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Tuesday, June 6, 2023

Squat Foot Placement: Unique Hip Anatomy and Squat Form

Squat Foot Placement: Unique Hip Anatomy and Squat Form
Brent Brookbush

Brent Brookbush

DPT, PT, MS, CPT, HMS, IMT

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Squat Foot Placement: Unique Hip Anatomy and Squat Form

by Dr. Brent Brookbush DPT, PT, MS, CPT, HMS, IMT

Squat Stance Myth Busting:

Modifying foot position or stance width during a barbell squat to compensate for "unique hip anatomy" is actually a pretty weird idea. Most individuals have similar, or at least proportional bone structures. It seems to be a logical leap to jump from the hip joint to addressing foot positioning (skipping the knee). And, what happened to addressing mobility (e.g. knee flexion restriction, hip flexion, ankle dorsiflexion, etc.), muscle activation (e.g. gluteus medius activity, tibialis anterior activity, etc.), and even strength issues of the primary muscle worked (e.g. gluteus maximus, quadriceps, and soleus strength). I am not sure why any personal trainer, strength coach, or clinical professional would want to jump to conclusions regarding hip morphology and squat form. And this concept has implications for most lower-extremity strength exercises, including back-loaded squat foot placement, low bar squat foot placement, leg press foot placement, hack squat variations, smith machine squat, sumo squats, leg press, etc. By the end of this article, we think you might agree that the foot placement angle for most lower extremity exercises should be toes forward, feet hip to shoulder width, and that discomfort in this position is not serious but may be a sign that optimizing performance will include additional mobility or corrective exercise techniques.

There is no research to demonstrate that changing foot position during a squat will increase performance or decrease the risk of injury, for the few individuals who exhibit significantly different hip morphology.

Hip Anatomy and Foot Position Summary:

  • Normally Distributed: Research suggests that variations in hip anatomy are normally distributed, and could be plotted on a "bell curve”. That is, the gross majority of individuals exhibit bone shape, angles, and alignment, that are within a relatively small range of variation.
  • Little to No Correlation: There may be no correlation between hip morphology and foot placement. In fact, it is likely that other structural angles compensate for normal variations in hip morphology during development.
  • A Logical Error: Excessive hip retroversion and excessive hip anteversion cannot both be addressed by the same recommendation (feet wider and/or feet turned out). Further, if the standard deviation in hip anteversion is about 10°, how does anyone justify 20 - 50° of feet turn out during squats?
  • A Functional Anatomy Error: Feet turn out is not hip external rotation, it is tibia (knee) external rotation.
  • Correlated with Pain, Dysfunction, and Injury: Research demonstrates that feet turn out and knees wide (functional varus) are correlated with pain, dysfunction, and/or a higher risk of injury (11-16).
  • A Better Solution: Before accepting small imperfections in movement as evidence of permanent, life-long, structural abnormalities, it may be recommended that these very addressable and common issues (e.g. feet turn out, knees bow in, etc.) are targeted with a "corrective exercise" or "movement prep" routine. Research has demonstrated that corrective exercise can improve alignment, and performance and reduce the risk of injury (17-20).

Our Recommendation is Simple.

Perform a movement assessment (like the Overhead Squat Assessment ), address the issues you identify with corrective exercise, and then modify squat form, if necessary, based on comfort or performance needs. Chances are that addressing issues with corrective exercise noted during a movement assessment will greatly reduce the amount of compensation necessary to feel comfortable during a squat.

Sample Routine for "Feet Turn Out"

Corrective Exercise Routine or Movement Prep Warm-up: Ankle Mobility (21 -23 annotated citations)

Additional Strength and Performance Articles

Related Courses

Strength Progressions

An illustration of the "range" of varitation of femoral version. This is an example of the extremes, not normal distribution.
Caption: An illustration of the "range" of varitation of femoral version. This is an example of the extremes, not normal distribution.

This image of two femurs is representative of the "range" of femoral version, not the distribution. Although the understanding of range is instructive, range represents the extremes, and may have very little correlation with what is exhibited by the majority of individuals (distribution).

