The fitness industry holds the words "core training exercise" in high regard, but some people have misconceptions about their meaning. While often used to describe all types of abdominal exercise, the word core actually describes the deeper layer of abdominal muscles, responsible for maintaining posture, breathing and spinal stability. Strong core muscles improve balance and prevent lower back injuries. Exercises that impose a balance challenge provide effective core muscle training.
Core Anatomy
The transversus abdominis, the multifidus and the pelvic floor comprise the core musculature. The transversus abdominis sits under the surface abdominal muscles, such as the rectus abdominis and the obliques. The multifidus, which lies on either side of the spine, connects to the spinal vertebra, and the pelvic floor creates a sling from the base of your spine to the front of your pelvis. These muscles work in concert to stabilize the spine.
Core Muscle Paradox
Your body has two basic types of muscle fibers. Fast-twitch muscle fibers activate during short-duration activities, and slow-twitch fibers support endurance activities. Fast-twitch muscles are usually mobilizers, and slow-twitch fibers are stabilizers, according to the Freeport Integrated Health Center website. The large, superficial abdominal muscle called the rectus abdominis flexes the spine and functions as a fast-twitch mobilizing muscle. You use the rectus abdominis during crunches and when you go from a supine to seated position in the morning. Performing crunches tones the abdominal muscles but does not enhance spinal stability, according to the Freeport Health website. Crunches, therefore, do not qualify as deep core exercise.
Transversus Abdominis
University of Queensland physical therapist Paul Hodges put the transversus abdominis muscle on the fitness programming map. His experiments show that people free of back pain instinctually activate this muscle group a fraction of a second before limb movement. In contrast, people with back problems have a delayed transversus abdominis reaction, implying that they lack spinal stability during movement. During exhalation, the transversus abdominis presses against the diaphragm to assist in expelling the air. Breathing exercise, with an emphasis on drawing the belly in during exhalation, provides effective basic core training. Bracing or voluntarily contracting your abdominal muscles also engages the core, says chiropractor Craig Liebenson, in an article on the Council of Chiropractic Physiological Therapeutics and Rehabilitation website.
Multifidus
If you tend to slouch at your work station, there is a good chance that your multifidus has atrophied. This muscle group, because of its proximity to your spinal vertebra, is tasked with maintaining alignment and keeping your back straight. Physical therapists from the P3 Sports Care Clinic in California recommend the bird dog exercise for working the multifidus. Kneel on all fours, draw your belly in to create a straight line from the top of your head to the base of your spine. Prepare with an inhalation, then exhale and simultaneously lift and extend your right leg behind you and your left arm in front of you. Return to center and repeat on the other side. Avoid letting your spine sag.
Pelvic Floor
The pelvic floor muscles support spinal stability by working in conjunction with the other core muscle groups. Pregnant women learn pelvic floor exercises, which involve imagining that they are trying to stop their urine flow, but physical therapists also use them to treat back patients, says Ruth Sapsford of the University of Queensland. The results of a 2002 study published in the "International Urogynecology Journal" indicate that co-contractions of the transversus abdominis muscle create more efficient pelvic floor contractions. Lead author P. Neumann advises that voluntary abdominal muscle contraction is necessary for effective pelvic floor training.
References
- Freeport Integrated Health Center: Getting To the Core
- SportsInjuryClinic.net: Introduction to Core Stability
- Council of Chiropractic Physiological Therapeutics and Rehabilitation: Core Training: The Dangers of What Our Patients Think They Know; Craig Liebenson
- "Archives of Physical Medicine and Rehabilitation"; Altered Trunk Muscle Recruitment In People With Low Back Pain With Upper Limb Movement At Different Speeds; P.W. Hodges; September 1999
- "International Urogynecology Journal"; Pelvic Floor and Abdominal Muscle Interaction: EMG Activity and Intra-abdominal Pressure; P. Neumann; 2002
- P3 Sports Care: Bird Dog Exercise
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