Dietary nitrate supplementation does not improve cycling time-trial performance in the heat

This investigation examined the effect of beetroot juice (BR) supplementation, a source of dietary nitrate (NO₃^?), on cycling time-trial (TT) performance and thermoregulation in the heat. In a double-blind, repeated-measures design, 12 male cyclists (age 26.6 ± 4.4 years, VO_2peak 65.8 ± 5.5 mL.kg^?1.min^?1) completed four cycling TTs (14 kJ.kg^?1) in hot (35°C, 48% relative humidity) and euthermic (21°C, 52%) conditions, following 3 days supplementation with BR (6.5 mmol NO₃^? for 2 days and 13 mmol NO₃^? on the final day), or NO₃^–depleted placebo (PLA). Salivary NO₃^? and nitrite, core (T_c) and mean skin temperature (T_sk) were measured. Salivary NO₃^? and nitrite increased significantly post-BR supplementation (p < 0.001). Average TT completion time (mm:ss) in hot conditions was 56:50 ± 05:08 with BR, compared with 58:30 ± 04:48 with PLA (p = 0.178). In euthermic conditions, average completion time was 53:09 ± 04:35 with BR, compared with 54:01 ± 04:05 with PLA (p = 0.380). The TT performance decreased (p < 0.001), and T_c (p < 0.001) and T_sk (p < 0.001) were higher in hot compared with euthermic conditions. In summary, BR supplementation has no significant effect on cycling TT performance in the heat.     

“I Could Not Believe That Would Happen”: Challenges and Opportunities in a Critical,Project-Based Clinical Experience

As part of a youth summer program—a partnership between a large Southeastern university and the local school district—middle-school-aged youth, preservice teachers, and doctoral candidates interested in arts-based literacy practices spent their mornings in June 2016 engaging in activities that both explored and expanded thinking around their communities, schools, and families. Whereas the youth were enrolled in a monthlong creative arts and tentative unschooling experiment that ran roughly the length of a typical school day, university faculty and graduate students were engaged in a course on the application of youth participatory action research (YPAR). This article is an examination of the experience of preservice teachers, through an analysis of their reflections on events within the course, to suggest ways forward through the promises and perils of project-based, clinical preservice teaching experiences. In our exploration of the experiences of focal preservice teachers when engaged with youth coresearchers in a monthlong YPAR project, we found the work to have been filled with contradictions, unexpected shifts, and moments of great understanding, community affiliation, and suffering.     

Book reviews

Clinical sports medicine, Robert C. Cantu, (ed.), The Collamore Press, Lexington, Massachusetts, Toronto, 1984. 219 pp, £19.95 (hb), ISBN 0 669 06842 X

Sports injuries, a self‐help guide, Vivian Grisogono, John Murray Ltd, London, 1984. 293 pp, £7.95 (hb), ISBN 0 7195 4111 5

Athletes’ guide to mental training, Robert N. Nideffer, Human Kinetics, Champaign, Illinois (distributed in the UK by Eddington Hook & Co.) 1985. vii +156 pp, $9.95 (pb), ISBN 0 931250 96 X

Scientific foundations of coaching, R.R. Pate, B. McClenaghan and R. Rotella, Saunders College Publishing, Philadelphia, 1984. xii + 344 pp, £21.95(hb), ISBN 0 03 057961 9

Mathematics in sport, M. Stewart Townend, Ellis Horwood, Chichester, 1984. 202 pp (hb), ISBN 0 85312 717 4

Frontiers of exercise biology, ’Big Ten Body of Knowledge’ symposium series, Vol. 13 K.T. Borer, D.W. Edington and T.P. White (eds), Human Kinetics Publishers Inc., Champaign, Illinois, (distributed in the UK by Edington Hook & Co.), 1983. vii + 295 pp, $31.95(hb), ISBN 0 931250 49 8

The knee, Philippe Segal and Marcel Jacob, Wolfe Medical Publications, Frome, Somerset, 1984. 143 pp (hb), £15, ISBN 2 224 00887 2

Psychological foundations of sport, J.M. Silva and R.S. Weinberg (eds), Human Kinetics, Champaign, Illinois, (distributed in the UK by Eddington Hook & Co), 1984. xxiv + 528 pp, £22.50 (hb), ISBN 0 93 1250 59 5

Physical activity and the social sciences, W. Neil Widmeyer, Mouvement Publications Inc., Ithaca, 1983. 472 pp, £9.00 (pb), ISBN 0 932392 13 X     

A three-dimensional kinematic analysis of the long jump take-off

The long jump has been widely studied in recent years. Two models exist in the literature which define the relationship between selected variables that affect performance. Both models suggest that the critical phase of the long jump event is the touch-down to take-off phase, as it is in this phase that the necessary vertical velocity is generated. Many three dimensional studies of the long jump exist, but the only studies to have reported detailed data on this phase were two-dimensional in nature. In these, the poor relationships obtained between key variables and performance led to the suggestion that there may be some relevant information in data in the third dimension. The aims of this study were to conduct a three-dimensional analysis of the touch-down to take-off phase in the long jump and to explore the interrelationships between key variables. Fourteen male long jumpers were filmed using three-dimensional methods during the finals of the 1994 (n = 8) and 1995 (n = 6) UK National Championships. Various key variables for the long jump were used in a series of correlational and multiple regression analyses. The relationships between key variables when correlated directly one-to-one were generally poor. However, when analysed using a multiple regression approach, a series of variables was identified which supported the general principles outlined in the two models. These variables could be interpreted in terms of speed, technique and strength. We concluded that in the long jump, variables that are important to performance are interdependent and can only be identified by using appropriate statistical techniques. This has implications for a better understanding of the long jump event and it is likely that this finding can be generalized to other technical sports skills.     

The influence of Cardan rotation sequence on angular orientation data for the lower limb in the soccer kick

Abstract

The influence of the Cardan rotation sequence on the orientation angles for joints is well known but has not been explored for dynamic sports movements. The purpose of this study is to establish the influence of Cardan rotation sequence on the orientation angles of the ankle, knee, and hip of the support leg and pelvis during dynamic sports movements, typified by a maximal instep kick in soccer. We found that: (a) the X (flexion/extension) axis rotations provide data that are robust for any sequence used other than the YXZ sequence, although the Y (abduction/adduction) and Z (internal/external) axes rotations are variable in both shape and offset magnitude; (b) the preferred rotation sequence is either XYZ or XZY for dynamic sports movements, although for the soccer kick the XYZ rotation sequence has been widely used and so this is recommended as a standard; and (c) most uncertainties exist in the Y and Z axes and are most apparent at the beginning of the movement. Where uncertainty exists in identifying Y and Z axes orientations, the integrated angular velocity may be considered as an alternative to determine the relative changes in segment orientation.     

Convergence of Sequences and Series 2: Interactions Between Nonvisual Reasoning and the Learner’s Beliefs about their own Role

This paper examines the work of students who, when reasoning about real analysis, do so almost exclusively by means of verbal and algebraic reasoning, and tend not to incorporate visual images into their work. It examines the work of students from two parallel courses of introductory real analysis, whose reasoning ranges from those who introduce definitions appropriately and work with them competently, to those who cannot recall definitions and appear to manipulate notation without regard for its reference. It presents a theory that relates the differences to students expectations regarding their role as learners of mathematics. Throughout, the argument is illustrated with interview data from which the theory was inductively generated.