Core training is the strengthening and conditioning of the core muscles surrounding the middle of the body—the abdomen, hips, pelvis, and lower back. These muscles protect the spine and are responsible for stabilizing and balancing the body during movement. Therefore core training is sometimes referred to as core stabilization or balance training.
Strong core muscles that contract appropriately are important for good posture and balance, and for the stability and mobility of the spine, rib cage, pelvis, and hips. Movement is more powerful and efficient with a strong core. Strong core muscles also give better definition to the superficial muscles of the trunk and can help prevent or reduce lower back pain and injuries.
Every part of the body is connected directly or indirectly, and every movement affects other parts of the body and depends on the strength of the trunk for stability and power. The bones, discs, tough fibrous tissue, cartilage, and ligaments of the spine are all connected by muscles. If these muscles are strong and functioning properly, movement is stabilized and impact from the ground is absorbed. “Kinetic chains” extend from each foot, through the ankles, calves, knees, thighs, pelvis, and spine, coming together in the trunk. These kinetic chains form the bases of balance, posture, and coordinated movement.
The deep muscles are the most important for core stabilization. These include the transverse abdominis, the multifidus, and the pelvic-floor muscles. The transverse abdominis wraps around the front of the abdomen and pulls in the stomach. The multifidus extends along the spine, from the neck to the pelvis, with short fibers that connect each vertebra of the spine to other nearby vertebrae. The muscles of the pelvic floor are those that are felt when holding back urination.
Physical stability and balance depend on three coordinated systems in addition to the core muscles: the vestibular or auditory system of the inner ear, the visual system, and the proprioceptive system. Sensory nerves called proprioceptors in the muscles, tendons, and joints signal the central nervous system, providing spatial and body-posture awareness. In addition to weak or unbalanced core muscles; poor posture, illness, or injury can interfere with equilibrium and result in physical unsteadiness or instability.
Core training fell to number nineteen on the American College of Sports Medicine's survey of the top ten worldwide fitness trends for 2016, but core training to promote health and strength is an ancient practice. Yoga, martial arts, T'ai chi, and Pilates all involve core training. Physical therapists and athletic trainers have long utilized core-training techniques, and most fitness centers now offer some form of balance or core training. In addition, core training is often incorporated into other exercise regimens, including strength, flexibility, and endurance training, and land and water aerobics classes.
Many core-training exercises are easy and can be performed anywhere at any time. Simple yoga poses, such as the tree pose, improve balance and stability. Changing the direction of one's gaze or balancing on one foot with the eyes closed makes such poses more challenging. Pilates is also a good core-training choice for beginners. A physical therapist, trainer, or exercise physiologist can help identify specific core weaknesses and muscle imbalances and suggest appropriate exercises.
Although core training requires no equipment, it is often performed with a balance or core board or an exercise ball, also called a Swiss, balance, or stability ball. Core training on an inflatable ball requires more coordination of major muscle groups and may work the muscles harder, providing cardiorespiratory and strength training, as well as balance training. Such props can also enliven a workout.
Most core-training exercises are either isometric exercises that are held for a time or low-intensity exercises that use only the body weight as resistance and are repeated about 12 times or until the muscles tire. In general, core muscles are believed to respond better to more resistance with fewer repetitions. If the muscles have not tired after 12 repetitions, resistance can be increased with weights. Circuit core training, without resting between exercises, increases the intensity and burns more calories.
The two most basic core-training exercises are contraction of the transverse abdominis and bridging. To contract the transverse abdominis, the belly is pulled in toward the neutral spine. The spine is held in the neutral position—with its three natural curves—so that the back does not bend forward. The contraction is held for about 6 seconds while breathing normally, followed by a 10-second rest, with 8 to 12 repetitions. This exercise can be performed anywhere—sitting at a desk, standing, or driving. Bridging is performed while lying on the back with knees bent and feet flat on the floor. With the spine neutral and pushing with the feet, exercisers tighten the transverse abdominis and raise the buttocks a few inches. The position is held for about six seconds, while breathing normally, with up to ten seconds of rest between repetitions.