Your hip anatomy is probably NOT unique

Citing extreme examples as if they are common and/or representative of the average (mean) is a logical error. It is the equivalent of selecting a 3'6" individual with achondroplasia, and a 7'1" basketball player, and presenting them as common variations in the heights of men. Although these heights exist, we cannot say they are representative of the average, or the majority. A little digging and you will soon find that nearly 70% of men are between 5'7" and 6'1", 96% are between 5'4" and 6'4", and the heights in our example likely represent less than 1% of 1%.

Height, like many measures of human anatomy, can be plotted on a "bell curve" (a.k.a. normal distribution). Hip morphology (a.k.a. angles) appears to be another measure that can be plotted on a bell curve. Although extremes exist we find that the gross majority of individuals fall within a relatively narrow range. Based on available research (see annotated bibliography below), hip anteversion exhibits an approximate mean of 9° with a standard deviation of 9° and a range -5° to 25°.

  • Note, the mean version angles in the annotated bibliography below vary between 9-20°, but standard deviations tend not to exceed 10°. It would be a mathematical error to add the largest standard deviation to the widest range of mean values from all studies. Standard deviation is specific to the analysis being done, and not directly applicable to other studies. In summary, although the mean value for anteversion may be between 9-20°, the standard deviation reported in most studies is about 9°, which means the variation between most individuals is still about 18° (1 standard deviation in either direction). Some of the variations in mean values may just be due to differences in measurement technique.

Bell curve distruction of findings from Pierrepont, J. W., Marel, E., Baré, J. V., Walter, L. R., Stambouzou, C. Z., Solomon, M. I., ... & Shimmin, A. J. (2020). Variation in femoral anteversion in patients requiring total hip replacement. HIP International, 30(3), 281-287.
Caption: Bell curve distruction of findings from Pierrepont, J. W., Marel, E., Baré, J. V., Walter, L. R., Stambouzou, C. Z., Solomon, M. I., ... & Shimmin, A. J. (2020). Variation in femoral anteversion in patients requiring total hip replacement. HIP International, 30(3), 281-287.

This bar graph from a study by Pierrepont et al. (2020) illustrates an increase in the prevalence of extreme anteversion among patients requiring total hip replacement (this would be a reasonable expectation). Note, that even with this increase, the values for anteversion are still normally distributed (10).

  • Pierrepont et al. (2020) demonstrated that the median anteversion in males was 12.7° (range: −27.1 – 45.5°, Interquartile range (IQR): 6.0 – 19.1°), compared to female anteversion of 16.0° (range: −14.0° - 54.5°; IQR 9.7° - 22.4°). Gender differences were statistically significant, p < 0.0001. 14% of patients had extreme anteversion (<0° or >30°) (10).

There may be no correlation between hip morphology and foot placement.

There is no research correlating hip anatomy and ideal foot placement during a squat. To be more specific, there is no research to imply that foot placement could have a significant effect on performance, pain, or the risk of injury, for the small group of individuals who exhibit hip morphology that is significantly different from mean values. One factor decreasing the relationship between foot placement and hip position is the number of structural angles that occur between the hip and foot that may compensate for altered hip morphology. For example, it is possible that a person's body structure compensates for a 5° increase in structural anteversion with a 1° change in the following structural angles (which would be within normal variation):

  • Talar neck angle
  • Angle of axis of the ankle
  • Tibial torsion
  • Genu valgum angle
  • Femoral angle of inclination

Toogood et al. 92009) provided evidence of this occurrence, noting "...as either neck version or angle of inclination increased, translation in the same direction (anterior for neck version, superior for angle of inclination) at the head-neck junction tended to decrease" (3).

