published 11/30/06
Endurance Training for Injury Rehabilitation
What to do when your usual strength training workout isn’t working … or isn’t an option
by Paul Ingraham, Vancouver, Canada MORE
Credentials and qualifications
I am a writer and retired Registered Massage Therapist (unusually well-trained for a massage therapist, a 3000-hour program). I’m almost done with a Bachelor of Health Sciences degree. I am a peer reviewer for The Natural Standard, and a copyeditor for Science-Based Medicine. My most important qualification is more than a decade of workaholic post-graduate study, clinical experience, and constant conversations with readers from around the world, including many experts who have provided countless suggestions and criticisms.
For more information, see: Who Am I to Say? More information about my qualifications, credentials and professional experiences for my readers and customers.
Credentials and qualifications
I am a writer and retired Registered Massage Therapist (unusually well-trained for a massage therapist, a 3000-hour program). I’m almost done with a Bachelor of Health Sciences degree. I am a peer reviewer for The Natural Standard, and a copyeditor for Science-Based Medicine. My most important qualification is more than a decade of workaholic post-graduate study, clinical experience, and constant conversations with readers from around the world, including many experts who have provided countless suggestions and criticisms.
For more information, see: Who Am I to Say? More information about my qualifications, credentials and professional experiences for my readers and customers.
I often need to talk to clients about switching them to endurance training at the gym. Usually, they have noticed that their usual strength training workout isn’t working: it feels too intense, it feels exhausting “and not in a good way,” they don’t seem to be making progress anyway, and they are worried that training may be a problem for a current injury or pain problem. Often, they have already stopped working out altogether.
If you enjoy the gym, this is an exasperating situation. You are eager for a solution. You want to get back to work!
If you don’t especially enjoy the gym — if you are only strength training for weight loss, or as part of a general fitness program that your doctor put you up to — then you are eager for an excuse to stop!
Does your strength training workout feel exhausting “and not in a good way”?
What’s going on here? Why do strength training workouts sometimes seem to stop working? And how can a switch to endurance training help?
Quick definitions
If you’ve spent any time at the gym, you will have heard people talking about “reps” for repetitions and “loads” for the heaviness of a weight. Strength training refers to “high load, low rep” exercises — lifting weights so heavy that you can only manage a few repetitions. Endurance training is the opposite: lifting light weights lots of times.
Endurance training and strength training are the top half of a spectrum of intensity in basic rehabilitation exercises:
| Spectrum of intensity of rehabilitative exercises | |||
| Repetitions | Loading | Challenge | |
|---|---|---|---|
| PF-ROM Exercises | 25–100 | extremely low | painless |
| Mobilizing! | 25–75 | low | mild discomfort |
| Endurance Training | 12–50 | low to moderate | moderate exertion discomfort |
| Strength Training | 6–12 | moderate to high | strong exertion discomfort |
The trouble with strength training
Strength training probably doesn’t work well on muscles that contain significant muscle knots.1 The evidence is circumstantial, not direct: to the best of my knowledge, the subject has not been studied. However, it is a reasonable theory, based on what is known about muscle knots.
Common muscle knots — technically known as a myofascial trigger points — are involved in virtually every pain problem or injury. They either cause it, or complicate it, or both.
Strength training probably doesn’t work well on muscles that contain significant muscle knots.
Trigger points may develop for months or years before causing obvious symptoms. These “latent” trigger points may interfere with strength training long before you are aware of any problem, whether you are injured or not.
A trigger point is a small, dysfunctional patch of muscle tissue, a localized spasm. It is unhealthy: usually painful to press on, full of waste metabolites. Muscle cells affected by trigger points may not be as neurologically responsive, and probably cannot recover from training as well as unaffected muscle cells.
More importantly, trigger points actually weaken a muscle.2
The wimpifying effect
Although the physiology is complex and imperfectly understood, there is a straightforward “mechanical” reason why trigger points probably make you weaker.
The smallest functional unit of muscle physiology is the sarcomere, which is like a microscopic muscle: a bundle of overlapping protein fibres that can grab onto each other and pull, like living Velcro that can suck itself together. A muscle is basically several million sarcomeres working in together.3
In a trigger point, the sarcomeres are over-contracted … which means that the sarcomeres up and down the line are, to some extent, over-stretched.4
The over-stretched sarcomeres on either side of a trigger point cannot contract efficiently. Their fibres, barely overlapping, cannot get a “grip” on each other. It’s like trying to start a car in third gear.
Contracting a muscle with trigger points is like trying to start a car in third gear.
Anyone experienced with weight training knows that it’s harder to start a lift with stretched out muscles. In a muscle with trigger points, it’s like the muscle is always stretched out.
