Influence of Hip Joint Position on Muscle Activity During Prone Hip Extension with Knee Flexion

• Age:  20.2 ± 0.4 years old
• Gender: Males
• Characteristics:
  • Other Subject Characteristics:
    • Height - 171.1 ± 5.0 cm
    • Weight - 64.3 ± 10.5 kg

  • Study Framework/Protocol
    • Electromyographic activity (EMG) was recorded for the right gluteus maximus (GM), right hamstrings (HS), right and left lumbar multifidus (LM) on L5/S1, and right and left erector spinae (ES)
      • Surface Electrode Placements
        • GM - Placed approximately halfway between the greater trochanter and second sacral vertebrae
        • HS - Placed approximately halfway between the gluteal fold and the popliteal fold
        • LM -Placed lateral to the spinous process on L5/S1
        • ES - Placed on L1 muscle bulk of ES

      • Goniometric Landmarks used in Measurement of Hip Abduction and External Rotation in Conditions Below
        • Hip Abduction - Measured by the angle formed by the thigh center line and a line perpendicular to a line connecting both posterior superior iliac spines
        • Hip External Rotation - Measured by the angle formed by the lower leg center line and a plumb line passing through the patella

    • Experimental Conditions Measured (participant placed on stomach, right knee bent to 90° in every condition)
      • Hip Position (measured with goniometry)
        • Neutral hip position (N) - 0° of hip abduction and 0° of hip external rotation
        • Abduction hip joint position (AB) - 15° of hip abduction and 0° of hip external rotation
        • Abduction and external rotation position (ABER) - 15° of hip abduction and 20° of hip external rotation

    • Data Recording Protocol
      • Maximum voluntary isometric contraction was calculated using standard manual muscle testing positions for each muscle group
      • Each participant was allowed 5 minutes to practice the hip extension exercise for familiarization of testing protocol
      • Each participant performed each condition for 3 times each, with 2 minutes in-between each measurement; order was randomized (not specified how) and all measurements taken by one examiner
      • In each condition, vertical bars were installed to control the abduction angle for each condition
      • Participants were instructed to lift their right thigh 5 cm above the platform for 5 seconds while maintaining the knee flexion, hip abduction, and hip external rotation angles of the respective condition

    • Relevant EMG Data Processing Information
      • Authors reduced variability in the data by averaging the three trials for each participant for each condition and used that value to calculate the average amplitude during maximum voluntary isometric contraction
      • GM/HS ratio - GM activation divided by HS activation to determine if GM could be selectively activated over the HS during each of the experimental conditions

    • Statistical Analyses
      • Normal distribution of the muscle activation data was tested using Shapiro-Wilk test
        • Result was not normally distributed; Friedman repeated measures ANOVA used to detect differences in muscle activities between the three conditions
        • Post-hoc testing was performed using Wilcoxon signed-rank with a Holm's correction
        • Significance set at p < 0.05

      • Intra-rater reliability was tested using intraclass coefficient correlations (ICCs)

• Inclusion Criteria: N/A
• Exclusion Criteria:
  • Any musculoskeletal pain within the past 12 months
  • Any history of surgery in the lower half of the body
  • Any hip flexor shortness as evidenced by the Thomas Test
  • Any tensor fascia latae shortness as evidenced by Ober Test

• Activation levels of GM, HS, ES, LM in each of the three different conditions (N, AB, ABER)
• GM:HS ratio in each of the three different conditions
• Intra-rater reliability of the muscle activations in each of the conditions (N, AB, ABER)

• Intra-rater reliability was excellent for measuring muscle activities in each of the testing positions (0.91-0.98)
• The table below illustrates the median (middle 50%) activation and interquartile range of each of the muscles during each of the three different experimental conditions (N, AB, ABER).

Significant differences are indicated with a (¹) (p < 0.017), a (²) (p < 0.025), and a (³) (p < 0.05)

• Results of importance:
  • GM activity and GM /HS ratios highest in ABER position, followed by AB, and N
    • Significantly greater GM activation and GM/HS ratio in ABER position over the other positions (AB, N)
      • GM activation and GM/HS ratio significantly greater in AB position over N position
    • HS, right ES , and left LM showed lowest activation of all conditions during ABER position; AB and N followed with significantly increasing levels of activation
  • Bilateral ES activity was lowest in AB condition over N condition
  • Right LM showed increased activation in AB condition over N condition

Conclusions

• GM activation increases with increasing levels of hip abduction and hip external rotation (ABER > AB > N)
• HS activation decreases with increasing levels of hip abduction and hip external rotation (ABER < AB < N)
• Bilateral ES activation decreases with increasing levels of hip abduction and hip external rotation (AB < N)
• Right LM activation increases with increasing levels of hip abduction and external rotation (AB > N)

Conclusions of the Researchers

• GM activation can be facilitated, while HS and bilateral ES activation can be suppressed, in a bent-knee, prone hip extension exercise by the addition of hip abduction and external rotation

Caption: Note the huge muscle mass that is gluteus maximus

Note the huge muscle mass that is the gluteus maximus - https://corawen.com/sacrum-gluteus-dance-links/

Review & Commentary:

The current study investigated whether or not the addition of hip abduction and hip external rotation influenced GM activation patterns in a bent-knee, prone hip extension exercise. The authors used an experimental design that allowed for data to be collected on the activation levels of the gluteus maximus , and commonly overactive synergists (hamstrings and erector spinae ) during a commonly used hip extension exercise. The experimental protocol was simple, effective, and reproducible based on the study design, and included appropriate exclusion criteria to minimize confounding factors. The addition of vertical bars to standardize hip abduction and external rotation angles increased reliability of the data recorded. Further, analysis of the GM /HS ratio is important to human movement professionals because the gluteus maximus is frequently underactive, so providing quantifiable data as to its activation patterns with respect to the hamstrings is clinically useful over just reporting its relative activation in each of the conditions.

