Gym Hacks: How I Compared Three Fitness Classes Using Self-Tracking Data
This year I decided to “outsource” my gym workout, and instead of experimenting with various workout routines from fitness magazines and blogs, joined my gym’s “Total Body Conditioning” classes. The classes are completely free and are held every Monday, Wednesday, and Friday between 12:30 p.m. and 1:15 pm. Each class is led by a different trainer, and as a result, the routines and pace of the workout considerably vary across the days. For example, on Wednesdays, the focus is more on weights and core training, whereas on Mondays and Fridays it is mostly plyometrics and cardio. Curious to see if classes differ in terms of efficiency, I turned to Bodymedia and my own self-tracking data. Which class burns more calories and brings me closer to my six pack abs? The answer was just a couple of calculations away.
So far I attended three classes on Monday, three classes on Wednesday, and three classes on Friday, and that should be enough data points to make some preliminary evaluations. First, let’s take a look at the objective data collected by Bodymedia. I am particularly interested in number of calories burned, number of steps taken, and minutes of vigorous activity. While dashboard lets you isolate the number of calories burned between any two time points (in our case, between 12:30 pm and 1:15 pm), the number of steps taken and time of vigorous activity are reported on an hourly basis (e.g., total steps taken between 1pm and 2pm).
To make all three metrics comparable, I looked at the Bodymedia data collected between 12 p.m. and 2 p.m. on the days of workout. Since the distance between my office and gym is always the same, and I leave for gym and come back approximately at the same time, and my office routine right before and after the gym is the same, I can safely assume that any differences in the number of calories burned, steps taken, or minutes of vigorous activity can be attributed to the workout.
Finally, in addition to objective data from Bodymedia, I also have some subjective metrics. After each workout, I use a 10-point version of the Rated Perceived Exertion (RPE) scale to rate the intensity of my workout.
This is how the average numbers look like when you compare all three classes:
As you can see, the caloric expenditure chart suggests that I burn approximately the same number of calories during any of three classes, and my subjective exertion ratings (RPE) are relatively the same, too. The steps chart confirms my observations that on Wednesdays, workout involves less jumping and hopping: I take on average 500 less “steps” during Wednesday classes. Perhaps because of that Bodymedia also counts Wednesday routines as less vigorous. Based on these findings, I conclude that it is worth to continue attending all three classes.
If I had Amiigo, I would probably be able to parse out the contribution of different exercises to the total calorie burn, and see in detail the differences in exercise routines across all three classes. I may get it, after all, to complement my Bodymedia data.
I also always wanted to see how accurately can I predict the amount of calories burned based on my subjective perception of workout intensity. In other words, I would like to see if there is a good correlation between RPE and calories burned. Unfortunately, there is not enough data points to conduct this kind of analysis at this point.
PS A week ago I added another data point to my log: my subjective rating of the music “beat” during the class. In other words, I rate on 10-point scale, how well does the music during the class keep me moving. I suspect that there may be some correlation between my feel of the music and performance in the class. The data will show