Influence of wheel size on muscle activity and tri-axial accelerations during cross-country mountain biking

ABSTRACT

This study aimed to investigate the influence of different mountain bike wheel diameters on muscle activity and whether larger diameter wheels attenuate muscle vibrations during cross-country riding. Nine male competitive mountain bikers (age 34.7 ± 10.7 years; stature 177.7 ± 5.6 cm; body mass 73.2 ± 8.6 kg) participated in the study. Riders performed one lap at race pace on 26, 27.5 and 29 inch wheeled mountain bikes. sEMG and acceleration (RMS) were recorded for the full lap and during ascent and descent phases at the gastrocnemius, vastus lateralis, biceps brachii and triceps brachii. No significant main effects were found by wheel size for each of the four muscle groups for sEMG or acceleration during the full lap and for ascent and descent (P > .05). When data were analysed between muscle groups, significant differences were found between biceps brachii and triceps brachii (P < .05) for all wheel sizes and all phases of the lap with the exception of for the 26 inch wheel during the descent. Findings suggest wheel diameter has no influence on muscle activity and vibration during mountain biking. However, more activity was observed in the biceps brachii during 26 inch wheel descending. This is possibly due to an increased need to manoeuvre the front wheel over obstacles.     

How does a physical education teacher become a health and physical education teacher?

The purpose of this study is to explore what the role of a health and physical education (HPE) specialist teacher in the primary school entails. The new Australian Curriculum: HPE Framework requires schools and teachers to implement the HPE key learning area. Many self-perceived physical education (PE) teachers have voiced concern about not knowing how they go about this. This research investigates ‘How PE teachers best become HPE teachers?’ We are reminded by Kirk that this is not the first time teachers have implemented this very change in Australia. Many similarities can be drawn between the recent national Australian Curriculum: HPE and the 1994 HPE National Statement and Profile, which provided a foundation for the construction of the 1999 Queensland HPE (P-10) Syllabus. As recommended by Kirk this study ‘look[s] to the past for lessons about the present and where we might be heading in the future’, by investigating school responses to the 1999 Queensland HPE (P-10) syllabus and curriculum documents. Within the constructionist paradigm, an interpretivist study was conducted. The methodology chosen to construct meanings through capturing the context of each school was ‘evaluative’ and ‘multiple’ case study. The sites for the three case studies involved: one small; one medium; and one large-sized Brisbane Catholic Education primary school. The three case studies were selected as representative of different demographics and the methods engaged so as to enable precision of details were semi-structured interviews, reflective journal, observations and document analysis. Data gathered suggest that enacting the HPE key learning area is very achievable. Implementation is enhanced by HPE leadership, underpinned by clear communication. More so, barriers can be overcome through professional development and support. This study is significant nationally, and the findings may be of wider international interest. It models how school leaders can optimise the health opportunities within their context and models how PE teachers can become HPE teachers.     

Partial swing golf shots: scaled from full swing or independent technique?

Abstract

During practice and competition, golfers are required to use submaximal effort to hit the ball a given distance, i.e., perform a partial shot. While the full golf swing has undergone extensive research, little has addressed partial shots and the biomechanical modifications golfers employ. This study investigates the biomechanical changes between full and partial swings, and determines if the partial swing is a scaled version of the full swing. Using a repeated measures design, 13 male golfers completed a minimum of 10 swings in the full and partial swing conditions, whilst club, ball, kinematic, and kinetic parameters were recorded. Large and statistically significant reductions in body motion (centre of pressure ellipse: 33.0%, p = 0.004, d = 2.26), combined with moderate reductions in lateral shift (25.5%, p = 0.004, d = 0.33) and smaller reductions in trunk rotation (arm to vertical at top of backswing: 14.1%, p = 0.002, d = 2.58) indicate golfers favour larger reductions in proximal measures, combined with diminished reductions as variables moved distally. Furthermore, the partial swing was not found to be a scaled version of the full swing implying a new approach to coaching practices might be considered.     

The relationships between exercise intensity, heart rate, and blood pressure during an incremental isometric exercise test

Currently, it is not possible to prescribe isometric exercise at an intensity that corresponds to given heart rates or systolic blood pressures. This might be useful in optimizing the effects of isometric exercise training. Therefore, the aim of this study was to explore the relationships between isometric exercise intensity and both heart rate and systolic blood pressure during repeated incremental isometric exercise tests. Fifteen participants performed seated isometric double-leg knee extension, during which maximum voluntary contraction (MVC) was assessed, using an isokinetic dynamometer. From this, a corresponding peak electromyographic activity (EMG(peak)) was determined. Subsequently, participants performed two incremental isometric exercise tests (at least 48 h apart) at 10, 15, 20, 25, and 30% EMG(peak), during which steady-state heart rate and systolic blood pressure were recorded. In all participants, there were linear relationships between %EMG(peak) and heart rate (r at least 0.91; P < 0.05) and between %EMG(peak) and systolic blood pressure (r at least 0.92; P < 0.05). Also, when repeated tests were compared, there were no differences in the slopes (P > 0.50) or elevations (P > 0.10) for either of the relationships. Therefore, these linear relationships could be used to identify isometric exercise training intensities that correspond to precise heart rates or systolic blood pressures. Training performed in this way might provide greater insight into the underlying mechanisms for the cardiovascular adaptations that are known to occur as a result.     

Reliability and concurrent validity of light's retention scale

Light's Retention Scale was completed for 123 candidates to repeat the first grade. These same first-grade children were tested with a number of measures of maturity, including achievement tests, measures of intellectual functioning, visual-motor integration, self-concept, and physical maturity. Results indicated that Light's total score is not sufficiently reliable and has little concurrent validity for making retention decisions. The total score should never be used.     

Instruments for evaluating school psychologists' functioning and service

The evaluation of school psychological services is both a responsibility and an opportunity too long ignored. Unique problems must be overcome in evaluating school psychologists, but the task is not insurmountable. This paper describes and presents examples of five data collection devices which can be used in the evaluation effort: the vignette-based questionnaire, the role-model questionnaire, the services received questionnaire, the teacher interview, and nonobtrusive measurement.     

Can computer-aided instruction accommodate all learners equally?

This exploratory study investigated the impact of learning styles on human-computer interaction. Seventy learners who were enrolled in a large urban post-secondary institution participated in the study. The Gregorc Style Delineator™ was used to obtain subjects' dominant learning style scores. Results indicated that patterns of learning indices did not differ significantly based on subjects' dominant learning style. Five of the six measures indicating human-computer interaction behavior were not significant at the p < 0.05 level. However, learning styles significantly affected learning outcomes, as indicated by a significant main effect, as well as an interaction effect between dominant learning style and achievement scores. It would appear that Abstract Random learners may be at-risk for doing poorly with certain forms of computer-aided instruction. Based on the review of literature and results found in this study, it was concluded that computer-aided instruction may not be the most appropriate method of learning for all students.