The Relationship Between Stride Rates, Lengths and Body Size and their Affect on Elite Triathletes’ Running Performance During Competition

Previous research has suggested that a degree of predictability exists in the relationship between self-selected running stride rates (SR) and stride lengths (SL) with measures of body size such as mass, height and limb lengths. Significant correlations have also been revealed between these body size measures and performance and between SL and performance. However, there is also evidence to suggest that triathlon performance may be related to maintaining a longer SL during the final run. Hence, the aim of this investigation was to examine whether there was any relationship between SR and SL, with body masses and heights of senior elite triathletes during the run stage of a triathlon. The SRs and SLs of 37 male senior elite Triathlon World Championships competitors were analysed via videography and Video Expert II Coach. These values were correlated with the athletes’ body masses and heights (p\u3c0.01). The results indicated a limited relationship between height and mass with SR in the early stages of the run. However, a significant, positive correlation existed between SL and height at all points from 3 km to the end of the run. Those triathletes who were taller used longer strides. Further research is warranted to examine the effects of cycling on the subsequent run discipline during triathlon and if body size and shape of triathletes have evolved as the young sport of triathlon develops

Cadence, Stride Rate and Stride Length During Triathlon Competition

Triathlon research shows cycling alters the physiological response of subsequent running but, at present, biomechanical changes are unresolved. This study examined cycling cadence and running stride rate (SR) and length (SL) used by senior elite triathletes during competition. These variables were then compared to running and triathlon performance. Data from 51 elite male World Championships triathletes were analysed via video recordings and Video Expert II Coach. Triathletes revealed consistent cadences throughout the majority of the cycle (96.8 +2.7 rpm) and run (90.9 +2.4 rpm) disciplines. However, a cadence increase (99.6 +5.7 rpm) was recorded at the completion of the cycle prior to running. Running SR and SL was significantly lower at the end of the run indicating a level of fatigue (p\u3c0.01). Running SL was significantly and positively correlated with running and triathlon performance (p\u3c0.01) suggesting those that could maintain a longer SL had a faster run and better final finishing position

Home Swimming Pool Design to Improve Diving Safety

This study sought to establish home swimming pool design guidelines to minimize risk of diving injury. Using a qualitative design, interviews with representatives of home pool companies were analyzed and common themes were determined. Pool company display centers and advertising materials were also examined. The typical in-ground fiberglass home pool was described by manufacturers as 8m in length, with a constant gradient of 0.9m to 1.8–2.0m deep. Comparisons between this profile and the underwater pathways of young adults in previous studies by the authors showed that, if the dives had been performed in this typical pool, impact would have occurred for some dives. Safety features such as depth markings and signage were absent from all pools. We concluded that recreational swimmers with limited diving skills are at risk of diving injury in the typical home swimming pool. Recommendations are provided of strategies that can be implemented by home pool owners to improve pool safety

MORPHOLOGY AND HYDRODYNAMIC RESISTANCE IN YOUNG SWIMMERS

Morphology and hydrodynamic drag were measured of 6 males and 6 females, from each of the 9, 11 and 13 yr age groups. Net forces were examined when towing swimmers while prone streamlined gliding and flutter kicking at 1.3 to 2.5 ms-1. The passive drag force at 1.9, 2.2 and 2.5 ms-1 increased with age and anthropometry, but no changes were found at 1.3 and 1.6 ms-1. Stepwise regression revealed passive drag best predicted net active drag at velocities of 1.3, 1.9, 2.2 and 2.5 ms-1. Results supported the Froude number theory that increased height will reduce wave-making drag

Swim Positioning and its Influence on Triathlon Outcome

Questions have been raised regarding which of the three legs of a triathlon influences the final finishing position. Some coaches subjectively believe that the swim and run are more important than the cycle, especially since the introduction of drafting during the cycle. This study analysed race position shifts between each of the three disciplines to assess the importance of the swim finish position and final finish position during draft legal Olympic distance triathlon events. Ten male and 10 female triathlon world cup events during one season were analysed. The results suggested that the triathlon swim leg is important because the winner exited the water in the first pack in 90% of elite male and 70% of elite female races. Correlations were also derived from finishing order for the whole triathlon and a finishing order that included the swim only, cycle only or run only time. For men, the average correlations for final finishing order with each of the swim, cycle and run, respectively, were 0.49, 0.67 and 0.86 and for the women; average correlations were 0.39, 0.67 and 0.85. Hence, this indicated that it was important to exit the water in the first pack and run well after cycling to achieve a successful final finishing position

