The math behind exercising – Time spent vs Time gained

By | January 28, 2014

I realize that this is not exactly scientific, but I thought it would be a fun exercise to do the math and see some numbers. From my past experience with the Insanity workout, each workout generally takes 1 to 1.5 hours depending on the exercise. For the purposes of this post, let’s try to be conservative and round that to 1 hour and 2 hours.

Now, if you don’t know anything about the Insanity workout, it’s a 2-month program with a very simple schedule. There are 9 weeks total, each week consisting of 6 exercise days and 1 rest day per week. However, let’s maintain the conservative aspect so that we can account for things like prep, travel, and rest.

So let’s get to the numbers:

Time 1 hr avg 2 hrs avg
1 day 1 hr 2 hrs
1 week 7 hrs 14 hrs
1 month ~28 hrs ~56 hrs
1 year 364 hrs 728 hrs
In days 15.2 days 30.3 days

So what does this all mean? It means that exercising takes up A LOT OF TIME. If you’re consistently working out, you’re spending around 15 to 30 entire days exercising per year, or 4.1% to 8.2%.

Mother of god

Ok then, the next question is: What does that mean in the long term? To answer that, let’s start figuring out what long term means. According to Wikipedia, the average life expectancy of the US is approximately 80 years.

With that in mind, here are the long-term numbers:

Time Starting age 1 hr avg 2 hrs avg
1 year 79 15.2 days (.04 yrs) 30.3 days (.08 yrs)
10 years 70 152 days (.42 yrs) 304 days (.83 yrs)
20 years 60 304 days (.83 yrs) 608 days (1.67 yrs)
30 years 50 456 days (1.25 yrs) 912 days (2.50 yrs)
40 years 40 608 days (1.67 yrs) 1216 days (3.33 yrs)
50 years 30 760 days (2.08 yrs) 1520 days (4.16 yrs)
60 years 20 912 days (2.50 yrs) 1824 days (5.00 yrs)

More big numbers! How did I even read this?

Well, in my particular case, I am nearly 30 years old. That means that I’m looking at the second-to-last row, which is where the Starting Age column is 30. From here, I see that I would spend about 2.08 to 4.16 years exercising over the next 50 years before hitting the age expectancy of 80.

That means that if I live 4.16 years more, then I’m coming out ahead. In other words, if I live more than 84.16 years, then I’m coming out ahead and the exercise was definitely worth it. Mathematically, at least, because time spent > time gained.

Unfortunately, there’s really no way to tell how long I would live (both with and without exercise). Thus one could argue that all this math is moot. Nevertheless, I found it interesting to do the math and see some concrete numbers; it gives me a different way of looking at the benefits of exercise.

So how about you? After looking at the numbers, did you change the way you think about exercise?

Disclaimer: This post is all about the math behind exercising. It does not describe any of the numerous benefits of exercising, which are of course very valuable and will dramatically increase quality of life.

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