Although today's ski waxing chemicals and micro-machining techniques of the ski base are highly sophisticated, objective procedures for testing and verification of the results have not yet been developed and evaluation is based on comparison of subjective experience. The purpose of the present study was thus to compare different setups for testing the glide of cross-country skis. Two differently waxed ski pairs were tested for glide inside a ski tunnel. Inertial measurement units (IMUs) were attached to each ski; instantaneous velocities monitored by three different speed-traps; the velocities during the acceleration phase determined by Doppler radar. Kinetic, potential and total energy, giving the energy dissipation, were calculated for four representative trials during the acceleration phase. No reliable data were obtained from the IMUs due to high drift. The mean maximal velocity for the two ski pairs were 6.97, s = 0.09 and 6.70, s = 0.09 m·s − 1, respectively. Higher differences between the skis were identified during the retardation phase compared to the acceleration phase. The mean difference between the velocities determined by the speed-trap and Doppler radar was 0.6, s = 1%, demonstrating that the latter provides accurate data for evaluation of gliding characteristics and performance. However, theoretical confirmation of the friction coefficient, on the basis of data provided by Doppler radar and energy calculations requires exact measurements of the inclination and topography of the track in question. © 2015 Taylor & Francis.

This study aimed to profile the activity patterns of elite downhill (DH) mountain bikers during off-road descending, and to determine the influence of course types on activity patterns. Six male elite DH mountain bikers (age 20 ± 2 yrs; stature 178.8 ± 3.1 cm; body mass 75.0 ± 3.0 kg) performed single runs on one man-made (MM) and one natural terrain (NT) DH courses under race conditions. A 5 Hz global positioning systems (GPS) unit, including a 100 Hz triaxial accelerometer, was positioned in a neoprene harness between the C7 and T2 vertebrae on each rider. GPS was used to determine the temporal characteristics of each run for velocity, run time, distance, effort, heart rate (HR), rider load (RLd) which reflects instantaneous rate of change in acceleration, and accumulated rider load (RLdAcc), which reflects change in acceleration over the event duration. Significant differences were found between NT and MM courses for mean velocity (p<.001), peak velocity (p=.014), mean RLd (p=.001) and peak RLd (p=.002). Significant differences were also found both within and between courses for all velocity parameters, when analysed by intensity zone (p<.05). No significant differences were found between courses for HR parameters by zone, though significant differences were revealed between HR zones within courses (p<.05). This study indicates that course terrain has a significant impact on the activity profiles of DH and that GPS can provide a practical means of monitoring these differences in activity.

Background:This study examined the effects of different levels of compression (0, 20 and 40 mmHg) produced byleg garments on selected psycho-physiological measures of performance while exposed to passive vibration (60 Hz,amplitude 4-6 mm) and performing 3-min of alpine skiing tuck position.Methods:Prior to, during and following the experiment the electromygraphic (EMG) activity of different muscles,cardio-respiratory data, changes in total hemoglobin, tissue oxygenation and oscillatory movement ofm. vastuslateralis, blood lactate and perceptual data of 12 highly trained alpine skiers were recorded. Maximal isometric kneeextension and flexion strength, balance, and jumping performance were assessed before and after the experiment.Results:Thekneeangle(−10°) and oscillatory movement (−20-25.5%) were lower with compression (P<0.05inall cases). The EMG activities of thetibialis anterior(20.2-28.9%),gastrocnemius medialis(4.9-15.1%),rectus femoris(9.6-23.5%), andvastus medialis(13.1-13.7%) muscles were all elevated by compression (P< 0.05 in all cases).Total hemoglobin was maintained during the 3-min period of simulated skiing with 20 or 40 mmHg compression,but the tissue saturation index was lower (P< 0.05) than with no compression. No differences in respiratory parameters,heart rate or blood lactate concentration were observed with or maximal isometric knee extension and flexionstrength, balance, and jumping performance following simulated skiing for 3 min in the downhill tuck positionwere the same as in the absence of compression.Conclusions:These findings demonstrate thatwith leg compression, alpine skiers could maintain a deeper tuckposition with less perceived exertion and greater deoxygenation of thevastus lateralismuscle, with nodifferences in whole-body oxygen consumption or blood lactate concentration. These changes occurred withoutcompromising maximal leg strength, jumping performance or balance. Accordingly, our results indicate that theuse of lower leg compression in the range of 20-40 mmHg may improve alpine skiing performance by allowing adeeper tuck position and lowering perceived exertion.

Alpine ski race helmets are subjected to multiple impacts during a race caused by the skiers hitting the gates on their way down the course. This study investigated the difference between expanded polystyrene (EPS) and expanded polypropylene (EPP) cores in alpine ski race helmets when subjected to repetitive violence, caused by alpine slalom gates. A special test rig was developed where a rotating slalom pole impacted the helmets with a velocity of 13.3 m·s^− 1. All helmets (six EPS and six EPP) were attached to a headform, monitored with a triaxial accelerometer at the center of mass. Each helmet sustained 1000 impacts and acceleration data were collected around every 200 impacts. No significant differences were observed between the first hit and after 1000 hits for either the EPS or the EPP helmets. However, the total group mean acceleration and mean peak acceleration were 15% and 16% higher, respectively, for the EPS series compared with the EPP series. Also, all EPS helmets showed cracked cores after 1000 impacts compared with 1 cracked EPP core. Findings suggest that EPP cores might be more suitable for absorbing multiple low impacts caused by alpine gates and that repeated violence is a relevant parameter to consider when constructing alpine ski race helmets.

The aim of the study was to develop an objective classification method for cross-country ski poles. A test device was designed to expose different pole models to maximal loading and impact tests. A load cell measured the axial forces in the pole shafts, and a laser distance meter measured shaft deflection when a load was applied via the wrist strap. In the loading tests, each shaft reached a plateau where no more force could be transferred. This maximal force transfer (MFT) value was a characteristic measure for flexural rigidity and thereby also strength. The developed test method enables a loading that is more similar to real-life skiing than a standard three-point bending test. Results show that the introduction of shaft indices for buckling strength is beneficial for comparison purposes. The MFT is a relevant parameter used in the characterization of poles. © 2013 International Sports Engineering Association.