Chest: Worked by anything pushing the arm across the body (presses, flyes, dips). Upper (clavicular) vs mid/lower (sternal) heads — incline/closer-grip presses bias the upper; decline/dips bias the mid-lower. Exercises: 45° Incline Barbell Press, Cable Crossover Ladder, Barbell Bench Press, Bottom-Half DB Flye, 45° Incline DB Press, Pec Deck, Machine Chest Press, Bottom-Half Seated Cable Flye.
Lats: Worked by pulling the arm down to the front or in from the side. Often hard to "feel" — a variety of cues/exercises are used. Exercises: Wide-Grip Pull-Up, Pendlay Deficit Row, Neutral-Grip Lat Pulldown, Chest-Supported Machine Row, Neutral-Grip Seated Cable Row, Dual-Handle Lat Pulldown, Smith Machine Row, Lean-Back Lat Pulldown, Chest-Supported T-Bar Row, Dual-Handle Elbows-Out Cable Row.
Mid-back (mid-traps, rhomboids): Worked by squeezing the shoulder blades together (rows, face pulls). Exercises: Pendlay Deficit Row, Chest-Supported Machine Row, Neutral-Grip Seated Cable Row, 1-Arm 45° Cable Rear Delt Flye, Smith Machine Row, Chest-Supported T-Bar Row, Dual-Handle Elbows-Out Cable Row.
Biceps: Worked by flexing the elbow — directly on curls, indirectly on back work. Crossing both elbow and shoulder, arm position varies activation. Exercises: Bayesian Cable Curl, EZ-Bar Cable Curl, Machine Preacher Curl, Cable Rope Hammer Curl, DB Concentration Curl.
Triceps: Worked by extending the elbow — directly on extensions, pressdowns, kickbacks; indirectly on presses. Long head also works on pull-ups/pullovers. Arm position (overhead, by the side, hyperextended behind torso) shifts emphasis. Exercises: Overhead Cable Triceps Extension (Bar/Rope), Cable Triceps Kickback, EZ-Bar Skull Crusher, Triceps Pressdown (Bar).
Shoulders (front/side/rear delts): Front delts get hit hard on all pressing — no isolation needed. Side delts get some pressing work but get dedicated isolation. Rear delts aren't hit by presses; trained on pulls plus direct isolation (since larger lats/mid-back take over). Exercises: 45° Incline Barbell Press, High-Cable Lateral Raise, Barbell Bench Press, 1-Arm 45° Cable Rear Delt Flye, Machine Shoulder Press, 45° Incline DB Press, Machine Chest Press, Seated DB Shoulder Press.
Upper traps: Function is debated — likely better targeted by shrugging "up and in" (upward scapular rotation) than straight up. Also assist on horizontal rows, lateral raises, and isometrically on RDLs. Exercises: Machine Shrug, Cable Paused Shrug-In. (No direct neck work is included, but adding ~3 sets neck extension + 3 sets neck flexion 1–2x/week is suggested for those interested.)
Quads: Worked by extending the knee. Three heads cross only the knee; the rectus femoris crosses knee and hip, so squats/leg presses don't hit it as well — leg extensions and sissy squats involve it more. Exercises: Smith Machine Squat, Leg Extension, Leg Press, DB Bulgarian Split Squat, Smith Machine Static Lunge w/ Elevated Front Foot, Hack Squat, Walking Lunge.
Hamstrings: Worked by flexing the knee and/or extending the hips (leg curls, hip hinges). Crossing both hip and knee, they aren't hit well by squats/leg presses. Exercises: Lying Leg Curl, Barbell RDL, Seated Leg Curl, 45° Hyperextension.
Glutes: Main bodybuilding action is hip extension — hit on squats, leg presses, lunges, deadlifts. Glute medius (hip abduction) trained via direct abduction work and stabilizes lower-body compounds. Exercises: Smith Machine Squat, Barbell RDL, Leg Press, DB Bulgarian Split Squat, Machine Hip Abduction, Smith Machine Static Lunge w/ Elevated Front Foot, 45° Hyperextension, Hack Squat, Walking Lunge.
Adductors: Inner thigh, commonly neglected; hit substantially on squats but trained with direct adduction work too. Exercises: Smith Machine Squat, Leg Press, Machine Hip Adduction, Hack Squat, DB Bulgarian Split Squat, Smith Machine Static Lunge w/ Elevated Front Foot, Walking Lunge.
Calves: Worked by plantar flexion (pointing the feet down). The gastrocnemius crosses the knee, so it's indirectly worked on leg curls. Stubborn but responsive to proper training. Exercises: Leg Press Calf Press, Standing Calf Raise.
Abs: Here = rectus abdominis (the 6-pack); main function is rounding the spine (crunches bring torso to legs; leg raises bring legs to torso — both included). Some direct transverse abdominis/oblique work, which also stabilize many exercises. Exercises: Cable Crunch, Roman Chair Leg Raise, Machine Crunch, Ab Wheel Rollout.