Isometric Hip Abduction Using a Thera-Band Increases Gluteus Maximus Activity and Reduces Anterior Pelvic Tilt During Bridge Exercise

Research Review: Isometric Hip Abduction Using a Thera-Band Increases Gluteus Maximus Activity and Reduces Anterior Pelvic Tilt During Bridging Exercise

By Nicholas Rolnick SPT, MS, CSCS

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

Original Citation: Choi SA, Cynn HS, Yi CH, et al. (2015). Isometric hip abduction using a Thera-Band alters gluteus maximus muscle activity and the anterior pelvic tilt angle during bridging exercise. Journal of Electromyography and Kinesiology. 25: 310-315. - ABSTRACT

Caption: The exercise performed in the current study. -https://www.pinterest.com/pin/392235448771328589/

The exercise performed in the current study. -https://www.pinterest.com/pin/392235448771328589/

Why is this relevant?: The bridge is one of the most commonly performed exercises in rehab, fitness and performance settings. Generally, this exercise is performed with the intent of facilitating gluteus maximus activation. This intent may be thwarted by synergistic dominance (over-activity) of the biceps femoris , adductor magnus and erector spinae , which may contribute to an excessive lordosis (anterior pelvic tilt) . Research has shown that increasing hip abduction angle in the bridge may reduce the occurrence of an anterior pelvic tilt during the bridge exercise, as well as reduce over-activity of the erector spinae and biceps femoris . Before the publication of this study, research had not been conducted on whether isometric hip abduction against a Thera-band® would accomplish similar results (1). The purpose of the current study was to determine the effect of isometric hip abduction using a Thera-band® on gluteus maximus , biceps femoris , and erector spinae activity and anterior pelvic tilt angle during the bridge exercise.

