A new skate allowing powerful plantar flexions improves performance

“Dear IOC”: Considerations for the Governance, Valuation, and Evaluation of Trends and Developments in eSports

In 2021, the International Olympic Committee ventured virtual space by launching their first ever Olympic Virtual Series – featuring virtual baseball, cycling, rowing, sailing and motor racing. Interestingly, all these virtual events take strongly after their physical counterparts. Which begs the question: Where are the massively popular esports games like Fortnite, League of Legends, and Dota?–What do the Olympic Virtual Series have that these popular video games do not? Here, we argue for the inclusion of esports within the Olympic program. In many respects, esports “act” and “behave” just like traditional sports. We argue that esports and traditional sports share many of the same values, like the values of meritocracy, competition, fair play, and the value of having a “level playing field”. Yet, in esports, many of these values remain underappreciated, losing out to negative values such as physical inactivity and game-addiction. To preserve what is worth preserving, we borrow from Value Sensitive Design to ameliorate the design-tensions that are foregrounded in esports. Thereby, paving possible ways toward the inclusion of esports in the Olympic program. Ultimately, the question for the IOC should not be “does it look like ‘real sport’, as we know it?”, but rather: are they sporting, rule-led, and fair activities worth preserving and setting an example for a new digitally savvy generation?

Wingate Test as a Strong Predictor of 1500-m Performance in Elite Speed Skaters

Wingate test scores are strongly associated with anaerobic capacity in athletes involved in speed-endurance sports. In speed skating Wingate results are known to predict performance cross-sectionally but have not been investigated relative to their ability to predict performance longitudinally. Purpose: To investigate whether Wingate tests performed during summer training are predictive of 1500-m speed-skating performance the subsequent winter in elite speed skaters. Methods: Wingate test results from the summer training periods and 1500-m performances during the subsequent winter were analyzed over a 3-y period in 5 female and 8 male elite (Olympic, World Championship, and World Cup medalists) speed skaters. Regression analyses using generalized estimating equations (GEE) were used to estimate the relationship between Wingate test variables and 1500-m speed-skating performance. Wingate peak power (PP) and mean power (MP) were used to predict 1500-m time and 400-m lap times. Results: Improvements of 1 W/kg on PP and MP in women predict improvements of −0.75 s and −2.05 s, respectively, on 1500-m time (World Record 110.85 s). In men, improvements in PP and MP were associated with performance improvements of −0.92 s and −2.32 s on 1500-m time per 1 W/kg (World Record 101.04 s). Conclusion: Wingate test results achieved during the summer training period are a good predictor of improvements in 1500-m speed-skating performance during the subsequent winter. For the smallest worthwhile improvement in 1500-m performance, a gain in PP and MP of 2.1% and 1.4% (0.38 and 0.14 W/kg) for females and 1.2% and 0.9% (0.29 and 0.12 W/kg) for males is needed.

How Hinge Positioning in Cross-Country Ski Bindings Affect Exercise Efficiency, Cycle Characteristics and Muscle Coordination during Submaximal Roller Skiing

The purposes of the current study were to 1) test if the hinge position in the binding of skating skis has an effect on gross efficiency or cycle characteristics and 2) investigate whether hinge positioning affects synergistic components of the muscle activation in six lower leg muscles. Eleven male skiers performed three 4-min sessions at moderate intensity while cross-country ski-skating and using a klapskate binding. Three different positions were tested for the binding’s hinge, ranging from the front of the first distal phalange to the metatarsal-phalangeal joint. Gross efficiency and cycle characteristics were determined, and the electromyographic (EMG) signals of six lower limb muscles were collected. EMG signals were wavelet transformed, normalized, joined into a multi-dimensional vector, and submitted to a principle component analysis (PCA). Our results did not reveal any changes to gross efficiency or cycle characteristics when altering the hinge position. However, our EMG analysis found small but significant effects of hinge positioning on muscle coordinative patterns (P < 0.05). The changed patterns in muscle activation are in alignment with previously described mechanisms that explain the effects of hinge positioning in speed-skating klapskates. Finally, the within-subject results of the EMG analysis suggested that in addition to the between-subject effects, further forms of muscle coordination patterns appear to be employed by some, but not all participants.

World Records: How Much Athlete? How Much Technology?