A practical example of how foot placement and hip morphology are not correlated can be observed by comparing an individual's squat foot placement and their lunge (or Bulgarian split squat) foot placement. If the issue resulting in a wide stance during squats was hip morphology, then an awkward wide stance would also be necessary during lunges; after all, both exercises require similar hip ROM. However, most individuals can perform a full ROM lunge with feet and hips in neutral alignment, even when their squat form is wide with feet turned out. Note, lunges are generally easier to perform with neutral alignment because the rear foot support allows for an individual to move their center of mass posteriorly, which reduces the need for optimal dorsiflexion.

An illustration of the &quot;range&quot; of varitation in pelvic structure. This is an example of the extremes, not normal distribution.
Caption: An illustration of the &quot;range&quot; of varitation in pelvic structure. This is an example of the extremes, not normal distribution.

Again, this image of two pelves is representative of "range" not "normal distribution." This is cherry-picking the extremes, not accurately depicting normal variation (within 1 standard deviation of the mean).

Why does everyone get the same recommendation?

If the argument supporting altered foot position during a squat is, "everybody is unique so ideal foot placement does not exist", then why does everybody get the same recommendation? Why is the recommendation always to turn the feet out, and/or take a wider stance? It is unlikely that excessive hip anteversion and excessive hip retroversion could both be addressed by the same recommendation. Shouldn't one of these structural abnormalities (e.g. retroversion) make "turning the feet in and/or feet closer together" more comfortable?

Further, how does any professional justify cuing 20 - 50° of feet turn out when variations in hip version angle are unlikely to exceed 10°? If someone actually had 45° of additional anteversion they would likely exhibit significant disability, and surgical intervention would almost undoubtedly be recommended. If you do not know the difference between 10° and 45°, it is worth looking up. A visual example; when the minute hand on a clock travels from the top (0 position) to the 2-minute hash, it has traveled 12°. When it has traveled from the top to the 8-minute hash, it has traveled 48° That is a big difference when you consider that the latter is 4 times as much rotation.

A Functional Anatomy Error

This is the error that is making some otherwise smart professionals look pretty dumb. Feet turn out is not hip external rotation, it is tibia (knee) external rotation. The assertion that turning the feet out will alter hip position is actually a functional anatomy error. Feet turn out, when the knees are flexed, is achieved by external rotation of the tibia, and not the external rotation of the hips. Hip external rotation at the bottom of a squat would NOT cause your feet to turn out. If your hips mildly externally rotate at the bottom of a squat, your femurs would rotate outward, forcing your knees to bow out, resulting in a "functional knee varus (knees bow out) ". Significant external rotation of the hips would result in your ankles crossing, and you sitting into the yoga position known as "lotus position." If the hips mildly internally rotate during a squat your femurs turn inward, resulting in a "functional knee valgus (knees bow in) ". And, a significant amount of internal rotation would cause your ankles to splay outward, resulting in a sitting position commonly observed in children called "W sitting". In summary, "feet turn out" during squats is the result of the rotation of the tibia at the knee, not the rotation of the hips. For a visual demonstration of hip internal and external rotation during a squat, consider this image of seated hip internal rotation and hip external rotation goniometry.

In our humble opinion, this one simple fact should have stopped this myth from ever developing.

Seated hip internal and external rotation.
Caption: Seated hip internal and external rotation.

Feet Turn Out and Knees Bow Out (Knee Varus) are Correlated with Dysfunction

Maybe at this point, you think there might be a few flaws in the idea that "hip morphology affects ideal foot placement during squats." But, you still feel better when you squat with your feet turned out and wide, so "what's the harm"? The truth is that alignment does matter; however, how you feel is not a great way to determine ideal alignment. Research demonstrates that feet turn out and knees wide (functional varus) are correlated with pain, dysfunction, and a higher risk of injury (11-16). Although you may feel like these modifications result in better performance or a reduction in your symptoms, they are likely ways to "cheat" in the short-term. Sure, they feel better now, but they could inhibit future improvements in performance, or increase your risk of injury over time.

