This study used kinematic data on springboard diving performances to estimate viscoelastic parameters of a planar model of a springboard and diver with wobbling masses in the trunk, thigh, and calf segments and spring dampers acting at the heel, ball, and toe of the foot segment. A subject-specific angle-driven eight-segment model was used with an optimization algorithm to determine viscoelastic parameter values by matching simulations to four diving performances. Using the parameters determined from the matching of a single dive in a simulation of another dive resulted in up to 31% difference between simulation and performance, indicating the danger of using too small a set of kinematic data. However, using four dives in a combined matching process to obtain a common set of parameters resulted in a mean difference of 8.6%. Because these four dives included very different rotational requirements, it is anticipated that the combined parameter set can be used with other dives from these two groups.
Search Results
Parameter Determination for a Computer Simulation Model of a Diver and a Springboard
Maurice R. Yeadon, Pui W. Kong, and Mark A. King
A Procedure for the Automatic Determination of Filter Cutoff Frequency for the Processing of Biomechanical Data
John H. Challis
This article presents and evaluates a new procedure that automatically determines the cutoff frequency for the low-pass filtering of biomechanical data. The cutoff frequency was estimated by exploiting the properties of the autocorrelation function of white noise. The new procedure systematically varies the cutoff frequency of a Butterworth filter until the signal representing the difference between the filtered and unfiltered data is the best approximation to white noise as assessed using the autocorrelation function. The procedure was evaluated using signals generated from mathematical functions. Noise was added to these signals so mat they approximated signals arising from me analysis of human movement. The optimal cutoff frequency was computed by finding the cutoff frequency that gave me smallest difference between the estimated and true signal values. The new procedure produced similar cutoff frequencies and root mean square differences to me optimal values, for me zeroth, first and second derivatives of the signals. On the data sets investigated, this new procedure performed very similarly to the generalized cross-validated quintic spline.
Computational Methods Used in the Determination of Loading Rate: Experimental and Clinical Implications
C. Mark Woodard, Margaret K. James, and Stephen P. Messier
Our purpose was to compare methods of calculating loading rate to the first peak vertical ground reaction force during walking and provide a rationale for the selection of a loading rate algorithm in the analysis of gait in clinical and research environments. Using vertical ground reaction force data collected from 15 older adults with symptomatic knee osteoarthritis and 15 healthy controls, we: (a) calculated loading rate as the first peak vertical force divided by the time from touchdown until the first peak; (b) calculated loading rate as the slope of the least squares regression line using vertical force and time as the dependent and independent variables, respectively; (c) calculated loading rate over discrete intervals using the Central Difference method; and (d) calculated loading rate using vertical force and lime data representing 20% and 90% of the first peak vertical force. The largest loading rate, which may be of greatest clinical importance, occurred when loading rates were calculated using the fewest number of data points. The Central Difference method appeared to maximize our ability to detect differences between healthy and pathologic cohorts. Finally, there was a strong correlation between methods, suggesting that all four methods are acceptable. However, if maximizing the chances of detecting differences between groups is of primary importance, the Central Difference method appears superior.
A Comparison of Three Methods of Determination of Energy Density of Elite Figure Skaters
Paula J. Ziegler, Judith A. Nelson, Chloe Tay, Barbara Bruemmer, and Adam Drewnowski
Dietary energy density (kcal/g) is defined as available dietary energy per unit weight or volume of food. The consumption of energy-dense foods has been associated with increased obesity risk and with excessive weight gain. The objectives of this study were to compare how dietary energy density, calculated using three different methods relates to food choices and nutrient composition of the diets of elite figure skaters. Participants were 159 elite figure skaters attending training camps. Mean age was 18.4 y for boys (n = 79) and 15.9 y for girls (n = 80). Heights and weights were measured to calculate body-mass indices (BMI). Dietary intakes were based on 3-d food records analyzed using the Nutritionist IV program. Mean energy intakes were 2326 kcal/d for boys and 1545 kcal/d for girls. Dietary energy density, based on foods and caloric beverages only, was 1.0 kcal/g. Dietary ED was positively associated with percent energy from fat and negatively with percent energy from sugar. The main sources of dietary energy in this group were baked goods, cereals, regular soda, low-fat milk, fruit juices, bagels and pizza. Percent energy from fast foods was associated with higher dietary energy density, whereas percent energy from dairy products, soft drinks, vegetables, and fruit was associated with lower dietary energy density. These results are consistent with past observations; higher energy density diets were higher in fat. In contrast, there was a negative relationship between sugar content and energy density of the diet.
