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  • Author: Marco J.M. Hoozemans x
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Dionne A. Noordhof, Carl Foster, Marco J.M. Hoozemans and Jos J. de Koning

Speed skating posture, or technique, is characterized by the push-off angle or effectiveness (e), determined as the angle between the push-off leg and the ice; the preextension knee angle (θ 0); and the trunk angle (θ 1). Together with muscle-power output and environmental conditions, skating posture, or technique, determines velocity (v).

Purpose:

To gain insight into technical variables that are important to skate efficiently and perform well, e, θ 0, θ 1, and skating v were determined every lap during a 5000-m World Cup. Second, the authors evaluated if changes (Δ) in e, θ 0, and θ 1 are associated with Δv.

Methods:

One camera filmed the skaters from a frontal view, from which e was determined. Another camera filmed the skaters from a sagittal view, from which θ 0 and θ 1 were determined. Radio-frequency identification tags around the ankles of the skaters measured v.

Results:

During the race, e progressively increased and v progressively decreased, while θ 0 and θ 1 showed a less consistent pattern of change. Generalized estimating equations showed that Δe is significantly associated with Δv over the midsection of the race (β = −0.10, P < .001) and that Δθ 0 and Δθ 1 are not significantly associated with Δv.

Conclusions:

The decrease in skating v over the race is not due to increases in power losses to air friction, as knee and trunk angle were not significantly associated with changes in velocity. The decrease in velocity can be partly ascribed to the decrease in effectiveness, which reflects a decrease in power production associated with fatigue.

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Dionne A. Noordhof, Carl Foster, Marco J.M. Hoozemans and Jos J. de Koning

A meaningful association between changes (Δ) in push-off angle or effectiveness (e) and changes in skating velocity (v) has been found during 5000-m races, although no significant association was found between changes in knee (θ0) and trunk angle (θ1) and Δv. It might be that speed skating event, sex, and performance level influence these associations.

Purpose:

To study the effect of skating event, sex, and performance level on the association between Δe and Δv and between Δθ0 and Δθ1 and Δv.

Methods:

Video recordings were made from frontal (e) and sagittal views (θ0 and θ1) during 1500- and 5000-m men’s and women’s World Cup races. Radio-frequency identification tags provided data of v.

Results:

Skating event influenced the association between Δe and Δv, which resulted in a significant association between Δe and Δv for the 5000-m (β = –0.069, 95% confidence interval [–0.11, –0.030]) but not for the 1500-m (β = –0.011 [–0.032, 0.010]). The association between Δθ0 and Δθ1 and Δv was not significantly influenced by skating event. Sex and performance level did not substantially affect the association between Δe and Δv and between Δθ0 and Δθ1 and Δv.

Conclusions:

Skating event significantly influenced the association between Δe and Δv; a 1° change in e results in a 0.011-m/s decrease in v during the 1500-m and a 0.069-m/s decrease in v during the 5000-m. Thus, it seems especially important to maintain a small e during the 5000-m.

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Levi Heimans, Wouter R. Dijkshoorn, Marco J.M. Hoozemans and Jos J. de Koning

Purpose: Since the aim of the men’s team pursuit in time-trial track cycling is to accomplish a distance of 4000 m as fast as possible, optimizing aerodynamic drag can contribute to achieving this goal. The aim of this study was to determine the drafting effect in second, third, and fourth position during the team pursuit in track cycling as a function of the team members’ individual frontal areas in order to minimize the required power. Method: Eight experienced track cyclists of the Dutch national selection performed 39 trials of 3 km in different teams of 4 cyclists at a constant velocity of 15.75 m/s. Frontal projected areas were determined, and together with field-derived drag coefficients for all 4 positions, the relationships between frontal areas of team members and drag fractions were estimated using generalized estimating equations. Results: The frontal area of both the cyclist directly in front of the drafter and the drafter himself turned out to be significant determinants of the drag fraction at the drafter’s position (P < .05) for all 3 drafting positions. Predicted required power for individuals in drafting positions differed up to 35 W depending on team composition. For a team, a maximal difference in team efficiency (1.2%) exists by selecting cyclists in a specific sequence. Conclusion: Estimating required power for a specific team composition gives insight into differences in team efficiency for the team pursuit. Furthermore, required power for individual team members ranges substantially depending on team composition.

