The gluteus medius muscle is an important frontal plane stabilizer of the pelvis. Although its primary function is pelvic stabilization in singe leg stance (closed-chain), many therapists and trainers continue to strengthen the gluteus medius in an open chain using hip abduction.  The addition of an unstable surface such as a Thera-Band® Stability Trainer is thought to increase muscle activation due to the increased challenge of stabilizing the pelvis in the frontal plane while balancing on a labile surface.

Researchers at the Mayo clinic in Rochester Minnesota performed a descriptive electromyographic (EMG) study to quantify the activation of the gluteus medius during different closed-chain weight-bearing exercises. Young, healthy subjects performed 5 exercises: bilateral stance, unilateral stance, unilateral stance on foam, single leg squat, and single leg squat on foam.

older adult single leg balance on Thera-Band Stability Trainer

The researchers found that single leg stance exercises produced significantly greater EMG activity compared to bilateral stance. In addition, single leg squats produced significantly more EMG activity than single leg stance. While not statistically significant, performing single-leg exercises on a foam pad did produce more EMG activity of the gluteus medius than a stable surface.

Below are the estimated peak muscle activation levels for each exercise. Unfortunately, the authors did not provide the actual % maximal contraction values (MVICs) of each exercise, instead providing only a graphical summary.

  • Double limb stance ~ 4% MVIC
  • Single leg stance ~ 20% MVIC
  • Single leg stance on foam ~ 26% MVIC
  • Single leg squat ~ 50% MVIC
  • Single leg squat on foam ~ 60%

In conclusion, the authors suggested that in order to challenge the gluteus medius, weight bearing exercises should be performed unilaterally. In addition, single leg stance on foam pads such as Thera-Band Stability Trainers may provide additional demand on the gluteus medius muscle. This paper also outlined a clinical progression of activation of the gluteus medius during closed-chain exercises. Further research on patients with weakness or inhibition of the gluteus should validate this progression in the clinical setting.

Reference: Krause DA, et al. Electromyographic analysis of the gluteus medius in five weight-bearing exercises. J Strength Cond Res. 2009 Dec;23(9):2689-94.

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