Great emphasis is placed on core strengthening (training) in the fitness industry. To strengthen the core muscles and to improve balance, free weights and advanced exercises are not recommended. Instead, the use of devices on which you balance yourself such as wobble boards, different size balls, rollers and uneven surfaces are used. However, does exercising on such equipment strengthen the core muscles to prepare you, for dynamic movements?
A decade ago, balance was considered as mostly a negative factor in the fitness exercise field. Most recommendations for doing strength exercises revolved around the use of exercise machines that were supposedly safer since they did not require balance when doing the exercise. As a result, free weights were not recommended.
Free weights were considered dangerous because they required balance, which if not possessed, could cause injury. However, it has been well known for many decades that the use of free weight exercises develop balance, and especially core muscle strength, and do it more effectively than the use of any balance equipment now in use.
To substantiate this statement, we can look at some of the exercises presently being done for core training and some of the free weight exercises that are available. When using wobble boards, balls, and uneven surfaces, most effort is expended on maintaining balance. Any strength that is gained is basically isometric with a little concentric and eccentric strength within the limited range of motion that one experiences when doing the balance exercises.
In essence, you maintain normal posture in which the spine is held in or close to its neutral position while you do different exercises. Even if you do free weight exercises while balancing yourself on a wobble board or ball, the effects are still minimal because you cannot do two exercises at one time to get maximum gains from either one. It may feel more difficult, but it does not require greater amounts of strength.
When doing core exercises such as ball crunches, crunches with a twist and side crunches, the range of motion is very limited and hardly affects movement of the lumbar spine, the major area in which the abdominal and lower back muscles have an effect. For example, when you do a crunch, the axis of rotation is in the thoracic spine, not in the lumbar spine. Because of this, a negative consequence of doing excessive crunches is development of a rounded upper back, which in some cases leads to kyphosis (a hunchback condition).
The crunch with a twist is also very limited. When you have a flexed thoracic spine, it is almost impossible to get any rotation in this area. The rotation must be in the lumbar area. Keep in mind that the rib cage limits movement in the thoracic area. Thus, when you twist when the thoracic spine is flexed, you can only twist for ten to twenty degrees, but yet the range of motion in a flexible person is up to ninety or more degrees in the waist.
The reverse crunch can be a valuable exercise to develop mainly the lower abdominals, but the way many people do this exercise limits its effectiveness and may even create a dangerous situation. For example, rather than keeping the knees flexed and held in position as you rotate the pelvis off the floor up toward the chest, many people do it with straight legs and extend the legs straight up to the ceiling.
Doing this, if you go through a sufficient range of motion, will switch the muscle involvement to the erector spinae muscles of the lower back rather than emphasizing the abdominals. This switching can be injurious if you are not expecting it or striving to involve the lower back muscles.
In addition to the balance training, the Superman exercise is the main exercise recommended for strengthening the erector spinae muscles of the lower back. It is effective for strengthening this muscle, but the range of motion is only in hyperextension. It does not strengthen the muscles through the full range of motion, beginning with a flexed spine through a completely extended spine.
Yet, this is the range of motion that is used most often in various sports activities and in everyday movements. Most injuries and the pain that people experience who suffer from back problems are in this range of motion and area of the spine. Developing the core with balance exercises does not help this problem.
Many athletes in the iron game do not effectively strengthen the core muscles. Most often they rely on specific training exercises to strengthen these muscles. For example, the squat, dead lift, and good morning are typically used as back strengthening exercises, but they are not. Is analogous to what happens when doing balance exercises.
The strength gained is secondary and occurs because the lower back must be locked in position and held in position as the exercise is done. This involves an isometric contraction which, if held long enough and if the weights are heavy enough, will develop greater isometric strength which is needed to hold the normal, slightly arched lumbar spine position. But, it does not strengthen the muscle through its range of motion!
Understand that strengthening a muscle in a particular range of motion does not strengthen the muscle through other points in the range of motion. The development is very specific. If you want to strengthen the lower back muscles when the spine is flexed, you must work in that position, not when the spine is in a normal position.
The same situation occurs in the core training exercises. There is little to no range of motion in the lumbar spine. Almost all of the exercises are static in nature where the spine is concerned. You do not get strength development through the full range of motion.
To strengthen the abdominal muscles through a full range of motion and to develop all the abdominal muscles, it is necessary to do free weight exercises such as the reverse trunk twist, 45-degree sit-ups with the knees bent and feet on the floor, and reverse crunches (sit-ups) with the knees bent and held in this position. Advanced exercises include the Russian twist and sit ups beginning with the spine in a hyperextended position.
To strengthen the lower back muscles, the most effective exercise is the back raise. In the back raise, you lie over a Roman chair (if it fits you) or a Yessis Back Machine (also known as a Glute Ham Developer) which can be adjusted so that you can get the correct positioning. In the back raise the axis of rotation is in the waist, not in the hip joint which involves the hip extensors. In the back raise you strengthen the erector spinae muscles through their full range of motion. No other exercise does this.
For more information on these and other spinal exercises, see Kinesiology of Exercise in which these exercises are explained in detail with photographs so that you can get a good idea how they are executed and why they are so effective. Since this book is no longer in print are you can read Explosive Golf that deals with this topic extensively. It too has photographs to illustrate the exercises. In addition, to see the exercises in action see the Explosive Golf DVD.