So I keep on hearing that if you do the same exercise each week it becomes less and less efficient at burning calories and doing all the stuff you want exercise to do. Thus, if you walk five miles a day every day eventually it will have no or little effect. (Except perhaps on your muscles.)
So is this true? And if its based on your heart rate, ie how knackered you get each time, if you’re really unfit and get knackered each time you exercise – even if its over a long period – won’t it still make a difference?
In a sense this is true. If you weigh 200 lbs you burn about 7 calories a minute doing medium intensity exercise (Walking, mowing, skating, etc.). However as you drop to about 180 lbs, you’re only burning 6 calories a minute for the same exercise.
The benefits of exercise are more than just losing weight. You’ve pointed out the main one… to build stamina. That is the ability to exercise more without getting tired, so that you can ultimately exercise longer and lose more weight continuing the cycle.
According to what my trainer told me, it’s not that you’ll get no benefit from the exercise, it’s just that you could get more benefit if you switch things up.
Your brain is good at learning motor tasks. Over time, it will find more and more efficient ways to perform a certain movement—up to some limit, obviously. If you’re exercising primarily to burn calories, you don’t want to be efficient. You probably want to burn X calories in Y minutes. If you always do the same thing, then you’ll grow more efficient and burn fewer calories when exercising the same amount of time. You’ll still be burning more calories than if you were sitting on the couch, of course, but fewer calories than when you first started doing this type of exercise.
On the other hand, if you’re doing different things, such as varying your speed, changing your route (so that you’re going through a different pattern of elevations), or doing a different type of exercise once in a while, you’ll be burning more calories in a given amount of time.
Incidentally, this applies both to doing the same workout every day, and also to doing the same thing throughout you workout. You’ll burn fewer calories if you run for ten mintunes and then walk for ten minutes than if you spend 20 minutes alternating between 1 minute running and 1 minute walking. If you keep changing the motions that you’re doing, your body has a harder time settling into that efficient groove.
I’m not sure what effect this has on building muscle and improving cardiovascular fitness but I imagine if your body is working harder, less efficiently, then you’re just getting a better workout overall.
In terms of cardiovascular benefits, it could well be true. If your goal is revving your heart up to 130 beats per minute for 20 minutes three times a day, it will take a certain level of exertion to get it done. As you get into better shape, that same activity may only take you to 120 beats per minute. So, you’ll have to work harder to get the same result.
I hate chiming in with just anecdotal stuff, but what you describe seems common.
I used to run a route that I became so accustomed to that I would feel my heart rate rick up a little BEFORE I’d get to a particular hill. I could run flatter profiles over the same distance that were more difficult for me.
IMHO, the best way to mix it up (and get faster. . .running, biking or swimming) is to throw in some intervals. Do some “wind sprints” to get that heart rate jacked up. No matter what you do, you’ll never get too efficient at intervals.
Even when doing interval training, there’ll come a point when you no longer get ‘fitter’ (faster, in the case of running) - regardless of what you do. If this were not so, we’d all be able to run 4 second miles…
However, regarding the OP, if you run 5 miles, that will always require a significant amount of calories, and you will never reduce this requirement greatly. That’s a bit different to a training effect, though. So:
If you do a given exercise, it will always require energy.
If you repeatedly do a given exercise in the hope of becoming fitter, the exercise will not make you get fitter indefinitely.