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Nico Hofman, Jac Orie, Marco J.M. Hoozemans, Carl Foster and Jos J. de Koning

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.

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Thom T.J. Veeger, Annemarie M.H. de Witte, Monique A.M. Berger, Rienk M.A. van der Slikke, Dirkjan (H.E.J.) Veeger and Marco J.M. Hoozemans

Objective: This study aimed to investigate which characteristics of athlete, wheelchair and athlete-wheelchair interface are the best predictors of wheelchair basketball mobility performance. Design: A total of 60 experienced wheelchair basketball players performed a wheelchair mobility performance test to assess their mobility performance. To determine which variables were the best predictors of mobility performance, forward stepwise linear regression analyses were performed on a set of 33 characteristics, including 10 athlete, 19 wheelchair, and 4 athlete-wheelchair interface characteristics. Results: A total of 8 of the characteristics turned out to be significant predictors of wheelchair basketball mobility performance. Classification, experience, maximal isometric force, wheel axis height, and hand rim diameter—which both are interchangeable with each other and wheel diameter—camber angle, and the vertical distance between shoulder and rear wheel axis—which was interchangeable with seat height—were positively associated with mobility performance. The vertical distance between the front seat and the footrest was negatively associated with mobility performance. Conclusion: With this insight, coaches and biomechanical specialists are provided with statistical findings to determine which characteristics they could focus on best to improve mobility performance. Six out of 8 predictors are modifiable and can be optimized to improve mobility performance. These adjustments could be carried out both in training (maximal isometric force) and in wheelchair configurations (eg, camber angle).

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Dionne A. Noordhof, Elmy van Tok, Florentine S.J.G.M. Joosten, Florentina J. Hettinga, Marco J.M. Hoozemans, Carl Foster and Jos J. de Koning

Half the improvement in 1500-m speed-skating world records can be explained by technological innovations and the other half by athletic improvement. It is hypothesized that improved skating economy is accountable for much of the athletic improvement. Purpose: To determine skating economy in contemporary athletes and to evaluate the change in economy over the years. Methods: Contemporary skaters of the Dutch national junior team (n = 8) skated 3 bouts of 6 laps at submaximal velocity, from which skating economy was calculated (in mL O2 ・ kg–1 ・ km–1). A literature search provided historic data on skating velocity and submaximal V̇O2 (in mL ・ kg–1 ・ min–1), from which skating economy was determined. The association between year and skating economy was determined using linear-regression analysis. Correcting the change in economy for technological innovations resulted in an estimate of the association between year and economy due to athletic improvement. Results: A mean (± SD) skating economy of 73.4 ± 6.4 mL O2 ・ kg–1 ・ km–1 was found in contemporary athletes. Skating economy improved significantly over the historical time frame (–0.57 mL O2 ・ kg–1 ・ km–1 ・ y–1, 95% confidence interval [–0.84, –0.31]). In the final regression model for the klapskate era, with altitude as confounder, skating economy improved with a nonsignificant –0.58 mL O2 ・ kg–1 ・ km–1 ・ y–1 ([–1.19, 0.035]). Conclusions: Skating economy was 73.4 ± 6.4 mL O2 ・ kg–1 ・ km–1 in contemporary athletes and improved over the past ~50 y. The association between year and skating economy due to athletic improvement, for the klapskate era, approached significance, suggesting a possible improvement in economy over these years.

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Annemarie M.H. de Witte, Monique A.M. Berger, Marco J.M. Hoozemans, Dirkjan H.E.J. Veeger and Lucas H.V. van der Woude

The aim of this study was to determine to what extent mobility performance is influenced by offensive or defensive situations and ball possession and to what extent these actions are different for the field positions. From video analysis, the relative duration of the various wheelchair movements during team offense/defense and individual ball possession was compared in 56 elite wheelchair basketball players. A two-way analysis of variance indicated that during offense, the guards and forwards performed longer driving forward than during defense. Overall, centers stood still longer during offense than during defense. Without ball, centers performed driving forward longer than with ball possession. It is concluded that offense, defense, and ball possession influenced mobility performance for the different field positions. These differences can be used to design specific training protocols. Furthermore, field positions require potentially different specific wheelchair configurations to improve performance.