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Unique Neural Mechanisms Underlying Speed Control of Low-Force Ballistic Contractions.
Kim, Joongsuk J; Delmas, Stefan; Choi, Yoon Jin; Hubbard, Jessica C; Weintraub, Michelle; Arabatzi, Fotini; Yacoubi, Basma; Christou, Evangelos A.
Afiliación
  • Kim JJ; Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.
  • Delmas S; Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.
  • Choi YJ; Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.
  • Hubbard JC; Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.
  • Weintraub M; Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.
  • Arabatzi F; School of Physical Education and Sports Science (Serres), Aristotle University of Thessaloniki, Serres, Greece.
  • Yacoubi B; Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.
  • Christou EA; Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.
J Hum Kinet ; 90: 29-44, 2024 Jan.
Article en En | MEDLINE | ID: mdl-38380304
ABSTRACT
According to the speed-control hypothesis, the rate of force development (RFD) during ballistic contractions is dictated by force amplitude because time to peak force (TPF) remains constant regardless of changes in force amplitude. However, this hypothesis has not been tested at force levels below 20% of an individual's maximum voluntary contraction (MVC). Here, we examined the relationship between the RFD and force amplitude from 2 to 85% MVC and the underlying structure of muscle activity in 18 young adults. Participants exerted ballistic index finger abductions for 50 trials in each of seven randomly assigned force levels (2, 5, 15, 30, 50, 70, and 85% MVC). We quantified TPF, RFD, and various EMG burst characteristics. Contrary to the speed-control hypothesis, we found that TPF was not constant, but significantly varied from 2 to 85% MVC. Specifically, the RFD slope from 2 to 15% MVC was greater than the RFD slope from 30 to 85% MVC. Longer TPF at low force levels was associated with the variability of EMG burst duration, whereas longer TPF with higher force levels was associated with the EMG burst integral. Contrary to the speed-control hypothesis, we found that the regulation of TPF for low and high force levels was different, suggesting that neuronal variability is critical for force levels below 30% MVC and neuronal amplitude for force levels above 30% MVC. These findings present compelling new evidence highlighting the limitations of the speed-control hypothesis underscoring the need for a new theoretical framework.
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: J Hum Kinet Año: 2024 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Polonia
Texto completo
Añadir a Mi BVS
Imprimir
XML
PubMed Links
Buscar en Google

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: J Hum Kinet Año: 2024 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Polonia