The Determination of Subcutaneous Body Fat Percentage by Measuring Skinfold Thickness in Teenagers in Turkey
Vatan Kavak
Our aim in this study was to determine the body fat percentage of teenagers in Diyarbakir, a city in southeast Turkey. The study included 1118 children between the ages of 10 to 15. Basic anthropometric measurements including body-mass index (BMI) and skinfold thickness were taken. The skinfold thickness were measured with a Lange skinfold caliper. Fat mass percentage (FM %) was predicted by using skinfold thickness equations. Differences between boys and girls across age groups for weight, height, and BMI were found to be statistically significant (P < 0.0001). With respect to skinfold thickness in the 10-y-old group, the thickness at triceps and subscapular sites in girls was higher than those of boys. In the 12-y-old group, the thickness was found to be higher in girls than boys at the triceps, biceps, and subscapular sites. We found that an increase in skinfold thickness in the 13, 14, and 15-y-old groups was significantly higher among girls than boys and tended to increase with age. However, such a tendency was not shown in boys. This tendency was found only at the triceps site in 10, 12, and 13-y-old boys. In addition, the skinfold thickness at the biceps site was found to be greater in the 14-y-old boys. The body fat mass percent in girls, especially those older than age 13, was also increased.
Load Determination for the 3-Minute All-Out Exercise Test for Cycle Ergometry
Nathan D. Dicks, Nicholas A. Jamnick, Steven R. Murray, and Robert W. Pettitt
Purpose:
To investigate a new power-to-body-mass (BM) ratio 3-min all-out cycling test (3MT%BM) for determining critical power (CP) and finite work capacity above CP (W ′).
Methods:
The gas-exchange threshold (GET), maximal oxygen uptake (VO2max), and power output evoking VO2max (W peak) and GET (W GET) for cycle ergometry were determined in 12 participants. CP and W′ were determined using the original “linear factor” 3MT (3MTrpm^2) and compared with CP and W′ derived from a procedure, the 3MT%BM, using the subject’s body mass and self-reported physical activity rating (PA-R), with values derived from linear regression of the work–time model and power–inverse-time model (1/time) data from 3 separate exhaustive squarewave bouts.
Results:
The VO2max, VO2GET, W peak, and W GET values estimated from PA-R and a non-exercise-regression equation did not differ (P > .05) from actual measurements. Estimates of CP derived from the 3MT%BM (235 ± 56 W), 3MTrpm^2 (234 ± 62 W), work–time (231 ± 57 W), and 1/time models (230 ± 57 W) did not differ (F = 0.46, P = .72). Similarly, estimates of W′ between all methods did not differ (F = 3.58, P = .07). There were strong comparisons of the 3MT%BM to 1/time and work–time models with the average correlation, standard error of the measurement, and CV% for critical power being .96, 8.74 W, and 4.64%, respectively.
Conclusion:
The 3MT%BM is a valid, single-visit protocol for determining CP and W′.
Clinical Assessment of Drop-Jump Landing for Determination of Risk for Knee Injury
Nelson Cortes and James Onate
Context:
Clinical assessment tools are needed to identify individual athletes who possess elevated risk for anterior cruciate ligament injury. Existing methods require expensive equipment and the investment of a large amount of time for data processing, which makes them unfeasible for preparticipation screening of a large number of athletes.
Objective:
To assess the extent of agreement between LESS and the iLESS classifications of jump landing performance and the level of agreement between ratings assigned by a novice evaluator and an expert evaluator.
Methods:
Ratings of drop-jump landings from 20 video recordings of NCAA Division I collegiate athletes, which were randomly selected from a large database.
