ERGOMETER ROWING 'PERFORMANCE IMPROVES OVER 2000 M WHEN USING A STEEPER FOOT·STRETCHER ANGLE

The effect of changing foot-stretcher angle on a rowers' mechanics, power output and 2000 m race ergometer performance time were examined. Eight male and seven female national rowers completed a 2000 m rowing race on three consecutive days with the footstretcher angle set to 36°, 41° (currently used angle) or 46°. The Concept 11' ergometer was instrumented to measure normal force under the feet, handle force and seat position. Concept 11 ergometer power output improved when the foot-stretcher angle was increased from 36° to 46°. The magnitude of the effect was related to gender as at 46° the mean improvement for experienced males was 2.4% and for experienced females was 0.8%

RELIABILITY OF POWER OUTPUT DURING ROWING CHANGES WITH ERGOMETER TYPE AND RACE DISTANCE

The percent standard error of measurement (%SEM) in performance of fifteen national level rowers was determined for five repeated 500 m and two repeated 2000 m races on a Concept 11 and RowPerfect ergometer. The %SEM in mean power between 5 x 500 m races, regardless of gender, was 2.8% (95% CL = 2.3 to 3.4%) for the Concept 11 ergometer and 3.3% (95% CL = 2.5 to 3.9%) for the RowPerfect ergometer. Over 2000 m the "loSEM in mean power was 1.3% (95% CL 0.9 -2.9%) for the Concept 11 ergometer and 3.3% (95% CL 2.2 -7.0%) for the RowPerfect ergometer. The results highlight an increase in %SEM during: (1) performance races of less than 2000 m on the Concept 11 ergometer, and (2) performance races on the RowPerfect ergometer compared with the Concept II ergometer over 500 m and 2000 m

Using stiffness to assess injury risk:comparison of methods for quantifying stiffness and their reliability in triathletes

Background: A review of the literature has indicated that lower body stiffness, defined as the extent to which the lower extremity joints resists deformation upon contact with the ground, may be a useful measure for assessing Achilles injury risk in triathletes. The nature of overuse injuries suggests that a variety of different movement patterns could conceivably contribute to the final injury outcome, any number and combination of which might be observed in a single individual. Measurements which incorporate both kinetics and kinematics (such as stiffness) of a movement may be better able to shed light on individuals at risk of injury, with further analysis then providing the exact mechanism of injury for the individual. Stiffness can be measured as vertical, leg or joint stiffness to model how the individual interacts with the environment upon landing. However, several issues with stiffness assessments limit the effectiveness of these measures to monitor athletes’ performance and/or injury risk. This may reflect the variety of common biomechanical stiffness calculations (dynamic, time, true leg and joint) that have been used to examine these three stiffness levels (vertical, leg and joint) across a variety of human movements (i.e. running or hopping) as well as potential issues with the reliability of these measures, especially joint stiffness. Therefore, the aims of this study were to provide a comparison of the various methods for measuring stiffness during two forms of human bouncing locomotion (running and hopping) along with the measurement reliability to determine the best methods to assess links with injury risk in triathletes. Methods: Vertical, leg and joint stiffness were estimated in 12 healthy male competitive triathletes on two occasions, 7 days apart, using both running at 5.0 ms−1 and hopping (2.2 Hz) tasks. Results: Inter-day reliability was good for vertical (ICC = 0.85) and leg (ICC = 0.98) stiffness using the time method. Joint stiffness reliability was poor when assessed individually. Reliability was improved when taken as the sum of the hip, knee and ankle (ICC = 0.86). The knee and ankle combination provided the best correlation with leg stiffness during running (Pearson’s Correlation = 0.82). Discussion: The dynamic and time methods of calculating leg stiffness had better reliability than the “true” method. The time and dynamic methods had the best correlation with the different combinations of joint stiffness, which suggests that they should be considered for biomechanical screening of triathletes. The knee and ankle combination had the best correlation with leg stiffness and is therefore proposed to provide the most information regarding lower limb mechanics during gait in triathletes

INCREASES IN JOINT RANGE OF MOTION WITH THE BODYWALLTM SYSTEM

Flexibility has important implications in terms of sporting performance, health and fitness, and general movement function. The BodywallTM is a new training tool developed to help improve joint range of motion. This study aimed to determine the effectiveness of the BodywallTM system in improving joint range of motion. Forty-five subjects from the general active population were assigned to one of three groups (BodywallTM stretching; control stretching; no stretching) and measured for joint range of motion before and after a six-week intervention period. The two stretching groups both produced significant increases in joint range of motion, with the BodywallTM group showing greater improvement. No changes in range of motion were seen in the non-stretching group

