The multifidus muscle is actually a group of muscles referred to in the singular that run parallel to and the length of the spine. You can feel yours easiest in the lower back where it is thicker. The role of the multifidus is to stabilize the spine. A faulty multifidus can easily contribute to low back pain. Physical therapist Jim Johnson's book "The Multifidus Back Pain Solution" features six exercises that focus on the multifidus muscle. The basis of the exercises is that multifidus strengthening exercises cause quicker and more complete recovery after episodes of back pain.
There are three distinct multifidus exercises, two of which have multiple progressions. The same multifidus exercises Johnson numbers in order of progression resemble birddog or superman exercises common in physical therapy exercise programs. Mastering one exercise in order to progress to the next requires performing 20 repetitions or two minutes of the exercises. Perform the exercises two to three days per week with a day of rest between. Exercise six is the exception and can be done daily for better results.
Begin on all fours. Raise one leg close to horizontal and hold one second before lowering. Repeat on the other leg. Keep the lower back stable as you move. Continue to alternate legs to fatigue or you can no longer hold the back stable.
From the same position as exercise one, simultaneously raise one arm and opposite leg close to horizontal. Hold briefly and lower. Continue until you fatigue or lose form up to 20 repetitions or two minutes.
Exercise three adds ankle weights to exercise two for further challenge. Johnson suggests a 2-lb. ankle weight on each leg.
Lie stomach down propped with a pillow under your belly if that's more comfortable. Raise one straight leg off the floor no more than 6 inches. Avoid arching the back. Repeat, alternating legs until you reach fatigue.
Add ankle weights to each leg and perform exercise four. One- to 5-lb. ankle weights are recommended. Start with a weight that allows at least 30 seconds or 10 or more repetitions per leg.
The last of the multifidus-strengthening exercises can be done standing or seated. Place one hand on your abdominal muscles and the other across your belt line in back. Tense your muscles by pulling your navel in and up. Keep the rest of your body still. Hold for three to five seconds while you feel the tightening front and back with your hands. Perform up to 20 repetitions once a day.