Your comfort with feet turned out and wide is likely correlated with relatively minor issues related to mobility (e.g. reduction in ankle dorsiflexion or hip internal rotation), and/or neuromuscular coordination (e.g. tibialis posterior or gluteus maximus inhibition). These addressable issues may be decreasing your performance right now and could be some of the issues that contribute to the increase in the risk of injury demonstrated in the studies above. Note, these issues also affect other activities like sports, walking, or even standing posture. So, even if you are not worried about your squat, addressing these issues could have benefits for your other activities. Rather than "cheat" your way to better results, there are better alternatives.

You may be thinking... "But Olympic Lifters and strength athletes squat with their feet wide". Unfortunately, mimicking the form of professional athletes has a pretty horrible track record for informing the general public. Often professional athletes are capable of doing things that the average individual can not do, and/or the professional athlete has made the conscious choice to sacrifice their body for the sake of performance. For example, I am a basketball player, and I would like to think I have relatively strong and powerful legs; however, that does not mean I would recommend that my Mom starts playing basketball to improve her lower extremity strength. Trying to apply the form of strength athletes to resistance training may sound less ridiculous, but it is conceptually similar. The general public should perform exercises with "good form" and a stronger correlation with their daily or sports activity. "Good form" could be defined as a form that is absent of any signs correlated with an increase in dysfunction, pain, or injury (see the Overhead Squat Assessment for signs correlated with injury).

Dr. Brent Brookbush breaks down the sign &quot;inadequate forward lean&quot;
Caption: Dr. Brent Brookbush breaks down the sign &quot;inadequate forward lean&quot;

A Better Recommendation:

Before accepting small imperfections in movement as evidence of permanent, life-long, structural abnormalities, it may be recommended that these very addressable and common issues (e.g. feet turn out, knees bow in, etc.) are targeted with a "corrective exercise" or "movement prep" routine. Research has demonstrated that corrective exercise can improve alignment, and performance, and reduce the risk of injury (17-20). Note, "movement prep" is a term often used to imply a circuit of corrective exercises used as a warm-up.

What we are recommending is that you make an attempt to address these issues as if they are soft tissue restriction, joint stiffness, and/or altered muscle activity. In the worst-case scenario, nothing happens, but in the best-case scenario, there is an improvement. Further, while feet turn out and knees bow out has been correlated with an increased risk of injury, corrective exercise (movement prep) has been correlated with improvements in performance, a reduction in pain and injury, and a reduction in the risk of future injury. In short, there are many potential benefits and likely no increased risk from adding some corrective exercises. If you tried corrective exercises for a couple of weeks and your foot placement still did not feel comfortable with feet hip width and parallel (2nd toe pointing forward), then perhaps it may be worth modifying your squat to compensate for any additional discomfort. We would love to see you continue your effort to learn about corrective exercise, and take a more sophisticated approach to mobility, alignment, and optimizing neuromuscular control. However, we also know that finding the right corrective exercise routine can be challenging.

A Little Help

Often the "desire" to turn the feet out or use a wide stance during a squat is driven by a loss of ankle dorsiflexion (21 -23 annotated citations). Integrating techniques from the following course is a great way to start improving mobility:

If you are a little more advanced or motivated, or your issue is a bit more "stubborn", try the sample routine below.

Corrective Exercise Routine or Movement Prep Warm-up: Ankle Mobility

Excuse-driven Practice and Blaming the Client

We believe in many cases that the assumption of structural differences, and dismissal of corrective exercise, is actually “excuse-driven practice”, or "excuse-driven therapy." That is, practitioners, looking for reasons not to study functional anatomy, movement assessment, corrective exercise, manual therapy (if within their scope), etc., and/or put in the hours, weeks, or months of practice required to become proficient and master these techniques. Although complacency and the dismissal of things we don't want to do might be called a "human trait", professionals are supposed to overcome that instinct to master their craft. We have been disturbed by what appears to be an increase in a contrarian or Nihilistic attitude; attempting to promote this idea that nothing works. We know the truth. This is just lazy practitioners, making excuses for reasons they didn't learn something.