Results:
The dichotomous iLESS score corresponded to the dichotomous classification of LESS score for 15 of 20 cases rated by the expert evaluator and 17 of 20 cases rated by the novice evaluator. For the iLESS, only 2 scores out of 20 differed between the evaluators.
Conclusions:
A high level of agreement was observed between the LESS and iLESS methods for classification of jump- landing performance. Because the iLESS method is inexpensive and efficient, it may prove to be valuable for preparticipation assessment of knee injury risk.
Age-Related Decreases in Finger Sensitivity Can Produce Error in Palpated Heart-Rate Determination
Nobuo Takeshima, William F. Brechue, Setsuko Ueya, and Kiyoji Tanaka
This study attempted to determine the accuracy of measuring heart rate by radial artery palpation in elderly individuals. Elderly (ELD; n = 26) and young (Y; n = 21) individuals completed 3 intensity levels of exercise on a treadmill, each carried out on a separate day. Participants determined their heart rate by palpating the radial artery (PR) after exercise. In ELD, there were significant differences between PR and electrocardiogram (ECG; p = .007). Heart-rate errors at each intensity of exercise were 7.2 ± 12.5, 6.6 ± 15.7, and 10.1 ± 16.5 beats/min. There were no differences in PR and ECG in Y. Fingertip sensitivity was significantly lower in ELD than in Y. A significant, negative correlation existed (r = -.56, n = 26) between heart-rate error and fingertip sensitivity in ELD. These data suggest that self-conducted PR by elderly individuals fails to accurately estimate heart rate. This appears to result from lessened vibrotactile sensitivity in the fingers.
EMG Activity of Six Muscles and VMO:VL Ratio Determination during a Maximal Squat Exercise
Peter A. Schaub and Teddy W. Worrell
During knee rehabilitation, squats are a commonly used closed kinetic chain exercise. We have been unable to locate data reporting electromyographic (EMG) activity of lower extremity musculature during maximal effort squats and the contribution of gastrocnemius and gluteus maximus muscles. Therefore, the purposes of this study were (a) to quantify EMG activity of selected lower extremity muscles during a maximal isometric squat and during a maximal voluntary isometric contraction (MVIC), and (b) to determine ratios between the vastus medialis oblique (VMO) and vastus lateralis (VL) during maximal isometric squat and MVIC testing. Twenty-three subjects participated in a single testing session. Results are as follows: intraclass correlations for MVIC testing and squat testing ranged from .60 to .80 and .70 to .90, respectively. Percentage MVIC during the squat was as follows: rectus femoris 40 ± 30%, VMO 90 ± 70%, VL 70 ±40%, hamstrings 10 ± 10%, gluteus maximus 20 ± 10%, and gastrocnemius 30 ± 20%. No statistical difference existed in VMO:VL ratios during MVIC or squat testing. We conclude that large variations in muscle recruitment patterns occur between individuals during isometric squats.
Elementary School Students’ Self-Determination in Physical Education and Attitudes Toward Physical Activity
Weiyun Chen and Andrew J. Hypnar
Motivations for and positive attitudes toward physical activity (PA) developed during childhood are likely to be carried over to adulthood. The purpose of this study was to examine the relationship between three psychological needs satisfaction, motivational regulations in physical education (PE), and attitudes toward participation in leisure-time PA among upper elementary school students. One thousand and seventy-three students in grades 3-5 anonymously and voluntarily completed three measures, including Psychological Needs Satisfaction, Motivational Regulations, and Attitudes, which were modified from previous works and judged by a panel of experts to ensure the wording of each item was understandable for upper elementary school students. The data were analyzed with descriptive statistics, composite reliability coefficient, and multilevel confirmatory factor analysis methods. The results indicated that the composite reliability coefficients of the measures were above .60, ranging from .62 to .79. The results of structural equation model indicated that satisfactions of autonomy, competence, and relatedness were significantly instrumental to the enhancement of autonomous motivation in PE settings and attitudes toward PA participation. Elementary school students’ having fun, obtaining benefits, and being with friends were all major motivational factors contributing to positive attitudes toward PA outside of school.
