Influence of fatigue and velocity on the latency and recruitment order of scapular muscles

Guillermo Mendez-Rebolledo, Valeska Gatica-Rojas, Eduardo Guzman-Muñoz, Eduardo Martinez Valdes, Rodrigo Guzman-Venegas, Francisco Jose Berral De La Rosa

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)
277 Downloads (Pure)


Objectives: To determine the influence of velocity and fatigue on scapular muscle activation latency and recruitment order during a voluntary arm raise task, in healthy individuals. Design: Cross-sectional study. Setting: University laboratory. Participants: Twenty three male adults per group (high-velocity and low-velocity). Main outcome measures: Onset latency of scapular muscles [Anterior deltoid (AD), lower trapezius (LT), middle trapezius (MT), upper trapezius (UT), and serratus anterior (SA)] was assessed by surface electromyography. The participants were assigned to one of two groups: low-velocity or high-velocity. Both groups performed a voluntary arm raise task in the scapular plane under two conditions: no-fatigue and fatigue. Results: The UT showed early activation (p < 0.01) in the fatigue condition when performing the arm raise task at a high velocity. At a low velocity and with no muscular fatigue, the recruitment order was MT, LT, SA, AD, and UT. However, the recruitment order changed in the high-velocity with muscular fatigue condition, since the recruitment order was UT, AD, SA, LT, and MT. Conclusions: The simultaneous presence of fatigue and high-velocity in an arm raise task is associated with a decrease in the UT activation latency and a modification of the recruitment order of scapular muscles.
Original languageEnglish
Pages (from-to)80-86
JournalPhysical Therapy in Sport
Early online date19 Apr 2018
Publication statusPublished - 1 Jul 2018


  • timing
  • neuromuscular control
  • speed
  • recruitment pattern


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