The quality of performance during international competitions such as the Olympic Games and various world championships is often judged by the number of world records attained. The simple fact that world records continue to improve is evidence that sports performance is progressing. Does this also mean that athletes are improving? Is the continual progression of world-record performances evidence that contemporary athletes are superior to the athletes who performed in the past? Technological developments may obscure insight into the athletic enhancement made by athletes over the years. This commentary tries to separate technological and athletic enhancement in the progression of world records by the use of a power balance model.

Human locomotion on ice: the evolution of ice-skating energetics through history

More than 3000 years ago, peoples living in the cold North European regions started developing tools such as ice skates that allowed them to travel on frozen lakes. We show here which technical and technological changes determined the main steps in the evolution of ice-skating performance over its long history. An in-depth historical research helped identify the skates displaying significantly different features from previous models and that could consequently determine a better performance in terms of speed and energy demand. Five pairs of ice skates were tested, from the bone-skates, dated about 1800 BC, to modern ones.

This paper provides evidence for the fact that the metabolic cost of locomotion on ice decreased dramatically through history, the metabolic cost of modern ice-skating being only 25% of that associated with the use of bone-skates. Moreover, for the same metabolic power, nowadays skaters can achieve speeds four times higher than their ancestors could. In the range of speeds considered, the cost of travelling on ice was speed independent for each skate model, as for running. This latter finding, combined with the accepted relationship between time of exhaustion and the sustainable fraction of metabolic power, gives the opportunity to estimate the maximum skating speed according to the distance travelled.

Ice skates were probably the first human powered locomotion tools to take the maximum advantage from the biomechanical properties of the muscular system: even when travelling at relatively high speeds, the skating movement pattern required muscles to shorten slowly so that they could also develop a considerable amount of force.

Potential method of optimizing the klapskate hinge position in speed skating

Acceptance of the klap speed skate was fully realized on the world speed skating scene in 1997. However, one of the most important unknowns regarding the klapskate was the positioning of the point of foot rotation (pivot point), which is believed to play an important role in optimizing klapskate performance. The purposes of this study were to explore the ankle, knee, and hip joint mechanical changes that occurred when the pivot point location was modified, and to determine whether maximal ankle torques provide predictive ability as to where the optimal pivot point positioning is for a skater. We tested 16 proficient skaters at three pivot point PP) locations, ranging from just in front of the metatarsal-phalangeal joint to just in front of the first phalangeal joint. Of the 16 skaters, 10 were tested at a fourth position; tip of the toe. Push phase kinetics and kinematics were measured on a modified slide board. The optimal PP for each skater was defined as the position that allowed him to generate the most total push energy. Maximum voluntary static torque measures of the ankle and knee were collected on a Biodex dynamometer. Overall, anterior pivot point shifting led to a significant increase in ankle energy generated and a decrease in knee energy generated, with no significant change at the hip joint. We found no significant correlations between the static strength measures and the skaters' optimal pivot points.

Sprint performance-duration relationships are set by the fractional duration of external force application

We hypothesized that the maximum mechanical power outputs that can be maintained during all-out sprint cycling efforts lasting from a few seconds to several minutes can be accurately estimated from a single exponential time constant (k(cycle)) and two measurements on individual cyclists: the peak 3-s power output (P(mech max)) and the maximum mechanical power output that can be supported aerobically (P(aer)). Tests were conducted on seven subjects, four males and three females, on a stationary cycle ergometer at a pedal frequency of 100 rpm. Peak mechanical power output (P(mech max)) was the highest mean power output attained during a 3-s burst; the maximum power output supported aerobically (P(aer)) was determined from rates of oxygen uptake measured during a progressive, discontinuous cycling test to failure. Individual power output-duration relationships were determined from 13 to 16 all-out constant load sprints lasting from 5 to 350 s. In accordance with the above hypothesis, the power outputs measured during all-out sprinting efforts were estimated to within an average of 34 W or 6.6% from P(mech max), P(aer), and a single exponential constant (k(cycle) = 0.026 s(-1)) across a sixfold range of power outputs and a 70-fold range of sprint trial durations (R2 = 0.96 vs. identity, n = 105; range: 180 to 1,136 W). Duration-dependent decrements in sprint cycling power outputs were two times greater than those previously identified for sprint running speed (k(run) = 0.013 s(-1)). When related to the respective times of pedal and ground force application rather than total sprint time, decrements in sprint cycling and running performance followed the same time course (k = 0.054 s(-1)). We conclude that the duration-dependent decrements in sprinting performance are set by the fractional duration of the relevant muscular contractions.

