Biomechanical validation of a specific upper body training and testing drill in cross‐country skiing

The aim of this study was to perform a biomechanical validation of a double poling imitation drill on a rollerboard. Six elite cross‐country skiers performed three imitation drill trials at maximal speed at 13° inclination and in double poling on roller skis on a paved road of 3°. Pole and strap forces, elbow and hip angles and EMG activity of eight upper body muscles were measured. Force curves showed similar characteristics, except for impact force occurring only at pole plant in double poling on roller skis. Double poling on a rollerboard includes an eccentric roll‐down phase not appearing in double polling on roller skis. Forces on the rollerboard were similar to those on roller skis. Courses of the elbow angles indicated similar shapes, except for the angle at the start of the propulsion phase and, consequently, during flexion (p < 0.01). Propulsion time and cycle duration were longer and frequency lower on the rollerboard (all p < 0.001). Muscle activities were not significantly different, except for stronger biceps brachii (p < 0.01) and weaker erector spinae activation (p < 0.05) on the rollerboard. Muscle coordination patterns showed similar onset and offset points of each muscle and comparable activations in both activities, except for biceps brachii. Two movement strategies on the rollerboard were found, which led to small differences in measured variables. The biomechanical validity of double poling on a rollerboard can be judged as moderately high, being aware of the differences in some variables that might be considered in training sessions on the rollerboard, particularly when using intervals with high number of repetitions.     

Mathematics education as a ‘design science’

Mathematics education (didactics of mathematics) cannot grow without close relationships to mathematics, psychology, pedagogy and other areas. However, there is the risk that by adopting standards, methods and research contexts from other well-established disciplines, the applied nature of mathematics education may be undermined. In order to preserve the specific status and the relative autonomy of mathematics education, the suggestion to conceive of mathematics education as a design science is made.Revised and extended version of the paper Mathematikdidaktik als design science, published inJournal für Mathematikdidaktik 13 (1992), 55–70. I am indebted to Jerry P. Becker, P. Bender, H. Besuden, W. Blum, E. Cohors-Fresenborg, Th.J. Cooney, L. Führer, H.N. Jahnke, A. Kirsch, G.N. Müller, H._Chr. Reichel, H. Schupp, Ch. Selter, H.-J. Vollrath, J. Voigt, G. Walther and H. Winter for critical remarks to earlier drafts.     

An exploration of trans* kinship as a strategy for student success

Abstract

Although the notion of queer kinship has been well discussed within literature on queer individuals, it has not been used as a lens to make sense of how trans* college students successfully navigate rigidly gender dichotomous collegiate environments. Using interview data from the National Study of LGBTQ Student Success, this study explores the narratives of 18 trans* students concerning their experiences of success in college and the role of queer kinship in supporting their success. Analysis documented three domains of kinship (i.e. material, virtual, and affective), which promoted students’ success.