Worse, in this case of assuming structural differences, is an example of the “practitioner blaming the client” - i.e. "It's not my fault they can't get better, they have weird hips". Meanwhile, there are many practitioners who could help that client, because they have taken the time to learn and practice an additional skill set (e.g. assessment, corrective exercise, manual therapy, that could help). It is important as professionals that we assume as much responsibility as we can, dedicate ourselves to a life-long learning plan, and continue to add to our repertoire.

Our Recommendation is Simple

Perform a movement assessment (like the Overhead Squat Assessment ), address the issues you identify with corrective exercise, and then modify squat form, if necessary, based on comfort or performance needs. Chances are that addressing issues with corrective exercise noted during a movement assessment will greatly reduce the amount of compensation necessary to feel comfortable during a squat.

Isolated activation for the tibialis anterior muscle
Caption: Isolated activation for the tibialis anterior muscle

Annotated Bibliography of Hip Anatomy Studies

Cadaveric Studies:

1. Hoaglund, F. T., & Low, W. D. (1980). Anatomy of the femoral neck and head, with comparative data from Caucasians and Hong Kong Chinese. Clinical orthopaedics and related research, (152), 10-16.

  • In this study, measurements were made of caucasian and Chinese cadavers. The femoral neck anteversion angle for all specimens was a mean of 8°. In measurements that we made of femora from cadavers of Caucasians cadaver specimens exhibited an average anteversion angle of 7.0° in males (range: -2° - 35°) and 10.0° in females (range: -2° - 25°). Using similar techniques on cadavers of Hong Kong Chinese, we found that the average in males was 14.0° (range: -4° - 36°) and 16.0° in females (range: 7° - 28°).

2. .Eckhoff, D. G., Kramer, R. C., Watkins, J. J., Alongi, C. A., & Van Gerven, D. P. (1994). Variation in femoral anteversion. Clinical Anatomy: The Official Journal of the American Association of Clinical Anatomists and the British Association of Clinical Anatomists, 7(2), 72-75.

  • This study intended to investigate variations in femoral anteversion in an adult African skeletal population. This study demonstrated greater average anteversion (19°) and a significant right‐left variation (21° vs. 17°) when compared to previously reported Caucasian and Asian populations (average anteversion 9°).

3. Toogood, P. A., Skalak, A., & Cooperman, D. R. (2009). Proximal femoral anatomy in the normal human population. Clinical orthopaedics and related research, 467(4), 876-885.

  • This study investigated 200 adult skeletons (20th century, unclaimed dead from Cleveland city morguethis collection). To develop a representative set for the normal human population, samples were diversified based on race, age, and gender, and anatomically abnormalities and skeletons younger than 18 at the time of death were excluded. Specimens were digitally photographed in standardized positions, and measurements were obtained using ImageJ software. Mean anteversion was was 9.73° (± 9.28°) with a range −14.63°–35.90°. Additionally, this study noted correlations between angles that demonstrate compensation during development. For example, "...as either neck version or angle of inclination increased, translation in the same direction (anterior for neck version, superior for angle of inclination) at the head-neck junction tended to decrease."

Normal Hips in Living Subjects

4. Philippon, M. J., Ho, C. P., Briggs, K. K., Stull, J., & LaPrade, R. F. (2013). Prevalence of increased alpha angles as a measure of cam-type femoroacetabular impingement in youth ice hockey players. The American journal of sports medicine, 41(6), 1357-1362.

  • A total of 61 asymptomatic youth ice hockey players (aged 10-18 years) and 27 youth skiers (controls) (aged 10-18 years) underwent a clinical hip examination including hip angle measured by magnetic resonance imaging. The mean femoral anteversion of hockey players was 4.8° (± 10.0°), and skiers 4.5° (±8.8).

5. Sengodan, V. C., Sinmayanantham, E., & Kumar, J. S. (2017). Anthropometric analysis of the hip joint in South Indian population using computed tomography. Indian journal of orthopaedics, 51, 155-161.