Study Summary

Study Design	Single Group Repeated Measures
Level of Evidence	III Evidence from non-experimental descriptive studies, such as comparative studies, correlation studies, and case-control studies
Subject Demographics	Participant Characteristics: 21 subjects (6 males, 15 females) Age (Standard Deviation) - 22.5 ± 1.0 years Height (Standard Deviation) - 165.3 ± 7.1 cm Weight (Standard Deviation) - 57.5 ± 8.7 kg Body Mass Index (Standard Deviation) - 20.9 ± 1.8 kg/m² Characteristics of the Study: Electromyographic Set-up Two surface electrodes were placed on the upper fibers of gluteus maximus, the general part of the hamstrings, and the erector spinae bilaterally Gluteus Maximus - Electrodes were placed halfway between the greater trochanter and the second sacral vertebrae in the middle of the muscle belly Hamstrings - Electrode was placed parallel to the muscle on the back of the thigh midway between the knee and the gluteal fold Erector Spinae - Electrode was placed parallel and 2 cm lateral to the spine at the level of the iliac crest Electrodes were placed on the middle of the muscle belly and parallel to the muscle's fiber direction Maximum Voluntary Isometric Contractions (MVICs) were performed for each muscle group according to Kendall's Manual Muscle Testing (MMT) Positions Each subject performed two, 5-second MVIC's in the Kendall MMT position with 30-seconds rest between repetition The mean value of the middle three seconds of both trials were used in data analysis Calculation of Ratios Gluteus maximus/hamstring ratio was calculated by dividing the normalized gluteus maximus values by the normalized hamstring values Gluteus maximus/erector spinae ratio was calculated by dividing the normalized gluteus maximus values by the normalized erector spinae values Anterior Pelvic Tilt Calculation Two reflective markers were placed on the anterior superior iliac spine and the posterior superior iliac spine of the tested side The examiner took a picture of the subject's pelvis with a digital camera in each condition and transferred the pictures to a digital program where the anterior pelvic tilt angle was calculated Camera settings and location were kept consistent throughout data collection Anterior pelvic tilt angle was defined as the angle joining the anterior superior iliac spine with the posterior superior iliac spine and the vertical line extending from the anterior superior iliac spine Study Procedure Each subject spent up to 20 minutes familiarizing themselves with the two different variations of the bridging exercise to be performed Subjects performed two bridging variants - one without isometric hip abduction (IHA) and one with IHA using a theraband Non-IHA Condition Subjects were supine with both knees positioned to 90° of flexion, hips abducted to 30° (using a goniometer), and feet/toes pointing forward, resting on the floor; arms were crossed over the body Two plastic poles were placed vertically along the lateral aspect of the knees with a wooden target bar placed at the height of the middle point of the thigh between the greater trochanter and femoral condyle when the lower extremity was in neutral (0°) hip extension The subject was instructed to lift the pelvis at a self-selected pace while maintaining contact with the pole until the subject's pelvis reached the wooden target bar The subject was instructed to hold the position for 5 seconds without any additional pelvic or thigh movement IHA Condition The procedure was identical except for the addition of a Thera-band® around the distal thigh Appropriate tension was determined when the individual could perform more than 10 repetitions at 30° of hip abduction Each exercise was performed twice for 5-seconds each with a 1-minute rest in between each repetition and a 5-minute rest in-between each condition IHA was performed first for all subjects Statistical Analysis A priori power analysis was performed using the results of a pilot study with 5 individuals; power of 0.80, statistical significance set at p = 0.05, and an effect size of 0.89 (large) required at least 10 subjects Normality was assessed with the Kolmogorov-Smirnov Z-test Test-retest reliability of EMG and pelvic measurements in each of the conditions was assessed with Intraclass coefficients (ICCs), 95% confidence intervals (CI), standard error of measurement (SEM), and minimal detectable difference (MDC) One-way ANOVA was used to assess statistical significance of the different muscles investigated in each condition Effect size index (ESI) was calculated to be the meaningful change that occurs between the bridge exercise with and without IHA Inclusion Criteria: N/A Exclusion Criteria: Limitations in range of motion of the hip, knee, and ankle joints History of low back pain or other lower extremity injuries such as iliotibial band syndrome, patellofemoral pain syndrome, anterior cruciate ligament sprains, or chronic ankle instability in the past 12 months Positive Thomas Test, Ely's Test, or Modified Ober's Test Lumbopelvic instability (indicated by positive active straight leg raise test)
Outcome Measures	Test-retest reliability for the EMG measurements in each condition Mean value of gluteus maximus, hamstring, and erector spinae activation in different conditions Gluteus maximus/hamstring and gluteus maximus/erector spinae ratios in different conditions Anterior pelvic tilt angle in different conditions
Results	Test-retest reliability (in EMG measurements for each condition) All had an intra-class correlation coefficient above 0.93, suggesting excellent test-retest reliability and accuracy in measurement Gluteus maximus, hamstrings, and erector spinae muscle activity between conditions Significant (p = 0.007, effect size index (0.365)) increases in gluteus maximus muscle activity were observed between IHA and non-IHA conditions. Gluteus maximus activity increased 21.1% during the IHA condition. No significant differences (p > 0.05) were found in erector spinae or hamstring muscle activity between IHA and non-IHA conditions. Gluteus maximus/hamstrings, and gluteus maximus/erector spinae muscle activity ratios between conditions No significant differences (p > 0.05) were found in any of the muscle activity ratios between conditions. Anterior pelvic tilt angle A significant difference (p < 0.001) was found in pelvic tilt angle between the IHA and non-IHA conditions. Bridging with IHA significantly reduced anterior pelvic tilt angle by 20.5%.
Conclusions	Gluteus maximus activity increased by 21.1% and anterior pelvic tilt angle decreased by 20.5% when isometric hip abduction was added to a bridging exercise, but no changes in hamstrings or erector spinae activity were observed. Note, this could be viewed as a relative decrease in activity hamstrings or erector spinae, especially in light of the increased demand imposed by the Thera-band®.
Conclusions of the Researchers	Bridging with a Thera-band® around the thighs to promote isometric hip abduction facilitates gluteus maximus activation and reduces anterior pelvic tilt angle. The authors hypothesize that the increased gluteus maximus activation a result of a pre-activation stimulus which encourages the muscle to engage to maintain proper alignment throughout the exercise.

Caption: Gluteus maximus contracts to posteriorly rotate the pelvis. In the current study, as gluteus maximus activity increased, the anterior pelvic tilt angle decreased. - https://www.ncbi.nlm.nih.gov/pubmed/20118525

Gluteus maximus contracts to posteriorly rotate the pelvis. In the current study, as gluteus maximus activity increased, the anterior pelvic tilt angle decreased. - https://www.ncbi.nlm.nih.gov/pubmed/20118525

Review & Commentary:

This study was one of the first studies to investigate the effects of a bridge exercise with isometric hip abduction (using a Thera-band®) on gluteus maximus , hamstrings , erector spinae activity and anterior pelvic tilt angle. Other studies have shown increasing hip abduction angle from 0° to 30° in the bridge exercise increases gluteus maximus and hamstring activity while reducing erector spinae activity and the anterior pelvic tilt angle (1). The current study performed the isometric hip abduction (IHA) exercise in 30° of hip abduction, which leaves questions about relative activation levels of gluteus maximus , hamstrings , and erector spinae in hip abduction angles less than 30° as is commonly performed in the clinical setting. Future research should investigate IHA in varying degrees of hip abduction to determine the effectiveness relative to a normal bridge (in 0° of hip abduction).

