Physiological demands of downhill mountain biking

Abstract

Mountain biking is a popular recreational pursuit and the physiological demands of cross-country style riding have been well documented. However, little is known regarding the growing discipline of gravity-assisted downhill cycling. We characterised the physiological demands of downhill mountain biking under typical riding conditions. Riding oxygen consumption ([Vdot]O₂) and heart rate (HR) were measured on 11 male and eight female experienced downhill cyclists and compared with data during a standardised incremental to maximum ([Vdot]O_2max) exercise test. The mean [Vdot]O₂ while riding was 23.1 ± 6.9 ml · kg^?1 · min^?1 or 52 ± 14% of [Vdot]O_2max with corresponding heart rates of 146 ± 11 bpm (80 ± 6% HRmax). Over 65% of the ride was in a zone at or above an intensity level associated with improvements in health-related fitness. However, the participants’ heart rates and ratings of perceived exertion were artificially inflated in comparison with the actual metabolic demands of the downhill ride. Substantial muscular fatigue was evident in grip strength, which decreased 5.4 ± 9.4 kg (5.5 ± 11.2%, P = 0.03) post-ride. Participation in downhill mountain biking is associated with significant physiological demands, which are in a range associated with beneficial effects on health-related fitness.     

Increased shoe bending stiffness increases sprint performance

The purposes of this investigation were to determine if increasing the bending stiffness of sprint shoes increases sprinting performance and to determine whether simple anthropometric factors can be used to predict shoe bending stiffness for optimal performance. Thirty-four athletes were tested using four different shoe conditions--a standard condition consisting of their currently used footwear and three conditions where the bending stiffness was increased systematically. The sprinters performed maximal effort 40 m sprints and their sprint times were recorded from 20 to 40 m. On average, increasing the shoe bending stiffness increased sprint performance. The stiffness each athlete required for his or her maximal performance was subject specific but was not related to subject mass, height, shoe size or skill level. It is speculated that individual differences in the force-length and force-velocity relationships of the calf muscles may influence the appropriate shoe stiffness for each athlete to obtain their maximal performance.     

Inquiry-based civil discourse education

Course: Civil discourse, argumentation, debate, persuasion, political communication

Objectives: This unit activity will help students build an understanding of civil discourse and its function in society. Students will: (1) increase their capacity to examine arguments critically, (2) enhance their own ability to self-reflect critically, and (3) improve their ability to engage in civil discourse. This activity will employ inquiry-based learning strategies to apply students’ understanding of civil discourse in a dialogue with the broader campus community by partnering with campus media to develop and publish original opinion-editorial pieces.     

Power Plays: Problems With Empowerment in a Critical Pedagogy

In response to a Critical Notice published in these pages by Roberts (Vol. 32/1,2001), this article notes several specific reservations with regard to Shor's model of empowerment as outlined in When Students Have Power (1996). The original book documents one critical educator's attempts at negotiating power in a college classroom setting. While respecting Shor's bold efforts to craft a liberatory pedagogy, the author draws attention to specific inconsistencies and shortfalls in both the theory and practice described. The article offers a critical examination of problematic features of Shor's classroom practices and research methodology, in addition to concerns with both substantive and stylistic elements of his written account.     

Mapping the development of a new MA programme in higher education: comparing privately held perceptions of a public endeavour

After spending a year working on the development of a new online Master’s programme in higher education, members of the development team were interviewed to reveal their thoughts about the nature of the programme. The dialogue of each interview was summarised as a concept map. Analysis of the resulting maps included a modified Bernsteinian analysis of the focus of the concepts included in terms of their semantic gravity (i.e. closeness to context) and the degree of resonance with the underpinning regulative discourse of the programme. Data highlight a number of potential issues for programme delivery that centre around the use of appropriate language to manage student expectations in relation to the process of learning and the emotional responses this can stimulate, as well as the tensions that can be foregrounded between the demands of teaching and research within a university environment.     

Effects of Pre‐structuring Discussion Threads on Group Interaction and Group Performance in Computer‐supported Collaborative Argumentation

This study examined the effects of pre‐structuring discussion threads on group performance in computer‐supported collaborative argumentation where students labeled their messages as arguments, challenges, supporting evidence, and explanations on a threaded discussion board. In the pre‐structured group students were required to post supporting and opposing arguments to designated and separate discussion threads. In the control group no discussion threads were designated for posting supporting and opposing arguments. The mean number of challenges elicited per argument was 64% greater with pre‐structured threads (ES = +.47). No significant differences were found in the mean number of counter‐challenges, supporting evidence, and explanations posted in reply to challenges. The findings suggest that prestructured discussion threads can increase the frequency of argument→challenge exchanges needed to initiate critical discourse.     

The effect of translational and rotational traction on lower extremity joint loading

Previous studies have linked footwear traction to lower extremity non-contact injury; however, these studies mainly focussed on rotational traction exclusively. While studies have shown that increases in traction lead to increases in joint loading, represented by joint moments, these studies failed to determine how the individual components of rotational and translational traction affect joint loading. Therefore, this study investigated how each component of traction independently affects lower extremity joint loading. Traction testing was performed using a robotic testing machine on three shoes that had independent alterations of translational and rotational traction. All testing was conducted on a sample piece of artificial turf. Kinematic and kinetic data were then collected on 10 athletes performing two cutting movements in each shoe condition. As rotational and translational traction were independently altered, decreased rotational traction led to significant decreases in transverse and frontal plane joint loading at the ankle and knee joints, while increases in translational traction led to increases in frontal plane joint loading at the ankle and knee joints. Increases in joint loading in the transverse and frontal planes are one of the possible mechanisms of lower extremity non-contact injury. Both translational and rotational traction can independently alter the joint loading.     

Inclusive and exclusive masculinities in physical education: a Scottish case study

This research examines how adolescent males (ages 16–17 years) construct and experience their masculine identities within the context of physical education (PE). A class of 23 boys and 3 girls from a state secondary school in Scotland were observed over a period of 3 months. During the third month, five of the observed pupils volunteered to take part in a conversation with the lead researcher which was guided by their participation in a repertory grid task. The same five participants also took part in a one-to-one semi-structured interview. The analysis of the evidence revealed that the adolescent pupils internalised and performed an orthodox form of masculinity that centred on strength, pain tolerance and the policing of others. More inclusive masculinities appeared to be emerging, however, the hypermasculine and public nature of the PE environment made it very difficult for the pupils to freely adopt or perform these alternative, more inclusive forms of masculinity. Additionally, pupils who did perform traits associated with inclusive masculinity often exhibited a high degree of social and physical capital. In order to facilitate a culture where all individuals feel free to express their gendered identities, teachers are encouraged to recognise, promote and celebrate multiple masculinities. This could create a safer learning environment for pupils and help prevent identities from being ‘destroyed’ in PE.     

The relationship between extension of the metatarsophalangeal joint and sprint time for 100 m Olympic athletes

Selected kinematic variables of the foot segments and the metatarsophalangeal (MTP) joint were investigated in relation to sprinting performance among 100 m sprint athletes at the 2000 Summer Olympic Games. It was hypothesized that the kinematics of the MTP joint, and forefoot and rearfoot segments, are related to sprint performance for both male and female athletes. Kinematic sagittal plane data were collected using two digital video cameras recording at 120 fields per second. It was determined that faster male sprinters experienced higher maximal rates of MTP extension, and faster female sprinters touch down with higher posterior sole angles and take off with lower posterior sole angles.