditions. Results of the G-studies indicated that coders with several years of experience teaching and evaluating dance had less systematic coder bias and less systematic coder bias for a subset of dancers than coders who had little or no experience evaluating movement of any form. The performance ratings given by novice coders could be generalized for any randomly selected coder evaluating on any given day (G = .79). It was concluded the social dance test was valid and coders could be trained to obtain generalizable performance ratings.

Passing rates of American children and youth on the FITNESSGRAM criterion-referenced physical fitness standards.

The purpose of this study was twofold: (1) to determine the percentage of 6-18-year-old students who passed the FITNESSGRAM criterion scores for percent body fat (%BF), body mass index (BMI), mile run (MR), sit-ups (SU), pull-ups (PU), and sit and reach (S&R), and (2) to suggest and illustrate the instructed-uninstructed/mastery-nonmastery technique for the validation of criterion-referenced cut-off scores. The data base consisted of the NCYFS I and II national probability samples of students. Results showed that the most frequently passed item was the S&R (M = 90%; F = 97%), followed by the two body composition items (%BF: M = 89%; F = 91%) (BMI: M = 88%; F = 85%), the MR (M = 77%; F = 60%), SU (M = 65%, F = 57%), and finally the PU (M = 73%; F = 32%). It is recommended that the criterion cut-off scores be statistically validated using the illustrated technique when the active (instructed) group has been trained with documented levels of frequency, intensity, and duration and the inactive (uninstructed) group is truly sedentary.

Establishing reliability of biomechanical data using univariate and multivariate approaches.

The purpose of this study was to use generalizability theory with both univariate and multivariate approaches to examine reliability of total body center of mass (CM) values calculated from cinematographical data. Twenty-eight college-aged male volunteers were filmed by a LOCAM camera at 100 fps while performing the basic locomotion skill of walking. Film analysis was conducted on each subject using six frames of film depicting a one-stride walking cycle consisting of right heel strike, right foot flat, left toe-off, left heel strike, left foot flat, and right toe-off. Nineteen segmental endpoints and a reference point were digitized by three experienced plotters. The digitizing sequence was replicated three times by each plotter. A FORTRAN program calculated nine CM values (three plotters by three repetitions) for each subject filmed in each of the six positions of the stride. The x- and y-coordinates of the CM values were the dependent variables analyzed by fully crossed 3-way univariate and multivariate ANOVAs (subjects by plotters by repetitions). All measurement facets were considered to be random. Results indicate that there was very little repetition error but considerable interplotter error for most frames. Phi-coefficients for x- and y-coordinates, separately, fluctuated across frames. The univariate values for the x-coordinates were similar but slightly less than the multivariate values. The Phi-coefficients for Y, however, were considerably lower than the multivariate values. The multivariate Phi-coefficients for generalizing over three plotters and three repetitions ranged from .82 to .90.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular and mechanical property changes during aging of bone cement in vitro and in vivo.

The changes in mechanical properties and free radical concentration of curing Simplex P Radiopaque Bone Cement in vivo and in vitro conditions were studied. Samples were prepared so that each in vivo sample that cured and aged in the canine femoral intramedullary cavities had an in vitro counterpart that was cured and aged in a constant-temperature saline bath at 37 degrees C. An electron paramagnetic resonance (EPR) spectrometer was used to measure the growth and decay (curing) of polymerization radicals. The results of EPR measurements showed that the curing (disappearance of free radicals) of in vivo samples takes a much longer time (more than 4 weeks) than in vitro curing (less than 2 weeks). The mechanical tests indicate that, whether aged in vivo or in vitro, the strength increased rapidly for the first 1-2 weeks and then slight increases were seen for up to 6 months.