Primary movers describe muscle groups that move a joint, while stabilizers are muscles that keep the joint in alignment to prevent dislocation or tissue tears, according to physical therapist, Michael Clark, CEO of the National Academy of Sports Medicine. In sports and daily activities, all lower extremity muscles work together to produce movement, and they rarely function in isolation. Prime movers accelerate or decelerate movement, which are called concentric and eccentric movement, respectively. For example, when you flex your knee to your ribs, your hip flexors accelerate the movement while your buttocks decelerate the movement toward the end of the movement.
Quadriceps
The quadriceps are made up of four muscles in the front part of your upper thigh, called the rectus femoris, vastus lateralis, medius and intermedius. They all work together to concentrically extend the knee joint and eccentrically flex the knee joint, according to Clark.
Hamstrings
The hamstrings are made up of three muscles in the back part of your upper thigh, which are the bicep femoris, semimembranosis and semitendinosis. They work together to concentrically flex the knee joint and eccentrically flex the knee joint. The hamstrings also help your hip to extend. They constantly oppose movement patterns with the quadriceps in many daily activities, such as stair-climbing, walking and cycling.
Calves
The prime mover of the calf muscles is the gastrocnemius, which is the large muscle that you can see and feel in the back of your lower leg. It concentrically plantar flexes the foot where your toes point away from your shin, and eccentrically dorsiflexes the foot where your toes point toward your shin. The gastrocnemius works with the other leg and hip muscles to produce force when you jump up or run.
Iliopsoas
This group of muscle is made up of the psoas major and minor and the iliacus. All originates from the front part of the lower spine and inserts into part of your thighs and hip muscles. They work together to concentrically flex the hip joint and eccentrically extends the hip joint. If these muscles are tight, then they constantly pull at the lower spine and cause back pain, according to fitness professional, Anthony Carey, author of "Pain-Free Program."
Gluteal Complex
The gluteal complex, also called the buttocks, is made up of the gluteus maximus, medius and minimus. They work together to concentrically extend the hip joint and eccentrically flex the hip joint, opposing the movement of the iliopsoas and other hip flexors. They also work with other hip and leg muscles to rotate the hip joint.
References
- "NASM Essentials of Personal Fitness Training"; Michael Clark; 2007
- "Pain-Free Program"; Anthony Carey; 2005