The bent-knee sit-up, or abdominal crunch, is the iconic core-training exercise. It is most often performed with the lower back against the floor and the arms across the chest or behind the head, bending at the waist. Extending the arms overhead increases the intensity. Some experts now suggest that, rather than flattening the back to the floor, the hands should be placed, palms down, under the lower back to reduce pressure on the spine, with the head and shoulders lifted only slightly. With sit-up machines, an individual's chest pushes the padded bar toward the thighs. Sitting upright in the machine prevents neck strain.
Lower-back muscles are worked by back extensions and leg lifts. Back extensions are performed lying facedown with the arms at the sides and lifting the chest. If this is too difficult, the arms can be placed under the chest with the forearms on the floor facing forward. If possible, the back lifts the chest off the forearms. A back-extension machine, which may be safer than floor exercises, is the opposite of a sit-up machine, with a padded bar that is pushed with the back. Leg lifts are gentle exercises for both the lower back and abdominal muscles. Lying on one's back, with arms at the sides, one lifts the legs about 12 in. (30 cm) or as high as is comfortable. The legs can be lifted together or alternately.
Various standing exercises for the upper body, such as standing rows and shoulder presses, as well as lower-body exercises such as squats, lunges, and step-ups, contribute to core strength. Other common core-training exercises include:
Core-training exercises with props include:
A number of experts question the value of core training and of abdominal crunches, in particular. Some research suggests that repeated bending of the spine, which usually occurs with crunches, over time can contribute to spinal disc damage and rupture. Several experts argue that just six or eight crunches a few times per week are perfectly adequate. In any case, it is vital to perform crunches—and all core-training exercises—correctly. It is more important to do them correctly than to perform many repetitions. Learning core training from an exercise physiologist or physical therapist ensures that the correct muscles are being worked and that breathing is normal throughout.
Core training may be preceded by a general cardiorespiratory warm-up, perhaps five to ten minutes of low-to-moderate intensity aerobic activity such as walking or using a stationary bike or an elliptical trainer. Core training requires learning to use diaphragmatic breathing and maintaining a neutral spine. By breathing with the diaphragm, or the large muscle under the lungs, individuals move the abdomen and chest in and out rather than moving the chest and shoulders up and down. A neutral spine maintains the three normal curves—in the neck, upper back, and lower back. These curves help absorb shock and impact, whether sitting, standing, or moving. In contrast, slumping puts additional stress on the spine and other body parts.
Before core training, the neutral spine should be located while standing, sitting, and lying on one's back with knees bent. Recognizing and maintaining a neutral spine enables good posture, both while exercising and while performing daily activities. To locate the neutral spine:
Core training can be followed with a general cardiorespiratory cool down. This can be the same or similar exercises as performed during the warm-up.
Core training does not normally have any complications; however, as with any exercise, injuries are possible.
Everyone needs some degree of core strength for everyday activities, even for standing up from a chair, and athletes require more core strength than the average person. Although coaches, trainers, athletes, and the general public have emphasized core training in recent years, its value as a distinct training activity has been questioned. A study of novice adult runners with weak core muscles did find that six weeks of core training significantly improved times on 5-km runs compared with the control group who did not core train. Other studies, however, have found little or no benefit from core training. A study of college rowers found that, although eight weeks of strenuous core training tightened abdomens, it did not improve their rowing. A 2011 study evaluated back-, abdominal-, and side-muscle fitness by having young adults perform squats, lunges, twists, crunches, and rigid plank positions. The subjects were then given a series of physical performance tests, such as throwing a medicine ball backwards over the head and sprinting through an obstacle course. The researchers found little correlation between strong core muscles and athletic performance. They suggested that although core training should be a component of overall fitness programs, especially for preventing injuries, it should not be the main focus of any training program.
See also Balance training ; Exercise ; Pilates ; Yoga .
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Margaret Alic, PhD