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!
What’s going on here? Why do strength training workouts sometimes seem to stop working? And how can a switch to endurance training help?
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:
|Mobilize!||25–75||light, very easy|
|Strength Training||6–12||moderate to high|
The trouble with strength training
Strength training may not 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 never 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.
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 controversial, there may be a straightforward reason why trigger points make muscle 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, elongated.4 The contracted ones cannot contract much more, and contraction may be inhibited by discomfort as well. The elongated ones can still contact, but not efficiently. Sacromere contraction depends on the overlap of protein fibres; the less overlapped they are, the less strongly they can get a “grip” on each other. It’s like trying to start a car in third gear. This is why a fully stretched muscle is much weaker.
For a much more detailed explanation of how this all works, see Micro Muscles and the 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 Siegfried Mense, David G Simons, and IJ Russell, p. 214
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.
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!
“Blowing off steam” psychologically is one of the great benefits of endurance training
Of course any kind of exercise can be a fine outlet for frustration. But, assuming you’re healthy enough for it, nothing can beat a hard run when you’re really exasperated by life. Endurance training is the king of venting-by-exercising. Although everyone knows this, the interesting explanation for it is not widely known. It’s actually firmly grounded in biology and science: basically, exercise simulates a reaction to a stressful emergency which then also triggers the relaxation and recovery mode that follows. Robert Sapolsky:
The stress-response is about preparing your body for an explosive burst of energy consumption right now; psychological stress is about doing all the same things to your body for no physical reason whatsoever. Exercise finally provides your body with the outlet that it was preparing for.
~ Why Zebras Don’t Get Ulcers, by Robert M Sapolsky, 255
I think this is one of those really great little “user’s manual” things to understand about our own nature. The biology of stress is all about mobilizing biology resources for intense, life-saving activity, like running like hell from a predator, or (eek) fighting one. The curse of being human is that the same emergency biology can be triggered by abstract concerns, no predators required. But