  • The study investigated 200 individuals (400 hips) with normal hip joints with using computed tomography (CT) scanning. The mean value of hip anteversion was 18.64°, the mean value among males was 17.84° (range: 10°–33°) and for females was 19.45° (range: 11°–33°), and the mean value for the right side 18.05° (range: 11°–33°) and left side was 19.25° (10°–29°).

6. Saikia, K, Bhuyan, S, and Rongphar, R. Anthropometric study of the hip joint in Northeastern region population with computed tomography scan. Indian Journal of Orthopaedics 42(3): 260, 2008.

  • In this study, 104 individuals with normal hip joints (from different ethnic backgrounds) were evaluated, including physical evaluation, plain x-ray, and CT scan. 12 cases had a center edge angle (CE) of less 20 degrees (unilateral/bilateral), were diagnosed as dysplastic, and were excluded from the study findings. Study results included 92 individuals (184 normal hips, Mongoloids = 45; Caucasoid = 47) between 20-70 years of age. The mean parameters observed were as follows: acetabular angle 39.2°, center edge angle 32.7°, neck shaft angle 139.5°, acetabular version 18.2°, femoral neck anteversion 20.4°, acetabular depth 2.5 cm and joint space width 4.5 mm.

Pathological Hip in Living Subjects

7. Ezoe, M., Naito, M., Inque, T. (2006). The prevalence of acetabular retroversion among various disorders of the hip. The Journal of Bone and Joint Surgery. 88A (2). 372-379

  • The intent of this study was to assess the prevalence of acetabular retroversion in normal hips and in hips with osteoarthritis, developmental dysplasia, osteonecrosis, and Legg-Calvé-Perthes disease. The prevalence of acetabular retroversion was 6% (7 of 112 hips) in the normal group, 20% (14 of 70 hips) in the osteoarthritis group, 18% (thirteen of seventy-four hips) in the developmental dysplasia group, 6% (2 of 36 hips) in the group with osteonecrosis of the femoral head, and 42% (21 of 50 hips) in the group with Legg-Calvé-Perthes disease.

8. Atkinson, H. D., Johal, K. S., Willis-Owen, C., Zadow, S., & Oakeshott, R. D. (2010). Differences in hip morphology between the sexes in patients undergoing hip resurfacing. Journal of orthopaedic surgery and research, 5(1), 76.

  • This study analyzed the CT scans of 100 consecutive Caucasian patients (61 males and 39 females) receiving hip resurfacing arthroplasty surgery for hip osteoarthritis. Gender differences in femoral torsion/anteversion, femoral neck angle, and acetabular inclination were statistically insignificant. Males had a mean femoral torsion/anteversion of 8° (range -5° - 26°), a mean femoral neck angle of 129° (range 119°-138°), and a mean acetabular inclination of 55° (range 40°-86°). Females had a mean femoral torsion/anteversion of 9° (range -2° - 31°), a mean femoral neck angle of 128° (range 121°-138°), and a mean acetabular inclination of 57° (range 44°-80°). Females had a significantly greater acetabular version of 23° (range 10°-53°) compared with 18° in males (range 7°-46° (p = 0.02) and males had a significantly greater femoral offset of 55 mm (range 42 to 68 mm) compared with 48 mm (range 37 to 57 mm) in females (p = 0.00).

9. Koerner, J. D., Patel, N. M., Yoon, R. S., Sirkin, M. S., Reilly, M. C., & Liporace, F. A. (2013). Femoral version of the general population: does “normal” vary by gender or ethnicity? Journal of orthopaedic trauma, 27(6), 308-311.

  • In this study 417 (between 2000 and 2009,) consecutive patients with femur fractures were treated with an intramedullary nail at a level I trauma and tertiary referral center. Of these, 328 had computed tomography scanogram of the normal, uninjured contralateral femur, The images of the normal hip were included in this study. The mean alignment for all patients was 8.84° ± 9.66° of anteversion. There were no statistically significant differences in the mean version between African American, white, and Hispanic patients for males or females. Retroversion was found to be common in white males (21.4%), African American males (15.1%), and all groups of females (>14.3%). Furthermore, nearly 6% of both African American males and females exhibited >10° retroversion.

