LB – GLUTEUS MAXIMUS – X – RESEARCH

#3. Effects of hip joint angle position on muscle activation

– The gluteus maximus is uniformly activated to a greater degree when it is working at a short length, relative to when it is working at a long length.
– The gluteus maximus functions as a hip extensor, a hip abductor, and a hip external rotator (among other things)
– Its activation during hip extension is maximized when the hip is extended, abducted, and externally-rotated.
– This suggests that exercises that involve peak force production when the muscle is shortened (such as hip thrusts and glute bridges) will be better for training the gluteus maximus than exercises that involve peak force production when the muscle is lengthened (such as squats).
– Activation of the gluteus maximus is very likely maximized at short muscle lengths because that is when it has the longest internal moment arm, relative to the other hip extensors.
– In contrast, when the gluteus maximus is lengthened, its internal moment arm decreases dramatically, while the internal moment arms of the other hip extensors increases.
– The principle of neuromechanical matching: muscles working the same joint are activated in proportion to their leverage for a joint action

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#4. Effects of knee joint angle position on muscle activation

– When the knee is maintained in an extended (straight leg) position during hip extension movements, the hamstrings are very active, and this seems to suppress gluteus maximus activation.
– In contrast, when the knee is maintained in a flexed (bent leg) position during hip extension movements, the hamstrings not very active, and this seems to encourage greater gluteus maximus activation.
– It seems likely that the central nervous system (CNS) recognizes the straight leg position allows hamstrings to contribute to force production more easily due to positions of their muscle fibers on the length-tension relationship, and thereby increases hamstrings activation relative to gluteus maximus activation
– Similarly, it likely recognizes bent leg positions prevent hamstrings from contributing to force production very effectively, and thus increases GMax activation

#5. Effects of combining hip extension with knee extension actions

– When knee extension force production occurs at the same time as hip extension force production, activation of the GMax is decreased relative to the same hip extension force being produced in isolation. In contrast, the activation of the single-joint quadriceps is increased.
– It’s unclear why this happens; it seems to result from knee extensors being able to contribute to hip extension force production during multi-joint exercise
– In practice, it suggests that the gluteus maximus is best trained with exercises that involve predominantly or exclusively hip extension (such as deadlifts or back extensions) and not exercises that combine both hip and knee extension at the same time (such as squats).
N.B. An alternative (and potentially more plausible) hypothesis for why gluteus maximus and hamstrings activation are reduced when a knee extension force is applied during hip extensions is that adductor magnus activation is increased. This would be a simpler explanation that does not require complex biomechanical maneuvering, but to date this has not been assessed

#6. Effects of abdominal muscle activation

– When the abdominals are deliberately activated during hip extension actions, this increases gluteus maximus muscle activation.
– This may occur because of the greater stability that bracing the abdominals provides to the muscles working at the hip joint.
– When working in a more stable environment, muscles are typically able to achieve higher levels of voluntary activation (motor unit recruitment).

EMG STUDIES

GLUTEUS MAXIMUS-MEDIUS-MINIMUS
– Multiple Exercises

Gluteal Muscle Forces during Hip-Focused Injury Prevention and Rehabilitation Exercises – Collings 2023
Procedure:
– 14 female footballers (18-32 yr old) with at least 3 months of lower limb strength training experience. 
Review:
– PhysioTutors.com 
– Hip extension–dominant movements (split squat, single-leg squat, RDL, and hip thrust) created similar muscle forces in the gluteus medius and minimus compared to hip abduction movements (hip hike, banded side step, side-lying leg raise). Thus when you want to target the lateral stabilizers of the hip, you can use more functional hip-extension dominant exercises
– The results indicate that for many exercises, the gluteus minimus produced more force compared to the gluteus medius, when the force production was normalized to the muscle size, particularly for hip hikes, side-lying leg raises, and side planks. As the gluteus minimus is more of a hip stabilizer by helping the capsule hold the femoral head in the acetabulum, you can use these exercises to increase local hip stabilization. 
– Subjects with gym experience and playing rugby were included and this may not be generalizable to people suffering from hip pathology or injury. The same is true for sex as all players in this study were female.

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