Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
Androit-APP Journal of Sports Science and Medicine
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©Journal of Sports Science and Medicine (2016) 15, 483 - 491

Research article
Muscle Contraction Velocity: A Suitable Approach to Analyze the Functional Adaptations in Elite Soccer Players
Irineu Loturco1,2, , Lucas A. Pereira1, Ronaldo Kobal1, Katia Kitamura1, Rodrigo Ramírez-Campillo4, Vinicius Zanetti5, Cesar C. Cal Abad1, Fabio Y. Nakamura1,3
Author Information
1 NAR - Nucleus of High Performance in Sport, São Paulo, SP, Brazil
2 Department of Mechatronics Engineering, University of São Paulo, SP, Brazil
3 Department of Physical Education, State University of Londrina, PR, Brazil
4 Department of Physical Activity Sciences, Universidad de Los Lagos, Osorno, Chile
5 Red Bull Brazil Football, São Paulo, SP, Brazil

Irineu Loturco
✉ Nucleus of High Performance in Sport, Av. Padre José Maria, 555 – 04753 – 060 - São Paulo – SP – Brazil
Email: irineu.loturco@terra.com.br
Publish Date
Received: 02-02-2016
Accepted: 26-06-2016
Published (online): 05-08-2016
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ABSTRACT

Tensiomyography (TMG) has been used as a simple and non-invasive tool to assess the mechanical properties of skeletal muscles. The TMG-derived velocity of contraction (Vc), which can be calculated from the ratio between maximal radial displacement and the sum of contraction time and delay time, has been proposed for evaluating athletes. However, its sensitivity to training effects and possible relation with changes in soccer players’ neuromuscular performance have not yet been addressed. To test this possibility, twenty-two male Brazilian elite soccer players were assessed using TMG-derived Vc, unloaded squat jump, countermovement jump and drop jump at 45 cm, loaded jump squat and linear (20 m) and change of direction (COD) sprint tests, prior to and after an 8-week period, between two consecutive official tournaments, during which the concurrency between endurance and strength-power training commonly impairs neuromuscular capacities. Magnitude-based inference was used to detect meaningful training effects. From pre- to post-tests, it was observed likely to almost certainly improvements in all modes of jumping tests. In addition, we could verify decrements in the 20-m and COD sprint performances, which were rated as very likely and almost certainly, respectively. Finally, both rectus femoris and biceps femoris muscles presented a likely reduction in Vc. Therefore, chronic decreases in sprinting speed are possibly accompanied by a reduced TMG-derived Vc. From a practical standpoint, the TMG-derived Vc can be used to monitor negative specific-soccer training effects related to potential impairments in maximum speed.

Key words: Football, concurrent training, muscle function, elite athletes, muscle power


           Key Points
  • Tensiomyography (TMG) can be considered a useful technology for coaches and sport scientists seeking for non-invasive and practical tools to assess the muscle function of elite athletes;
  • Velocity of contraction (Vc) is a single index able to integrate several of the reliable mechanical outcomes provided by TMG, which was shown to be sensitive to detect neuromuscular impairments in professional soccer players;
  • After 8 weeks of specific soccer training, the changes in the Vc seem to occur in the same direction as the reductions in maximal sprint ability and COD speed.
 
 
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