Kinematics of the running-like sprint start in long-track speed skating

Velocity-Load Jump Testing Predicts Acceleration Performance in Elite Speed Skaters: But Does Movement Specificity Matter?

PURPOSE

In this study, we compared the influence of movement specificity during velocity-load jump testing to predict on-ice acceleration performance in elite speed skaters.

METHODS

Elite long-track speed skaters (N = 27) performed velocity-load testing with 3 external loads during unilateral horizontal jumping, lateral jumping, and bilateral vertical countermovement jumping. For the unilateral tests, external load conditions were set to 10 N, 7.5% and 15% of external load relative to body weight. For the countermovement jumping, load conditions were body weight and 30% and 60% of external load relative to body weight. On-ice performance measures were obtained during maximal 50-m accelerations from a standing start, including maximal skating speed, maximal acceleration capacity, and maximum horizontal power. The 100-m split time from a 500-m race was also obtained. Regularized regression models were used to identify the most important predictors of on-ice acceleration performance. In addition to regularized regression coefficients, Pearson correlation coefficients (r) were calculated for all variables retained by the model to assess interrelationships between single predictors and on-ice performance measures.

RESULTS

The countermovement jump with 30% of body mass demonstrated the strongest association with maximal skating speed, maximum horizontal power, and 100-m time (regularized regression coefficient = .16-.49, r = .84-.97, P < .001). Horizontal jump with 15% of body mass was the strongest predictor of maximal acceleration capacity performance (regularized regression coefficient = .08, r = .83, P < .001).

CONCLUSIONS

The findings of this study suggest that mechanical specificity rather than movement specificity was more relevant for predicting on-ice acceleration performance.

Modeling the Early and Late Acceleration Phases of the Sprint Start in Elite Long Track Speed Skaters

ABSTRACT

Zukowski, MH, Jordan, MJ, and Herzog, W. Modeling the early and late cceleration phases of the sprint start in elite long track speed skaters. J Strength Cond Res 38(2): 236-244, 2024-This study established the reliability of an exponential function to model the change in velocity during the speed skating sprint start and the validity of associated model parameters in a group of subelite and elite long track speed skaters. Long track speed skaters ( n = 38) performed maximal effort 50-m on-ice accelerations from a standing start while tethered to a horizontal robotic resistance device that sampled position and time data continuously. An exponential function was applied to the raw data to model the change in velocity throughout the acceleration phase and compute the maximal skating speed (MSS), maximal acceleration capacity (MAC), maximum relative net horizontal power ( PMax ), and an acceleration-time constant ( τ ). All constructed models provided a sufficient fit of the raw data ( R -squared > 0.95, mean bias <2%). Intraday reliability of all model parameters ranged from good to excellent (intraclass correlation coefficient >0.8 and coefficient of variation <5%). Strong negative correlations ( r : -0.72 to -0.96) were observed between MSS and PMax and the 10 and 20 m split times measured with the robotic resistance and with 100 split times obtained from 500 m races. Moderate-to-large between-group differences were observed in MSS, MAC, and PMax between the elite vs. subelite speed skaters (Cohen d effect sizes: 1.18-3.53). Our results indicate that monoexponential modeling is a valid and reliable method of monitoring initial acceleration performance in elite level long track speed skaters.

In vivo vastus lateralis fascicle excursion during speed skating imitation

Mechanical power is a key performance indicator in long track speed skating. Maximal power output in athletic performance can be achieved when mechanical properties of muscles, such as the force-length relationship, are optimized. The purpose of this study was to determine the in vivo operating range of vastus lateralis (VL) fascicle lengths during speed skating imitation and compare the fascicle lengths to those that define the VL force-length relationship. Sixteen sub-elite long track speed skaters (7 females and 9 males; body mass: 72.5 [11.5] kg; age: 22.1 [2.7] years) performed maximal voluntary isometric knee extensions at nine different knee joint positions (20-120°) on the left leg to obtain the maximal vastus lateralis (VL) force-length relationship. Participants then performed a speed skating imitation exercise, the turn-cable, at three progressive perceived efforts (50%, 75%, 100%) to identify the VL fascicle excursion during a complete imitation skating stroke. Fascicle lengths and knee joint angles were examined at initial-contact, peak EMG, and take-off. Fascicles between initial contact and peak EMG covered the descending limb of both the maximal and submaximal force-length relationships while operating over the plateau region from peak EMG to take-off. We conclude that the VL works at sub-optimal length during the gliding phase of skating, but at optimal length for maximal force production during the crucial push-off phase where propulsion is provided.

Single Leg Lateral and Horizontal Loaded Jump Testing: Reliability and Correlation With Long Track Sprint Speed Skating Performance

ABSTRACT

Zukowski, MH, Jordan, MJ, and Herzog, W. Single leg lateral and horizontal loaded jump testing: reliability and correlation with long track sprint speed skating performance. J Strength Cond Res 37(11): 2251-2259, 2023-This study examined the intraday reliability of 2 novel unilateral loaded jump protocols designed for long track speed skaters. Highly trained ( n = 26), national level athletes performed single leg jumps with a horizontal robotic resistance across 3 external load conditions (10 N, 7.5% of body mass and 15% of body mass) using their dominant limb. Jumps were performed in both the horizontal (Jump Horz ) and lateral (Jump Lat ) direction to replicate the body position and line of force application observed during the running and gliding phases of on-ice acceleration. Subjects completed 2 consecutive trials of the same jump protocol to examine the intraday reliability of the peak velocity achieved for each loading condition. Peak velocity across each jump type and loading condition had good reliability (intraclass correlation coefficient >0.8, coefficient of variation <5%). Significant positive relationships ( r = 0.5-0.8, p < 0.05; n = 22) were observed between all jump conditions and on-ice sprint race split times obtained including 100, 400, and 500 m. Our results indicate that unilateral loaded jump tests are reliable in speed skating athletes and may help practitioners diagnose and monitor lower-limb maximal muscle power capacity in a sport-specific manner.

Evolutions in the physiology of skiing, skating and running in the Olympics

Cross-country skiing, biathlon, Nordic combined, short track speed skating, and speed skating (12+11+3+8+14=48 events), i.e. five of the 15 disciplines in the 2018 Winter Olympics, require participants to reach the finish line in minimum time, while exerting mechanical propulsion power through flat terrain, uphill, and downhill. This article compares distances and times for these disciplines systematically with each other and with running, walking, and swimming in the Summer Olympics. Regarding physiological implications, the absence of distances below 6 km in biathlon, 5 km in Nordic combined, 1.2-1.5 km in cross-country skiing, and 0.5 km in speed skating means recruiting fewer competitors with sprint characteristics (type IIx fast isoforms muscles, etc.). The absence of distances above 10 km in speed skating and Nordic combined, and 20 km in biathlon, means recruiting fewer or other kinds of competitors with long distance characteristics. For example, high anaerobic threshold is important at greater distances, and high VO2max is important above intermediate distances. A new recruitment criterion for Olympic events is proposed, argued to recruit athletes fairly and be fair to spectators. The new criterion supplements current criteria such as popularity, relevance, and cooperation. The article recommends assessing 26 new events for future Winter Olympics within the five disciplines, equivalently for men and women. Formats are specified for the new events. Regarding equal distances for men and women, women use 8.7-13.6% more time than men in most events, except when upper-body power is important (above 13.6%) and in ultraendurance events (below 5.3%).