Research article - (2022)21, 402 - 412
DOI:
https://doi.org/10.52082/jssm.2022.402
Backstroke-to-Breaststroke Turns Muscular Activity. A Study Conducted in Age Group Swimmers
Phornpot Chainok1,2,, Jessy Lauer2,3, Pedro Gonçalves2,3, Karla de Jesus2,3,4, Ricardo J. Fernandes2,3, Joao Paulo Vilas-Boas2,3
1Faculty of Sport, Burapha University, Chonburi, Thailand
2Centre of Research, Education, Innovation and Intervention in Sport, Faculty of Sport, University of Porto, Porto, Portugal
3Porto Biomechanics Laboratory, University of Porto, Portugal
4Faculty of Physical Education and Physiotherapy, Federal University of Amazonas, Manaus, Brazil

Phornpot Chainok
✉ Faculty of Sport Science, Burapha University, No. 169 Longhaad Bangsaen Road, Saensook, Mueang, ChonBuri 20131, Thailand
Email: phornpot@go.buu.ac.th
Received: 29-03-2022 -- Accepted: 08-08-2022
Published (online): 01-09-2022

ABSTRACT

The aims of this study were to compare surface electromyographic (EMG) activity and kinematic variables among open, somersault, bucket and crossover backstroke-to-breaststroke turning techniques, and identify relationships between the integrated electromyography (iEMG) and kinematics profile focusing on the rotation and push-off efficacy. Following a four-week of systematically increasing contextual interference intervention program, eight 12.38 ± 0.55 years old male swimmers randomly performed twelve repetitions (three in each technique) turns in and out of the wall at maximum speed until the 7.5 m reference mark. Surface EMG values of the right vastus lateralis, biceps femoris, tibialis anterior, gastrocnemius medialis, rectus abdominis, external oblique, erector spinae and latissimus dorsi were recorded and processed using the integrated electromyography (iEMG) and the total integrated electromyography (TiEMG) that was expressed as a percentage of iEMGmax to normalize per unit of time for each rotation and push-off phase. Complementarily, 2D sagittal views from an underwater video camera were digitized to determine rotation and push-off efficacy. The crossover turn presented the highest rotation and push-off iEMG values. Erector spinae and gastrocnemius medialis had the highest activity in the rotation and push-off phases (89 ± 10 and 98 ± 69%, respectively). TiEMG depicted a very high activity of lower limb muscles during push-off activity (222 ± 17 to 247 ± 16%). However, there were no relation between TiEMG and rotation and push-off time, tuck index and final push-off velocity during the rotation and the push-off phases across all the studied turning techniques. The rotation efficacy in age-group swimmers were dependent on rotation time (p = 0.04). The different turning techniques were not distinguishable regarding iEMG activity as a possible determinant of rotation and push-off efficacy. Our study has direct implications for selecting appropriate exercises and designing training programs for optimizing the rotation and push-off phases of backstroke-to-breaststroke turning at young ages.

Key words: Surface electromyography, turning techniques, individual medley, young swimmert

Key Points
  • The orientation during rotation phase of the backstroke-to-breaststroke turns is related to difference core body and lower limb muscular activation that affects the rotation efficacy.
  • Erector spinae revealed the highest activity during the rotation phase and gastrocnemius medialis and tibialis anterior were mainly activated during the push-off phase.
  • The use of different core body and lower limb muscles showed promising evidence in the crossover turn throughout the rotation and push-off phases.
  • Independent of the turning variant on the upper and lower limb muscles co-activation should be considered in specific closed kinetic chain of the lower limb for improving “active” push-off phase, strengthening core muscles to improve the effectiveness of muscles co-activation to speed up the rotation.








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