BRINGING SCIENCE TO TREATMENT

Which exercises are the best for glute strengthening?

Running injuries to the knees and ankles often occur as a result of gluteal weakness. Without stability at the pelvis, the lower body bears the brunt of the forces of running in ways they weren’t designed to do. Therefore, strengthening the gluts is usually a priority for injured runners. Which exercises are the best to choose?

Researchers in New Zealand performed a systemic literature review to evaluate the excitability of the gluteus maximus (glut max) during body weight hip extension exercises using electromyography (EMG) converted to a percentage of maximal voluntary isometric contraction (MVIC). After an exhaustive search, they included 39 studies of healthy individuals in their review. The studies were deemed to be of high quality using a modified version of the Downs and Black quality index. With all studies combined, 938 participants completed 77 different exercises.

The researchers grouped the exercises according to the direction of the force vector in relation to the body. The vertical force vector occurred in upright exercises and the horizontal in supine or prone exercises. In the horizontal plane, the exercises were performed in either the anteroposterior direction (in supine) or the posteroanterior direction (in prone). The average excitability in all directions was similar, however, the ranges and absolute excitability varied greatly.

As one might presume, the exercises in the vertical force direction progressed in recruitment of the glut max as they progressed in difficulty. Those exercises in bilateral stance showed the lowest percentage of activation. Activities with lunges and step-ups demonstrated moderate recruitment of the glut max. Exercises that elicited greater than 60% of the MVIC of the glut maximus were the skater squat and the single leg squat. The exercise with the highest absolute excitability in vertical was the single leg wall squat with the opposite leg extended.

In the horizontal plane with an anteroposterior force vector (performed in supine), bridging with both feet on an unstable recruited 20% or less of a MVIC of the glut max. This came as a surprise since unstable surfaces, such as a Swiss ball or BOSU ball are often thought to increase muscle recruitment. Single leg bridging with both feet on the floor elicited a much stronger contraction in the glut max. Of note, verbal cues improved the glut max recruitment in bridging compared with regular bridging.

Exercises performed in the posteroanterior direction showed the greatest absolute measures of glut max recruitment. Plank on elbows with bent knee hip extension and prone hip extension with upper body on a table and the opposite bent knee supported on a chair both required a greater than 60% MVIC of the glut max. The other exercises in this plane progressed from prone hip extension with varying degrees of hip and knee flexion, to quadruped, then back extension / reverse hyperextension. Hip abduction and external rotation, as well as drawing the navel in, all increased glut max recruitment (see figure 1).

Practical application

What does this mean for you as you plan your treatment strategy? Firstly, assess not only how weak your client is, but also their ability to recruit their glut max. Amazingly, runners compensate for weak gluts with strategies such as higher cadence, knee adduction, over pronation, and arm abduction on the opposite side. Therefore it is possible for them to run miles and miles with significant glut weakness. If the weakness is substantial, start them in supine performing exercises in the anteroposterior direction, progressing then to stance and finally prone as they become stronger. Further progress exercises from bilateral to unilateral stance and from prone to plank for greater glut max activity.

This study found that both verbal and tactile cues increase glut recruitment; therefore, cuing during the exercise will help those who have difficulty starting a contraction or sustaining a maximal contraction. Finally, bracing at the pelvis by contracting the abdomen and pulling in the navel also improves the glut max recruitment. Watch the athlete carefully throughout the entire exercise and notice if their technique falters, especially after only a few reps. If so, they may not be ready for that challenging of an exercise yet.

This study only reviewed research using body weight exercises. Therefore, the information gleaned cannot be applied to exercises with resistance. While these studies were generally of high quality, they differed in methodology, execution of some of the exercises, and the electrode placement. In addition, EMG analysis has its own inherent limitations in representing muscle function. However, it serves as an accepted guide to muscle activity.

Figure 1: Typical prone progression of exercise difficulty

To begin, perform hip extension in prone with hip abduction and external rotation, then progress to plank on elbows, again with hip abduction and external rotation. Once they master that exercise, perform hip extension in plank with knee bent. 


Reference:

IJSPT. 2019 Feb;14(1):14

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