Passive tools for enhancing muscle-driven motion and locomotion

Musculo–skeletal systems and body design in general have evolved to move effectively and travel in specific environments. Humans have always aspired to reach higher power movement and to locomote safely and fast, even through unfamiliar media (air, water, snow, ice). For the last few millennia,human ingenuity has led to the invention of a variety of passive tools that help to compensate for the limitations in their body design. This Commentary discusses many of those tools, ranging from halteres used by athletes in ancient Greece, to bows, skis, fins, skates and bicycles, which are characterised by not supplying any additional mechanical energy, thus retaining the use of muscular force alone. The energy cascade from metabolic fuel to final movement is described, with particular emphasis on the steps where some energy saving and/or power enhancement is viable. Swimming is used to illustrate the efficiency breakdown in complex locomotion, and the advantage of using fins. A novel graphical representation of world records in different types of terrestrial and aquatic locomotion is presented, which together with a suggested method for estimating their metabolic cost (energy per unit distance), will illustrate the success of the tools used.

The Effects of Klapskate Hinge Position on Push-off Performance: A Simulation Study

PURPOSE

The introduction of the klapskate in speed skating confronts skaters with the question of how to adjust the position of the hinge in order to maximize performance. The purpose of this study was to reveal the constraint that klapskate hinge position imposes on push-off performance in speed skating.

METHOD

For this purpose, a model of the musculoskeletal system was designed to simulate a simplified, two-dimensional skating push off. To capture the essence of a skating push off, this model performed a one-leg vertical jump, from a frictionless surface, while keeping its trunk horizontally. In this model, klapskate hinge position was varied by varying the length of the foot segment between 115 and 300 mm. With each foot length, an optimal control solution was found that resulted in the maximal amount of vertical kinetic and potential energy of the body's center of mass at take off (Weff).

RESULTS

Foot length was shown to considerably affect push-off performance. Maximal Weff was obtained with a foot length of 185 mm and decreased by approximately 25% at either foot length of 115 mm and 300 mm. The reason for this decrease was that foot length affected the onset and control of foot rotation. This resulted in a distortion of the pattern of leg segment rotations and affected muscle work (Wmus) and the efficacy ratio (Weff/Wmus) of the entire leg system.

CONCLUSION

Despite its simplicity, the model very well described and explained the effects of klapskate hinge position on push off performance that have been observed in speed-skating experiments. The simplicity of the model, however, does not allow quantitative analyses of optimal klapskate hinge position for speed-skating practice.

How Klapskate Hinge Position Affects Push-Off Mechanics in Speed Skating

In speed skating, the conventional skate has been replaced by the klapskate, in which the shoe can rotate around a hinge between shoe and blade. It has been hypothesized that the improved performance with klapskates vs. conventional skates can be attributed to the difference in the anterior/posterior position of the foot’s center of rotation relative to the ice. This study investigated the effect of the position of the foot’s center of rotation on push-off mechanics in speed skating. Eight elite speed skaters skated four 2000-m trials on instrumented klapskates at a fixed velocity. In each trial the hinge was placed at a different position between the 5th metatarso-phalangeal joint and the tip of the toes. 3-D kinematics and pushoff forces were measured to analyze push-off kinematics and kinetics. Shifting the hinge from the most posterior to the more anterior positions resulted in a delayed onset of foot rotation and longer duration of push-off. This delay coincided with an increase in angular displacement and peak angular velocity of the knee and hip joint, an increase in the flexing knee joint moment at the end of the push-off, and a reduction in work generated at the knee joint. Total work per stroke was similar for the various hinge positions. Besides the similar work per stroke, the observed effects are in accordance with the differences between klapskating and conventional skating. It was concluded that the position of the foot’s center of rotation affects the timing of foot rotation, and therefore the balanced pattern of segmental rotations. Although it could not be proven in this study, it was shown that this constraint could affect work per stroke and might explain the difference between klapskates and conventional skates.

