Overview of Muscles

by Dan DeFigio, Nashville personal trainer and author of Beating Sugar Addiction For Dummies.

What exercises work which muscles?

In order to put together a complete weight training routine, you must learn which exercises work which muscle groups.

Overview of muscles

We’ll start with the muscles of the legs and hips:

The muscles in the front of the thigh are called the quadriceps (“quads”). Their main function is to straighten the knee. A nearby and related group is the hip flexors, which pull the knee up towards your chest.

The hamstrings are the muscles in the back of the thigh. They have two main functions: bending the knees, and in conjunction with the glutes (butt muscles), they pull the leg behind you (a movement known as hip extension). The glutes are also responsible for pulling the leg out away from the body. This is called hip abduction.

The muscles on the inside of the thigh called the adductors. They pull the leg inwards toward the centerline of the body. This movement is called (you guessed it) hip adduction.

In the lower leg there is a group of muscles known as the calves which push the foot down (point the toes). The group in the front of the shins is called the dorsiflexors. They pull the foot and toes up toward the shin. So you can sound intelligent at cocktail parties, the movement your calves produce (going up on your tip-toes) is called plantarflexion. The opposite movement (toes up towards the shin) is dorsiflexion.

Moving up to the torso, the chest muscles, or pectorals (“pecs”) pull the arms inward toward the centerline of the body, like a hugging motion. The shoulder muscles – deltoids – pull the arms out away from the body until they’re overhead.

The functions of the muscles of the back are slightly more complex. There are large muscles in the upper back called the trapezius (“traps”), and the rhomboids. Their main function is to pull the shoulder blades together. The trapezius, in conjunction with other muscles, also shrugs, depresses, and rotates the shoulder blades. There is a pair of big, V-shaped muscles in the back called the latissimus dorsi (“lats”) which pull the arms down towards your ribcage and behind you. Other muscles in the rear part of the shoulder are also very active during this pulling down movement.

The muscles that run along the back of the spine are called the spinal erectors. They are also known as the “lower back” muscles, even though the group runs all the way from your sacrum up to the skull. The spinal erectors, together with some deeper muscles, bend the spine backwards — a movement known as spine extension or back extension.

The abdominal muscles (your “abs”) consist of the rectus abdominis, the obliques, and a bunch of deeper stuff that all move and stabilize the spine. The rectus abdominis runs from the sternum down to the pelvic bone. Its function is to round the spine, thus pulling the ribcage and pelvis together and flexing the torso.

Despite what the informercials promise you, there are no “upper” and “lower” abs, by the way, so you can get rid of that idea. One big muscle in the front.

The obliques are diagonal muscles on the sides of the waist. They are mainly responsible for twisting and side bending movements. A good abdominal strengthening program should contain all three movements — spine rounding, twisting, and side bending (not necessarily all in the same workout); more advanced practitioners should make ample use of multi-planar diagonal movements too. The musculature of the trunk is crucial for stabilization of the spine. For back safety and correct posture, core strength is very important.

The biceps are the muscles in the front part of the upper arm. They bend the elbow (flex the arm) and also turn the palms up (supinate the forearm). The triceps are opposite the biceps, and they straighten the elbow (extend the arm).

Here’s a list of the major muscle groups and some common exercises for each:

Leg Press
Step up

Single joint movements for legs:
Knee extension
Hamstring curl
Calf raise
Hip adduction/abduction

Reverse curl up
Twisting movements (crunch with a twist, standing tubing twists, etc.)
Back extension
Side bends, side crunches

Rows – bent over row, one arm DB row, machine row, cable row, etc.
Reverse fly

Barbell press
Dumbbell press
Machine press

Single joint chest exercises: 
Pec deck
Dumbbell fly
Cable crossover

Overhead press
Lateral raise
External rotation i.e. Hitch-hiker

Single joint exercises for arms:

Barbell curls
Dumbbell curl
Machine curl
Suspension curl (using rings or TRX)

Lying extension
Overhead extension
Suspension tricep (using rings or TRX)