The study had many strengths to its methodology. The protocol was clearly described with appropriate exclusion criteria that could influence the EMG activity of the muscles involved. Second, the electrode placement on the superior portion of gluteus maximus was appropriate, as other research has shown the superior fibers to be more than the inferior fibers in abduction movements (2). Third, the authors performed a pilot study with 5 individuals and did an a priori power analysis with a strong effect size (0.89), expecting the effect of the intervention to be very strong on gluteus maximus recruitment. The authors included more than double the amount of subjects required based on the results of the power analysis which reduce the chance of a type I errors (false positive). Clinicians interpreting this study can be confident that the addition of isometric hip abduction (IHA) to the bridge exercise has a significant effect on gluteus maximus activity when compared to a "traditional bridge". Finally, Thera-band® resistance was appropriately set for each subject based on their current strength levels. The resistance level chosen is frequently used in the clinical setting for gluteal complex strengthening and re-education, which increases external validity (generalizability).

The study did have weaknesses that must also be addressed before integration into clinical practice. First, the subjects always performed the IHA condition prior to the non-IHA condition. The authors wanted to avoid the "carryover" or "learning effect"; however, always performing the IHA condition first may have biased the muscle activities seen in the non-IHA condition. Second, there is potential for reporting bias as the authors did not include any tables for EMG data of the different conditions. The absence of this EMG data leaves questions to be answered about the clinical significance of the results. Third, hip force measurements were not taken in either condition. Hip force measurements comparing the two conditions would be interesting, considering the IHA condition increased gluteus maximus activity so dramatically - Force output may have important implications for strength, hypertrophy and peformance training. Future studies are also needed to determine how this technique affects other commonly overactive synergists including the adductor magnus , piriformis and deep rotators of the hip . Last, only healthy subjects were used; future studies should investigate subjects with lower extremity pathologies.

Why is this study important?

This study adds to the growing body of literature investigating exercise strategies designed to maximize gluteus maximus recruitment, specifically relative to supine bridging exercise (1). This study is of particular clinical value, as it included an easily implementable strategy for increasing gluteus maximus recruitment relative to muscles the commonly over-active hamstrings , and erector spinae - Isometric hip abduction (IHA) using a Thera-band®.

How does it affect practice?

The bridge is one of the most common exercises used to facilitate gluteus maximus activation in individuals with excessive anterior pelvic tilt and/or under-activity of the gluteus maximus and gluteus medius . The current study suggests that adding IHA can be used to increase gluteus maximus (relative to hamstrings or erector spinae activity) activation and reduce an anterior pelvic tilt during the bridge exercise.

IHA did not significantly alter hamstrings or erector spinae activity from the non-IHA condition. Previous research indicates improvements in gluteus maximus /erector spinae and gluteus maximus /hamstrings ratios in bridges performed at 30° of hip abduction vs. 0° of hip abduction (1). Adding IHA at 30° may provide additional benefit; however, future research is needed comparing a traditional bridge, to hip abducted bridge, to neutral bridge with IHA and hip abducted bridge with IHA.

How does it relate to Brookbush Institute Content?

The gluteus maximus muscle is commonly classified as “long/under-active” in many of the postural dysfunction models proposed by the Brookbush Institute. As such, gluteus maximus activation, as well as bridge progressions for core activation, are commonly indicated during integrated warm-ups/movement prep and rehabilitation programs. The current study supports the Brookbush Institute’s addition of abduction to gluteus maximus strengthening in an attempt to reduce recruitment of over-active synergists.

For more on how the Brookbush Institute integrates the "bridge" into movement prep, fitness and rehabilitation routines check out:

The following videos are related to gluteus maximus manual muscle testing and strengthening using the bridging exercise and its progressions.

Brookbush Institute Videos

Gluteus Maximus MMT For An Active Population

Gluteus Maximus Isolated Activation

Glute Activation Circuit

Ball Bridge

Static Ball Bridge with Trunk Rotation:

Dynamic Ball Bridge with Trunk Rotation:

References:

Isometric Hip Abduction Using a Thera-Band Increases Gluteus Maximus Activity and Reduces Anterior Pelvic Tilt During Bridge Exercise

Research Review: Isometric Hip Abduction Using a Thera-Band Increases Gluteus Maximus Activity and Reduces Anterior Pelvic Tilt During Bridging Exercise

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