From a One-Legged Vertical Jump to the Speed-Skating Push-off: A Simulation Study

To gain a better understanding of push-off mechanics in speed skating, forward simulations were performed with a model comprising four body segments and six muscles. We started with a simulated maximum height one-legged jump, obtained by optimization of muscle stimulation time histories. The simulated jump was very similar to one-legged jumps produced by a human, indicating that the model was realistic. We subsequently studied how performance was affected by introducing four conditions characteristic of speed skating: (a) We changed the initial position from that in jumping to that at the start of the push-off phase in skating. This change was accommodated by a delay in stimulation onset of the plantar flexors in the optimal solution. (b) The friction between foot and ground was reduced to zero. As a result, maximum jump height decreased by 1.2 cm and performance became more sensitive to errors in muscle stimulation. The reason is that without surface friction, the foot had to be prevented from slipping away, which constrained the solution space and reduced the tolerance to errors in stimulation. (c) We introduced the requirement to maintain the upper body in a more or less horizontal position. This change could be accommodated by a delay in stimulation onset of the hamstrings, which inevitably caused a reduction in maximum jump height by 11.6 cm. (d) We increased the effective foot length from 16.5 cm, representative of jumping, to 20.5 cm, representative of skating with klapskates. At the 20.5-cm foot length, rotation of the foot did not start during the buildup of plantar flexion moment as it did at smaller foot lengths, but was delayed until hip and knee extension moments decreased. This caused an unbalanced increase in segment angular velocities and muscle shortening velocities, leading to a decrease in muscle force and muscle work and a further decrease in maximum jump height by approximately 5 cm. Qualitatively, these findings help clarify why and how performance of speed skaters depends on the location of the hinge of their skate.

Ice friction in speed skating: can klapskates reduce ice frictional loss?

PURPOSE

Reducing ice friction was one of the motives for developing the klapskate. However, the magnitude of power dissipation that occurs with conventional skates when a skater plantar flexes his ankle and the tip of the blade is pressed into the ice has not been quantified previously. In this study, we examine how ice friction varies during a single stroke with conventional skates and estimate the reduction in ice friction that might be obtained with klapskates.

METHODS

Five elite speed skaters performed a series of trials at constant velocity and a series of maximal accelerations. Energy dissipated to ice friction during a stroke with conventional skates was analyzed using an instrumented skate and high-speed 3D kinematic analysis. The energy that would be dissipated when klapskates were used was estimated from the collected data with conventional skates.

RESULTS

The estimated difference in power loss between conventional and klapskates was less dramatic than has been suggested frequently. Pressing the tip of the blade into the ice comprises only 0.84 W of the total power dissipated by ice friction (54 W) during constant velocity speed skating. During an all-out acceleration, this power loss reached 4.55 W.

CONCLUSION

We conclude that only a minor part of the benefit of klapskates can be attributed to a reduction in ice friction. It is shown that this relatively small increase in ice friction is related to the large length of the skate blade.

Push-off mechanics in speed skating with conventional skates and klapskates

PURPOSE

Personal and world records in speed skating improved tremendously after the introduction of the klapskate, which allows the foot to plantar flex at the end of the push-off while the full blade continues to glide on the ice. The purpose of this study was to gain insight into the differences in skating technique with conventional versus klapskates and to unveil the source of power enhancement using klapskates.

METHODS

Ten elite speed skaters skated four 400-m laps at maximal effort with both conventional and klapskates. On the straight high-speed film, push-off force and EMG data were collected. An inverse dynamics analysis was performed in the moving reference plane through hip, knee, and ankle.

RESULTS

Skating velocity increased 5% as a result of an increase in mean power output of 25 W when klapskates were used instead of conventional skates. The increase in mean power output was achieved through an 11-J increase in work per stroke and an increase in stroke frequency from 1.30 to 1.36 strokes x s(-1). The difference in work per stroke occurs during the final 50 ms of the push-off. This is the result of the ineffective way in which push-off forces are generated with conventional skates when the foot rotates about the long front end of the blade. No differences in muscle coordination were observed from EMG.

CONCLUSION

A hinge under the ball of the foot enhances the effectiveness of plantar flexion during the final 50 ms of the push off with klapskates and increases work per stroke and mean power output.