Yeah, yeah -- I know. A major exercise objective is motivating ourselves to do it, not looking for reasons not to do it. Unless we've picked sports so intrinsically rewarding that staying in shape is icing on the cake, it's vital to make exercise a habit.
Yet even though developing a habit includes repeating it without fail, there are times we should skimp on or even skip a workout altogether, times it might do more harm than good. Fatigue, illness, or injury can be valid reasons to back off, but how do we distinguish valid reasons from flimsy excuses?
Let's start with our favorite excuse, stated in a grating, full-bore whine: "I'm too tired." Sounds simple, but that simple one-liner can have several implications and even an immediate solution. (Remember ... if your exercise were some obsessive sport, you wouldn't get too tired for it in the first place.)
If by tired you mean just ... tired, then at least fill the square. Exercise at half your usual effort or for half the usual time, just to fill the square and reinforce the habit.
Why am I so willing to encourage slacking off on a workout? Because filling the square to develop the habit leads to some of our most vigorous, lengthy, enthusiastic workout sessions. Those first few minutes of rowing, lifting or swimming boost our blood sugar, adrenaline and/or will power, often leading to enjoying a very strenuous session. So if your fatigue is just a funk (more likely a bout of depressed blood sugar), a few strokes or reps or laps often solves that problem in a heartbeat -- or at least a few hundred heartbeats. Worst outcome? You fill the square and reinforce the exercise habit. More likely outcome? You bootstrap yourself into a good, solid workout and fill the square and reinforce the habit -- a win/win/win outcome.
But at some point, fatigue is a valid reason to skimp on, or even skip, a session of play or exercise. Our cue? Diminished performance due to overexercise. If we're really hitting the old machine or iron or track but our performance is backsliding, it's probably time to back off. Skip a day or cut the effort back by 50% for a few days, and see whether your performance returns. If so, you were probably overdoing it or had a bug.
Literally. You might actually be ill, which might be a valid excuse to skip the exercise for a while. What are our criteria for skipping the exercise when we're sick?
Coughing up blood, lack of consciousness, and/or dry heaves come to mind, but I had in mind the ubiquitous, generic but undefined bugs such as flu, cold, cough or "crud" which are less distinctive than, say, amyotrophic lateral sclerosis. Sorry, but nondescript "bugs" don't automatically preclude a beneficial workout. They certainly are not going to keep me from my chosen sports; that's why I chose them (or they chose me). If the mailman can get my junk mail to me, one or another of my sports is doable. If it's doable, it feels better than lying in bed concentrating on my achey, breaky head.
Here's some guidance on whether to back off or gut it out. If your flu, cold or "crud" is primarily above your neck, or if your fever is under a hundred, go play. It's safe and advisable to fill the square, and even a heavy session will do us no harm. But if your cold/flu/crud has descended to your chest, with significant coughing or wheezing, or if your fever hits a hundred, it's time to lay off. By that time our body needs all its energy to fight the invaders. Let it, and you'll be running your course soon after the bug runs its course. (Realize, though, that "stomach flu" is more often food poisoning, so cook the darned burgers better next time.)
Other, more specific, illnesses or diseases? Ask your doctor about exercise with them, but realize that her primary expertise and bias are in treating bugs and boo-boos, not in exercise physiology. If the illness will be prolonged or you have a specific need (as opposed to a compulsion) to exercise, add common sense, research your illness, consult an exercise specialist about exercise with illness (and consider his expertise and bias), and listen to your body. A week or two sans exercise will affect only your habit, not your conditioning, and may -- may -- have you feeling better sooner.
But what about exercise with injury? When do we stop and when do we work or play through it?
First, let me define injury. In this context, I'm referring to any mechanical abnormality, from a broken leg to a knuckle that feels funny. Funny thing is ... the leg presents the simpler dilemma. A serious injury such as that is thoroughly assessed, its treatment and limitations are probably well defined, it lets us know when we do something that harms it, and it commands respect. The doc and the PT staff have already told you how to exercise for and with that level of injury, and probably said that anything that doesn't hurt much is OK. (They may not have told you that strength training one limb measurably strengthens its lateral mate.)
But that hinky finger, or barely perceptible knee or hip twinge you think you feel with each step or stroke ... what the heck do you do or stop doing with that? If on a pain scale of zero to ten the twinge doesn't even rate a wince, we're tempted to ignore it, especially if it hurts no more on the thousandth stroke than it did on the first.
Ahh, but mighty pains from tiny twinges may grow. Twinges can stem from injury or inflammation, or just temporary misalignment of healthy parts. If a joint "feels funny", I'll flex it without load throughout its range, shake it all about, maybe even do the hokey-pokey, and if that resolves the twinge, I'll play or work out normally. That little offending part is back in its nest, doing its job in comfort, as designed.
If the twinge persists after the hokey-pokey, and even if it's more an odd sensation than a pain, I'll pamper it that day. Something's inflamed, or overstressed, or just mad at the world, and is telling me it resents what I'm making it do. It's not worth exacerbating it just to do that particular exercise that particular day. A precautionary day without half-squats beats a month with a sore knee.
I began "skating" on an indoor slide-board (in big woolly socks on a slippery surface with stops at each end so I don't slide out the front door) because it's a great aerobic workout, it really works our quads and back, and it builds great support for our knees. Because I expect protests from any new exercise, I ignored the twinge I thought I felt at the outside top of my femur whenever I thrust my left leg towards my left.
Wrong decision. The bursa at that spot got so inflamed I limped for months and had to give up the skating altogether. The 0.1 twinge blossomed into a 6.0 pain because I blew it off as insignificant. If I had just stopped skating that day and resumed more gently in a couple of days to relieve the twinge, I could have avoided the x-ray, the doctor visits, the pain, the limp, the several months' infirmity, and the propensity for future re-injury.
I realize that "macho" is Spanish for "stupid", but this was not machismo. It was ignorance of how quickly something barely noticeable can become something barely sufferable.
Knowing what causes a twinge or a full-blown pain allows an intelligent assessment of whether it can safely be ignored. Although my abdominal IBS cramps were so painful I'd literally dive to the ground from my mountain bike to curl into the fetal position in self-pity when the cramps overwhelmed the fun, I had fun between the most severe cramps and the exercise helped alleviate the gut problems. Somehow the cramps hurt less when I was having fun than when I was at home or the office.
Distraction is a great analgesic, exercise can be a great healer, and pleasure is a great motivator, if you know when to prescribe each of them. Similarly, exercise can help us tolerate many simple illnesses and even help heal some of them.