Opposing Muscle Groups - Biceps and Triceps (either side of the upper arm) ^0e4315 - Quadriceps and Hamstrings (either side of the upper leg) - Deltoids and Latissimus Dorsi (shoulders and upper back) - Pectoralis Major and Trapezius/Rhomboids (upper chest and upper back) - Abdominals and Erector Spinae (stomach and lower back) - Iliopsoas and Gluteus Maximus (front and back of the hip) - Hip Adductor and Gluteus Medius (inside and outside of the hip)/