From http://www.ahs.uwaterloo.ca/~mcgill/fitnessleadersguide.pdf
Enhancing Low Back Health through stabilization exercise
Stuart M. McGill, Professor (Spine Biomechanics), University of Waterloo
An excerpt:
Caveats for Exercise
1. While there is a common belief among some Aexperts@ that exercise sessions should be
performed at least 3 times per week, it appears low back exercises have the most
beneficial effect when performed daily.
2. The "no pain-no gain" axiom does not apply when exercising the low back in pained
individuals particularly when applied to weight training, and scientific and clinical wisdom
would suggest the opposite is true.
3. While specific low back exercises have been rationalized in this guide, general exercise
programs that also combine cardiovascular components (like walking) have been shown
to be more effective in both rehabilitation and for injury prevention. The exercises shown
here only comprise a component of the total program.
4. Diurnal variation in the fluid level of the intervertebral discs (discs are more hydrated
early in the morning after rising from bed), changes the stresses on the disc throughout
the day. Specifically, they are highest following bedrest and diminish over the
subsequent few hours. It would be very unwise to perform full range spine motion while
under load, shortly after rising from bed.
5. Low back exercises performed for maintenance of health need not emphasize strength,
with high-load low repetition tasks, rather more repetitions of less demanding exercises
will assist in the enhancement of endurance and strength. There is no doubt that back
injury can occur during seemingly low level demands (such as picking up a pencil) and
that the risk of injury from motor control error can occur. While it appears that the chance
of motor control errors, resulting in inappropriate muscle forces, increase with fatigue
there is also evidence documenting the changes in passive tissue loading with fatiguing
lifting. Given that endurance has more protective value than strength, strength gains
should not be overemphasized at the expense of endurance.
6. There is no such thing as an ideal set of exercises for all individuals. An individuals=
training objectives must be identified, (be they rehabilitation, specifically to reduce the risk
of injury, optimize general health and fitness, or maximize athletic performance), and the
most appropriate exercises chosen. While science cannot evaluate the optimal exercises
for each situation, the combination of science and clinical experiential Awisdom@ must be
utilized to enhance low back health.
7. Be patient and stick with the program. Increased function and reduction pain may not
occur for 3 months.
Years ago, as I began to develop our scientific investigations into various aspects of understanding low back problems, I would ask my graduate students to find the scientific foundation for many of the "common sense" recommendations I was hearing both in the clinic and in industrial settings. To my surprise, they would report that the literature yielded no, or very thin, evidence. Examples of such "common sense" recommendations include -- if you are to perform a sit-up, bend the knees; if you are going to perform a lift, bend the knees and keep the back straight; reducing the load throughout the workday will reduce the risk of back troubles. In fact, the benefit of each of these have been shown to be highly questionable.
It is widely believed that stretching the back, and increasing the range of motion is beneficial, and reduces back problems – however the scientific evidence shows that, on average, those who have more range of motion in their backs have a greater risk of future troubles. Clearly there is a tradeoff between mobility and stability where the optimal balance is a very personal and individual variable. Indeed, the “stability/mobility balance” may shift during a progressive exercise program as symptoms resolve, or with advancing age, or as rehab/training objectives change. Another generally perceived goal of training the back is to increase strength, believing in the “no pain-no gain” philosophy. Strength has little association with low back health, in fact, many hurt their backs in an attempt to increase strength. It could be argued that this is an artifact, in that exercise programs intended to enhance strength contained poorly chosen exercises such as sit-ups. Performing sit-ups both replicates a potent injury mechanism (specifically posterior disc herniation) and results in high loads on the spine. On the other hand, muscle endurance, as opposed to strength, has been shown to be protective for future troubles. Further, for many, it is better to train for stability rather than stretching to increase range of motion.
Recent investigations into injury mechanisms have revealed that many back training practices actually replicate the loads and motions that cause the parts of the low back to become injured. For example, disc herniations need not have excessive loading on the back to occur, rather repeated forward flexion motion of the spine is a more potent mechanism. Thus, if full flexion or deviation is avoided in the spine, the risk of herniation is remote. But for most exercise professionals the link between injury and exercise needs to be better developed. Injury is caused by damage to supporting tissues. This damage reduces the normal stiffness in the spine resulting in unstable joints. Thus, while injury results in joint instability, an event characterized by improper muscle activation can cause the spine to buckle, or become unstable. There is no question that excessive loading can lead to back injury, but instability at low loads is also possible and problematic. For example, it is possible to damage the passive tissues of the back while bending down and picking up a pencil, or sneezing, if sufficient stability is not maintained. Some people recommend that during training, one should exhale upon exertion (when weight training for example, exhaling upon the lifting phase and inhaling on the lowering). In terms of grooving stabilizing motor patterns for all tasks, this is a mistake. In other words, breathing in and out should occur continuously, and not be trained to a specific exertion effort – this helps to maintain constant abdominal muscle activation and ensure spine stability during all possible situations (of course the opposite is true for maximal effort competitive lifting where a valsalva manoeuvre with the breathe held is necessary – but performance training is not the emphasis here). Further, specific muscle activation patterns are essential to avoid injury but have also been documented to become perturbed following injury. Pain is a powerful instigator in the deprogramming of normal/healthy motor patterns into perturbed patterns. The exercises and programs described here are based on the latest scientific knowledge of how the spine works, and becomes injured. In addition, they have been quantified for spine load, resultant spine stability, and muscle oxygenation, to name a few. These are only a few examples to begin a program. The goals are to enhance spine stability through grooving motion and muscle activation patterns to prepare for all types of challenges. Of course, other exercises may be required subsequently to enhance daily functioning, but once again, these will depend upon the characteristics and objectives of the individual.
Two other concepts must be emphasized at this point. First, training approaches intended to enhance athletic performance are often counterproductive to the approaches used when training for health. Too many patients are rehabilitated using athletic philosophies, or worse yet “body building” approaches designed primarily to isolate and hypertrophy specific muscles, and in so doing thwart progress. Many bad backs are created from using inappropriate performance philosophies. Identifying the training objectives is paramount. The emphasis here is on enhancing spine health – training for performance is another topic. Second, many of the training approaches that are used at joints such as the knee, hip, shoulder etc are mistakenly applied for the back. The back is a very different, and complex structure, involving a flexible column, with complex muscle and ligamentous support. The spine contains the spinal cord and lateral nerve roots, and whose musculature is intimately involved in several other functions including breathing mechanics, to give just one example. Many of the traditional approaches for training other joints in the body are not appropriate for the back – either they do not produce the desired result or they create new patients.
A daily routine for enhancing low back health
The following exercises have been chosen to spare the spine, enhance the muscle challenge, and enhance the motor control system to ensure that spine stability is maintained in all other activities. Each one has been quantified for these metrics. Having stated this, they are only examples of well designed exercises and may not be for everyone – the initial challenge may or may not be appropriate for an individual nor will the graded progression be similar among all people. These are simply examples to challenge all of these torso muscles.
The PDF document describes Cat-Camel, Curl-Up, Side Bridge, and Birddog lower back exercises with images.
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