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Tuesday, June 6, 2023

Hip Muscle Activity During Hip Strengthening Exercises in Distance Runners

Brent Brookbush

Brent Brookbush


Research Review: Hip Muscle Activity During Hip Strengthening Exercises in Distance Runners

By David Chessen DPT, PT, MBA, CSCS

Edited by Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation: McBeth, J. M., Earl-Boehm, J. E., Cobb, S. C., and Huddleston, W. E. (2012). Hip muscle activity during 3 side-lying hip-strengthening exercises in distance runners. Journal of Athletic Training47(1), 15-23. ARTICLE

Why the Study is Relevant: Several studies have correlated a reduction in hip abductor strength (the gluteus medius specifically) with knee pain (2-4). This 2012 study investigated muscle activity of the gluteus medius , tensor fascia latae , anterior hip flexors and gluteus maximus during side-lying hip strengthening exercises. Side-lying abduction was found to activate the gluteus medius more effectively than other exercises examined in this study.

Gluteus medius in unembalmed dissection.
Caption: Gluteus medius in unembalmed dissection.

Gluteus medius in unembalmed dissection.

Study Summary

Study DesignSingle session quasi-experimental laboratory study
Level of EvidenceIIB evidence from at least one other type of quasi-experimental study
Subject Characteristics

Twenty distance runners, including members of running clubs and collegiate teams.


  • Men (n=9)
    • Age (y): 26.6 ± 6.5
    • Height (m): 1.75 ± 0.08
    • Mass (kg): 69.3 ± 7.1
    • Average miles run per week: 45.2 ± 17.0
    • Body mass index (kg/m²): 22.6 ± 1.2

  • Women (n=11)
    • Age (y): 26.1 ± 5.2
    • Height (m): 1.68 ± 0.03
    • Mass (kg): 61.3 ± 6.6
    • Average miles run per week: 40.7 ± 13.4
    • Body mass index (kg/m²): 21.7 ± 1.5

Inclusion Criteria:

  • Age 18-40
  • Ran an average of 25 miles/wk for 6 weeks prior to the study

Exclusion Criteria:

  • Lower extremity injury 6 or fewer months prior to the study that required modifying a regular training regimen
  • Lower extremity injury or muscle soreness at the time of the study
  • History of lower extremity surgery
  • Pregnant
  • Incorporating hip-strengthening exercises into the training regimen
  • Body mass index of 25 or more

Testing took place in a single session in a laboratory setting.

Participants performed three side-lying hip-strengthening exercises including abduction (ABD), abduction with external rotation (ABD-ER) and the CLAM exercise.

  • To perform the ABD exercise, participants laid on their non-dominant side, flexing the non-dominant leg for stability.
    • Hip abduction was standardized at 35°.

  • For the ABD-ER exercise, participants externally rotated their hips and pointed their toes up as far as possible.
    • Participants were instructed to keep the pelvis in a neutral position and were monitored with a stabilizer pressure bio-feedback unit.

  • For the CLAM exercise, participants laid on their sides with the dominant limb up, feet together and the top leg rotated upward in a clamshell-like motion.

All participants performed 4 practice sets of 5 repetitions each, and one researcher instructed all participants on how to perform the exercises.

After the practice sets, participants warmed up on a treadmill for 5 minutes, followed by skin preperation for surface electromyographic (EMG).

Maximal voluntary isometric contraction (MVIC) were performed to confirm minimal muscle crosstalk, and for normalization.

After the MVIC data was collected, participants rested for 2 minutes before exercise data was collected.

  • Participants performed 7 repetitions with oral feedback, pressure biofeedback and resistance of 5% body mass.
Data Collection and Analysis

A one-way, repeated measures analysis of variance comparing GMed, GMax, TFL and AHF muscle activity was  done for each of the 3 exercises (ABD, ABD-ER, CLAM).

The α level was set a priori at < 0.05; if a main effect was found, post hoc pairwise comparisons were done with a Bonferroni correction.

Outcome MeasuresExercise EMG amplitude was expressed as a percentage of the average MVIC for each muscle (%MVIC).The %MVIC for the 3 repetitions of each exercise were averaged for each participant.

Differences in muscle activity were recorded for the ABD (F = 25.903, P<0.001), ABD-ER (F=10.458, P<0.001), and CLAM (F = 4.640, P = 0.006)

For the ABD exercise:

  • GMed (79.1% ± 29.9%), TFL (54.3% ± 19.1%), and AHF (28.2% ± 21.5%) were muscle activity varied widely (P range, 0.001 - 0.004)
  • GMax (25.3% ± 24.6%) and  AHF (P=0.99) were less active than the GMed (P<0.001) and TFL (P=0.004)

For the ABD-ER exercise:

  • TFL (70.9% ± 17.2%) was more active than the AHF (54.3% ± 24.8%, P=0.03), the GMed (53.03% ± 28.4%, P=0.03), and the GMax (31.7% ± 24.1%, P<0.001)

For the CLAM exercise:

  • AHF (54.2% ± 25.2%) was more active than the TFL (34.4% ± 20.1%, P=0.05) and the GMed (32.6% ± 16.9%, P=0.002) but did not differ from the GMax (34.2% ± 24.8%, P=0.20)
Our ConclusionsThe researchers' conclusions reinforce the practice of the Brookbush Institute: side-lying leg raises into abduction are optimal for activating the GMed. A notable finding is that the CLAM exercise activated the TFL and AHF to a greater extent than the GMed. (Note: this was not done in the same manner as recommended by the Brookbush Institute for introducing gluteus medius strengthening.
Researchers' Conclusions

The ABD exercise was found to be optimal for activating the GMed with little activation of the TFL and AHF. The CLAM exercise resulted in the greatest activation of the AHF and very little activation of the GMed and GMax. Performing the ABD-ER exercise induces excessive activation of the TFL, beyond what may be desired, depending on the goals of the exercise program.

Hip Abduction with Manual Resistance
Caption: Hip Abduction with Manual Resistance

Abduction with Manual Resistance

Review & Commentary:

As much as 79% of runners will develop a lower extremity injury, and the most commonly reported symptoms are those related to knee pain (1). A functional valgus , decreased hip abductor strength, and increased stress on the knee joint appears to play a key role (2). This study adds to the significant body of research on common exercises prescribed in rehabilitation, fitness, and performance settings for targeting the hip abductor muscles, specifically the gluteus medius (GMed) (4-5). The exercises examined in this study include side-lying hip abduction, side-lying hip abduction with external rotation and the clamshell . The side-lying hip abduction preferentially recruited the gluteus medius better than the other exercises in the study.

The study had many methodological strengths, including:

  • Clinically relevant exercises commonly used by human movement professionals were performed. These exercises include side-lying hip abduction, side-lying hip abduction with external rotation, and the clamshell .
  • Participants followed a standardized set of procedures to perform the exercises, were monitored with a pressure biofeedback unit, and observed by a single researcher.
  • Unlike other similar studies, this study examined several muscles of the hip. This allows "relative recruitment" to be ascertained.

Weaknesses that should be noted prior to clinical integration of the findings include:

  • The participants were distance runners; performing a high volume of exercise each week. The results may not be generalizable to a more sedentary population.
  • Surface EMG was used, which may not allow for analysis of deeper muscles (6) and may be susceptible to crosstalk.
  • A control group was not used; the study relied on the intervention group for statistics analysis.
  • EMG data recorded the activity of specific muscles but not the timing or order of recruitment during the exercises.

How This Study Is Important:

This study is one of a relatively small batch of studies that could be labeled "practical, comparative studies." The Brookbush Institute is very supportive of all such research, and hopes that more studies of this type will be done with the intent of "optimizing intervention selection." Specifically, this study provides data on hip muscle activation during side-lying hip strengthening exercises commonly used in rehab, fitness, and performance settings. The findings demonstrate that side-lying hip abduction provides the the best selective recruitment of the gluteus medius  among common hip strengthening exercises. In addition, the CLAM exercise was shown to produce the highest activation of the anterior hip flexors (AHF)  with very little activation of the gluteus medius and gluteus maximus .

How the Findings Apply to Practice:

These findings can help human movement professionals refine their selection of exercise for gluteus medius activation. It also appears that the CLAM exercise is need of modification, careful cuing and instruction, or should be eliminated from programs intended to reduce hip flexor activity and strengthen the gluteus medius .

How Does It Relate to Brookbush Institute Content?

The Brookbush Institute (BI) recommends the 3 side-lying hip strengthening exercises investigated in this study with modification for reciprocally inhibiting over-active synergists. The intent of these recommendations is to optimize the quality of human movement, and is generally based on assessment of postural dysfunction/movement impairment . Specifically, the gluteus medius is often assessed as under-active in those exhibiting lumbo-pelvic-hip complex dysfunction (LPHCD) and/or lower extremity dysfunction (LED) . The BI recommends that exercises like this follow any necessary mobility work, but precede any multi-joint movements.

The following videos illustrate Brookbush Institute some of the techniques used for Gluteus Medius Activation:

Gluteus Medius Isolated Activation

Side Stepping Progressions Gluteus Medius Reactive Activation (Reactive Activation)

Resisted Walking (Integration)


  1. van Gent, B. R., Siem, D. D., van Middelkoop, M., van Os, T. A., Bierma-Zeinstra, S. S., and Koes, B. B. (2007). Incidence and determinants of lower extremity running injuries in long distance runners: a systematic review. British Journal of Sports Medicine.
  2. Powers, C. M. (2010). The influence of abnormal hip mechanics on knee injury: a biomechanical perspective. Journal of Orthopaedic and Sports Physical Therapy40(2), 42-51.
  3. Earl, J. E., and Hoch, A. Z. (2011). A proximal strengthening program improves pain, function, and biomechanics in women with patellofemoral pain syndrome. The American Journal of Sports Medicine39(1), 154-163.
  4. Ebert, J. R., Edwards, P. K., Fick, D. P., and Janes, G. C. (2016). A Systematic Review of Rehabilitation Exercises to Progressively Load Gluteus Medius. Journal of sport rehabilitation, 1-35.
  5. Distefano, L. J., Blackburn, J. T., Marshall, S. W., and Padua, D. A. (2009). Gluteal muscle activation during common therapeutic exercises. journal of orthopaedic & sports physical therapy39(7), 532-540.
  6. Merletti, R., and Di Torino, P. (1999). Standards for reporting EMG data. J Electromyogr Kinesiol9(1), 3-4.
  7. Neumann, D. A. (2010). Kinesiology of the hip: a focus on muscular actions. Journal of Orthopaedic and Sports Physical Therapy40(2), 82-94.

© 2017 Brent Brookbush

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