Hip- and thigh-muscle activation during the star excursion balance test

J Sport Rehabil. 2011 Nov;20(4):428-41. doi: 10.1123/jsr.20.4.428.


Context: The Star Excursion Balance Test (SEBT) is often used to train and assess dynamic balance and neuromuscular control. Few studies have examined hip- and thigh-muscle activation during the SEBT.

Objective: To quantify hip- and thigh-muscle activity during the SEBT.

Design: Repeated measures.

Setting: Laboratory.

Participants: 22 healthy individuals, 11 men and 11 women.

Methods: EMG measurements were taken as participants completed 3 trials of the anterior (A), medial (M), and posteromedial (PM) reach directions of the SEBT.

Main outcome measures: Mean EMG data (% maximal voluntary isometric contraction) from the gluteus medius (Gmed), gluteus maximus (Gmax), and vastus medialis (VM) were measured during the eccentric phase of each SEBT reach direction. Test-retest reliability of EMG data across the 3 trials in each direction was calculated. EMG data from each muscle were compared across the 3 reach directions.

Results: Test-retest reliability ranged from ICC3,1 values of .91 to .99. A 2-way repeated-measure ANOVA revealed a significant interaction between muscle activation and reach direction. One-way ANOVAs showed no difference in GMed activity between the A and M directions. GMed activity in the A and M directions was greater than in the PM direction. There was no difference in GMax and VM activity across the 3 directions.

Conclusion: GMed was recruited most effectively when reaching was performed in the A and M directions. The A, M, and PM directions elicited similar patterns of muscle recruitment for the GMax and VM. During all 3 SEBT directions, VM activation exceeded the 40-60% threshold suggested for strengthening effects. GMed activity also exceeded the threshold in the M direction. GMax activation, however, was below the 40% threshold for all 3 reach directions, suggesting that performing dynamic lower extremity reaching in the A, M, and PM directions may not elicit strengthening effects for the GMax.

MeSH terms

  • Adult
  • Analysis of Variance
  • Biomechanical Phenomena
  • Buttocks / physiology
  • Electromyography
  • Female
  • Hip / physiology
  • Humans
  • Isometric Contraction / physiology*
  • Lower Extremity / physiology*
  • Male
  • Muscle, Skeletal / physiology*
  • Postural Balance / physiology*
  • Thigh / physiology
  • Young Adult