The lunge is an intense exercise that predominetaly targets your lower body. Being that more than one joint is being activated, this classifies lunges as compound exercises. Not only do these exercises involve more than one joint, but they also involve more than one muscle. Being that lunges are performed in a staggered stance, they will improve your balance as well as your strength.
Hip Flexion
Hip flexion takes place when you move your thigh toward your stomach. Flexion itself occurs when you decrease the angle between two body parts. During the lunge, you flex your hips when you lower yourself down and move your thigh toward your stomach. This causes you to work the hip flexors which consist of the iliacus and psoas major. You also partially recruit the quadriceps with hip flexion.
Knee Flexion
Knee flexion is the backward movement of the lower leg as you bend your knee. This takes place in the lowering portion of a lunge. The main muscles targeted are the hamstrings. These sit on the back of the thighs and they consist of the biceps femoris, semitendinosus and semimembranosus.
Hip Extension
Hip extension takes place when you move your thigh backward. You do this during a lunge when you rise up. The main muscle targeted here is the glutes. This muscle group consists of the gluteus maximus, medius and minimus in order from largest to smallest. Your hamstrings also get activated with hip extension.
Knee Extension
Knee extension is the movement pattern that straightens your lower leg. You extend your knees during the rising movement of a lunge. This places a high amount of emphasis on the quadriceps which sit on the front of the thighs. The root word "quad" means four. The four parts of the quadriceps are the rectus femoris, vastus intermedius, vastus lateralis, and vastus medialis.
Plantar Flexion
The word "plantar" is used in reference to the bottom of the foot. Plantar flexion takes place when you bend your ankle and move your foot downward. You perform this motion in a lunge when you push off your back foot and begin your next repetition. This causes you to work the calves which consist of the gastrocnemius and soleus. The gastroc has a lateral and medial head and sits right beneath the knee on the back of the leg. The soleus is in front of the gastroc.
Dorsiflexion
Dorsiflexion is the movement that causes your foot to move back toward your shin. This takes place on the back foot when you lower yourself into a lunge. A thin band of muscle that runs down the front of the shin called the anterior tibialis gets activated with dorsiflexion.
