How Gluteal Atrophy Affects Posture & Performance

How Gluteal Atrophy Affects Posture & Performance

As the world has advanced to extreme technological means, sedentary lifestyles have also increased. More people are sitting at desks today than ever before; and as assumed, these same individuals leave work and sit in front of a computer in their homes. As technological advancements have made communication and business more efficient, unfortunately, it has made the human body less efficient. More people are engaged in a sedentary lifestyle that is composed of prolonged static positions (seated or standing); and spend less time moving or exercising.

Is it possible that a sedentary lifestyle, absent of purposeful loaded activity or exercise, can cause atrophy of muscles? Take the example of a broken bone. Once fractured and encased in a splint or cast for several weeks (depending on the type of fracture and bone involved), the muscles surrounding that bone are no longer active. They are not active because the “lever system” that they are associated with is impaired. Therefore, without proper muscle firing or use, the muscles lose tonus, weaken, and decrease in neural response.

Studies have been shown that unloaded inactivity induces atrophy and functional de-conditioning of skeletal muscle—especially in the lower extremities. (1) In this case, “unloaded” should be defined as absence of an external load, and “inactivity” is defined as little to no muscular movement, stimulation, or locomotion. In this particular study, ten healthy males were subjected to 5 weeks of experimental bed rest. Each participant was matched with an associate to assist in minimal tasks. Their lower body muscles were tested using isometric hip and knee extension exercises. After the 5 weeks, atrophy was more pronounced in the extensor muscles of the gluteal region, thigh, and calf. Furthermore, radiological density tests indicated a bone mineral loss already after 5 weeks.

The study’s use of bed rest as the intended unloaded inactivity is somewhat similar to the conditions a sedentary individual undergoes when the occupation calls for a majority of time seated (secretary, computer tech, call service, office worker, etc, etc). Because bed rest is an extremely inactive state, we can only assume that the seated position sustained over a number of years is just as detrimental to skeletal muscle given the amount of time (duration in years); frequency (how often), and duration (how long each time).

Sitting and Lower Back Pain

As with most sedentary individuals, lower back pain is a common association with inactivity and prolonged sitting. Lower back pain that is categorized as mechanical will typically involve musculoskeletal factors that may be influenced by lifestyle, activity, and body composition. Other types of low back pain are structurally specific to the spine and involve conditions such as arthritis, disc herniations, and degeneration. In mechanical low back pain, muscular length-tension relationships change over time in relation to the stress put on the body. For example, in the seated position, the hip flexors are in a constant shortened state and the knee flexors—primarily the gastrocnemius remains shortened. To exacerbate the effects of prolonged sitting, poor posture such as slouching, shoulder protraction, and cervical flexion, cause the erectors of the back to become overactive and fatigue causing the associated “creep”.

The gluteals remain inactive in a seated position. Sitting for long periods can lead to the gluteal muscles atrophying through constant pressure and disuse. Movements that require the gluteal muscles become more difficult (such as climbing stairs or rising from a seated position); therefore, extra stress is put on the lumbar spine leading to low back pain.

Function & Characteristics of the Gluteals

The gluteals are comprised of 3 muscles: glute minimus, glute maximus, and glute medius.  These muscles are involved in extending and outwardly rotating the hip, and extending the trunk. The powerful gluteus max inserts into the iliotibial band and gluteal tuberosity of the femur. Because of its attachment, it provides the human body incredible leverage and sets our species apart from other primates (upright versus four legged). Lower body exercises, such as squats, deadlifts, lunges, and good mornings, strengthen the gluteal muscles. These exercises focus on glute strengthening because there is a muscle action demand that corresponds with the muscle’s responsibility. 

In a seated position, there is no demand for the muscles to act (unloaded inactivity); therefore, over the course of time, the gluteals will decrease in neural output. If there is a decrease in the “call time” of a muscle, surrounding muscles will enact to complete a movement causing muscular imbalances and stress on joints. In the case of functional performance, the lumbar spine receives the brute of this compensatory pattern.

Typically, when there is a lack of gluteal function, there is a visible lack of gluteal development in an individual. The gluteal muscles are only partially responsible for giving the buttocks their characteristic shape. The subcutaneous fat that also contributes to the “roundness” of the buttocks is called the panniculus adipose. If the gluteus musculature is atrophied and subsequently “absent” from providing shape, then the overlying panniculus adipose is responsible for the “sagging butt” appearance. This appearance is no illusion and gives credible evidence that the glutes do not function properly – by means of weakness and neural deviation.