10. Pierrepont, J. W., Marel, E., Baré, J. V., Walter, L. R., Stambouzou, C. Z., Solomon, M. I., ... & Shimmin, A. J. (2020). Variation in femoral anteversion in patients requiring total hip replacement. HIP International, 30(3), 281-287.

  • This study investigated the native femoral anteversion angle of 1215 patients prior to hip replacement surgery. As implied by the study by Ezoe et al. (2006) it may be reasonable to conclude that this population would have a higher proportion of individuals who fall outside of the normal range (beyond 2 standard deviations). Native femoral neck anteversion was measured from 3-dimensional CT reconstructions. The median femoral anteversion across all 1215 subjects was 14.4° (−27.1 – 54.5°, IQR 7.4 – 20.9°) (Figure 2). The median anteversion in males was 12.7° (range: −27.1 – 45.5°, Interquartile range (IQR): 6.0 – 19.1°), compared to female anteversion of 16.0° (range: −14.0° - 54.5°; IQR 9.7° - 22.4°). Gender differences were statistically significant, p < 0.0001. 14% of patients had extreme anteversion (<0° or >30°).

Bell curve distruction of findings from Pierrepont, J. W., Marel, E., Bar&eacute;, J. V., Walter, L. R., Stambouzou, C. Z., Solomon, M. I., ... &amp; Shimmin, A. J. (2020). Variation in femoral anteversion in patients requiring total hip replacement.&nbsp;HIP International,&nbsp;30(3), 281-287.
Caption: Bell curve distruction of findings from Pierrepont, J. W., Marel, E., Bar&eacute;, J. V., Walter, L. R., Stambouzou, C. Z., Solomon, M. I., ... &amp; Shimmin, A. J. (2020). Variation in femoral anteversion in patients requiring total hip replacement.&nbsp;HIP International,&nbsp;30(3), 281-287.

Additional Research

Dysfunction Correlated with Feet Turn Out (Tibia External Rotation)

11. Willson, J. D., & Davis, I. S. (2008). Lower extremity mechanics of females with and without patellofemoral pain across activities with progressively greater task demands. Clinical biomechanics, 23(2), 203-211.

12. Winslow, J., & Yoder, E. (1995). Patellofemoral pain in female ballet dancers: correlation with iliotibial band tightness and tibial external rotation. Journal of Orthopaedic & Sports Physical Therapy, 22(1), 18-21.

Dysfunction Correlated with Knee Varus (Hip Rotation)

13. Lo, G. H., Harvey, W. F., & McAlindon, T. E. (2012). Associations of varus thrust and alignment with pain in knee osteoarthritis. Arthritis & Rheumatism, 64(7), 2252-2259.

14. Skou, S. T., Wrigley, T. V., Metcalf, B. R., Hinman, R. S., & Bennell, K. L. (2014). Association of knee confidence with pain, knee instability, muscle strength, and dynamic varus–valgus joint motion in knee osteoarthritis. Arthritis care & research, 66(5), 695-701.

15. Ellison, JB., Rose, S., Sahrmann, S. (1990). Patterns of Hip Rotation Range of Motion: A Comparison Between Healthy Subjects and Patients with Low Back Pain. Phys Ther 1990. 70: 537-541

16. Van Dillen, L. R., Bloom, N. J., Gombatto, S. P., & Susco, T. M. (2008). Hip rotation range of motion in people with and without low back pain who participate in rotation-related sports. Physical Therapy in Sport, 9(2), 72-81.

Corrective Exercise Improves Performance

17. Bennell, K. L., Dobson, F., Roos, E. M., Skou, S. T., Hodges, P., Wrigley, T. V., ... & Hinman, R. S. (2015). Influence of biomechanical characteristics on pain and function outcomes from exercise in medial knee osteoarthritis and varus malalignment: exploratory analyses from a randomized controlled trial. Arthritis care & research, 67(9), 1281-1288.

