Exercise-induced rib stress fractures: potential risk factors related to thoracic muscle co-contraction and movement pattern

A Vinther, IL Kanstrup, E Christiansen, T Alkjaer, B Larsson, SP Magnusson, Charlotte Ekdahl, P Aagaard

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29 Citations (SciVal)


The etiology of exercise-induced rib stress fractures (RSFs) in elite rowers is unclear. The purpose of the study was to investigate thoracic muscle activity, movement patterns and muscle strength in elite rowers. Electromyographic (EMG) and 2-D video analysis were performed during ergometer rowing, and isokinetic muscle strength was measured in seven national team rowers with a history of RSF and seven matched controls (C). RSF displayed a higher velocity of the seat in the initial drive phase (RSF: 0.25 +/- 0.03, 0.25 (0.15-0.33) m/s vs C: 0.15 +/- 0.06, 0.18 (-0.11-0.29) m/s P = 0.028) (Mean +/- SEM, median and range). Further, RSF had greater co-contraction of m. serratus anterior and m. trapezius in the mid-drive phase (RSF: 47.5 +/- 3.4, 48.5 (35.8-60.2)% EMG signal overlap vs C: 30.8 +/- 6.5, 27.0 (11.2-61.6)% P = 0.043). In addition, the RSF subjects showed a lower knee-extension to elbow-flexion strength ratio (RSF: 4.2 +/- 0.22, 4.3 (3.5-5.1) vs C: 4.8 +/- 0.16, 5.0 (4.2-5.3) P = 0.043), indicating stronger arms relative to legs compared with controls. In conclusion, increased thoracic muscle co-contraction, altered movement patterns and reduced leg/arm strength ratio were observed in the RSF subjects, which may all predispose toward an increased risk of RSF.
Original languageEnglish
Pages (from-to)188-196
JournalScandinavian Journal of Medicine & Science in Sports
Issue number3
Publication statusPublished - 2006

Bibliographical note

The information about affiliations in this record was updated in December 2015.
The record was previously connected to the following departments: Division of Physiotherapy (Closed 2012) (013042000)

Subject classification (UKÄ)

  • Sport and Fitness Sciences


  • athletes
  • rowing biomechanics


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