Causes for Gluteal Atrophy

Sway back posture is characterized as the pelvis” swayed forward and the hips in extension. The sway back posture places excessive strain on the low lumbar spine, most commonly at the lumbo-sacral joint, which becomes problematic with extension. This is often seen in those that are seated for long periods of time, that exhibit pain upon standing still. Postural gluteal contraction, particularly the glute maximus, appears deficient in sway back posture.  This is because the line of gravity drops behind the hip joint producing passive hip extension via body weight. This passive hip extension renders active extension from the gluteus maximus unnecessary and it ‘switches off’, the hamstring muscles, however, maintain activation to control postural sway.

Gluteal atrophy is often seen in those with sway back posture, and the neural deviation previously mentioned can be a result of the “flattening” of the lumbar spine causing compression or herniation of the vertebra discs. Cosmetically, it is unsightly for those desiring a more “bountiful” rear.  For the prolonged sitter, abetting this process is the so called “ergonomic thought process”. This thought process calls for keeping all frequently used office tools (i.e.: stapler, tape, pens) in close proximity to avoid sudden movements. Such practices prevent the sedentary from moving regularly, and thus, reinforcing the gluteals to shut down.

Flat back posture is somewhat similar to sway back posture. It is characterized as a malformation in which the individual has a decreased curve in the low back region.

Optimal Performance & Function Affected

Taking an individual or athlete, one needs to function properly to maintain an efficient quality of life, and the other needs to perform optimally for sport. The degree of malformation in posture will greatly influence how the glutes function during common actions. For instance, an athlete with a swayback posture will often have tight hip extensors (hip rotators and hamstrings) and tight low back muscles. The athlete will often have weak hip flexors, weak lower abdominals, and weak shoulder blade muscles. These athletes are less likely to be powerful and explosive. Those with flat back posture characteristics will have tight hip muscles and weak low back and hip flexor muscles.

In the world of athletics, optimal posture and alignment help to provide good shock absorption, assist in weight acceptance, and promote the transfer of energy during movement.

In other words, optimal posture allows the body to move more efficiently, fatigue less easily, and place less stress on the joints. Optimal posture will assist in trecoerhe prevention of overtraining, muscle imbalances, and decreased performance. In the world of average Joe’s, optimal posture will decrease the likelihood of cumulative injury due to static positions.

Typically, when an injury presents itself in a sedentary individual, it is the symptom of a problem—and not directly related to the site of pain. Posture helps determine which muscles are strong and weak by lengthening or shortening certain muscles. There is an optimum length at which the muscle is capable of developing maximal tension.

Optimal posture has many benefits in the world of athletics

For the gluteal muscles to perform optimally—whether it is simply standing upright, or running after the ball—the length-tension relationships surrounding the area should be ideal. This includes proper lengths of the TFL (tensor fascia latae), hip flexors, adductors, hamstrings, trapezius, erectors, and multifidius. All of which are affected negatively by the seated posture. If the gluteal muscles function correctly and optimally, hip extension and rotation will occur freely without compensation and it will spare the lumbar spine. Once the lumbar spine is spared of “picking up the slack” of the glutes, pain will be avoided and the human body can become more efficient at the given tasks.

In order to reverse the degeneration of the gluteal muscles, loaded activity should be introduced regularly. Immobilization studies (study used bed rest) in humans suggest that most of lost muscle and strength can be regained with appropriate resistance training several weeks after a period of disuse. (3)

From a functional performance standpoint, a basic program to isolate the gluteals with specific exercises and then integrate them into functional movements is key.

For instance, the following basic program can be used:

Weeks 1-2 (Performed daily) Weeks 3-4 (Performed 4 times a week)  Weeks 4-6 (Performed 1-3 times per week)
Sit to Stand StretchActive Hamstring StretchIsolated Glute Stretch(Introducing mobilization and decreasing associated “creep”) Quadruped Glute ExtensionClam ExerciseFire Hydrant ExerciseBridges (2 to 1 leg)

(Moderate foam rolling performed)

Bodyweight SquatsDeadliftsSingle Leg Squats(Foam rolling performed before each workout/stretch post-workout)

Poor lifting habits are born through mechanical disadvantages and invalid instruction.  Both can be a result of one or the other. For instance, most indoor cyclists demonstrate enormous quadriceps development and hip flexor action. This popular fitness activity demands resisted knee flexion in a high stressful hip flexion position.  The seated position also exacerbates the inactivity of the gluteals during a class, and reinforces the degeneration of this muscle.

Most participants will attest that a typical indoor cycling class also involves simulated hill jumps, whereas the buttocks are raised off the seat, which may involve the gluteals to some degree. Even so, the neural programming shuts off the gluteals simply because it cannot “undo” itself to fulfill an activity that supposedly involves its potential action in such a short time period.

Invalid instruction contributes to neural programming due to the exerciser unknowingly laying the foundation for dysfunction by continuously performing the erroneous movement. During a typical task of lifting, the gluteus maximus has an important role in extending the hips and stabilizing the pelvis. Research shows that an emphasis on contraction of the glutes aids in stabilizing the pelvis and ensures a safe and effective movement to occur.  Exercises that assist this occurrence are: deadlifts, Romanian deadlifts, squats, split squats, stationary lunges, and step-ups. However, most typical exercisers resort to leg extensions, seated leg curls, leg presses, and adductors/abductors; furthering the “shut down” process.

