Preloading of the Thrust Phase in Cross-Country Skiing

Pv, Komi; Rw, Norman

doi:10.1055/s-2008-1025703

Cited by 65 publications

(44 citation statements)

References 15 publications

(24 reference statements)

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“…Slightly later during the kick, both KE and GPE increase together, which may reflect a recovery of GPE from elastic energy stored in the tendons. Through kinematic analysis, it has been previously concluded that elastic energy storage of GPE is possible due to the pre-stretch of the preload phase of DIA (Komi and Norman, 1987).…”

Section: Research Articlementioning

confidence: 99%

Forces and mechanical energy fluctuations during diagonal stride roller skiing; running on wheels?

Kehler¹,

Hajkova²,

Holmberg

et al. 2014

Journal of Experimental Biology

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Mechanical energy can be conserved during terrestrial locomotion in two ways: the inverted pendulum mechanism for walking and the spring-mass mechanism for running. Here, we investigated whether diagonal stride cross-country roller skiing (DIA) utilizes similar mechanisms. Based on previous studies, we hypothesized that running and DIA would share similar phase relationships and magnitudes of kinetic energy (KE), and gravitational potential energy (GPE) fluctuations, indicating elastic energy storage and return, as if roller skiing is like 'running on wheels'. Experienced skiers (N=9) walked and ran at 1.25 and 3 m s -1 , respectively, and roller skied with DIA at both speeds on a level dual-belt treadmill that recorded perpendicular and parallel forces. We calculated the KE and GPE of the center of mass from the force recordings. As expected, the KE and GPE fluctuated with an out-of-phase pattern during walking and an in-phase pattern during running. Unlike walking, during DIA, the KE and GPE fluctuations were in phase, as they are in running. However, during the glide phase, KE was dissipated as frictional heat and could not be stored elastically in the tendons, as in running. Elastic energy storage and return epitomize running and thus we reject our hypothesis. Diagonal stride cross-country skiing is a biomechanically unique movement that only superficially resembles walking or running.

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Section: Research Articlementioning

confidence: 99%

Forces and mechanical energy fluctuations during diagonal stride roller skiing; running on wheels?

Kehler¹,

Hajkova²,

Holmberg

et al. 2014

Journal of Experimental Biology

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“…S ohledem na terén je maximální vertikální síla vytvářená dolními končetinami při odrazu u střídavé-ho běhu dvoudobého na úrovni 1,6−3násobku tělesné hmotnosti. Absolutní hodnoty těchto sil dosahují u špičkových závodníků velikosti až 1500−2000 N (Komi, Norman 1987, Rusko 2003. Při volném způ-sobu běhu dosahuje maximální kolmá síla při odrazu 0,8-2násobek hmotnosti těla běžce, to znamená 600-1300 N (např.…”

Section: úVodunclassified

Síla odrazu běžců na lyžích u vybraných technik běhu

Korvas¹,

Suchý²

2012

StS

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AbstraktPříspěvek ÚvodBěh na lyžích zaznamenal za posledních 20-30 let významný rozvoj sportovní výkonnosti, který lze hodnotit zejména stálým zvyšováním rychlosti špičkových závodníků na světových soutěžích (Korvas 2009, Hottenrott 2004. Tento progres má svůj základ především v rozvoji technologií lyží i tratí a jejich úpravy, stálým zlepšováním techniky a efektivity pohybu a samozřejmě zvyšováním úrovně trénovanos-ti, především silové vytrvalosti.Běh na lyžích je kvadrupedální pohybová činnost, při které tvoří hybné síly ve směru pohybu jak dolní, tak horní končetiny, a částečně i trup. Hlavní podíl na produkci hybné síly u obou způsobů běhu a jejich technik na většině trati mají dolní končetiny. Podle Belliziho (1998) lyžaři vytváří při běhu střídavém dvoudobém za různých rychlostí 69 % dopředné energie dolními končetinami a 31 % pažemi. Ovšem u volného způsobu běhu ve stoupání může být tento poměr až 50:50 % (Street 1989, Ilavský 2005. S ohledem na terén je maximální vertikální síla vytvářená dolními končetinami při odrazu u střídavé-

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“…Because signiˆcant diŠerences between the two conditions were shown only in gliding distance, not in push-oŠ distance, skiers in the moderate condition might obtain support length by gliding their ski forward. Norman and Komi (1987) and Komi and Norman (1987) have investigated the kinematics of the diagonal technique for diŠerent grades of slopes. However, the authors of these studies have not investigated the importance of the gliding and push-oŠ motions from the viewpoint of stride length.…”

Section: Stroke Analysismentioning

confidence: 99%

“…A larger backward segment angular velocity of the support shank and thigh in the early support phase on a steep slope might help to avoid slippage of the support ski. Pierce et al (1987), Komi and Norman (1987) and V äah äas äoyrinki et al (2008) investigated ski and pole reaction forces during the diagonal technique on the snow track. Pierce et al (1987) has only measured forces on a single grade of slope.…”

Section: Push-oš Leg Motionmentioning

confidence: 99%

Diagonal Technique of Cross-country Skiing on Different Slopes in a Classical 10 km Race

Hoga¹,

Sambongi²

2010

Int. J. Sport Health Sci.

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Purpose: The purpose of this study was to investigate the kinematic diŠerence in the skiing motion of the diagonal technique between diŠerent slopes during classical style cross-country 10 km o‹cial race. Methods: Data were collected from two o‹cial men 10 km cross-country races of classical technique on the same 5 km circuit course. Skiers passing in the uphill sections of the course were videotaped with a VTR camera (60 Hz) positioned at 0.4 km point (3.8 degree slope) in one race, and at 1 km point (12.4 degree slope) in another race. To reconstruct the two dimensional coordinates of the motion of subjects, a two dimensional direct linear transformation technique was used. Seven skiers including national class junior and collegiate skiers of Japan were selected as subjects on each race. Results: The time from the instant of the heel contact on the ski to the instant of the ski detaching the snow on the moderate slope was almost same as that on the steep slope. However, the gliding length after heel contact on the ski on the moderate slope was larger than that on the steep slope. The length of ski gliding resulted in the large skiing speed on the moderate slope.

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Preloading of the Thrust Phase in Cross-Country Skiing

Cited by 65 publications

References 15 publications

Forces and mechanical energy fluctuations during diagonal stride roller skiing; running on wheels?

Forces and mechanical energy fluctuations during diagonal stride roller skiing; running on wheels?

Síla odrazu běžců na lyžích u vybraných technik běhu

Diagonal Technique of Cross-country Skiing on Different Slopes in a Classical 10 km Race

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