This paper describes a system that was developed to measure ski pole and roller-ski reaction forces in three dimensions during roller-ski skating. Uni-axial force transducers mounted in the right and left ski poles measure axial loading of the poles. Six transducers in one roller-ski measure biaxial loads beneath the foot. A remote computer stores the amplified transducer signals transmitted from the skier through 100 m cables. Three-dimensional video-graphy determines the orientations of the poles and roller-ski in order to resolve the resultant poling and skating forces into three components. Calibration data suggest that the resolution of the force measurement system is ±3 to 9% of the actual poling and skating forces, respectively. Sample data are presented from a VI skating trial during roller-skiing. These data provide the first glimpse at the major functions of the upper and lower body during roller-ski skating and show how the tool could be used to examine the size and effectiveness of skier-generated forces.
Glenn M. Street and Edward C. Frederick
Martin D. Hoffman, Philip S. Clifford, Božo Bota, Michael Mandli and Gregory M. Jones
A theoretical analysis was used to evaluate the effect of body mass on the mechanical power cost of cross-country skiing and roller skiing on flat terrain. The relationships between body mass and the power cost of overcoming friction were found to be different between cross-country skiing on snow and roller skiing. Nevertheless, it was predicted that the heavier skier should have a lower oxygen cost per unit of body mass for roller skiing, as is the case for snow skiing. To determine whether the theoretical analysis was supported by experimental data, oxygen consumption measurements were performed during roller skiing by six male cross-country ski racers who spanned a 17.3-kg range in body mass. The theoretical analysis was supported by the experimental findings of decreases in oxygen consumption for each kg increase in body mass of approximately 1.0% for the double pole technique, 1.8% for the kick double pole technique, and 0.6% for the VI skate technique.
Stéphane Perrey, Guillaume Millet, Robin Candau and Jean-Denis Rouillon
The purpose of this study was to examine the effects of speed on the stretch-shortening cycle (SSC) behavior during roller ski skating. Ten highly skilled male cross-country skiers roller skied at 4.56, 5.33 m · s–1 and maximal speed using the V2-alternate technique on a flat terrain. Knee and ankle joint kinematics, and EMG of the vastus lateralis (VL) and gastrocnemius lateralis (GL) muscles were recorded during the last 40 s of each bout of roller skiing. Maximal speed was associated with increases in cycle rate combined with decreases in cycle length. For VL, no significant differences were observed for the integrated EMG eccentric-to-concentric ratio (iEMG Ecc/Conc) and for the stretching velocity over the range of speeds. For GL, stretching velocity and iEMG Ecc/Conc were significantly greater at maximal speed. The analysis of GL EMG activity suggests that speed improved GL stiffness so that more elastic energy was stored, a better force transmission occurred, and coupling time decreased. These findings suggest that the efficiency of roller ski skating locomotion may be increased with speed through a better use of the stretch-shortening cycle pattern in the ankle extensors.
Pierre Gervais and Craig Wronko
In the past few years there has been a change from emphasizing the classical cross-country ski technique to introducing the skating technique. Use of the skating stride has led to the adoption of roller skates instead of the ratchet-type roller skis for dryland training. Therefore the question arises as to whether the roller skates simulate the movement pattern observed on snow. This study attempted to answer this question and to evaluate the movement similarity between a newly designed skating-specific roller ski and snow skis in performing the skating stride. The marathon skate was chosen for analysis as it was the most established and consistent skating stride. Biomechanical cinematography was used to acquire a sagittal and anterior view of the skiers. Temporal and angular kinematic data were collected. Both dryland devices approximated the snow skiing pattern, yet it was found that due to the discrepancies in the propulsion phase between the roller skates and the snow skis, the “Nordic Skate” roller skis proved to more closely simulate the on-snow technique.
Nicolas Fabre, Stéphane Perrey, Loïc Arbez and Jean-Denis Rouillon
This study aimed (1) to determine whether paced breathing (synchronization of the expiration phase with poling time) would reduce the metabolic rate and dictate a lower rate of perceived exertion (RPE) than does spontaneous breathing and (2) to analyze the effects of paced breathing on poling forces and stride-mechanics organization during roller-ski skating exercises.
Thirteen well-trained cross-country skiers performed 8 submaximal roller-skiing exercises on a motorized driven treadmill with 4 modes of skiing (2 skating techniques, V2 and V2A, at 2 exercise intensities) by using 2 patterns of breathing (unconscious vs conscious). Poling forces and stride-mechanics organization were measured with a transducer mounted in ski poles. Oxygen uptake (VO2) was continuously collected. After each bout of exercise RPE was assessed by the subject.
No difference was observed for VO2 between spontaneous and paced breathing conditions, although RPE was lower with paced breathing (P < .05). Upper-limb cycle time and recovery time were significantly (P < .05) increased by paced breathing during V2A regardless of the exercise intensity, but no changes for poling time were observed. A slight trend of increased peak force with paced breathing was observed (P = .055).
The lack of a marked effect of paced breathing on VO2 and some biomechanical variables could be explained by the extensive experience of our subjects in cross-country skiing.
Martin D. Hoffman, Philip S. Clifford and Frank Bender
This investigation examined the adjustments made in cycle rate and length to velocity changes during roller skiing with the double pole (DP), kick double pole (KD), and VI skate (VS) techniques. Eight cross-country ski racers roller skied with each technique on a flat track at submaximal and maximal velocities while being videotaped from a lateral view. Increases in submaximal velocities were associated with increases in cycle rate and cycle length for KD and VS but only with increases in cycle rate for DP. Maximal sprint velocities were approximately 7% lower (p < .01) for KD than for DP and VS and were associated with increases (p < .01) in cycle rate for each technique combined with decreases (p < .01) in cycle length for DP and VS. The findings indicate that there are differences among techniques in the manner in which cycle rate and length are adjusted to change submaximal velocity, but each technique relies upon an increase in cycle rate to achieve maximal velocity.
Tom Toolis and Kerry McGawley
) performance. 2 Few studies have assessed the effects of compression garments during cross-country (XC) skiing. Heil and McLaren 3 reported that upper- and lower-body garments led to reductions in heart rate (HR) and blood lactate (BLa) concentration when roller-skiing at various submaximal intensities and
Evgeny B. Myakinchenko, Andrey S. Kriuchkov, Nikita V. Adodin and Victor Feofilaktov
11 km·h −1 (BF), or 12 km·h −1 (BM), or 13 km·h −1 (XC). After that, athletes ran until exhaustion. The same trainers checked the data during supervised training, taking blood lactate measurements 3 to 4 times a year. The field roller-skiing tests with blood lactate measurements showed that the HR
Bent R. Rønnestad, Tue Rømer and Joar Hansen
of our knowledge, the VO 2 in roller-ski skating intervals, involving 4 active limbs with a large muscle mass, have not been investigated. Given the differences in VO 2 kinetics during exercise with a large muscle mass (ie, running) compared with a smaller muscle mass (ie, cycling), 17 , 18 it
Guro Strøm Solli, Espen Tønnessen and Øyvind Sandbakk
link between strength and the endurance sessions became much clearer for me. We related all the training to the technique on skis and found strength exercises that I recognized when skiing.” Coach: “ We started to talk the same language regardless of whether we were on the roller ski treadmill, in the