Muscle Maturity

Muscle maturity is a new consideration in the realm of hypertrophic and performance needs. Under efficient instruction, one can develop athletic ability and skill quickly and be able to use it under the most physically demanding activities. For instance, most athletic persons are proficient at any sport. If you ever have played a pickup game of basketball or baseball, the player who is the best is generally the one that has participated in sports for most of their life. This is also seen in those that have spent a great deal of time in the gym performing the basic weight-lifting exercises. Gluteal function and development is achieved early on because exercises such as squats, lunges, and deadlifts are performed through the years. Neural “wiring” is developed early in life and proficiency is achieved much quicker than the seated video game player. Exercise longevity is obtained because proper progressions in load are practiced. And a continuity of longevity finds that most loading is performed under the supervision of a coach, trainer, or experienced partner. Under valid instruction, most exercisers that show maturity also have an enhanced overall athletic ability with enhanced muscular coordination and decreased low back pain. 

It has been shown that injuries or pain also contribute to gluteal dysfunction or atrophy. In one study, patients who had suffered ankle sprains were shown to have a reduced activation level of the glute maximus. This may be caused by the damage to the proprioceptive feedback mechanism via lateral ankle sprain.  These findings confirm that changes in muscle firing patterns, particularly by the gluteus maximus, can lead to muscle inhibition and/or atrophy (neural program altered). This compromise could result in a compensation of the lower back. A situation where an injury has likely occurred and has altered the normal function of the human body (gait, running, sitting, getting in or out of a car, etc), should emphasize the importance of corrective exercise and rehabilitation.

Most individuals that do not receive proper rehabilitation for such injuries like ankle sprains develop scar tissue and immobilization of the ankle joint that further exacerbates atrophy of the gluteals.  Most basketball players that experience low back pain have a history of ankle sprains that have altered the function of the glutes, which become more important for the taller athlete because of the longer limbs creating a “longer lever” stress on the back.

Summary

The importance of gluteal function is imperative to proper posture and human performance. Without optimal function from the glutes, sedentary individuals may exhibit low back pain and other associated injuries. In severe cases, the gluteal muscles fail to absorb the shock impact in the load transfer during walking, which studies have shown to lead to contra-lateral hip osteoarthritis.

What types of modifications to daily lifestyle can sedentary people begin to do to combat the effects of gluteal atrophy?

Move more - According to Stuart McGill, PhD in his book, “Low Back Disorders”, moving and “fidgeting” while in a seated position breaks the constant pressure placed on the body by gravity. Constantly, changing seated or standing positions alleviates low back strain and repositions the glutes.

Walk - The office worker seldom has the chance to exercise during the day. Adding some “purposeful” movement, such as fast walking, during a lunch break is important to circulating pooling blood from the lower body, burn calories, and lengthens muscles.

Take stairs - Sounds simple, yet, the act of extending the hip under the load of the body will enhance glute performance - provided it is performed without the compensatory assistance of the lumbar spine.

Stretch more - Along with moving and walking, standing from a seated position regularly allows the vertebral discs to decompress and lengthens muscles that are otherwise in the process of shortening.

In conclusion, optimal posture is ultimately determined by optimal function of the gluteal muscles. The pelvic girdle houses the center of gravity for all postural points to stem from. Attached to this center is the body’s most powerful muscle group. The function of these muscles corresponds with mother nature’s intent. Humans are meant to be upright as a species and it is the function of the gluteal muscles that allow that. As the sedentary become more and more inclined to sit, the more obvious it becomes to see the damage caused.

With small modifications and changes made throughout one’s day, it is a battle that can be one in small increments through purposeful activity, and properly loaded exercises.

Written by John Izzo

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References
 
1. Berg HE, Eiken O, Miklavcic L, Mekjavic IB.(2007). Hip, thigh and calf muscle atrophy and bone loss after 5-week bedrest inactivity. Eur J Appl Physiol. 2007 Feb;99(3):283-9. Epub 2006 Dec 22.

2. Bloomfield SA. (1997). Changes in musculoskeletal structure and function with prolonged bed rest. Med Sci Sports Exerc. 1997 Feb;29(2):197-206

3. Alan D. Tyson, Ben T. Cook (2004). Jumpmetrics. New York, NY:  Human Kinetics.

4. www.authorstream.com/Presentation/markmckean-101830-posture-function-hips-lumbar-pelvic-tilt-assessing-sports-ppt-powerpoint

5. www.physiotherapy.org.nz/index02/Publications/JournalPDF/33(3)Nov05_p95-100.pdf

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