You step onto the treadmill and it asks you for your age and weight. After glancing around and covering your fingers (like you’re punching the buttons at the ATM) you’re off! At the end of the session you get a few numbers: how long you spent on the machine, how far away you’d be if you had actually been outside and how many Calories you’ve supposedly used up. I say supposedly because there is virtually no way this number is correct. Here’s why….
To reliably estimate how many Calories your body expends, the machine needs to know many things about you. Incidentally, your age and weight are amongst the least important. It needs to know about your internal workings: how hard your muscles are working and what chemical cycles are being utilized within your muscles. It needs to know how much heat your body is producing. It needs to know how much carbon-dioxide you are exhaling. It needs to know how much of your weight is made up of muscle, how much is fat and how much is bone tissue. It also needs to know where those muscles are within your body. And it should probably be told which fiber types are predominant in the muscles being utilized.
I can imagine what you are saying right now: “Matt, I don’t care if it is really accurate. I just want an idea of how many calories I used up”.
So maybe this is one of those situations where accuracy is not that important to you. But what if your treadmill tells you that the hour you spend running used up 1100 Calories, but you’d actually, maybe, used 400-500. Is that close enough? If you were counting calories and I gave you a sandwich and a label that said it contained “between 400 and 1100 Calories” would you be OK with that? You have to ask yourself how important these numbers are to you.Forget the numbers on those machines. Stop asking your trainer how many Calories you are burning. Don’t walk around with one of those things on your arm supposedly recording your Caloric expenditure. Instead, bike to work, take the stairs, swim at your cottage, walk your dog and work hard when you train. Enjoy the time you spend moving. Think about the gradual adaptations to your muscles, heart and lungs I talked about in the past. Allow them to happen by getting adequate rest between workouts. Numbers are for accountants and statisticians.
This is biology. Your body will adapt to the stresses you expose it to as long as the stresses are not so catastrophic that you break in the process. Don’t fool yourself, if you’re comfortable when you run you need to run faster. If your muscles don’t feel taxed after a weight session you could have done more.
Stress and recover, then repeat. And find someone to do it with. Everything else will fall into place. This is part of a healthy lifestyle.
Please leave questions or comments below!