Endre søk
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Passive Muscle Length Changes Affect Twitch Potentiation in Power Athletes.
Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).ORCID-id: 0000-0002-8580-6518
Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, Laboratoriet för biomekanik och motorisk kontroll (BMC).ORCID-id: 0000-0002-7879-9188
2014 (engelsk)Inngår i: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 46, nr 7, s. 1334-1342Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

INTRODUCTION: A conditioning maximal voluntary muscle action (MVC) has been shown to induce post-activation potentiation, i.e. improved contractile muscle properties, when muscles are contracted isometrically. It is still uncertain how the contractile properties are affected during ongoing muscle length changes. The purpose of this study was to investigate the effects of a 6 s conditioning MVC on twitch properties of the plantar flexors during ongoing muscle length changes.

METHODS: Peak twitch, rate of torque development (RTD) and relaxation (RTR), rising time and half relaxation time (HRT) were measured from supramaximal twitches evoked in the plantar flexors of 11 highly trained athletes. Twitches were evoked prior to a 6 s MVC and subsequently on 8 different occasions during a 10-minute recovery, for five different modes: fast lengthening, slow lengthening, isometric, fast shortening and slow shortening of the plantar flexors.

RESULTS: The magnitude and duration of effects from the conditioning MVC were significantly different between modes. Peak twitch, RTD and RTR significantly increased for all modes but more so for twitches evoked during fast and slow shortening as compared to lengthening. Rising time was reduced in the lengthening modes, but slightly prolonged in the shortening modes. HRT was significantly reduced for all modes except fast lengthening.

CONCLUSION: The findings show that the effects of a conditioning MVC on twitch contractile properties are dependent on direction and velocity of ongoing muscle length changes. This may imply that functional enhancements from a conditioning MVC might be expected to be greatest for concentric muscle actions, but are still present in isometric and eccentric parts of a movement.

sted, utgiver, år, opplag, sider
2014. Vol. 46, nr 7, s. 1334-1342
HSV kategori
Forskningsprogram
Medicin/Teknik
Identifikatorer
URN: urn:nbn:se:gih:diva-3193DOI: 10.1249/MSS.0000000000000245PubMedID: 24389516OAI: oai:DiVA.org:gih-3193DiVA, id: diva2:686978
Forskningsfinansiär
Swedish National Centre for Research in SportsTilgjengelig fra: 2014-01-13 Laget: 2014-01-13 Sist oppdatert: 2017-12-06bibliografisk kontrollert
Inngår i avhandling
1. Post activation potentiation: Modulating factors and mechanisms for muscle performance
Åpne denne publikasjonen i ny fane eller vindu >>Post activation potentiation: Modulating factors and mechanisms for muscle performance
2016 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Introduction: Acute enhancements of muscle contractile properties and performance subsequent to a maximal or near maximal conditioning contraction are often termed post activation potentiation (PAP). Although still controversial, PAP is commonly linked to enhancements in the myosin regulatory light chain phosphorylation, leading to improvements in the excitation–contraction coupling. The PAP seen after a conditioning task often coexists with fatigue and is known to depend on strength level, muscle fiber type and age. Less is known about how factors such as static and dynamic changes in muscle length affect PAP, and on the relative contribution of contractile and tensile components to PAP.

Aim: To enhance our understanding of how, and under what conditions, a single maximal isometric contraction affects plantar flexor muscle contractile performance, and other muscle tendon properties, in power athletes.

Methods: Supramaximal twitches were evoked via electrical stimulation of the tibial nerve of athletes before and on several occasions after a 6-second maximal voluntary isometric contraction (6-s MVIC) in both static muscle, and during passive muscle lengthening and shorting at different angular velocities. Several contractile variables were measured from the twitches. The effects of a 6-s MVIC on Achilles tendon stiffness was calculated from torque and ultrasonography based measurements of tendon length at two submaximal contraction intensities. Overall stiffness index was calculated by analyzing the passive lengthening torque/angle curve.Results: A single MVIC enhanced muscle contractile properties and electromechanical delay for up to 5 minutes. Plantar flexor twitch variables such as peak twitch, rate of torque development and rate of torque relaxation were enhanced during shortening compared to lengthening muscle actions, and in an extended as compared to a flexed knee position. Achilles tendon stiffness and overall stiffness index were not significantly modulated by a single 6-s MVIC.

Conclusion: The results of this thesis imply that functional enhancements from a 6-s conditioning MVIC would mainly come from improvements in contractile rather than tensile components. Stiffness changes should be monitored in future PAP-related studies since they may still occur after more extensive conditioning protocols than the current one. Improvements in contractile components subserving muscle strength after a conditioning MVIC suggests that enhancements in muscle power after a conditioning task should be greatest in fast concentric muscle actions, though still present in muscle lengthening. Conditioning should be performed in a position where full activation is easy to achieve and tailored to mach an athlete or group of athlete’s current status and characteristics, maximizing performance in a specific sport event.

sted, utgiver, år, opplag, sider
Stockholm: Gymnastik och idrottshögskolan, GIH, 2016. s. 53
Serie
Avhandlingsserie för Gymnastik- och idrottshögskolan ; 04
Emneord
Potentiation, twitch, triceps surae, knee angle, stiffnes, length changes, electromechanical delay
HSV kategori
Forskningsprogram
Medicin/Teknik
Identifikatorer
urn:nbn:se:gih:diva-4280 (URN)978-91-980862-4-9 (ISBN)
Disputas
2016-02-02, Aulan, Gymnastik- och idrottshögskolan, Lidingövägen 1, Stockholm, 12:30 (engelsk)
Opponent
Veileder
Prosjekter
Doctoral project: Post activation potentiation - Modulating factors and mechanisms for muscle performance.
Merknad

The project recived financial support from the Swedish National Centre for Research in Sports (CIF). Paulo Gago also wishes to thank the Fundação para a Ciência e Tecnologia (FCT), Portugal for the Ph.D. Grant (SFRH/BD/103572/2014).

New version 2015-01-25 updates the previous one by correcting the errors described in the correction list file (errata).

Tilgjengelig fra: 2016-01-07 Laget: 2015-12-31 Sist oppdatert: 2016-02-11bibliografisk kontrollert

Open Access i DiVA

fulltext(837 kB)276 nedlastinger
Filinformasjon
Fil FULLTEXT02.pdfFilstørrelse 837 kBChecksum SHA-512
5be1d777c5f07d669588d687144e39cc675178be37a9b3282734f992fe32a71802a9126d7a67368d69944d495e51d6211e354e851ea769464115cd35db2b2166
Type fulltextMimetype application/pdf

Andre lenker

Forlagets fulltekstPubMed

Personposter BETA

Gago, PauloEkblom, Maria M

Søk i DiVA

Av forfatter/redaktør
Gago, PauloEkblom, Maria M
Av organisasjonen
I samme tidsskrift
Medicine & Science in Sports & Exercise

Søk utenfor DiVA

GoogleGoogle Scholar
Totalt: 276 nedlastinger
Antall nedlastinger er summen av alle nedlastinger av alle fulltekster. Det kan for eksempel være tidligere versjoner som er ikke lenger tilgjengelige

doi
pubmed
urn-nbn

Altmetric

doi
pubmed
urn-nbn
Totalt: 465 treff
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf