Each joint action, with the role and emphasis the graph assigns each muscle. These are qualitative anatomical labels, not measured muscle activation.
Hip extensionprimary action
Gluteus maximus (prime mover, high emphasis); Gluteus maximus (prime mover, high emphasis); Biceps femoris long head (synergist, moderate emphasis); Semitendinosus (synergist, moderate emphasis); Semimembranosus (synergist, moderate emphasis); Adductor magnus (synergist, low emphasis)
Knee extensionsecondary action
Vastus lateralis (synergist, low emphasis); Vastus medialis (synergist, low emphasis); Vastus intermedius (synergist, low emphasis)
Spine extensionsecondary action
Erector spinae (stabilizer, moderate emphasis); Rectus abdominis (stabilizer, moderate emphasis)