OPTIMISING KINETICS IN THE FREESTYLE FLIP TURN PUSH-OFF

INTRODUCTION: Turning technique is an important component in swimming performance with turn times positively correlating with final event time. However, little is known about the mechanics of an effective turn. This study sought to provide an exploratory analysis of how various kinetic and hydrodynamic variables during wall push-off are related to the wall exit velocity. METHODS: Thirty experienced male swimmers with body types of within one SD of the mean for selected anthropometric parameters reported for elite male adult swimmers (Mazza et al., 1994) were recruited for the study. During three freestyle flip turns, selected kinetic, hydrodynamic and kinematic variables of the wall pushoff were recorded. The wall push-off phase was measured from the point of maximum knee flexion during wall contact until the feet left the wall. Kinetics were recorded via a 2D vertically mounted forceplate which recorded peak push-off force and total impulse. The acceleration of each swimmer’s centre of gravity (CG) and wall exit velocity of the CG were calculated from underwater videography. Hydrodynamic peak drag force and drag impulse were calculated from the kinetic and kinematic data using a derivative of Newton’s second law. RESULTS: A stepwise regression was performed with wall exit velocity as the criterion variable and push-off time, peak propulsive force, total propulsive impulse, peak drag force, and total drag impulse as the independent variables. The stepwise regression yielded peak drag force, peak propulsive force and push-off time in the equation, with beta values indicating that the peak drag force carried the highest weighting of the three variables. CONCLUSIONS: The results of the stepwise regression indicated that an optimal combination of a low peak drag force, high peak propulsive force and increased wall time produced the fastest wall exit velocity. The inclusion of the peak drag force in the regression equation as the most important predictor of wall exit velocity highlights the importance of drag in turning technique. Factors such as very high push-off forces and exaggerated movements during wall push-off may lead to higher peak drag forces which, in turn, could be detrimental to the overall turning performance

A retrospective evaluation of assessment in physical education

Assessment and reporting in Health and Physical Education (HPE) continues to evoke debate and confusion amongst Physical Education (PE) professionals. There is genuine concern that without objective measurement and evaluation of student learning and achievement, PE programmes could be placed in a vulnerable position during times of programme review, budget cuts and school restructuring. This paper revisits some of the fundamental assessment issues in PE and suggests guidelines for teachers to consider. A review of past practices reveals little consensus regarding the educational outcomes that should be measured, the levels of attainment expected to achieve a particular achievement grade, what degree of improvement or skill level was reached, and how PE teachers could derive and report meaningful assessment of student outcomes. An increase in public awareness of education has further emphasised accountability in all areas, including PE and has reinforced the demand for valid student measurement, evaluation and overall assessment. The problems identified through this evaluation were a catalyst in the development of an outcomesfocused approach by the curriculum authorities in Western Australian schools. Keywords: assessment, reporting, physical education South African Journal for Research in Sport, Physical Education and Recreation Vol. 27(1) 2005: 1-1

Technical note : the use of subject derived scale factors for one-camera 2D analysis in underwater swimming

This technical note describes a comparison of relative errors in one-camera 2D underwater motion annalysis when using two different control structure methods for calibrating video images. Eleven male and six female participants performed underwater kicking swim trials. A reference structure of known length and each swimmer's actual (land measured) thigh length were each used to calibrate the movement space from which digitised thigh lengths were calculated for each trial. For each trial, mean thigh lengths calculated using the two methods were then compared to actual thigh length for each swimmer and the differences recorded. Mean differences between actual and computed thigh lengths were shown to be similar. However, the spread of mean differences was much less when the actual thigh length was used for calibration. This result strongly supports the use of thigh length as a more accurate method of calibration for one-camera 2D underwater motion analysis

Kinanthropometric differences between 1997 World championship junior elite and 2011 national junior elite triathletes

OBJECTIVES: In 1997, anthropometry measures were made to determine the body size and shapes of both senior and junior elite triathletes. Since then, the junior event distance has changed and the optimal morphology of participants may have evolved. Thus the objective of this study was to compare the morphology of 1997 World championship junior elite triathlon competitors with junior elite competitors in 2011. DESIGN: Comparative study of junior elite triathlete kinanthropometry. METHODS: Twenty-nine males and 20 females junior elite competitors in the 1997 Triathlon World Championships underwent 26 anthropometric measurements. Results were compared with 28 male and 14 female junior elite triathletes who competed in the 2011 Australian National Junior Series, as qualifying for 2011 Triathlon World Championships. Comparisons were made on the raw scores, as well as somatotype, and body proportional scores. RESULTS: Both male and female junior elite triathletes in the 2011 group were significantly more ectomorphic than their 1997 counterparts. The 2011 triathletes were also proportionally lighter, with significantly smaller flexed arm and thigh girths, and femur breadths. The 2011 males recorded significantly longer segmental lengths and lower endomorphy values than the 1997 junior males. CONCLUSIONS: Junior elite triathlete morphology has evolved during the past 14 years possibly as a result of changing race distance and race tactics, highlighting the importance of continually monitoring and updating such anthropometric data