For a much more detailed explanation of how this all works, see Dance of the Sarcomeres.
Danger, Will Robinson!
At the very least, strength training when you have significant trigger points is probably futile. But it can certainly be hazardous as well.
There is also probably an increased risk of muscle strain (tear). This situation tends to result in poorly coordinated muscle contraction, and inappropriate muscles trying to “pinch hit” for the ones you are trying to use. But the most likely consequence is simply that your trigger points will get worse, which can lead to surprisingly intense flare-ups of pain that your trainer, doctor, or even physiotherapist will usually misinterpret.
Disturbances of motor function caused by trigger points include weakness of the involved muscle function, loss of coordination by the involved muscle, and decreased work tolerance of the involved muscle. Weakness and the loss of work tolerance are often interpreted as an indication for increased exercise, but if this is attempted without inactivating the responsible trigger points, the exercise is likely to encourage and further ingrain substitution by other muscles, with further weakening and deconditioning of the involved muscle.
Muscle Pain, by David G Simons, Siegfried Mense and IJ Russell, p214
Trainers simply aren’t aware of trigger point physiology, doctors have been proven by other doctors to be incompetent at physical therapy,5 and physiotherapists, although generally competent rehabilitation coaches, are not well-informed about trigger points specifically.6 I think they probably often misinterpret poor results in strength training as a natural, unavoidable part of the challenge of rehabilitation. This is a daily frustration for me as a therapist.
But there is an alternative!
Endurance training to the rescue
Gentler, more repetitive usage of the muscle is the solution. If you are in pain, mobilizations are even gentler than endurance training, and often more appropriate. But endurance training is simply a terrific way for enthusiastic weight lifters not just to safely continue training, but to actually help to relieve the trigger points and get back to strength training.
Endurance training can actually help to relieve the trigger points so that you can get back to strength training.
The low loads of endurance training simply minimize the risk of aggravating trigger points or tearing muscle, while the high repetitions provide the stimulation that is needed for healing. No tissue can thrive without some stimulation! A good endurance workout creates a significant metabolic demand, which increases circulation more than any massage ever could.7
Injury rehabilitation is all about taking “baby steps.” Understanding endurance training gives you another increment to work with, a way of using the gym without banging your head against a brick wall. Good luck!
Notes
- Which is not to say it doesn’t work, just probably not as well. At least two recent studies have shown that both strength and endurance training exercises may be equally good at resolving chronic neck pain. See Ylinen and Nikander. Return to text.
- Simons et al. Muscle Pain, p216. “EMG studies indicate that in muscles with active trigger points, the muscle starts out fatigued, fatigues more rapidly, and becomes exhausted sooner than do normal muscles.” Return to text.
- Tortora et al. Principles of Anatomy and Physiology. 1996. Return to text.
- Mense et al. Muscle Pain. 2000. Return to text.
Most doctors are well aware that there are serious shortcomings in the medical management of most musculoskeletal problems, especially chronic pain cases. Dr. Jonathon Tomlinson, an instructor at St. Leonards Hospital in Hoxton, explains that “undergraduate training is focused on hospital orthopedics (broken bones and anything else that’s amenable to surgery) or rheumatology (nasty inflammatory diseases) which comprise a minority of the aches/pains/strains and injuries that people actually suffer from.”
Medical researchers have done many studies showing that most doctors do not understand aches and pains or heed expert recommendations. A good recent example is a paper in the Archives of Internal Medicine showing that family doctors frequently ignore guidelines for the care of low back pain — see Williams et al.
More generally, the Journal of Bone and Joint Surgery, and the Journal of the American Osteopathic Association, have both published papers recently showing that physicians simply do not have an adequate understanding of musculoskeletal medicine. In 2002, Freedman et al felt that “It is ... reasonable to conclude that medical school preparation in musculoskeletal medicine is inadequate.” Then again in 2005 in JBJS, Matzkin et al concluded that “training in musculoskeletal medicine is inadequate in both medical school and non-orthopaedic residency training programs.” Most recently, in 2006, Stockard et al wrote “82% of allopathic graduates ... failed to demonstrate basic competency in musculoskeletal medicine.”
Return to text.- Although studied and thoroughly described by doctors and medical researchers, trigger points remain virtually unknown to front line practitioners in all fields, especially GPs (see Simons’ commentary). Unfortunately, even massage therapists, who usually at least know about trigger points, still tend to underestimate their clinical importance. Return to text.
- Most massage probably doesn’t increase circulation significantly! The right kind of massage can probably increase it a little, but it’s still nothing compared to what exercise will do. See Wakim. Return to text.
