Development and field validation of an omni-domain power-duration model

ABSTRACT

Purpose: To validate and compare a novel model based on the critical power (CP) concept that describes the entire domain of maximal mean power (MMP) data from cyclists.

Methods: An omni-domain power-duration (OmPD) model was derived whereby the rate of W? expenditure is bound by maximum sprint power and the power at prolonged durations declines from CP log-linearly. The three-parameter CP (3CP) and exponential (Exp) models were likewise extended with the log-linear decay function (Om3CP and OmExp). Each model bounds W? using a different nonconstant function, W?eff (effective W?). Models were fit to MMP data from nine cyclists who also completed four time-trials (TTs).

Results: The OmPD and Om3CP residuals (4 ± 1%) were smaller than the OmExp residuals (6 ± 2%; P < 0.001). W?eff predicted by the OmPD model was stable between 120–1,800 s, whereas it varied for the Om3CP and OmExp models. TT prediction errors were not different between models (7 ± 5%, 8 ± 5%, 7 ± 6%; P = 0.914).

Conclusion: The OmPD offers similar or superior goodness-of-fit and better theoretical properties compared to the other models, such that it best extends the CP concept to short-sprint and prolonged-endurance performance.     

Learning from the Experts: Practice Activities of Expert Decision Makers in Sport

Abstract

This study was an experimental investigation of the emotional responses of boys 9 through 15 years of age to highly organized competitive baseball. The subjects were 75 boys who participated in Little League Baseball, 50 boys who were members of Middle League teams, and 80 boys who did not play on an organized team.

The Galvanic Skin Response test was employed to measure the emotional changes of boys participating in league baseball and to compare the results of these tests with those of the same boys participating in softball competition in physical education classes. Insofar as the Galvanic Skin Response test can be taken to be a valid measure of emotional excitation of boys of this age level, the results of this study suggest that youngsters were no more stimulated by competition in league games than they were by competition in physical education games.     

International Communications

Lawrence W. Lichty's (ed.) World and International droadcasting: A Bibliography (Association for Professional Broadcasting Education, 1771 N St. Washington, D. C.) $15.00 ($10.00 to APBE individual members) paperbound)

William A. Hachten's Muffled Drums: The News Media in Africa (Iowa State University Press, $9.50)

Lynne Svenning's Modernization Among Peasants: Impact of Communications (Holt, Rinehart, and Winston, $8.00)

Will A. Boelke's The Secret Conferences of Dr. Goebbels: The Nazi Propaganda War 1939-43.

James W. Markham's (ed.) International Commnication as a Field of Study (University of Iowa Department of Publications, $3.00)     

Motion Pictures

Emerson, Naturalistic Photography for Students of the Art (1891)

Hicks, Words and Pictures: Introduction to Photojournalism (1952)

Bunnell, Nonsilver Printing Processes, $4.50

Lee R. Baker, Making Movies: From Script to Screen (New York: Harcourt Brace Javanovich, 1973—price not known, paper)

Johnny Minus and William Storm Hale's Your Introduction to Film-TV Copyright, Contracts and other Law (Seven Arts Press, 6655 Hollywood Blvd., Hollywood, Ca. 90028 1973— $10.00 paper)

Noel Burch Theory of Film Practice (New York: Praeger, 1973—$8.95)

Hector Currie and Donald Staples' Film: Encounter (Dayton, Ohio: Pflaum/Standard, 1973—$9.95, paper)

John G. Cawelti's Focus on Bonnie and Clyde (Englewood Cliffs, N.J.: Prentice-Hall, 1973—$5.95/2.45)

David Bordwell, Filmguide to La Passion de Jeanne d'Arc

Warren French, Filmguide to The Grapes of Wrath

Carolyn Geduld, Filmguide to 2001: A Space Odyssey

James Naremore, Filmguide to Psycho

E. Rubenstein, Filmguide to The General

Jay Leyda's Kino: A History of the Russian and Soviet Film (New York: Collier Books, 1973 reissue of 1960 original —$4.95, paper)     

Special school headship in times of change: impossible challenges or golden opportunities?

This article is based on empirical research undertaken by John Baker, headteacher of the largest day special school for pupils with a range of learning difficulties in Essex, as part of his EdD studies at the Institute of Education, University of London. Its focus is on the perceived challenges and opportunities which headteachers of special schools for pupils with learning difficulties and disabilities (LDD) are facing and on the strategies they are using to manage these challenges and opportunities. A group of nine head teachers from one local authority in the southern half of England formed the sample for this study. The methodology employed postal/email questionnaires with follow‐up semi‐structured interviews with a subgroup of four headteachers. The main challenges identified by the special school headteachers were constant change, relentless school improvement, funding concerns, bureaucracy and maintaining a balance between work and private life. Perceived opportunities included partnership links with other schools and outreach services to mainstream schools; other initiatives such as specialist school status and Building Schools for the Future were also identified. John Baker suggests strategies to help headteachers meet these challenges and ensure that opportunities become realities.     

Development of the Metacognitive Skills of Prediction and Evaluation in Children With or Without Math Disability

Metacognition refers to knowledge about one's own cognition. The present study was designed to assess metacognitive skills that either precede or follow task engagement, rather than the processes that occur during a task. Specifically, we examined prediction and evaluation skills among children with (n= 17) or without (n= 179) mathematics learning disability (MLD), from grades 2 to 4. Children were asked to predict which of several math problems they could solve correctly; later, they were asked to solve those problems. They were asked to evaluate whether their solution to each of another set of problems was correct. Children's ability to evaluate their answers to math problems improved from grade 2 to grade 3, whereas there was no change over time in the children's ability to predict which problems they could solve correctly. Children with MLD were less accurate than children without MLD in evaluating both their correct and incorrect solutions, and they were less accurate at predicting which problems they could solve correctly. However, children with MLD were as accurate as their peers in correctly predicting that they could not solve specific math problems. The findings have implications for the usefulness of children's self‐review during mathematics problem solving.