  • Bennell et al. demonstrated that neuromuscular re-education exercises (corrective exercise) were more effective than quad-sets for reducing knee osteoarthritis pain.

18. Bell, D. R., Oates, D. C., Clark, M. A., & Padua, D. A. (2013). Two-and 3-dimensional knee valgus are reduced after an exercise intervention in young adults with demonstrable valgus during squatting. Journal of athletic training, 48(4), 442-449.

  • Bell et al. demonstrated that corrective exercise was an effective intervention for addressing assessed knee valgus.

19. Crow, J. F., Buttifant, D., Kearny, S. G., & Hrysomallis, C. (2012). Low-load exercises targeting the gluteal muscle group acutely enhance explosive power output in elite athletes. The Journal of Strength & Conditioning Research, 26(2), 438-442.

  • This RCT by Crow et al. demonstrated that using gluteus medius exercises as a warm-up resulted in larger improvements in peak power than whole-body vibration (or no warm-up at all).

20. Song, H. S., Woo, S. S., So, W. Y., Kim, K. J., Lee, J., & Kim, J. Y. (2014). Effects of 16-week functional movement screen training program on strength and flexibility of elite high school baseball players. Journal of exercise rehabilitation, 10(2), 124.

  • Song et al. demonstrated that 16 weeks of corrective exercise training based on the FMS significantly improved flexibility and strength.

A Loss of Ankle Dorsiflexion Correlated with a Loss of Squat Depth

21. Kim, S. H., Kwon, O. Y., Park, K. N., Jeon, I. C., & Weon, J. H. (2015). Lower extremity strength and the range of motion in relation to squat depth. Journal of human kinetics, 45, 59.

  • Kim et al. compared 101 healthy participants (64 males, 37 females; age: 25.69 ± 5.93 years) following hip flexion and dorsiflexion goniometric assessment, hip flexion, hip rotation, and dorsiflexion MVIC, and performance of the deepest bodyweight (hands behind head), shoulder-width stance, squat that could be maintained for 5 sec. The findings demonstrated that a decrease in ankle dorsiflexion ROM, hip flexion ROM, hip internal rotation ROM, or dorsiflexor strength were correlated with a decrease in squat depth. Wheras a decrease in hip external rotation and hip flexor strength were not correlatedwith a decrease in squat depth.

22. Mauntel, T. C., Begalle, R. L., Cram, T. R., Frank, B. S., Hirth, C. J., Blackburn, T., & Padua, D. A. (2013). The effects of lower extremity muscle activation and passive range of motion on single leg squat performance. The Journal of Strength & Conditioning Research, 27(7), 1813-1823.

  • Mauntel et al. selected 40 healthy recreationally active individuals (age: 18-35 years) from a larger group to compare lower extremity passive range of motion and EMG of 20 individuals with visual knee valgus, and 20 individuals without medial during 5 single leg squats. The results demonstrated that individuals with knee valgus exhibited a relative reduction in gluteus medius and gluteus maximus activity relative adductor activity, a reduction in passive dorsiflextion.

23. Macrum, E., Bell, D. R., Boling, M., Lewek, M., & Padua, D. (2012). Effect of limiting ankle-dorsiflexion range of motion on lower extremity kinematics and muscle-activation patterns during a squat. Journal of sport rehabilitation, 21(2), 144-150.

  • Macrum et al. compared 15 male and 15 female recreationally active individuals without a history of lower extremity injury (age: 18 - 30 years) during 7 trials of squats with feet flat and 7 trials of squats with a 12° forefoot wedge (simulating reduced dorsiflexion). The findings demonstrated the wedge decreased knee flexion, increased knee valgus, decreased quadriceps activity, and increased soleus activity. These changes are similar to those noted in individuals with patellofemoral pain syndrome (PFPS).

© 2023 Brent Brookbush (B2C Fitness, LLC d.b.a. Brookbush Institute )

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