This study does have limitations. First, the demographics of the study were young, healthy males with no history of lower extremity injury, limiting transferability to females and injured populations. Second, surface EMG electrodes were used and were in close proximity to one another, making cross-talk between sensors a potential confounding factor. Replication of this experiment in the future should include intramuscular EMG recording to minimize chance of cross-talk between receivers. Third, while the authors investigated hamstring activity in the study, more specific measurement of the biceps femoris /semimembranosus/semitendinosus contributions would have added additional credence to the data. Fourth, lumbopelvic motion was not recorded, so data regarding the pelvic positioning (in relative anterior or relative posterior tilt) is unavailable. As a result, only inferences can made with respect to lumbopelvic motion. Last, temporal firing patterns of the muscles were not measured, so no inferences can be made about healthy (the participants in this study) and clinically pathologic hip extension movement patterns.

Why is this study important?

Research has shown a reduction or delay in gluteus maximus activity in individuals with low back pain, lumbar instability, sacroiliac joint pain, knee valgus, an anterior pelvic tilt, hip osteoarthritis and achilles tendinopathy (2, 4-10). A systematic review concluded that targeted exercise to improve the delayed latency of gluteus maximus firing is effective (3). The current study indicates that gluteus maximus activation increases in a bent-knee, prone hip extension exercise with increased levels of hip abduction and hip external rotation; this position also reduced the relative hamstring activity. Further, a reduction in erector spinae activity was also observed as hip abduction angle increased.

How does it affect practice?

The current study suggest that adding hip abduction and hip external rotation in hip extension exercise will minimize activity of the hamstrings and erector spinae , and maximize gluteus maximus activity. Further, while measurement of the gluteus maximus ' temporal activation pattern with respect to the hamstrings and erector spinae was not recorded, it may be inferred that these exercises may have a positive affect on the gluteus maximus /hamstring ratio. This may improve hip extension force output and improve performance, on activities like squats , lunges , deadlifts , or box jumps .

How does it relate to Brookbush Institute Content?

In all models of postural dysfunction (lumbopelvic hip dysfunction , sacroiliac joint dysfunction , lower leg dysfunction , and upper body dysfunction via underactivity of the posterior oblique subsystem , the gluteus maximus is classified as "long/under-active." Techniques to optimize gluteus maximus activation include release of the (biceps femoris , erector spinae , adductor magnus ) and stretch (biceps femoris , erector spinae ) of overactive synergists followed by isolated gluteus maximus activation and integration . Further, techniques to restore mobility of the lumbopelvic complex can include self-administered joint mobilization to restore capsular flexibility of the hip .

The Brookbush Institute has previously suggested that hip abduction is included when performing gluteus maximus activation exercises to inhibit overactive biceps femoris and adductor magnus and to improve neuromuscular coordination of the gluteus maximus and gluteus medius . The current study supports that exercise recommendation.

The following videos are initial steps in addressing under-activity of the gluteus maximus . Gluteus Maximus Manual Muscle Testing and the Overhead Squat Assessment may be used to assess under-activity.

Brookbush Institute videos

Biceps Femoris SA Static Release

Biceps Femoris Active Stretch

Erector Spinae SA Release

Latissimus Dorsi and Erector Spinae Static Stretch: Child Pose

Gluteus Maximus Isolated Activation

Bibliography:

1. RESEARCH REVIEW: Ito J. (1996). Morphological analysis of the human lower extremity based on the relative muscle weight. Okajimas Folia Anat. Jpn. 73(5): 247-252.
2. Bruno PA, Bagust J. (2007). An investigation into motor pattern differences using a prone hip extension between subjects with and without low back pain. Clin Chiropract. 10: 68-80.
3. Crow J, Pizzari T, Buttifant D. (2011). Muscle onset can be improved by therapeutic exercise: a systematic review. Phys Ther Sport. 12: 199-209.
4. Hungerford, B., Gilleard, W., Hodges, P. (2003) Evidence of altered lumbopelvic muscle recruitment in the presence of sacroiliac joint pain. Spine 28(14), 1593-1600
5. Padua, D. A., Bell, D. R., & Clark, M. A. (2012). Neuromuscular characteristics of individuals displaying excessive medial knee displacement. Journal of athletic training, 47(5), 525
6. Tateuchi, H., Taniguchi, M., Mori, N., Ichihashi, N. Balance of hip and trunk muscle activity is associated with increased anterior pelvic tilt during prone hip extension (2013) Journal of Electromyography and Kinesiology 22 (3). 391-397
7. Grimaldi, A., Richardson, C., Durbridge, G., Donnelly, W., Darnell, R., Hides, J. (2009). The association between degenerative hip joint pathology and size of the gluteus maximus and tensor fascia latae muscles. Manual Therapy. 14. 611-617
8. Jung, H., Kang, S., Park, J., Cynn, H., & Jeon, H., (2015). EMG activity and force during prone hip extension in individuals with lumbar segmental instability. Manual Therapy, 20(3), 440-444
9. Cooper, N., Scavo, K., Strickland, K., Tipayamongkol, N., Nicholson, J., Bewyer, D., Sluka, K. Prevalence of gluteus medius weakness in people with chronic low back pain compared to healthy controls. J Euro Spine. 26 May 2015
10. Franettovich, S. M., Honeywill, C. O. N. O. R., Wyndow, N., Crossley, K. M., & Creaby, M. W. (2014). Neuromotor control of gluteal muscles in runners with achilles tendinopathy. Medicine and science in sports and exercise, 46(3), 594-599

© 2016 Brent Brookbush

Questions, comments, and criticisms are welcomed and encouraged -