CARRYING A BALL CAN INFLUENCE SIDESTEPPING MECHANICS IN RUGBY

Sidestepping mechanics have been implicated as a risk factor for knee injury in rugby. Carrying a ball is proposed to alter movement patterns. Therefore the purpose of the study was to examine the effects of sidestepping with a ball compared to sidestepping without a ball on lower-extremity biomechanics in male rugby athletes. Three-dimensional kinematics of 18 male rugby athletes were recorded during a maximal effort 45° sidestepping task without and with a ball. Sidestepping with a ball resulted in 15% greater knee adduction angle during weight acceptance and 18% greater hip adduction angle during peak pushoff than without a ball. Future biomechanical evaluations of athletes require the inclusion of the ball specific to the sport to ensure accurate interpretation of movement patterns

ANTHROPOMETRY AND STRENGTH PREDICTORS OF GRINDING PERFORMANCE IN AMERICA'S CLIP SAILORS

This study aimed to determine what anthropometric and strength factors could predict performance in America's Cup grinding. Eleven male America's Cup sailors were measured for 42 anthropometric dimensions, and bench pull strength, and their power output was obtained from repeated eight-second maximal bursts of high load backwards grinding. Strength and body mass had the highest relationships with grinding performance. Stepwise regression analysis indicated that strength was the major determinant in grinding ability, explaining 64% of the known variance in grinding performance. Total arm length and total leg length were the best anthropometric predictors of performance, each explaining 9% of the remaining variance

AMERICA'S CUP GRINDERS' POWER OUTPUT CAN BE IMPROVED WITH A BIOMECHANICAL TECHNIQUE INTERVENTION

Grinding provides the power behind tacking and gybing, where the yacht crosses the wind to change direction. This study evaluated the effect of a technique intervention on grinding performance. Ten America's Cup grinders were assessed, via videoed joint kinematics and grinder ergometer power output, before and after a technique intervention based on biomechanical principles. Anthropometric measures were obtained from each grinder using ISAK protocols. Maximal strength was assessed using 1 RM bench pull. The intervention produced a 4.7% increase in mean power output (p = 0.012). Regression analysis indicated predictors for grinding performance were COM. position and maximal strength

TEST-RETEST RELIABILITY OF SELECTED ERGOMETER GRINDING PERFORMANCE MEASURES

Reliability of grinding performance on a custom-built ergometer was assessed using 18 highly trained America’s Cup sailors. Sixteen grinding conditions varied by load, deck heel (tilt), and grinding direction (forward or backward) were examined. Performance measures were peak power (W) and external work over five seconds (kJ). Statistics were difference in mean (Mdiff), standard error of measurement (SEM) and intra-class correlation coefficients (ICC). External work (SEM = 1.6-6.9%; ICC = 0.91-0.99) was more reliable than peak power (SEM = 1.3-9.6%; ICC = 0.84-0.99). Performance was more consistent when varied by load than by heel condition, and was most reliable in lighter load conditions. Within heel conditions, downhill-uphill tilt was more reliable than right-left tilt. Grinding direction did not appear to affect performance reliability

The Influence of Head Impact Threshold for Reporting Data in Contact and Collision Sports: Systematic Review and Original Data Analysis

- Background - Head impacts and resulting head accelerations cause concussive injuries. There is no standard for reporting head impact data in sports to enable comparison between studies. - Objective - The aim was to outline methods for reporting head impact acceleration data in sport and the effect of the acceleration thresholds on the number of impacts reported. - Methods - A systematic review of accelerometer systems utilised to report head impact data in sport was conducted. The effect of using different thresholds on a set of impact data from 38 amateur senior rugby players in New Zealand over a competition season was calculated. - Results - Of the 52 studies identified, 42 % reported impacts using a >10-g threshold, where g is the acceleration of gravity. Studies reported descriptive statistics as mean ± standard deviation, median, 25th to 75th interquartile range, and 95th percentile. Application of the varied impact thresholds to the New Zealand data set resulted in 20,687 impacts of >10 g, 11,459 (45 % less) impacts of >15 g, and 4024 (81 % less) impacts of >30 g. Discussion Linear and angular raw data were most frequently reported. Metrics combining raw data may be more useful; however, validity of the metrics has not been adequately addressed for sport. Differing data collection methods and descriptive statistics for reporting head impacts in sports limit inter-study comparisons. Consensus on data analysis methods for sports impact assessment is needed, including thresholds. Based on the available data, the 10-g threshold is the most commonly reported impact threshold and should be reported as the median with 25th and 75th interquartile ranges as the data are non-normally distributed. Validation studies are required to determine the best threshold and metrics for impact acceleration data collection in sport. Conclusion Until in-field validation studies are completed, it is recommended that head impact data should be reported as median and interquartile ranges using the 10-g impact threshold