Doug Rosemond

Effect of long haul travel on maximal sprint performance and diurnal variations in elite skeleton athletes.

Objective: To quantify the impact of eastward long haul travel on diurnal variations in cortisol, psychological sensations and daily measurements of physical performance. Methods: Five elite Australian skeleton athletes undertook a long haul eastward flight from Australia to Canada (LHtravel), while seven elite Canadian skeleton athletes did not travel (NOtravel). Salivary cortisol was measured on awakening, 60 min and 120 min after awakening. Psychological sensations were measured with a questionnaire, and maximal 30 m sprints were performed once a day between 09:30 and 11:00 h local time. Results: Compared with baseline, average (SD) resting salivary cortisol decreased by 67% immediately after long haul travel (23.43 (5.71) nMol/l) (mean±90% confidence interval) in the LHtravel group (p = 0.03), while no changes were found in the NOtravel group (p = 0.74). There were no significant differences in 30 m sprint time between baseline and post-flight tests in the LHtravel group (p>0.05). The LHtravel group perceived themselves as “jet lagged” for up to 2 days after the flight (p = 0.01 for both midday lunch and evening dinner). Conclusions: Despite a distinct phase change in salivary cortisol rhythmicity and the athletes perceiving themselves as “jet lagged”, minimal disturbances in “one-off” maximal sprinting ability between 09:30 and 11:00 h local time were seen in a group of elite skeleton athletes after long haul eastward travel from Australia to Canada.

Characteristics of the start in women's World Cup skeleton

This study characterizes key elements of the start in elite female World Cup skeleton athletes. The top 20 female competitors in three World Cup races were videotaped within a calibrated space to allow the following components of the start to be quantified: (1) acceleration (velocity at 15-m mark, time to 15-m mark), (2) capacity (time to load, total number of steps to load), and (3) load (velocity at 45-m mark). A correlation analysis was used to establish the relationship between the variables of interest and overall start time (15- to 65-m mark). Velocity at the 15-m mark accounted for 86% of the variance in overall start time at St. Moritz and 85% at Sigulda. A stepwise regression analysis revealed that approximately 89% of the variation in start time could be explained by velocity at the 15-m mark, time to load, and velocity at the 45-m mark. Of the variables analysed in this study, rapid acceleration to attain a high velocity at the 15-m mark was the most important component of a fast overall start time. The importance of the time to load and velocity at the 45-m mark vary according to the different track characteristics.

Development and validation of a method to directly measure the cable force during the hammer throw

The development of cable force during hammer-throw turns is crucial to the throw distance. In this paper, we present a method that is capable of measuring cable force in real time and, as it does not interfere with technique, it is capable of providing immediate feedback to coaches and athletes during training. A strain gauge was mounted on the wires of three hammers to measure the tension in the wire and an elite male hammer thrower executed three throws with each hammer. The output from the gauges was recorded by a data logger positioned on the lower back of the thrower. The throws were captured by three high-speed video cameras and the three-dimensional position of the hammers head was determined by digitizing the images manually. The five best throws were analysed. The force acting on the hammers head was calculated from Newtons second law of motion and this was compared with the force measured via the strain gauge. Qualitatively the time dependence of the two forces was essentially the same, although the measured force showed more detail in the troughs of the force–time curves. Quantitatively the average difference between the measured and calculated forces over the five throws was 76 N, which corresponds to a difference of 3.8% for a cable force of 2000 N.

An acute bout of whole-body vibration on skeleton start and 30-m sprint performance

Abstract Maximal 30-m upright sprinting and bent over, skeleton push performance were examined in five female national team skeleton athletes before and 10 min after an acute bout of whole-body vibration or no vibration. The whole-body vibration was applied at a frequency of 45 Hz with 4-mm displacement for 3×1-min treatments separated by 1 min. All changes in 30-m sprint and skeleton push times before and after whole-body vibration were small or trivial and within the tests’ typical variation (∼3.7% for the skeleton push and ∼3.2% for the upright sprint). Athletes were able to achieve 75–79% of their 30-m upright sprinting velocities when pushing a skeleton sled. These results question the effectiveness of whole-body vibration as an ergogenic aid immediately before performing a maximal upright sprint or skeleton push following a comprehensive warm-up.

An analysis of the relationship between the linear hammer speed and the thrower applied forces during the hammer throw for male and female throwers

The purpose of this study was to investigate the relationship between the cable force and linear hammer speed in the hammer throw and to identify how the magnitude and direction of the cable force affects the fluctuations in linear hammer speed. Five male (height: 1.88 ± 0.06 m; body mass: 106.23 ± 4.83 kg) and five female (height: 1.69 ± 0.05 m; body mass: 101.60 ± 20.92 kg) throwers participated and were required to perform 10 throws each. The hammers linear velocity and the cable force and its tangential component were calculated via hammer head positional data. As expected, a strong correlation was observed between decreases in the linear hammer speed and decreases in the cable force (normalised for hammer weight). A strong correlation was also found to exist between the angle by which the cable force lags the radius of rotation at its maximum (when tangential force is at its most negative) and the size of the decreases in hammer speed. These findings indicate that the most effective way to minimise the effect of the negative tangential force is to reduce the size of the lag angle.

Analysis of the separation angle between the thorax and pelvis, and its association with performance in the hammer throw

The hammer throw is perhaps one of the most misunderstood and difficult events to learn in track and field. Improvements in technique are focused on strategies designed to increase implement release velocity. The purpose of this cross-sectional investigative study was to examine the association between the angle of separation between the thorax and pelvis and performance in the hammer throw. Two male and four female throwers were used to assess positional data of the hammer, thorax, and pelvis. Hammer positional data were used to determine linear hammer speed at release, release angle, and release height. Thorax and pelvis positional data were used to determine thorax rotation relative to the pelvis (separation angle). The association between values of separation angle at key instances and performance was examined. Performance was determined by distance thrown (55.69 ± 3.42 m). Release speeds (24.32 ± 0.70 m/s) were also examined as a contributory factor towards performance and were included to account for instances where throwers released the hammer using sub-optimal release heights and angles which negatively affected distance thrown. The separation angle at its smallest within each turn was found to have a strong negative association with the performance indicators, especially in the first two turns (significant correlates ranged from −0.82 to −0.97). This finding indicates when throwers reduced the separation to a smaller value, performance was enhanced. Separation angle was at its smallest in double support. This suggests that throwers may improve performance by reducing the separation angle during double support phases.